The Spine Journal

Published by Elsevier BV

Print ISSN: 1529-9430


10:02OPA1. Response of Charité total disc replacement under physiologic loads: prosthesis component motion patterns
  • Article

November 2005


111 Reads


Michael Nicolakis


Mark A Lorenz




Total disc replacement (TDR) has been recommended to reduce pain of presumed discogenic origin while preserving spinal motion. The floating core of Charité TDR is professed to allow the replication of the kinematics of a healthy disc under physiologic loads. While segmental motion after Charité TDR has been measured, little is known about the effects of a physiologic compressive preload on vertebral motion and the motion of prosthesis components after TDR. (1) Does Charité TDR allow restoration of normal load-displacement behavior of a lumbar motion segment under physiologic loads? (2) How do the prosthesis components move relative to each other under physiologic loads when implanted in a lumbar motion segment? A biomechanical study using human lumbar spines (L1-sacrum). Five lumbar spines (age: 52+/-9.3) were used. Specimens were tested under flexion (8 Nm) and extension (6 Nm) moments with compressive follower preloads of 0 N and 400 N in the following sequence: (i) intact, (ii) Charité TDR at L5-S1, (iii) simulated healed fusion at L5-S1 with Charité TDR at L4-L5. Segmental motion was measured optoelectronically. Motions between prosthesis end plates and core were visually assessed using sequential digital video-fluoroscopy over the full range of motion. Here we report on kinematics of 10 Charité TDRs: 5 at L5-S1 and 5 at L4-L5. Charité TDR increased the flexion-extension range of motion of lumbar segments (p<.05). At 400 N preload, the range of motion increased from intact values of 6.8+/-4.4 to 10.0+/-2.4 degrees at L5-S1 and from 7.0+/-2.6 to 10.8+/-2.9 degrees at L4-L5. Charité TDR increased segmental lordosis by 8.1+/-6.9 degrees at L5-S1 (p<.05) and 5.4+/-3.5 degrees at L4-L5 (p<.05). Four patterns of prosthesis component motion were noted: (1) angular motion only between the upper end plate and core, with little or no visual evidence of core translation (9 of 10 TDRs at 0 N preload and 5 of 10 TDRs at 400 N preload); (2) lift-off of upper prosthesis end plate from core or of core from lower end plate (observed in extension in 9 of 10 TDRs under 0 N preload only); (3) core entrapment, resulting in a locked core over a portion of the range of motion (observed in extension in 8 of 10 TDRs under 400 N preload); (4) angular motion between both the upper and lower end plates and core, with visual evidence of core translation (1 of 10 TDRs at 0 N preload, 5 of 10 TDRs at 400 N preload). The pattern of load-displacement curves was substantially changed under a physiologic preload in 8 of 10 TDRs; instead of a relatively gradual change in angle with changing moment application as seen for an intact segment, the TDR displayed regions of both relatively small and relatively large angular changes with gradual moment application. Charité TDR restored near normal quantity of flexion-extension range of motion under a constant physiologic preload; however, the quality of segmental motion differed from the intact case over the flexion-extension range. Whereas some TDRs showed visual evidence of core translation, the predominant angular motion within the prosthesis occurred between the upper end plate and the polyethylene core. Likely factors affecting the function of the Charité TDR include implant placement and orientation, intraoperative change in lordosis, and magnitude of physiologic compressive preload. Further work is needed to assess the effects of the prosthesis motion patterns identified in the study on the load sharing at the implanted level and polyethylene core wear.

