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The biomechanics of vertebroplasty in multiple myeloma and metastatic bladder cancer: A preliminary cadaveric investigation - Laboratory investigation
Abstract
The vertebral column is the most common site for secondary bone metastases and lesions arising from hematological malignancies such as multiple myeloma (MM). These infiltrations can be lytic in nature and cause severe weakening of the vertebral body, an increased risk of fracture, and spinal cord compression leading to neurological deficit. Qualitatively it is apparent that increasing infiltration of these lytic lesions will have a deleterious effect on the mechanical behavior of the vertebrae. However, there is little quantitative information about the relationship between tumor deposits and the impact on the mechanical behavior of the vertebrae. In addition, there have been limited biomechanical assessments of the use of vertebroplasty in the management of these malignancies. The purpose of this preliminary study was to evaluate the mechanical behavior of lesion-infiltrated vertebrae from 2 malignant cancers and to investigate the effectiveness of vertebroplasty with and without tumor debulking.
Individual vertebrae from 2 donor spines--one with MM and another with bone metastases secondary to bladder cancer-were fractured under an eccentric flexion load, from which failure strength and stiffness were derived. Alternate vertebrae defined by spinal level were assigned to 2 groups: Group 1 involved removal of lesion material with Coblation (ArthroCare Corp.) preceding vertebroplasty; Group 2 received no Coblation prior to augmentation. All vertebrae were fractured postaugmentation under the same loading protocol. Micro-CT assessments were undertaken to investigate vertebral morphology, fracture patterns, and cement distribution.
Multiple myeloma involvement was characterized by several small lesions, severe bone degradation, and multiple areas of vertebral shell compromise. In contrast, large focal lesions were present in the vertebrae with metastatic bladder cancer, and the shell generally remained intact. The mean initial failure strength of the vertebrae with metastases secondary to MM was significantly lower than in vertebrae with bone metastases secondary to bladder cancer (Load = 950 +/- 300 N vs 2200 +/- 750 N, p < 0.0001). A significant improvement in relative fracture strength was found postaugmentation for both lesion types (1.4 +/- 0.5, p < 0.001). Coblation provided a marginally significant increase in the same parameter postaugmentation (p = 0.08) and qualitatively improved the ease of injection and guidance of cement.
In the vertebral column, metastatic lesions secondary to bladder cancer and MM showed variations in the pattern of infiltration, both of which led to significant reductions in fracture strength. Account should be taken of these differences to optimize the vertebroplasty intervention in terms of the cement formulation, delivery, and any additional surgical procedure.
... Kostní postižení ve formě osteolytických lézí nebo osteoporózy je přítomno u 70-80 % nemocných s MM, bolest zad a postižení páteře nereagující na běžnou analgetickou léčbu ve 40-50 % případů [1]. MM je tedy primární a systémové hematologické nádorové onemocnění postihující především páteř [2]. ...
... Naopak u sekundárních páteřních nádorů je operace prováděna spíše výjimečně, ale vzhledem k dobré prognóze se právě MM stává smysluplnou indikací k chirurgické léčbě. Navíc máme v léčbě osteolyticky se chovajících MM, na rozdíl od většiny ostatních páteřních tumorů, možnost miniinvazivního ošetření na úseku hrudní a bederní páteře pomocí vertebroplastiky nebo kyfoplastiky [2,15]. ...
The management of spinal multiple myeloma (MM) is a complex process, including causal treatment (i.e. efforts to suppress the tumor clone), as well as supportive therapy, including surgery. The aim of this article is to present retrospective evaluation of surgical indications in patients with MM or solitary spinal plasmocytoma.
A total of 10 patients (8 males and 2 females) aged from 32 to 74 years (the mean age of 53.3) were included in the study. The enrolment criteria were the following: patients operated for MM or solitary spinal plasmocytoma during the past 7-year period, with the minimum follow up period of 6 months. The procedures were indicated for progressing neurological deficit (Frankel score) and for axial spinal pain (VAS classification), not responding to conservative therapy. The extent of the disease was assessed based on plain x-ray, MRI and whole- body 18F-FDG PET/CT. Paliative vertebroplasty was indicated in patients with no neurological deficit to control pain, paliative laminectomy without stabilization in subjects with partial neurological lesions, with transpedicular fixation in concomitant pathological fractures or kyphotizations. More radical approach, i.e. the procedure included somatectomy, was indicated in patients with solitary plasmocytoma and in procedures on cervical or thoracolumbar regions. Control clinical and MRI examinations were performed at 6 weeks, at 6 months and then at yearly intervals. At the end of the study, the authors evaluated effectivity of the employed surgical procedures, based on all control findings, and the data were compared with prognostic scoring systems in surgery for spinal metastases (Tomita score, Tokuhashi modified score and Bauer score).
No local relapses of the tumor or stabilization failure were detected. The effect of surgery on pain control and on prevention of neurological dysfunction was maintained over the follow up period. The authors concluded that all surgical procedures and their radicality were adequate in all subjects. The agreement between the authors approach (the procedure's radicality) and the Tomita score, the Tokuhashi modified score and the Bauer score were recorded in 50% of patients, 80% of patients and in 50% of patients, respectively.
MM is characterized by increased oseteolysis, which is not followed by new bone formation. Despite successful conservative therapy of MM, the bone defects fail to heal, cause spinal pain and may result in spinal instability. These specific MM signs represent the principal factor in the decision- making process concerning indication for surgery. Furthermore, favourable prognosis, with survival times usually exceeding the required expected minimum survival time of 3-6 months, is yet another reason for indication for surgical therapy in patients with spinal MM. Due to advances in chemotherapy and the use of autologic grafts of peripheral stem cells and radiotherapy, the prognosis of patients have significantly improved in last 10 years. The mean survival time has increased from 2.5 years to 4.5 years.
1. Prevention or improvement of neurological dysfuction and pain control are the main indication criteria for surgery in MM. 2. Surgery should be considered in MM with osteolytic spinal disorder and because of favourable prognosis of the disease when surgery is used. 3. Surgical procedures, including paliative methods resulted in sufficient control of spinal stability in all the study subjects. 4. Using all scoring systems for spinal metastases could result in indications for unnecessary more radical procedures. However, Tokuhashi score appeared to be the most suitable existing prognostic scoring system.
... However, no data exist on the real risk of dorsal leakage and on related complications. This study, in order to have a homogeneous population, focused on high risk vertebral lesions with dorsal wall osteolysis or fracture related to MM (a primary osteolytic cancer of the vertebral body) because of its particular pathophysiologic and morphologic mechanisms [4] . The vertebral column is the most common site for secondary bone metastases and lesions arising from hematological malignancies such as MM. ...
... The vertebral column is the most common site for secondary bone metastases and lesions arising from hematological malignancies such as MM. Cadaveric studies show that MM spinal involvement is characterized by several small lesions, severe bone degradation, and multiple areas of vertebral shell compromise [4]. In patients with MM, vertebroplasty has been reported to provide significant and long-lasting pain relief for patients with intractable spinal pain caused by compression fractures resulting from MM [5]. ...
The goal of this study was to specifically address the incidence of dorsal leakage when performing vertebroplasty in patients with posterior wall osteolysis or fracture, by using a delayed injection of cement with the aim of increasing its viscosity.
We prospectively reviewed the records of 24 patients (13 women, 11 men; age range 42-67 years; mean age 54.7) with diagnosis of multiple myeloma (MM) who underwent 34 vertebroplasties between January 2007 and January 2010 for painful osteolytic localization of MM with dorsal cortical osteolysis or fracture. All vertebroplasties were performed with an 8 min delay, which was half of the allotted injecting time given for the chosen cement. In 11 cases there were fractures involving the posterior wall, in 1 case with dorsal fragment dislocation, and in 33 cases there was dorsal cortical osteolysis. All of the patients showed no response to standard treatments such as radiotherapy, chemotherapy, and analgesic treatments.
Technical success was achieved in all cases. In 20 patients, we treated only one high-risk vertebral lesion, in six patients we treated two segments, and in one patient we treated three segments. All patients experienced improvement in symptoms after the procedure as demonstrated by improved visual analogue scores (VAS) and performance status (PS) and decreased doses of analgesic. There was a dorsal leakage in 2/34 (5.8%) treated vertebral bodies in which an epidural space tumor extension was also diagnosed, without increasing neurological symptoms after the intervention.
From these results vertebroplasty with delayed injection of cement is safe and effective in the treatment of vertebral localization of myeloma with osteolysis or fracture of the posterior vertebral wall.
... The augmented vertebrae were also found to increase forces exerted on the endplate of adjacent vertebrae in the osteoporotic model though, suggesting that vertebroplasty may increase the risk of adjacent segment breakdown in those with osteoporotic spines. Studies in cadaveric spine have echoed these results [136,137], and other computerized models have suggested that posterior placement of the cement within the vertebral body decreases the risk of burst fracture [138]. ...
Spinal metastases are the most common type of vertebral column tumor, affecting up to 70% of all patients with neoplastic disease. Though seldom the primary determinant of survival, these lesions are clinically important for the mass effect they exert on a patient’s neural elements as well as the mechanical instability they generate within affected vertebrae. Osteolytic lesions are of particular concern as they significantly decrease axial loading strength of the vertebral column, increasing the risk of fracture and subsequent deformity. Diagnosis of deformity is made using computed tomography imaging, which can also be used for surgical planning in patients indicated for operative management. Other interventions include prophylaxis against vertebral collapse using a combination of vertebral body cement augmentation and administration of anti-osteolytic agents, such as bisphosphonates and denosumab. In this chapter, we provide an overview of the biomechanics of the metastatic spine, give background on the pathophysiology of osteolysis in metastatic segments, and outline the therapeutic interventions for those with spinal deformity or mechanical instability in the context of disseminated cancer.
... However, its application in the treatment of multiple thoracic metastases has never been reported. Metastasis destroys the vertebral body by causing micro-fractures and compression fractures, resulting in spinal instability (13). The nerve endings inside and outside the vertebral body are stimulated and damaged, which is the most common reason for thoracolumbar and back pain (14,15). ...
The present study aimed to explore the clinical implications of percutaneous vertebroplasty (PVP) in the treatment of multiple thoracic metastases. A total of 104 involved vertebrae of 28 patients with multiple thoracic metastases underwent PVP and the injection of bone cement. The pain relief rate and activity of daily life were assessed, and the morphological changes of the involved vertebral bodies and the invasiveness of the intraspinal tumor were also observed at 1 week, and 3, 6 and 12 months post-surgery, respectively. The pain relief rate increased at each time-point following PVP. The quality of life scores were also significantly higher than the pre-operative scores. After 12 months of follow-up, the post-operative heights of the anterior border, center and posterior border of the vertebral bodies were not noted to be statistically different from those prior to PVP (P>0.05). The present study concluded that PVP has a good analgesic effect on multiple thoracic metastases. PVP not only improves the quality of life of patients significantly, but also prevents further vertebral collapse and the invasiveness of intraspinal tumors, avoiding the nerve dysfunction caused by spinal cord compression.
... Measurements of bone density (BMD) for the L1 -L4 levels, combined (mean and standard deviation) value of 0.42 (0.13)g/cm 2 , indicated that these spines were osteoporotic (Lewiecki, 2005;Melton et al., 2005). These values are within the range reported for human vertebrae with lytic metastasis (Oakland et al., 2008). They reflect the low BMD values common in postmenopausal women with hormone receptor-positive breast cancer patients who have undergone treatment using aromatase inhibitors (Bruning et al., 1990;Maxwell and Viale, 2005). ...
Background:
Pathologic vertebral fractures are associated with intractable pain, loss of function and high morbidity in patients with metastatic spine disease. However, the failure mechanisms of vertebrae with lytic defects and the failed vertebrae's ability to retain load carrying capacity remain unclear.
Methods:
Eighteen human thoracic and lumbar vertebrae with simulated uncontained bone defects were tested under compression-bending loads to failure. Failure was defined as 50% reduction in vertebral body height. The vertebrae were allowed to recover under load and re-tested to failure using the initial criteria. Repeated measure ANOVA was used to test for changes in strength and stiffness parameters.
Findings:
Vertebral failure occurred via buckling and fracture of the cortex around the defect, followed by collapse of the defect region. Compared to the intact vertebrae, the failed vertebrae exhibited a significant loss in compressive strength (59%, p<0.001), stiffness (53%, p<0.05) and flexion (70%, p<0.01) strength. Significant reduction in anterior-posterior shear (strength (63%, p<0.01) and stiffness (67%, p<0.01)) and lateral bending strength (134%, p<0.05) were similarly recorded. In the intact vertebrae, apart from flexion strength (r(2)=0.63), both compressive and anterior-posterior shear strengths were weakly correlated with their stiffness parameters (r(2)=0.24 and r(2)=0.31). By contrast, in the failed vertebrae, these parameters were strongly correlated, (r(2)=0.91, r(2)=0.86, and r(2)=0.92, p<0.001 respectively).
Interpretation:
Failure of the vertebral cortex at the defect site dominated the initiation and progression of vertebral failure with the vertebrae failing via a consolidation process of the vertebral bone. Once failed, the vertebrae showed remarkable loss of load carrying capacity.
... As for the prophylactic use of VP, there is some argument in case of osteoporosis. [41][42][43] However, prophylactic cement augmentation of vertebral body with metastatic lesion without fracture is worthwhile to relieve axial pain and improve the patient's quality of life. ...
Impending spinal cord compression and vertebral fractures are considered contraindications for radionuclide bone pain palliation therapy. However, most of the patients with widespread bone metastases already have weakened vertebral segments that may be broken. Therefore, local field external-beam radiotherapy or percutaneous vertebroplasty (VP) should be considered to improve the patient's quality of life and to institute subsequent appropriate treatment, including radionuclide therapy for bone pain palliation. The objective of this study was to develop a strategy for an effective treatment of bone metastases in patients with widespread bone metastases and intolerable pain, associated with impending cord compression or vertebral fractures. Eleven patients (5 females and 6 males, aged 32-62 years; mean age 53.8 ± 2.7 years) with multiple skeletal metastases from carcinomas of prostate (n = 3), breast (n = 3) and lung (n = 5) were studied. Their mean pain score measured on a visual analogue scale of 10 was found to be 8.64 ± 0.15 (range 8-9) and the mean number of levels with impending cord compression or vertebral fracture was 2.64 ± 0.34 (range 1-4). All patients underwent vertebroplasty and after 3-7 days received Sm-153 ethylene diamine tetra methylene phosphonic acid (EDTMP) therapy. Sm-153 EDTMP was administered according to the recommended standard bone palliation dose of 37 MBq/kg body weight. Whole body (WB) bone scan, computed tomography and magnetic resonance imaging (MRI) were performed before and after treatment in all patients. Pain relief due to stabilization of vertebrae after VP occurred within the first 12 hours (mean 4.8 ± 1.2 hours; range 0.5-12 hours), and the mean pain score was reduced to 4.36 ± 0.39 (range 2-6). Subsequent to Sm-153 EDTMP treatment, further pain relief occurred after 3.91 ± 0.39 days (range 2-6 days) and the pain score decreased to 0.55 ± 0.21 (range 0-2). The responses to treatment were found to be statistically significant (P < 0.0001). Based on the results on this limited patient population, we conclude that spinal stabilization using VP in patients with widespread bone metastases and impending cord compression is an effective way to decrease disability with pain and to facilitate subsequent systemic palliation of painful skeletal metastases by Sm-153 EDTMP therapy.
... A commonly presented theory is that vertebroplasty increases the mechanical load threshold for fracture and stabilizes the vertebra [23]. This, however, cannot explain why the analgesic effect is not signi cantly affected by the volume of PMMA used or by a speci c injection protocol [24,25]. ...
Percutaneous vertebroplasty is the injection of bone cement, usually polymethylmethacrylate into the vertebral body. This procedure is most often performed in a percutaneous fashion on an outpatient (or short-stay) basis. Among other indications, the procedure is designated for painful vertebral compression fractures due to primary or metastatic spinal tumors. Published literature favors the use of this procedure in cancer pain management. The overall risk of the procedure is low, although serious complications (including spinal cord compression) can occur. Recent advances in technique and materials may reduce the incidence of adverse outcomes. Proper patient selection and meticulous technique are required to achieve best results and to avoid complications.
spine, bone metastasis, radiofrequency ablation, interventional radiology
Metastatic bone tumors can replace and compress normal healthy tissue, causing structural instability, elicit pain, and cause fractures which often require treatment. Treatment has historically focused on radiation, medical, and surgical options with interventional therapies providing a limited role. Interventional therapies, however, continue to evolve providing additional treatment options such as vertebroplasty, kyphoplasty, radiofrequency ablation, and cryoablation for metastatic bone malignancies, particularly for treatment of spinal tumors and their associated pathologies. These interventional therapies can provide alternate or complimentary therapies for patients in the appropriate clinical setting. This chapter provides an overview of these interventional treatment options and discusses some of the more recent developments in this rapidly growing field.
Multiple myeloma (MM) and solitary plasmacytoma (SP) are the most frequent primary tumors of the spine. Management of the spinal MM and SP is a complex process involving causal treatment to suppress the tumor clone, as well as supportive therapy, including surgery and radiotherapy. Surgery should be considered because of its favourable effect on disease prognosis. We proposed a surgical treatment algorithm in patients with spinal MM and SP and the aim of this article is to present prospective evaluation of this algorithm. Patients undergoing surgical treatment during the past 10 years were included in this study, with the minimum follow-up of one year. A total of 32 patients (20 males and 12 females) with the mean age of 61 years were included. Surgery of 61 vertebrae was performed. The procedures were indicated for progressing neurological deficit (Frankel score) and for axial spinal pain (VAS classification). We performed the following procedures: vertebroplasty, laminectomy, transpedicular fixation, somatectomy, and their combination, or occipito-cervical fixation. Frankel score and VAS was assessed one year after the surgery and X-ray and spinal MRI was performed every year. No local relapses of the tumor or stabilization failure were detected. The mean preoperative VAS was 6.8 and improved to 1.1 one year after the surgery. During the follow up period, we observed positive effect of surgery on pain control and on prevention or improvement of neurological dysfunction. The authors concluded that all surgical procedures, the extent of resection and timing were adequate in all subjects.
Lytic spinal lesions reduce vertebral strength and may result in their fracture. Vertebral augmentation is employed clinically to provide mechanical stability and pain relief for vertebrae with lytic lesions. However, little is known about its efficacy in strengthening fractured vertebrae containing lytic metastasis.
Eighteen unembalmed human lumbar vertebrae, having simulated uncontained lytic defects and tested to failure in a prior study, were augmented using a transpedicular approach and re-tested to failure using a wedge fracture model. Axial and moment based strength and stiffness parameters were used to quantify the effect of augmentation on the structural response of the failed vertebrae. Effects of cement volume, bone mineral density and vertebral geometry on the change in structural response were investigated.
Augmentation increased the failed lytic vertebral strength [compression: 85% (P<0.001), flexion: 80% (P<0.001), anterior-posterior shear: 95%, P<0.001)] and stiffness [(40% (P<0.05), 53% (P<0.05), 45% (P<0.05)]. Cement volume correlated with the compressive strength (r(2)=0.47, P<0.05) and anterior-posterior shear strength (r(2)=0.52, P<0.05) and stiffness (r(2)=0.45, P<0.05). Neither the geometry of the failed vertebrae nor its pre-fracture bone mineral density correlated with the volume of cement.
Vertebral augmentation is effective in bolstering the failed lytic vertebrae compressive and axial structural competence, showing strength estimates up to 50-90% of historical values of osteoporotic vertebrae without lytic defects. This modest increase suggests that lytic vertebrae undergo a high degree of structural damage at failure, with strength only partially restored by vertebral augmentation. The positive effect of cement volume is self-limiting due to extravasation.
Copyright © 2015. Published by Elsevier Ltd.
The aim of this study was to identify potential risk factors for and determine the rate of vertebral compression fracture (VCF) after intensity-modulated, near-simultaneous, CT image-guided stereotactic body radiotherapy (SBRT) for spinal metastases.
The study group consisted of 123 vertebral bodies (VBs) in 93 patients enrolled in prospective protocols for metastatic disease. Data from these patients were retrospectively analyzed. Stereotactic body radiotherapy consisted of 1, 3, or 5 fractions for overall median doses of 18, 27, and 30 Gy, respectively. Magnetic resonance imaging studies, obtained at baseline and at each follow-up, were evaluated for VCFs, tumor involvement, and radiographic progression. Self-reported average pain levels were scored based on the 11-point (0-10) Brief Pain Inventory both at baseline and at follow-up. Obesity was defined as a body mass index ≥ 30.
The median imaging follow-up was 14.9 months (range 1-71 months). Twenty-five new or progressing fractures (20%) were identified, and the median time to progression was 3 months after SBRT. The most common histologies included renal cancer (36 VBs, 10 fractures, 10 tumor progressions), breast cancer (20 VBs, 0 fractures, 5 tumor progressions), thyroid cancer (14 VBs, 1 fracture, 2 tumor progressions), non-small cell lung cancer (13 VBs, 3 fractures, 3 tumor progressions), and sarcoma (9 VBs, 2 fractures, 2 tumor progressions). Fifteen VBs were treated with kyphoplasty or vertebroplasty after SBRT, with 5 procedures done for preexisting VCFs. Tumor progression was noted in 32 locations (26%) with 5 months' median time to progression. At the time of noted fracture progression there was a trend toward higher average pain scores but no significant change in the median value. Univariate logistic regression showed that an age > 55 years (HR 6.05, 95% CI 2.1-17.47), a preexisting fracture (HR 5.05, 95% CI 1.94-13.16), baseline pain and narcotic use before SBRT (pain: HR 1.31, 95% CI 1.06-1.62; narcotic: HR 2.98, 95% CI 1.17-7.56) and after SBRT (pain: HR 1.34, 95% CI 1.06-1.70; narcotic: HR 3.63, 95% CI 1.41-9.29) were statistically significant predictors of fracture progression. On multivariate analysis an age > 55 years (HR 10.66, 95% CI 2.81-40.36), a preexisting fracture (HR 9.17, 95% CI 2.31-36.43), and baseline pain (HR 1.41, 95% CI 1.05-1.9) were found to be significant risks, whereas obesity (HR 0.02, 95% CI 0-0.2) was protective.