Migration patterns of herniated disc fragments: A study on 1,020 patients with extruded lumbar disc herniation

December 2013


5,084 Reads

Herniated disc fragments are known to migrate in various directions within the spinal canal. To date, no comprehensive studies have been undertaken to examine the migration patterns of herniated disc material using a standard nomenclature and classification system. To report migration patterns of extruded lumbar disc fragments. A review of magnetic resonance (MR) images. A total of 1020 consecutive Azeri patients with symptomatic extruded lumbar intervertebral disc herniation. Migration patterns of extruded lumbar disc fragments in vertical and horizontal planes, and their association with age, gender, body mass index (BMI) and the level of herniation. High-quality axial and sagittal MR images of the lumbar spine were used. Disc material that was displaced away from the site of extrusion, regardless of continuity, was considered "migrated". The migration patterns observed were rostral or caudal in the vertical plane, and central, paracentral, subarticular, foraminal, or extraforaminal in the horizontal plane. The authors declare no conflict of interests or outside sources of support. In the vertical plane, rostral and caudal migrations were observed in 27.8% and 72.2% of the patients, respectively. The number of rostral migrations increased significantly with increasing age and in higher levels in the lumbar spine (p<0.001 for both). Radiculopathy was significantly more frequent in caudal migrations than in rostral migrations (78.9% vs. 65.1%, p<0.001). There was no significant association between gender or BMI and migration patterns in the vertical plane. In the horizontal plane, central, paracentral, subarticular, foraminal, and extraforaminal migrations were reported in 17.3%, 74.2%, 4.3%, 2.5%, and 1.8% of the patients, respectively. The youngest (median age: 39 years, interquartile range: 13 years) and the oldest (median age: 55 years, interquartile range: 15 years) groups of patients (p<0.001) had the most formainal and extraforaminal migrations, respectively. Radiculopathy was present in 66.5%, 76.8%, 88.6%, 96%, and 27.8% of the patients with central, paracentral, subarticular, foraminal and extraforaminal migrations, respectively (p<0.001). No significant association was found between gender, BMI or the level of herniation and migration pattern in the horizontal plane. Caudal and paracentral migrations are the most common patterns of migration in patients with extruded lumbar disc herniation in the vertical and horizontal planes, respectively. Age and the level of herniation may affect the migration patterns of herniated lumbar disc material.

Intraoperative somatosensory evoked potential monitoring during anterior cervical discectomy and fusion in nonmyelopathic patients-a review of 1,039 cases

February 2007


178 Reads

Intraoperative somatosensory evoked potential (SSEP) monitoring has been shown to reduce the incidence of new postoperative neurological deficits in scoliosis surgery. However, its usefulness during cervical spine surgery remains a subject of debate. To determine the utility of intraoperative SSEP monitoring in a specific patient population (those with cervical radiculopathy in the absence of myelopathy) who underwent anterior cervical discectomy and fusion (ACDF) surgery. Retrospective review. A total of 1,039 nonmyelopathic patients who underwent single or multilevel ACDF surgery. The control group (462 patients) did not have intraoperative SSEP monitoring, whereas the monitored group (577 patients) had continuous intraoperative SSEP monitoring performed. A new postoperative neurological deficit. SSEP tracings were reviewed for all 577 patients in the monitored group and all significant signal changes were noted. Medical records were reviewed for all 1,039 patients to determine if any new neurological deficits developed in the immediate postoperative period. None of the patients in the control group had any new postoperative neurological deficits. In the monitored group there were six instances of transient SSEP changes (1 due to suspected carotid artery compression; 5 thought to be due to transient hypotension) which resolved with the appropriate intraoperative intervention (repositioning of retractors; raising the arterial blood pressure). Upon waking up from anesthesia, one patient in the monitored group had a new neurological deficit (partial central cord syndrome) despite normal intraoperative SSEP signals. ACDF appears to be a safe surgical procedure with a low incidence of iatrogenic neurological injury. Transient SSEP signal changes, which improved with intraoperative interventions, were not associated with new postoperative neurological deficits. An intraoperative neurological deficit is possible despite normal SSEP signals.