Stereotactic body radiotherapy is associated with a significant risk (20%) of VCF. Risk factors for VCF include an age > 55 years, a preexisting fracture, and baseline pain. These risk factors may aid in the selection of which spinal SBRT patients should be considered for prophylactic vertebral stabilization or augmentation procedures. Clinical trial registration no.: NCT00508443.
Improvements in diagnosis and treatment have prolonged cancer survival, with a consequent increase in the incidence of spinal metastases and vertebral compression fractures with associated axial pain, progressive radiculomyelopathy, and mechanical instability. Pain relief in malignant vertebral compression fractures is key to achieving a better quality of life in patients under palliative care. The gold standard for pain relief is nonsteroidal anti-inflammatory drugs and opioids. Nonresponsive cases are then treated with radiotherapy, which may require 2-4 weeks to take effect and in most cases does not provide complete pain relief. Percutaneous vertebroplasty and percutaneous kyphoplasty can in particular give relief in patients with vertebral body compression fractures that do not cause neurological deficits but severely compromise quality of life because of intractable pain.
Developed for benign conditions including osteoporotic fractures and haemangiomas, vertebroplasty has since been employed in neoplastic lesions, including myeloma. Advances in myeloma treatments, yielding improved survival times, have led to an increasing need for effective therapies that improve quality of life. The first randomised trials of vertebroplasty to treat painful osteoporotic crush fractures have cast doubt of its benefit over a placebo procedure, with a proposed rationale that fracture healing over time may account for the non-superiority of the results. However, these findings cannot be extrapolated to myeloma where the pathology is one of progressive bony destruction coupled with failure of new bone formation. In this paper, we present the outcome data for myeloma patients treated at our tertiary referral centre over a 5-year period, focusing on both subjective and objective measures of efficacy and safety. Records were reviewed to extract pain score, function and analgesia pre/post-procedure. Where possible, patients were then contacted directly and asked to assess their benefit by grading change in pain score, analgesia use and mobility. Performance status was assessed using the Eastern Cooperative Oncology Group scale. Of the 26 patients treated for painful thoraco-lumbar lesions, 77% reported improved pain score (P < 0.003). Analgesia reduction, better mobility and improved performance status were also seen. Our data support the consideration of vertebroplasty as a first-line treatment for painful myelomatous vertebral disease. Prospective randomised studies are now required to further define its role.
Combining percutaneous plasma-mediated radio-frequency (pmRF) ablation with vertebral body augmentation offers an alternative treatment to surgical intervention options for advanced metastatic spinal lesions and is particularly useful for cases with cortical destruction and/or epidural extension. This study evaluates bone cement deposition patterns and extravasation in treated vertebral bodies in relation to the metastatic lesion after using this combined approach.
Retrospective assessments of CT images performed before/after the procedures were evaluated in 37 patients (44 levels) with advanced metastatic lesions. A void was created in the anterior portion of the tumor-infiltrated vertebral body by using a bipolar plasma-mediated radio-frequency-based wand, followed by deposition of bone cement. Pain measured by visual analog scale score was recorded preprocedure and 2-4 weeks afterward.
In 19 (43%) levels, 90%-100% of the cement was deposited in the anterior two thirds of the vertebral body. In 34 levels (77%), 75% or more of the cement was deposited in the anterior two thirds of the vertebral body. In 13/15 (86%) levels with posterior lesions, cement was deposited anterior to the lesion. No extravasation was observed in 13 levels (29.5%). Two clinically insignificant incidences of epidural extravasation were noted. Pain relief after the procedure was reported by 25/28 (89.5%) patients with available data.
pmRF ablation may allow greater cement-deposition control, increasing the likelihood of successfully stabilizing the anterior two thirds of the vertebral body. This combined technique appeared particularly useful in cases with posteriorly located lesions. The incidence of cement extravasation was relatively high but clinically insignificant.
Indications for operative treatment in spinal metastatic disease depend on estimates of vertebral loadbearing capacity. There are no noninvasive diagnostic tools for estimating vertebral loadbearing capacity in the presence of a metastatic lesion. Thus, relationships between vertebral failure load and measurements from computed tomography data were investigated to determine if measurements that account for defect size and bone density can predict loadbearing capacity better than can defect size alone. Cylindrical defects were created in thoracic vertebrae of 20 anatomic specimen spinal segments, with 10 other segments serving as controls. Five vertebrae with actual metastatic defects also were tested. Vertebrae were scanned using quantitative computed tomography, and the defect size and the axial rigidity of the midvertebral cross section were calculated using an image analysis program. The spinal segments were tested to failure using a combination of axial compression and anterior flexion. Linear regressions between axial rigidity and absolute failure load showed a high positive correlation, but there was no correlation between defect size and failure load. Axial rigidity may prove useful as a noninvasive assessment of vertebral loadbearing capacity in patients with spinal metastatic disease.
(C) Lippincott-Raven Publishers.
Recent clinical trials have reported favorable early results for transpedicular vertebral cement reinforcement of osteoporotic vertebral insufficiencies. There is, however, a lack of basic data on the application, safety and biomechanical efficacy of materials such as polymethyl-methacrylate (PMMA) and calciumphospate (CaP) cements. The present study analyzed 33 vertebral pairs from five human cadaver spines. Thirty-nine vertebrae were osteoporotic (bone mineral density < 0.75 g/cm2), 27 showed nearly normal values. The cranial vertebra of each pair was augmented with either PMMA (Palacos E-Flow) or experimental brushite cement (EBC), with the caudal vertebra as a control. PMMA and EBC were easy to inject, and vertebral fillings of 20-50% were achieved. The maximal possible filling was inversely correlated to the bone mineral density (BMD) values. Cement extrusion into the spinal canal was observed in 12% of cases. All specimens were subjected to axial compression tests in a displacement-controlled mode. From load-displacement curves, the stiffness, S, and the maximal force before failure, Fmax, were determined. Compared with the native control vertebrae, a statistically significant increase in vertebral stiffness and Fmax was observed by the augmentation. With PMMA the stiffness increased by 174% (P = 0.018) and Fmax by 195% (P = 0.001); the corresponding augmentation with EBC was 120% (P = 0.03) and 113% (P = 0.002). The lower the initial BMD, the more pronounced was the augmentation effect. Both PMMA and EBC augmentation reliably and significantly raised the stiffness and maximal tolerable force until failure in osteoporotic vertebral bodies. In non-porotic specimens, no significant increase was achieved.
Little is known about the mechanical stabilization afforded by new materials proposed for use with vertebroplasty. This comparative ex vivo biomechanical study was designed to determine the strength and stiffness of osteoporotic vertebral bodies (VBs) subjected to compression fractures and stabilized with bipedicular injections of Cranioplastic altered in a manner consistent with the practice of vertebroplasty or BoneSource cement.
VBs T8-T10 and L2-L4 from 10 fresh spines were harvested from female cadavers (aged 91.5 years +/- 3.9 at death). These were screened for bone density (t score, -4.9 +/- 1.4; bone mineral density, 0.61 g/cm(2) +/- 0.19), disarticulated, and compressed to determine initial strength and stiffness. The fractured VBs were stabilized with bipedicular injections of a predetermined quantity and type of cement and then re-crushed.
At both the thoracic and lumbar levels, VBs repaired with altered Cranioplastic resulted in significantly greater strength (P <.05) than that in their prefracture states, whereas those repaired with BoneSource were restored to their initial strength. Cranioplastic resulted in significantly stronger repairs than BoneSource in the thoracic region; however, repair strengths in the lumbar region were not significantly different. The repaired stiffness was significantly lower than the initial stiffness in all treatments and in both regions. Differences in the repaired stiffness between the treatment groups in either region and differences in the mechanical parameters obtained by adding an additional 2 mL of BoneSource were not significant.
Both materials in the volumes used either restored or increased VB strength, but none restored stiffness.
The current North American experience with minimally invasive vertebro- and kyphoplasty is largely limited to the treatment of benign osteoporotic compression fractures. The objective of this study was to assess the safety and efficacy of these procedures for painful vertebral body (VB) fractures in cancer patients.
The authors reviewed a consecutive group of cancer patients (21 with myeloma and 35 with other primary malignancies) undergoing vertebro- and kyphoplasty at their institution. Ninety-seven (65 vertebro- and 32 kyphoplasty) procedures were performed in 56 patients during 58 treatment sessions. The mean patient age was 62 years (+/- 13 years [standard deviation]) and the median duration of symptoms was 3.2 months. All patients suffered intractable spinal pain secondary to VB fractures. Patients noted marked or complete pain relief after 49 procedures (84%), and no change after five procedures (9%); early postoperative Visual Analog Scale (VAS) pain scores were unavailable in four patients (7%). No patient was worse after treatment. Reductions in VAS pain scores remained significant up to 1 year (p = 0.02, Wilcoxon signed-rank test). Analgesic consumption was reduced at 1 month (p = 0.03, Wilcoxon signed-rank test). Median follow-up length was 4.5 months (range 1 day-19.7 months). Asymptomatic cement leakage occurred during vertebroplasty at six (9.2%) of 65 levels; no cement extravasation was seen during kyphoplasty. There were no deaths or complications related to the procedures. The mean percentage of restored VB height by kyphoplasty was 42 +/- 21%.
Percutaneous vertebro- and kyphoplasty provided significant pain relief in a high percentage of patients, and this appeared durable over time. The absence of cement leakage-related complications may reflect the use of 1) high-viscosity cement; 2) kyphoplasty in selected cases; and 3) relatively small volume injection. Precise indications for these techniques are evolving; however, they are safe and feasible in well-selected patients with refractory spinal pain due to myeloma bone disease or metastases.
Whether vertebroplasty increases the risk of adjacent-level vertebral fractures remains uncertain. Biomechanical and clinical studies suggest an increased risk, but compelling data have not yet been put forth to settle this difficult issue. We believe that an analysis of the time interval between vertebroplasty and subsequent fractures may shed additional light on this debate. We specifically hypothesized that subsequent fractures would occur sooner and more frequently in the vertebrae adjacent to the treated level.
We performed a retrospective analysis of the risk and timing of subsequent fractures in patients previously treated with vertebroplasty. Multiple linear regression was used to explore factors that influence the time to new fracture following vertebroplasty. Fractures were then divided on the basis of whether they occurred adjacent or non-adjacent to the treated level. Survival analysis was used to compare time to new fracture among the 2 groups, and the relative risk of both types of fracture was calculated.
In this study, 186 new vertebral fractures occurred in 86 (19.9%) of 432 patients. Seventy-seven (41.4%) fractures were of vertebrae adjacent to the level treated with vertebroplasty. Median times until diagnosis of new adjacent and non-adjacent level fractures were 55 days and 127 days, respectively. Time to fracture was significantly different between the 2 groups (logrank <0.0001). Distance of the new fracture from the treated level was also significantly associated with time to new fracture (P < .0001). Relative risk of adjacent level fracture was 4.62 times that for non-adjacent level fracture.
These data demonstrate an association between vertebroplasty and new vertebral fractures. Specifically, following vertebroplasty, patients are at increased risk of new-onset adjacent-level fractures and, when these fractures occur, they occur sooner than non-adjacent level fractures.
Study Design. A finite-element study and in vitro experimental validation was performed for a parametric investigation of features that contribute to burst fracture risk in the metastatically involved spine. Objectives. To develop and validate a three-dimensional poroelastic model of a metastatically compromised vertebral segment, to evaluate the effect of lytic lesions on vertebral strains and pressures, and to determine the influence of loading and motion segment status ( bone density, pedicle involvement, disc degeneration, and tumor size) on the relative risk of burst fracture initiation. Summary of Background Data. Finite-element analysis has been used successfully to predict failure loads and fracture patterns for bone. Although models for vertebra affected with tumors have been presented, these have not been thoroughly validated experimentally. Consequently, their predictive capabilities remain uncertain. Methods. A three-dimensional poroelastic finite-element model of the first lumbar vertebra and adjacent intervertebral discs, including a tumor of variable size, was developed. To validate the model, 12 cadaver spinal motion segments were tested in axial compression, in intact condition, and with simulated osteolytic defects. Features of the validated model were parametrically varied to investigate the effects of tumor size, trabecular bone density, pedicle involvement, applied loads, loading rates, and disc degeneration using outcome variables of vertebral bulge and vertebral axial deformation. Results. Consistent trends between the experimental data and model predictions were observed. Overall, the model results suggest that tumor size contributes most toward the risk of initiating burst fracture, followed by the applied load magnitude and bone density. Conclusions. The parametric analysis suggests that the principal factors affecting the initiation of burst fracture in metastatically affected vertebrae are tumor size, magnitude of spinal loading, and bone density. Consequently, patient-specific measures of these factors should be factored into decisions regarding clinical prophylaxis. Pedicle involvement or disc degeneration was less important according to the outcome measures in this study.
Study Design. Intradiscal pressure was measured after percutaneous disc decompression by nucleoplasty in human cadavers with different degrees of disc degeneration. Objectives. To assess intradiscal pressure change after disc decompression, and to analyze the influence of degeneration on the intradiscal pressure change. Summary of Background Data. Partial removal of the nucleus has been shown to decompress herniated discs, relieving pressure on nerve roots and, in some cases, offering relief from disc pain. Nucleoplasty, a new minimally invasive procedure using patented Coblation technology, combines coagulation and ablation for partial removal of the nucleus. Coblated channels remove the tissue volume and may decrease the disc pressure. Methods. Three fresh human cadaver spinal specimens ( T8-L5; age, 54-84 years; mean age, 70.7 years) were used in this investigation. The intradiscal pressure was measured at three points: before treatment, after each channel was created, and after treatment using a 25-guage 6-inch needle connected to a Merit Medical Systems Intellisystem Inflation Monitor. The needles were calibrated initially to approximately 30 pounds per square inch. For the control, the change in disc pressure was recorded by the same procedure without using Coblation energy. To evaluate the effectiveness of nucleoplasty, disc pressure changes were compared between treatment with and without Coblation energy. Results. Intradiscal pressure was markedly reduced in the younger, healthy disc cadaver. In the older, degenerative disc cadavers, the change in intradiscal pressure after nucleoplasty was very small. There was an inverse correlation between the degree of disc degeneration and the change in intradiscal pressure. Conclusions. Pressure reduction through nucleoplasty is highly dependent on the degree of spine degeneration. Nucleoplasty markedly reduced intradiscal pressure in nondegenerative discs, but had a negligible effect on highly degenerative discs.
Study Design. To assess the biomechanical effects of unipedicular vertebroplasty on nonfractured vertebrae. Objectives. To evaluate the potential benefits of vertebroplasty as a preventative treatment. To evaluate the effects of cement volume and bone mineral density on the mechanics of augmented intact vertebral bodies. Summary of Background Data. Many studies have been undertaken to examine the effects of augmentation procedures such as vertebroplasty or kyphoplasty on fractured vertebral bodies. However, the role of such procedures as a prophylactic or interventional tool has not been well studied. This approach may be of clinical interest due to the high occurrence of secondary compression fractures and potentially altered biomechanics following an isolated vertebroplasty procedure. Methods. Nonfractured osteoporotic vertebrae were measured to calculate volume and DEXA scanned to obtain bone mineral density information. Randomly selected specimens were injected with 10% and 20% bone cement by volume or left unfilled to serve as controls. After radiographs and noted cement leakage, specimens were subjected to destructive compression testing. Results. It was found that the injection of 20% bone cement by volume in the lumbar levels resulted in a statistically significant 36% strength increase as compared with the unfilled controls regardless of density levels. However, in the upper thoracic vertebrae there was no significant difference between the strengths of the three groups. Additionally, injection of 20% bone cement frequently resulted in extravasation through vascular channels or into the spinal canal. Conclusions. The introduction of 20% bone cement by volume results in a significant increase in the compressive strength of intact lumbar vertebrae, however upper thoracic vertebrae do not demonstrate a similar strength improvement. There was no difference in the stiffness of the vertebrae injected with cement regardless of location. Bone mineral density (BMD) may play a role in the magnitude of the strength increase, with lower BMD specimens realizing a relatively greater strength improvement. Cement leakage was frequently noted with 20% cement injection, especially in the specimens with higher BMD. The location of the cement did not appear to have an effect on the loading behavior of the bone but should be controlled to minimize the chance of cement escaping into the spinal canal.
Osteoporosis is a skeletal disorder characterized by compromised bone strength predisposing to an increased risk of fracture. Bone strength primarily reflects the integration of bone density and bone quality. Osteoporosis is an asymptomatic condition until fragility fracture occurs.
This study was conducted to review the efficacy and safety of oral bisphosphonates for the treatment of bone metastases in cancer patients.
Available published clinical studies of oral bisphosphonates in bone metastases from 1980 to the present were identified through a MEDLINE search and from literature references. Data were reviewed for efficacy and safety, with an emphasis on double blind, placebo-controlled studies; clinically relevant endpoints; and appropriate study methodology.
Etidronate, alendronate, pamidronate, risedronate, and tiludronate currently are available in the U.S. as either intravenous and/or oral formulations. Although newer bisphosphonates are more potent, oral bioavailability remains < 1%. Oral etidronate has been found to be ineffective in patients with multiple myeloma and prostate carcinoma bone metastases. Pamidronate has been found to be effective in reducing skeletal morbidity associated with bone metastases in both multiple myeloma and breast carcinoma patients when given intravenously, but is ineffective orally in multiple myeloma patients. To the authors' knowledge, there are no double blind, placebo-controlled trials of oral pamidronate in patients with breast carcinoma and bone metastases. Several clinical trials with clodronate, a bisphosphonate that is not available in the U.S., have shown mixed results in patients with myeloma and breast carcinoma bone metastases. To the authors' knowledge, there are no published trials evaluating oral alendronate, tiludronate, or risedronate in patients with metastases to bone.
Oral bisphosphonates do not appear to be as effective as intravenous administration in reducing skeletal complications in patients with metastases to bone lesions. Low oral bioavailability is the most likely reason for this difference. Oral dosing should not be substituted for intravenous administration in the treatment of malignant osteolysis. Cancer 2000;88:6–14.
Despite radiographic and histologic evidence of trabecular bone density changes within and adjacent to osseous metastases, there currently exist no data to demonstrate whether these changes are important in predicting the risk of fracture. To determine if these density changes result in significant reductions in mechanical properties, trabecular bone specimens were prepared from lower thoracic and lumbar vertebrae from two cadavers with radiographic, gross, and histologic evidence of lytic and/or blastic osseous metastases. Each specimen was classified as normal, lytic, or blastic based on appearance in fine-grain radiographs of 8-9 mm thick coronal plane sections. Specimens were tested to failure in uniaxial compression, and tissue and apparent densities were measured. Mean tissue densities were within normal ranges. The mean apparent density for all specimens combined was within the normal range for human vertebrae, and the mean apparent density for radiographically normal (0.131 g/ml) and lytic (0.111 g/ml) specimens was less than the mean apparent density of blastic (0.182 g/ml) specimens (p < 0.02). The moduli of lytic and blastic specimens were less than for normal specimens (p < 0.025). The strength of lytic specimens was less than normal (p = 0.057), but the strength of blastic specimens was not (p > 0.1). Apparent density explained significant fractions of the variations in both modulus (p < 0.001) and strength (p < 0.001). The data suggest that blastic changes associated with osseous metastases to trabecular bone disrupt the normal dependence of trabecular mechanical properties on apparent density, but lytic changes do not.(ABSTRACT TRUNCATED AT 250 WORDS)
Spines from 832 deceased patients with a terminal diagnosis of malignant neoplasm were examined grossly, microscopically and radiographically for evidence of tumor. Gross tumor and bone destruction or sclerosis were reliable signs of obvious metastases. Occult lesions visualized on gross sagittal sections but not detectable radiographically occurred in 26% of spines with confirmed metastatic deposits. Vertebral collapse was not a reliable indicator of metastases. Collapse was not caused by neoplasm in 22% of cases. Overall, metastases were found in 36% of patients dying from neoplastic disease. Although most metastases are obvious, occult lesions not visible radiographically occur. Collapsed vertebra may be impostors simulating metastatic disease.
Fourth and fifth lumbar vertebrae were obtained at post mortem examinations of human subjects in the range 26 to 86 years and at the same time specimens were taken from the iliac crests for histological assessment of trabecular density (iliac crest score). After removal of pedicles and spinous processes the vertebrae were compressed in a testing machine to mechanical failure. The following values were obtained; breaking stress (load per unit area at failure), strain (percentage deformation) at failure and relative ash content (ash per unit volume). Strain at failure was independent of the size and strength of the vertebrae. The relative ash content and the iliac crest score were closely correlated. The relative ash content and the breaking stress both declined with increasing age, but the relation between them was not linear since the breaking stress fell more quickly than the ash content. Euler's equation for the buckling stress of a loaded column readily explains how in osteoporosis the reduction of the diameter of the vertical trabeculae and the loss of transverse ties cause loss of strength proportionately greater than the loss of osseous tissue. The results give no reason to suppose that in osteoporosis the quality of the osseous tissue is changed.
The object of this study was to analyze the cortical thickness (Ct.Th) of the ventral and dorsal shell of the vertebral bodies throughout the human spine in aging and in osteoporosis. Therefore, the complete front column of the spine of 26 autopsy cases (aged 17-90, mean 42 years) without diseases affecting the skeleton and of 11 cases (aged 58-92, mean 77 years) with proven osteoporosis were removed. A sagittal segment prepared through the center of all vertebral bodies was undecalcified, embedded in plastic, ground to a 1 mm thick block, and stained using a modification of the von Kossa method. The analysis included the measurement of the mean cortical thickness of both the ventral and dorsal shell, respectively (from the third cervical to the fifth lumbar vertebral body). The qualitative investigation of the structure of the cortical ring completed the analysis. The presented data revealed a biphasic curve for both the ventral and dorsal shell, skeletally intact with high values of the cortical thickness in the cervical spine (285 microm), and a decrease in the thoracic (244 microm) and an increase in the lumbar spine (290 microm). The mean thickness of the ventral shell is in general greater than the thickness of the dorsal shell in both skeletally normal and osteoporotic cases. The cortical thickness of the spine showed no gender-specific differences (p = NS). There was a slight decrease of the cortical thickness with aging; however, this decrease and the correlation of cortical thickness to age was only significant below vertebral body T8 (r = 0.225-0.574; p(r) < 0.05-0.005). Most interestingly, however, osteoporosis presents itself with a highly significant loss of cortical thickness throughout the whole spine. This decrease of cortical thickness was more marked in the dorsal shell (p < 0.05) than in the ventral shell (ventral from C3 to T6 [p < 0.05] below T6 [p = NS]). We therefore conclude that in osteoporosis the loss of spinal bone mass is not only a loss of trabecular structure but also a loss of cortical thickness. Furthermore, these results may explain the development of regions of least resistance within the spine in aging and the clustering of osteoporotic fractures in the lower thoracic and lumbar spine.
This study was conducted to review the efficacy and safety of oral bisphosphonates for the treatment of bone metastases in cancer patients.
Available published clinical studies of oral bisphosphonates in bone metastases from 1980 to the present were identified through a MEDLINE search and from literature references. Data were reviewed for efficacy and safety, with an emphasis on double blind, placebo-controlled studies; clinically relevant endpoints; and appropriate study methodology.
Etidronate, alendronate, pamidronate, risedronate, and tiludronate currently are available in the U.S. as either intravenous and/or oral formulations. Although newer bisphosphonates are more potent, oral bioavailability remains < 1%. Oral etidronate has been found to be ineffective in patients with multiple myeloma and prostate carcinoma bone metastases. Pamidronate has been found to be effective in reducing skeletal morbidity associated with bone metastases in both multiple myeloma and breast carcinoma patients when given intravenously, but is ineffective orally in multiple myeloma patients. To the authors' knowledge, there are no double blind, placebo-controlled trials of oral pamidronate in patients with breast carcinoma and bone metastases. Several clinical trials with clodronate, a bisphosphonate that is not available in the U.S., have shown mixed results in patients with myeloma and breast carcinoma bone metastases. To the authors' knowledge, there are no published trials evaluating oral alendronate, tiludronate, or risedronate in patients with metastases to bone.
Oral bisphosphonates do not appear to be as effective as intravenous administration in reducing skeletal complications in patients with metastases to bone lesions. Low oral bioavailability is the most likely reason for this difference. Oral dosing should not be substituted for intravenous administration in the treatment of malignant osteolysis.
Comparative ex vivobiomechanical study.
To determine the strength and stiffness of osteoporotic vertebral bodies subjected to compression fractures and subsequently stabilized via bipedicular injection of one of two bone cements: one is a commercially available polymethylmethacrylate (Simplex P) and one is a proprietary glass-ceramic-reinforced BisGMA/BisEMA/TEGDMA matrix composite that is being developed for use in vertebroplasty (Orthocomp).
Osteoporotic compression fractures present diagnostic and therapeutic challenges for the clinician. Vertebroplasty, a new technique for treating such fractures, stabilizes vertebral bodies by injection of cement. Little is known, however, about the biomechanics of this treatment.
Five vertebral bodies (L1-L5) from each of four fresh spines were harvested from female cadavers (age, 80 +/- 5 years), screened for bone density using DEXA (t = -3.4 to -6.4), disarticulated, and compressed in a materials testing machine to determine initial strength and stiffness. The fractures then were repaired using a transpedicular injection of either Orthocomp or Simplex P and recrushed.
For both cement treatments, vertebral body strength after injection of cement was significantly greater than initial strength values. Vertebral bodies augmented with Orthocomp recovered their initial stiffness; however, vertebral bodies augmented with Simplex P were significantly less stiff than they were in their initial condition.
Augmentation with Orthocomp results in similar or greater mechanical properties compared with Simplex P, but these biomechanical results have yet to be substantiated in clinical studies.
To examine whether single-needle vertebroplasty is effective in strengthening vertebrae.
Four adjacent intact lumbar vertebrae were removed from each of nine adult post-mortem subjects. One or two vertebra of each set was injected with low viscosity acrylic bone cement using a single-track posterolateral approach. Vertebral strength was measured during constant rate axial compression.
Single-needle injection delivered different quantities of cement (1-8 ml) in an asymmetric distribution. Injected vertebrae were stronger than controls in 10 out of 12 cases (P < 0.01), suggesting that cement injection increases the load needed to cause initial vertebral fracture. Compression was continued past the point of initial failure, to simulate progressive vertebral collapse. Injected specimens were more resistant to deformation than control specimens (P < 0.05), most of which initially deformed with little increase in load.
Single-track injection of bone cement appeared to strengthen vertebrae against both initial failure and subsequent collapse. The magnitude of strength increase from vertebroplasty was variable, and did not correlate with the volume of cement injected. Further investigation is needed to optimize the technique.Gishen, P. (2000). Clinical Radiology55, 471-476.
It is necessary to prescribe the mechanical properties of tumor tissue when modeling the metastatically involved skeleton for clarifying the mechanisms of fracture. This study provides mechanical property data for lytic bone metastases. Specimens of human lytic tumor were tested under a confined compression uniaxial creep protocol and the mechanical behavior of the tumor tissue was modeled using linear biphasic theory. The tumor tissue was found to have an aggregate modulus (HA)of 3.6 ±1.6kPa and a hydraulic permeability (k) of 0.59 ± 0.46 mm4 N1>s1.Tumors with a higher percentage of stromal content were found to be stiffer and more permeable than those with a more cellular composition. No significant differences in aggregate modulus or hydraulic permeability were found between lytic metastases of different types. These data are useful for the development of models to simulate the behavior of the metastatically involved skeleton using theoretical or finite-element analysis techniques and also have significance for developing effective tumor–drug-transport models. We anticipate that specification of the mechanical behavior of this tissue may help to better focus future treatment of lytic bony metastases through better assessment of fracture risk and improved drug delivery. © 2000 Biomedical Engineering Society.
PAC00: 8719Rr, 8710+e
The vertebral column is the most frequent site of metastatic involvement of the skeleton. Due to the proximity to the spinal cord, from 5% to 10% of all cancer patients develop neurologic manifestations. As a consequence, fracture risk prediction has significant clinical importance. In this study, we model the metastatically involved vertebra so as to parametrically investigate the effects of tumor size, material properties and compressive loading rate on vertebral strength. A two-dimensional axisymmetric finite element model of a spinal motion segment consisting of the first lumbar vertebral body (no posterior elements) and adjacent intervertebral disc was developed to allow the inclusion of a centrally located tumor in the vertebral body. After evaluating elastic, mixed, and poroelastic formulations, we concluded that the poroelastic representation was most suitable for modeling the metastatically involved vertebra's response to compressive load. Maximum principal strains were used to localize regions of potential vertebral trabecular bone failure. Radial and axial vertebral body displacements were used as relative indicators of spinal canal encroachment and endplate failure. Increased tumor size and loading rate, and reduced trabecular bone density all elevated axial and radial displacements and maximum tensile strains. The results of this parametric study suggest that vertebral tumor size and bone density contribute significantly to a patients risk for vertebral fracture and should be incorporated in clinical assessment paradigms.
We prospectively evaluated the safety and efficacy of kyphoplasty in the treatment of osteolytic vertebral compression fractures resulting from multiple myeloma. The principle symptoms in multiple myeloma result from bone destruction, especially the spine. Kyphoplasty is a new technique that involves the introduction of inflatable bone tamps (IBT) into the vertebral body. The purpose of the IBT is to restore the vertebral body back toward its original height, while creating a cavity that can be filled with highly viscous bone cement.
Fifty-five consecutive kyphoplasty procedures were performed in 18 patients with osteolytic vertebral compression fractures resulting from multiple myeloma. Cement leakage and any complications were recorded. Early objective analysis was made by comparing preoperative and latest Short Form 36 Health Survey scores. Height restoration was estimated by measuring vertebral height on lateral radiographs.
The mean age of patients was 63.5 years, mean duration of symptoms was 11 months, and mean follow-up was 7.4 months. There were no major complications related directly to use of this technique. On average, 34% of height lost at the time of fracture was restored. Asymptomatic cement leakage occurred at two (4%) of 55 levels. Significant improvement in SF36 scores occurred for Bodily Pain (23.2 to 55.4, P =.0008), Physical Function (21.3 to 50.6, P =.0010), Vitality (31.3 to 47.5, P =.010), and Social Functioning (40.6 to 64.8, P =.014).
Kyphoplasty was efficacious in the treatment of osteolytic vertebral compression fractures resulting from multiple myeloma. Kyphoplasty is associated with early clinical improvement of pain and function as well as some restoration of vertebral body height.
To determine the efficacy and durability of percutaneous vertebroplasty for the treatment of back pain associated with vertebral body compression fractures.
One hundred patients (79 women, 21 men; mean age, 73.7 y) underwent 156 percutaneous injections of polymethylmethacrylate (PMMA) into a vertebra (68 thoracic and 88 lumbar) under fluoroscopic guidance over a 35-month period. Before the procedure and at follow-up, patients were asked to quantify their pain on a visual analog scale (VAS) and complete a follow-up questionnaire of our own design.
The procedure was technically successful in all patients. There were two complications. One patient sustained a sternal fracture and one experienced a transient radiculopathy. Ninety-seven patients (97%) reported significant pain relief 24 hours after treatment. Mean follow-up duration was 21.5 months (6-44 mo) in 99 patients. Ninety-two patients (93%) reported significant improvement in back pain previously associated with their compression fractures as well as improved ambulatory ability. Before vertebroplasty, the VAS score for the 99 patients was 8.91 +/- 1.12 compared to a score of 2.02 +/- 1.95 at follow-up. The mean difference in VAS scores was significant (P <.0001).
Percutaneous vertebroplasty of symptomatic vertebral body compression fractures is a minimally invasive procedure that provides immediate and sustained pain relief in patients with refractory pain.
To investigate the prevalence and findings of vertebral body compression fractures adjacent to those previously treated with percutaneous vertebroplasty.
The findings in 177 patients treated with percutaneous vertebroplasty for more than 2 years were reviewed retrospectively. The following parameters were reviewed: primary diagnosis, patient age and sex, date of treatment with vertebroplasty, vertebral level(s) treated, pedicular approach, and amount of polymethylmethacrylate injected per vertebral body. Patients with acute compression fractures secondary to osteoporosis were selected.
Of 177 patients treated with percutaneous vertebroplasty, 22 (12.4%) developed a total of 36 new vertebral body fractures following treatment. Of the 36 newly documented fractures, 24 (67%) involved vertebrae adjacent to the previously treated vertebral level(s), whereas 12 (33%) involved the collapse of nonadjacent vertebrae. In addition, 24 (67%) of the 36 new vertebral fractures occurred within 30 days after treatment of the initial fracture(s).
A substantial number of patients with osteoporosis develop new fractures after undergoing percutaneous vertebroplasty; two-thirds of these new fractures occur in vertebrae adjacent to those previously treated.
To determine the clinical and laboratory features of newly diagnosed multiple myeloma.
Records of all patients in whom multiple myeloma was initially diagnosed at the Mayo Clinic in Rochester, Minn, from January 1, 1985, to December 31, 1998, were reviewed.
Of the 1027 study patients, 2% were younger than 40 years, and 38% were 70 years or older. The median age was 66 years. Anemia was present initially in 73% of patients, hypercalcemia (calcium level > or = 11 mg/dL) in 13%, and a serum creatinine level of 2 mg/dL or more in 19%. The beta2-microglobulin level was increased in 75%. Serum protein electrophoresis revealed a localized band in 82% of patients, and immunoelectrophoresis or immunofixation showed a monoclonal protein in 93%. A monoclonal light chain was found in the urine in 78%. Nonsecretory myeloma was recognized in 3% of patients, whereas light-chain myeloma was present in 20%. Conventional radiographs showed an abnormality in 79%. The plasma cell labeling index was 1% or more in 34% of patients. Multivariate analysis revealed that age, plasma cell labeling index, low platelet count, serum albumin value, and the log of the creatinine value were the most important prognostic factors.
The median duration of survival was 33 months and did not improve from 1985 through 1998.
Intradiscal pressure was measured after percutaneous disc decompression by nucleoplasty in human cadavers with different degrees of disc degeneration.
To assess intradiscal pressure change after disc decompression, and to analyze the influence of degeneration on the intradiscal pressure change.
Partial removal of the nucleus has been shown to decompress herniated discs, relieving pressure on nerve roots and, in some cases, offering relief from disc pain. Nucleoplasty, a new minimally invasive procedure using patented Coblation technology, combines coagulation and ablation for partial removal of the nucleus. Coblated channels remove the tissue volume and may decrease the disc pressure.
Three fresh human cadaver spinal specimens (T8-L5; age, 54-84 years; mean age, 70.7 years) were used in this investigation. The intradiscal pressure was measured at three points: before treatment, after each channel was created, and after treatment using a 25-guage 6-inch needle connected to a Merit Medical Systems Intellisystem Inflation Monitor. The needles were calibrated initially to approximately 30 pounds per square inch. For the control, the change in disc pressure was recorded by the same procedure without using Coblation energy. To evaluate the effectiveness of nucleoplasty, disc pressure changes were compared between treatment with and without Coblation energy.
Intradiscal pressure was markedly reduced in the younger, healthy disc cadaver. In the older, degenerative disc cadavers, the change in intradiscal pressure after nucleoplasty was very small. There was an inverse correlation between the degree of disc degeneration and the change in intradiscal pressure.
Pressure reduction through nucleoplasty is highly dependent on the degree of spine degeneration. Nucleoplasty markedly reduced intradiscal pressure in nondegenerative discs, but had a negligible effect on highly degenerative discs.
A finite-element study and in vitro experimental validation was performed for a parametric investigation of features that contribute to burst fracture risk in the metastatically involved spine.
To develop and validate a three-dimensional poroelastic model of a metastatically compromised vertebral segment, to evaluate the effect of lytic lesions on vertebral strains and pressures, and to determine the influence of loading and motion segment status (bone density, pedicle involvement, disc degeneration, and tumor size) on the relative risk of burst fracture initiation.
Finite-element analysis has been used successfully to predict failure loads and fracture patterns for bone. Although models for vertebra affected with tumors have been presented, these have not been thoroughly validated experimentally. Consequently, their predictive capabilities remain uncertain.
A three-dimensional poroelastic finite-element model of the first lumbar vertebra and adjacent intervertebral discs, including a tumor of variable size, was developed. To validate the model, 12 cadaver spinal motion segments were tested in axial compression, in intact condition, and with simulated osteolytic defects. Features of the validated model were parametrically varied to investigate the effects of tumor size, trabecular bone density, pedicle involvement, applied loads, loading rates, and disc degeneration using outcome variables of vertebral bulge and vertebral axial deformation.
Consistent trends between the experimental data and model predictions were observed. Overall, the model results suggest that tumor size contributes most toward the risk of initiating burst fracture, followed by the applied load magnitude and bone density.
The parametric analysis suggests that the principal factors affecting the initiation of burst fracture in metastatically affected vertebrae are tumor size, magnitude of spinal loading, and bone density. Consequently, patient-specific measures of these factors should be factored into decisions regarding clinical prophylaxis. Pedicle involvement or disc degeneration was less important according to the outcome measures in this study.
Methods to quantify burst fracture risk and neurologic deficit for patients with spinal metastases have not been well defined. This study aims to develop objective biomechanically based guidelines to quantify metastatic burst fracture risk. An experimentally validated finite element model of a human lumbar motion segment was used to simulate burst fracture. Through parametric analysis, the behavior of metastatically involved vertebrae was quantified and a formula to relate patient-specific variables to burst fracture risk defined. The equation-based guidelines were able to describe the mechanical behavior of the metastatically involved vertebral model (R2 = 0.97) reflecting the risk and mechanism of fracture. Vertebral density was found to influence the mechanism of burst fracture with respect to endplate failure. These analyses provide clinically feasible equation-based guidelines for burst fracture risk assessment in the metastatically involved spine.
The goal of this study was to quantify volumetrically cement fill and leakage in patients with osteoporotic and metastatic vertebral lesions undergoing percutaneous vertebroplasty and to establish whether these factors have any clinical significance at follow up.
Digital computerized tomography data were retrospectively collected from all cases at the authors' institution in which percutaneous vertebroplasty was performed for osteoporosis or metastatic disease. Patient selection was based on the consensus of a multidisciplinary team consisting of an orthopedic surgeon, an oncologist, and a neuroradiologist. A semiautomated thresholding technique was used to measure vertebral body volume, the volume of cement injected directly into the vertebra, and the volume of cement leakage. Pain-related scores were collected at four early stages of treatment, and all clinical complications were recorded. Cement leakage was found in 87.9% of vertebrae treated with percutaneous vertebroplasty. In osteoporotic vertebrae it occurred mainly in the disc, whereas in metastatic lesions, it was found in multiple areas. Irrespective of leakage, both patients with osteoporotic and metastatic disease experienced significant immediate pain relief postoperatively.
Although there was no correlation between cement fill or cement leakage and pain relief, there exists a risk of serious complications due to cement leakage.
To assess the biomechanical effects of unipedicular vertebroplasty on nonfractured vertebrae.
To evaluate the potential benefits of vertebroplasty as a preventative treatment. To evaluate the effects of cement volume and bone mineral density on the mechanics of augmented intact vertebral bodies.
Many studies have been undertaken to examine the effects of augmentation procedures such as vertebroplasty or kyphoplasty on fractured vertebral bodies. However, the role of such procedures as a prophylactic or interventional tool has not been well studied. This approach may be of clinical interest due to the high occurrence of secondary compression fractures and potentially altered biomechanics following an isolated vertebroplasty procedure.
Nonfractured osteoporotic vertebrae were measured to calculate volume and DEXA scanned to obtain bone mineral density information. Randomly selected specimens were injected with 10% and 20% bone cement by volume or left unfilled to serve as controls. After radiographs and noted cement leakage, specimens were subjected to destructive compression testing.
It was found that the injection of 20% bone cement by volume in the lumbar levels resulted in a statistically significant 36% strength increase as compared with the unfilled controls regardless of density levels. However, in the upper thoracic vertebrae there was no significant difference between the strengths of the three groups. Additionally, injection of 20% bone cement frequently resulted in extravasation through vascular channels or into the spinal canal.
The introduction of 20% bone cement by volume results in a significant increase in the compressive strength of intact lumbar vertebrae, however upper thoracic vertebrae do not demonstrate a similar strength improvement. There was no difference in the stiffness of the vertebrae injected with cement regardless of location. Bone mineral density (BMD) may play a role in the magnitude of the strength increase, with lower BMD specimens realizing a relatively greater strength improvement. Cement leakage was frequently noted with 20% cement injection, especially in the specimens with higher BMD. The location of the cement did not appear to have an effect on the loading behavior of the bone but should be controlled to minimize the chance of cement escaping into the spinal canal.
A biomechanical cadaveric study of thoracic and lumbar vertebrae with simulated metastases quantifying intravertebral pressures during transpedicular vertebroplasty.
To compare intravertebral pressures during percutaneous vertebroplasty in vertebrae with and without simulated lytic metastases.
Percutaneous vertebroplasty is designed to provide stability to vertebrae weakened by osteoporosis or metastatic disease. The complication rate is higher when the procedure is used for the treatment of lytic vertebral lesions. The major complications reported are radiculopathy, spinal cord compression, and embolic phenomena.
Ten fresh-frozen cadaveric vertebrae were tested intact (7 lumbar, 3 thoracic) and 7 were tested with simulated lytic defects (4 lumbar, 3 thoracic). Defects were created by replacing a core of cancellous bone with soft tumor tissue in the center of the vertebral body. Simplex P (Howmedica Osteonics, Mahwah, NJ) cement was injected into each vertebra through a unipedicular approach at a constant rate of 3 mL per minute. Cement volume, injection force, and intravertebral pressures at the posterior vertebral body wall were recorded. Following the procedure, the vertebrae were sectioned to visualize cement and tumor disbursement.
There was no significant difference between the two groups for age, size, trabecular density, and cement volume. Vertebrae with simulated metastases generated an average maximum pressure of 39.66 kPa during cement injection versus 6.83 kPa in intact vertebrae (P < 0.05). Higher pressures were also generated in smaller vertebrae based on a power relationship (r2 = 0.71 intact, r2 = 0.43 tumor).
Percutaneous vertebroplasty produces higher intravertebral pressures in vertebrae containing a simulated lytic metastasis than in intact vertebrae. Pressures generated in the tumor specimens are sufficiently elevated to cause embolic phenomena.
Radiotherapy is an established treatment for metastatic bone pain. It may be delivered as a localised low dose treatment for localised bone pain or systemically for more widespread symptoms using hemibody external beam radiotherapy or intravenous bone-seeking radioisotopes. Bisphosphonates have been shown to reduce morbidity from bone metastases when given to patients with asymptomatic disease from myeloma and primary breast and prostate cancers. They also reduce metastatic bone pain in these sites. In the absence of randomised data comparing radiotherapy with bisphosphonates in the same clinical setting, comparison of the response rates from individual trials of the two modalities suggests that the overall pain response in all tumour types from radiotherapy is around 80% compared to a similar rate in myeloma with bisphosphonates but only 40% in solid tumours. Optimal use of the two modalities requires further investigation but since they have different dose limiting toxicities their incorporation in a combined modality approach to metastatic bone pain is rational using the concepts of additive effect and spatial co-operation in which bisphosphonates provide background control alongside acute pain relief using radiotherapy. They are also an important alternative for bone pain where radiation tolerance has been reached or radiotherapy is not readily available.
Partial removal of the nucleus has been shown to decompress herniated discs, relieving pressure on nerve roots and, in some cases, offering relief from disc pain. The nucleoplasty technique builds on earlier surgical approaches that helped validate the strategy of intranuclear tissue removal. Nucleoplasty, a new minimally invasive procedure using patented coblation technology, combines coagulation and ablation for partial removal of the nucleus pulposus to decompress the disc.
To determine if histologic changes of the intervertebral discs and surrounding tissues occur after nucleoplasty.
A light microscopic study of intervertebral disc and adjacent neural tissues after disc decompression by nucleoplasty in pig cadavers.
Light microscopy was used to examine disc and neural tissues in two pig cadaveric specimens (T12 to sacrum). Nucleoplasty was performed by 1) advancing a radiofrequency wand to a predetermined depth in the disc (ablation), and 2) withdrawing the wand to the starting point (coagulation). Discs and adjacent tissues were removed from treated and nontreated segments, and examined under light microscopy.
Histologic examination revealed no evidence of direct mechanical or thermal damage to the surrounding tissues. There was clear evidence of coblation channels with clean coagulation borders of the nucleus pulposus. Normal histologic findings of the annulus and end plate, with normal neural elements of the spinal cord and nerve roots at the level of the procedure, were observed.
The histologic findings of this study suggest that the nucleoplasty achieves volumetric removal of target disc tissue without overt thermal or structural damage to the adjacent tissues. Further studies in live animals will be needed to assess the effects of nucleoplasty on the annulus, end plate and neural tissues under physiologic conditions, including assessment of cell viability.
We describe seven patients with multiple myeloma who were treated for acute vertebral body fractures with percutaneous vertebroplasty to a total of 14 vertebrae. Six of the seven patients had at least a 50% decrease in their pain scores at 24 h following vertebroplasty. There were no procedure-related complications. These encouraging results prompt us to suggest further large-scale evaluation of this procedure in myeloma patients.
Multiple myeloma is a malignant disease of plasma cells that manifests as one or more of lytic bone lesions, monoclonal protein in the blood or urine, and disease in the bone marrow. Treatment for myeloma has changed beyond recognition in the past decade, and now includes state of the art supportive treatment and infusional chemotherapy courses, followed for younger patients by high-dose melphalan and an autologous transplant. Patients younger than 70 years can now expect a doubling of median survival to 5 years, a 20% chance of surviving longer than 10 years, and a 50% chance of attaining complete morphological and biochemical remission. Bisphosphonate control of bone disease is essential. Exploitation of the understanding of the biology of myeloma has led to the development of biological treatments, such as thalidomide, CC-5013, and bortezomib, which target the myeloma cell and the bone-marrow microenvironment, which plays a crucial part in the disease's pathogenesis. These treatments will hold the key to future success.
Vertebral compression fractures are common complications in advanced osteoporosis. In general, this disease of the elderly patient is characterized by severe local back pain. Pathophysiologically, bony instability triggers local pain during body movement. Serious pain immobilizes the patients and forces them to bed rest. As a result, complications like thrombosis or pneumonia occur. Invasive treatment with surgical instrumentation for vertebral stabilization is not indicated in elderly patients especially with additional diseases. The purpose of this study was to test the hypothesis that percutaneous polymethylmethacrylate (PMMA) vertebroplasty significantly reduces pain due to vertebral collapse in osteoporotic patients and improves quality of life.
A total of 38 patients with osteoporotic vertebral compression fractures of the thoracic and lumbar spine were treated by PMMA vertebroplasty. After admission, before discharge from the hospital, six weeks, half a year and one year later patients answered the Oswestry Low Back Pain Disability (OLBPD) Questionnaire for assessment of treatment related change in disability. In all patients percutaneous vertebroplasty was performed under local anesthesia.
A total of 92% of patients reported a significant pain reduction immediately after treatment. Also one year after vertebroplasty pain remained significantly reduced. Vertebroplasty was highly beneficial for patients with pain related to local instability of the spine. Extravasation of PMMA beyond the vertebral margins was observed in 26% of the cases. No treatment related clinical or neurological complications were noticed.
PMMA vertebroplasty is a useful and safe method of pain relief which rapidly regains quality of life for patients with osteoporotic vertebral compression.
Percutaneous vertebroplasty is a safe and efficacious technique for the treatment of persistent pain from a fractured vertebral body. Injection of cement into the vertebral body is made after insertion of a large-bore needle, frequently by a trans-pedicular approach. Vertebroplasty is most commonly used to treat painful osteoporotic fracture resistant to conservative therapy, but may be helpful in other conditions such as malignant collapse. NICE guidelines are now available for this procedure, which is relatively new in the UK, but has been performed for more than 15 years in continental Europe.
Complications due to vertebroplasty may be divided into two categories whether or not they are related to polymethylmethacrylate (PMMA) cement leakage from the compressed vertebral body. PMMA leakage is a very frequent occurrence in vertebroplasty is also the main source of complications. Neurological complications are due to cement leakage into the spinal canal and less exceptionally into the intervertebral foramen. The transpedicular needle approach reduces the risk of cement leakage into the foramen. Pulmonary embolism of PMMA may occur when there is a failure to recognize venous migration of cement early during the procedure. Cortical destruction, presence of an epidural soft-tissue mass, highly vascularized lesions, and severe vertebral collapse are factors which increase the rate of complications, which is therefore much higher in metastatic than in osteoporotic vertebral collapse. Prevention of PMMA leakage-related complications is a multifactorial issue including procedure preparation, needle approach and placement, and cement application. The technical refinements which may help reduce the risk of PMMA leakage are reviewed in this article. Experimental data have shown that systemic reactions may occur during vertebroplasty in the absence of cement leakage. These reactions may be partly related to vascular embolism of bone marrow fat. Another controversial issue is a possible increase in the risk of vertebral collapse of adjacent vertebrae following vertebroplasty. Prospective randomized studies are needed to resolve this issue.
To evaluate the risk factors related to the development of new fractures in adjacent vertebrae after vertebroplasty.
The study was conducted on 106 patients in whom 212 vertebroplasties were performed during a period of 3 years. Evaluations of the five vertebrae superior and inferior to the treated vertebra were performed. Consequently, 913 vertebrae were evaluated and the fracture-free interval of the vertebral body adjacent to the treated vertebra was calculated. Survival analysis was performed using the Kaplan-Meier method and Cox proportional hazards regression analysis.
Seventy-two (7.9%) new fractures were revealed. The Kaplan-Meier estimate of the 1-year fracture-free rate was 93.1%. The mean fracture-free interval was 32 months (95% CI, 32 to approximately 33 months). The greater degree of height restoration of the treated vertebra, the location of the adjacent vertebra in the TL junction, and the shorter distance between the treated and the adjacent vertebra increased the risk of new vertebral fractures.
Thoracolumbar junction, shorter distance from the treated vertebrae, and greater degree of height restoration of the cemented vertebrae may increase the fracture risk of vertebrae adjacent to cement vertebrae after vertebroplasty.
Percutaneous vertebroplasty may be indicated when a patient with a painful osteoporotic vertebral compression fracture remains intolerably symptomatic in spite of comprehensive, nonoperative management. Relief of pain and quality of life following percutaneous vertebroplasty, however, remain incompletely defined. We investigated these outcomes with use of a visual analog scale and a validated, osteoporosis-specific health-related quality-of-life instrument.
We performed a prospective study of consecutive patients who underwent percutaneous vertebroplasty. At the time of enrollment, all patients completed the Osteoporosis Quality of Life Questionnaire, a validated thirty-item, five-domain, 7-point response-option instrument that measures health-related quality of life in osteoporotic women with back pain due to vertebral compression fracture. At two weeks, two months, and six months postoperatively, all patients completed a validated extraction of the Osteoporosis Quality of Life Questionnaire. The minimal, clinically important difference in this 7-point scale is 0.5 unit per question. To assess pain, a visual analog scale (ranging from 1 to 10) was completed preoperatively, one day postoperatively, and at each evaluation thereafter.
Forty-six consecutive patients (thirty-two women and fourteen men) underwent forty-nine percutaneous vertebroplasty procedures for the treatment of sixty-six vertebral compression fractures. The mean age of the patients was 74.3 years. The mean fracture age was 2.5 months. The mean pain rating decreased from 7.7 preoperatively to 2.8 one day after the vertebroplasty (p < 0.001), and it remained substantially improved at two weeks, two months, and six months postoperatively (p < 0.001). All five domains of the Osteoporosis Quality of Life Questionnaire were improved at two weeks postoperatively and remained improved at each evaluation point through six months (p </= 0.007). Multivariate analysis demonstrated no consistent correlation between postoperative pain relief or any postoperative Osteoporosis Quality of Life Questionnaire domain score and gender, smoking history, previous or current steroid use, bone mineral density, dynamic mobility, or the presence of an intravertebral cleft. Immediate postoperative pain relief was weakly and positively associated with age (p < 0.03). Four incident vertebral compression fractures occurred in three (6.5%) of the forty-six patients, and five patients died within six months after the vertebroplasty. No deaths or serious adverse events appeared to be related to vertebroplasty.
Rapid and substantial relief of pain and improvement in the quality of life are observed following percutaneous vertebroplasty, and these improvements are maintained for at least six months. Percutaneous vertebroplasty can be performed safely in frail, elderly patients, with no apparent increase in the incidence of fractures postoperatively.
Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence.
Osteoporotic vertebral compression fractures are being recognized increasingly often in the elderly. They frequently cause severe and prolonged back pain and physical decline. Bed rest, narcotic analgesia, and external bracing were the only therapeutic modalities available in the past and had limited success.
The purpose of our study was to determine the efficacy of percutaneous vertebroplasty in treating osteoporotic vertebral compression fractures in the elderly.
Twenty-two vertebroplasties were performed in 16 elderly patients. Pain relief, medication requirements, and physical functioning were evaluated before and 24 h and 6 months after vertebroplasty.
There was 81% improvement in pain intensity 24 h after operation, and 94% improvement was noted at the 6-month follow-up checkup. Physical functioning improved 69% 24 h after vertebroplasty and 63% 6 months later. Medication requirements also decreased in 75% of the patients.
Percutaneous vertebroplasty for osteoporotic vertebral compression fractures is safe and effective and should not be withheld from the elderly.
To assess the immediate efficacy of percutaneous vertebroplasty (PVP) in relief of pain and improving mobility of patients with vertebral compression fractures (VCF) secondary to osteoporosis, 205 cases (175 patients) underwent 250 percutaneous injections of polymethylmethacrylate (PMMA; unilateral, 247 levels; bilateral, 3 levels) into vertebrae under CT and fluoroscopic guidance for 34 months. Patients were prospectively asked to quantify their pain on a visual analog scale (VAS) before and a day after PVP. The interval to mobilization was recorded in those who were immobilized because of pain and/or bed-rest therapy (115 cases). PVP was technically successful in all patients, with three cases of minimal complications. The mean VAS score available for 196 cases was improved from 7.22+/-1.89 (range, 3-10) to 2.07+/-1.19 (range, 0-10) by PVP. Ninety-four of 115 immobilized cases (81.7%) were mobile by 24 h after PVP, and the mean value was 1.9+/-2.8 days. The incidence of recurrent and new fractures was 15.6% in 4-25 months (mean, 15.3 months). PVP is a safe and effective treatment for relieving the pain associated with osteoporotic VCF and strengthening the vertebrae, avoiding refractures. This therapy leads to early mobilization and avoidance of the dangers of conservative therapy of bed-rest.
Pathologic fractures, especially of the axial skeleton, are extremely common in patients with multiple myeloma and cluster around the time of diagnosis. Osteoporotic fractures seem to be less of a problem in these patients.
It is generally believed that fractures are common in patients with multiple myeloma as a result of lytic bone lesions, generalized bone loss, and/or elevated bone turnover from excessive cytokine production, but the actual risk of pathologic versus osteoporotic fractures has not been quantified.
In a population-based retrospective cohort study, 165 Olmsted County, MN, residents with myeloma diagnosed from 1945 to 2001 (55% men; mean age, 70.7 +/- 11.1 years) were followed for 537 person-years. The relative risk of fractures was assessed by standardized incidence ratios (SIRs), and risk factors were evaluated in proportional hazards models.
Altogether, 134 patients experienced 463 fractures. In the year before diagnosis, 16 times more fractures were observed than expected, mostly pathologic fractures of the vertebrae and ribs. Subsequently, there was a 9-fold increase in fracture risk. However, 69% of these fractures were pathologic, and another 11% were found incidentally on myeloma monitoring. With the latter two groups excluded, subsequent fracture risk was elevated 3-fold, with a 2-fold increase in the risk of an osteoporotic fracture. In multivariate analyses, the predictors of overall fracture risk were oral corticosteroid use and elevated serum calcium levels, whereas pathologic fractures were additionally predicted by use of chemotherapy.
There is a dramatic increase in fractures around the time of diagnosis of myeloma, most of which are pathologic fractures. The most important predictor of overall fracture risk is oral corticosteroid use.
Annulotomy is a mandatory step to perform intradiscal decompression to resolve a disco radicular conflict. However, this manoeuvre can lead to post surgical complications such as vertebral instability and back pain.
Coblation assisted microdiscectomy (CAM procedure) allows a quoted removal of disc without anulus damage.
The major clinical manifestation of multiple myeloma is related to the osteolytic bone destruction. The bone disease can lead to pathologic fractures, spinal cord compression, hypercalcemia, and pain. It is also a major cause of morbidity and mortality in these patients. These patients frequently require radiation therapy, surgery and analgesic medications. Bisphosphonates are specific inhibitors of osteoclastic activity, and these agents have been evaluated in myeloma patients with bone disease during the past 15 years. Several large randomized trials have been conducted in myeloma patients also receiving chemotherapy. Orally administered bisphosphonates have shown little ability to slow the development of skeletal complications in these patients. In contrast, more potent intravenous monthly infusions of either pamidronate or zoledronic acid have reduced the skeletal complications among these patients and are now a mainstay of myeloma therapy. A number of other types of new anti-bone-resorptive agents are also in early clinical development.
We sought to determine whether percutaneous vertebroplasty--which involves the injection of cement to stabilize a fractured vertebral body--may be an effective treatment for vertebral fracture.
We enrolled 79 consecutive osteoporotic patients (24 men and 55 women; ages 51 to 93 years) presenting with acute vertebral fractures. Clinical characteristics and bone densitometry were measured at baseline. Pain scores (on a 0 to 25 scale) and levels of function (on a 0 to 20 scale) were recorded on presentation, at 24 hours, at 6 weeks, and 6 to 12 months after therapy.
Fifty-five patients (70%) were treated by percutaneous vertebroplasty and 24 (30%) were treated by conservative therapy alone. They were followed for a mean of 215 days (range, 57 to 399 days). The baseline clinical characteristics, bone densitometry, and fracture data were similar in the two groups. Twenty-four hours after vertebroplasty, there was a 53% reduction in pain scores (from 19 to 9; P = 0.0001) and a 29% improvement in physical functioning (from 14 to 18; P = 0.0001), whereas pain scores and physical functioning remained unchanged at 24 hours in the patients treated conservatively (both P = 0.0001 compared with the changes after percutaneous vertebroplasty). Thirteen patients (24%) treated by percutaneous vertebroplasty were able to cease all analgesia after 24 hours (P = 0.0001 compared with none of the 24 patients treated conservatively). Clinical outcomes at 6 weeks and 6 to 12 months were similar in both groups.
When compared with conservative therapy, percutaneous vertebroplasty results in prompt pain relief and rapid rehabilitation. In experienced hands, it is a safe and effective procedure for treating acute osteoporotic vertebral compression fractures.
Progressive bone destruction is the hallmark of multiple myeloma (MM) and is responsible for principal morbidity in the disease. The spine is the most afflicted skeletal organ, and vertebral fractures have significantly contributed to its poor prognosis. The principal underlying pathologic mechanism causing bone disease in MM is a shift in the balance of bone formation and bone resorption toward bone resorption, and eventually total dissociation between the 2 processes occurs in latter stages of the disease. During the past decade bisphosphonates have become an important adjunctive treatment in the management of MM, in which they have shown the ability to reduce bony complications associated with the disease. Advances in minimally invasive surgical techniques, such as percutaneous vertebroplasty and kyphoplasty, offer these patients less-invasive options for the treatment of vertebral collapse and restoration of their normal function. This report reviews recent advances in the understanding of bone disease in MM, the role of bisphosphonates in the prevention of skeletal events, and available data regarding percutaneous vertebroplasty and kyphoplasty.
There are no proven radiographic guidelines for predicting fracture risk in children and young adults with a benign skeletal lesion. An in vivo diagnostic study was conducted to determine whether a reduction in the load-carrying capacity of a bone measured with quantitative computed tomography was more accurate than current radiographic guidelines for predicting pathologic fracture in patients with a benign skeletal lesion.
Eighteen patients who presented with a fracture through a benign skeletal lesion were compared with eighteen patients who had a benign skeletal lesion that had been thought to be at increased risk for fracture on the basis of currently used radiographic criteria but had not fractured over a two-year period. Structural analysis was performed to calculate the resistance of the affected bones to compressive, bending, and torsional loads with use of serial transaxial quantitative computed tomography data obtained along the length of the bone containing the lesion and from homologous cross sections through the contralateral, normal bone. At each cross section, the ratio of the structural rigidity of the affected bone divided by that of the normal, contralateral bone was determined. The cross section with the greatest reduction in compressive, bending, and torsional rigidity was identified as that most likely to fracture.
The mean age (and standard deviation) of the thirty-six patients was 12.5 +/- 3.6 years. Twenty lesions were located in the femur; eleven, in the tibia; three, in the humerus; one, in the ulna; and one, in the pelvis. A combination of the minimum bending and torsional rigidities calculated from the tomographic data provided optimal performance in differentiating between the fracture and non-fracture groups (100% sensitivity and 94% specificity). In contrast, plain radiographic criteria demonstrated 28% to 83% sensitivity and 6% to 78% specificity.
The combination of bending and torsional rigidity measured noninvasively with quantitative computed tomography was more accurate (97%) for predicting pathologic fracture through benign bone lesions in children than were standard radiographic criteria (42% to 61% accuracy). We believe that this method can provide accurate objective criteria for planning treatment of benign bone lesions and monitoring treatment response.
Posterior lumbar interbody fusion (PLIF) and anterior lumbar interbody fusion (ALIF) have become routine alternatives to intertransverse process fusion. The use of Coblation (ArthroCare Corporation, Sunnyvale, CA) allows for routine and reproducible removal of cartilaginous endplate down to the bony endplate. Our experience with this new technology is reviewed. The authors used Coblation to prepare endplates of 10 consecutive patients undergoing interbody fusion. The results were compared to the following 10 consecutive patients undergoing interbody fusion with endplates prepared in the standard fashion with curettes and rongeurs. The same interbody grafts and instrumentation were used in all patients. Follow-up X-rays were done at 1 week, 6 weeks, 6 months, 1 year, and then each year thereafter. The 20 patients were reviewed along with their films. In each patient the disk spaces and the ALIF/PLIF cages appeared to be fused by 6 months. There was one superficial wound infection in each group. In each of the cases in which PLIF was performed, the cages were augmented by posterior lateral graft and pedicle screw fixation. All patients in both groups reported improvement in pain and/or neurologic symptoms by 6 months. The patients were followed for 4.6 years in the Coblation group and 4.1 years in the standard group. Disk space height was measured in all patients at 6 months. In the Coblation group, average disk space height was 9.0 mm compared to 8.2 mm in the standard group (p<0.1). We feel that the maintenance of normal structures within the lumbar spine with anterior/posterior lumbar interbody fusions and non-mechanical means of preparing the endplates are advantageous. Clearly, the number of patients involved and the length of follow-up limit this study, but it serves as an early indicator that endplate preparation may play a role in graft subsidence and fusion rates. Additional study is warranted.
Vertebral compression fractures (VCFs) are common in multiple myeloma (MM). Percutaneous vertebroplasty (PVP) is used to stabilize vertebral collapse and treat the pain. Few studies have been carried out on PVP in MM and follow-up has tended to be short. We have prospectively evaluated the safety and efficacy of PVP in the VCFs resulting from MM or plasmacytomas. Nineteen PVP were performed in 12 consecutive patients. We monitored their pain and functional status using visual analog (VAS) and Eastern Cooperative Oncology Group (ECOG) scale, respectively. For a subjective assessment, every patient was asked about his/her degree of satisfaction. The mean age of the participants was 66 yr. Significant improvement occurred 1 d after PVP according to the VAS score (7.5 pre-PVP to 3.7, P < 0.0001) and ECOG assessment (3.1 to 2.5, P = 0.002). This significant improvement was maintained after 3.2 yr of follow-up. Sixty-three percent of patients were highly satisfied with the result of the PVP and 37% were satisfied. The peri-operative mortality was 0%. Leakage of the cement outside of the vertebral body was noted in 16 of 19 injected vertebrae (84%) but none of the patients developed any clinical or neurological symptoms. At the last follow-up, no further collapse in the treated or neighboring vertebrae was noted. VCFs caused by MM or plasmacytomas can be effectively treated by vertebroplasty. PVP is associated with early clinical improvement of pain and function and can be maintained after a long follow-up without major procedure-related complications.
To put vertebral augmentation (eg, vertebroplasty) into perspective, the etiology and outcomes of vertebral fractures are reviewed. There is considerable debate about which criteria should be used to define a vertebral fracture because there is no consistent relation between symptoms and the degree of vertebral deformity. However, it is the more significant vertebral body deformities that are most closely associated with frequent or severe back pain, and the referrals for vertebral augmentation come mainly from this subset of patients. In addition to their vertebral fractures, these patients typically have osteoporosis or elevated bone turnover, and they are at greatly increased risk of subsequent fractures as a result of falling or, more often, excessive spinal loads from activities of everyday living. Additional risk factors for new vertebral fractures include the number and severity of vertebral deformities at baseline. Moreover, new fractures are most likely in nearby vertebrae, and they occur more frequently in the mid-thoracic or thoracolumbar regions of the spine. Interestingly, these are also the characteristics of the subsequent fractures of contiguous vertebrae considered by some to represent a complication of vertebral augmentation, yet they characterize vertebral fracture risk even in untreated patients. Vertebral fractures are very common among older men and postmenopausal women; they are associated with substantial morbidity and mortality; and they may have a devastating impact on the patient's quality of life. Vertebral augmentation may be able to help many of these patients, although opportunities exist to optimize management strategies with respect to the other factors that influence long-term outcomes in this patient population.