Is lumbar stenosis associated with thoracic stenosis? A study of 1,072 human cadaveric specimens

November 2012


43 Reads

Background context: Tandem stenosis of the cervical and lumbar spine is known to occur in 5% to 25% of individuals with symptomatic neural compression in one region. However, the prevalence of concurrent lumbar and thoracic stenosis is not known. Whether this relationship is because of an increased risk of degenerative diseases in these individuals or because of the tandem presence of stenosis in lumbar and thoracic canal is unknown. Purpose: To determine the prevalence of concurrent lumbar and thoracic stenosis, and whether the presence of stenosis in the lumbar spine is associated with stenosis in the thoracic spine. Study design: A morphoanatomic study of lumbar and thoracic cadaveric spines. Methods: One thousand seventy-two adult skeletal specimens from the Hamann-Todd Collection in the Cleveland Museum of Natural History were selected. Canal area at each level was also calculated using a geometric formula. A standard distribution for each level was created, and values that were 2 standard deviations below mean were considered as being stenotic. Linear regression analysis was used to determine the association between the additive canal areas at all levels in the lumbar and thoracic spine and between the number of stenotic lumbar and thoracic levels. Logistic regression was used to calculate the odds ratios (OR) for concurrent lumbar and thoracic stenosis. Results: The prevalence of concurrent lumbar and thoracic stenosis is 1.42%. A positive association was found between the additive areas of all lumbar and thoracic levels (p<.01). No association, however, was found between the number of stenotic lumbar and thoracic levels (p=.7). Log regression demonstrated no significant association (OR <1) between stenosis in the lumbar and thoracic spine. Conclusions: The stenosis of the lumbar spine is not associated with the thoracic stenosis. Thus, stenosis in lumbar and thoracic levels does not seem to be contributed by tandem stenosis.

Table 1 Sample characteristics
Table 2 Back pain prevalence for pregnant women
Low back pain in 1,100 Iranian pregnant women: prevalence and risk factors
  • Article
  • Full-text available

July 2009


767 Reads

Low back pain (LBP) is a common and costly problem in pregnancy. It is one of the main reasons for disability, absence from work, and responsible for huge direct and indirect economical impact. The purpose of this study was to determine the prevalence and risk factors of LBP during pregnancy. A cross-sectional study was carried out on Iranian pregnant women. Eleven hundred randomly selected pregnant women. A structured questionnaire including demographic, lifestyle, as well as prevalence and characteristics of LBP was used. Visual Analog Scale and Oswestry low back disability questionnaires were also used to assess the pain intensity and functional disability, respectively. After ethical approval from Medical Ethics Board at the Mazandaran University of Medical Sciences and Health Services, a cross-sectional study was conducted on 1,100 pregnant women from 18 health centers in Sari district, at northern Iran. Point, last-month, last 6-month, last-year, and lifetime prevalence of LBP were 40.2%, 55.9%, 59.4%, 76.2%, and 84.1%, respectively. Prolonged standing and rest were found to be the most significant aggravating and relieving factors (76.3% and 87.7%, respectively). LBP was significantly correlated with history of previous LBP and LBP in previous pregnancy (p=.000 in both cases). The prevalence of LBP in pregnant women appears to be high and future research should focus on different preventive strategies during pregnancy.

Outcome of Decompression with and without Fusion in Spinal Stenosis with Degenerative Spondylolisthesis in Relation to Preoperative Pain Pattern: A Register Study of 1,362 Patients

November 2014


55 Reads

Patients with spinal stenosis with concomitant degenerative spondylolisthesis (DS) and predominance of back pain have been shown to have inferior outcome after surgery. Studies comparing outcome according to preoperative pain predominance and treatment received are lacking. To study if adding spinal fusion to the decompression in DS impacts outcome in patients with predominant back pain (back pain VAS ≥ leg pain VAS) compared to predominant leg pain (back pain VAS < leg pain VAS). The Swedish Spine Register was used and included 1,624 patients operated for DS at the L4-L5 level. Self-reported measures were used, including a visual analogue scale (VAS) for back and leg pain, the Euroqol-5 (EQ-5D) and the physical and mental component summaries of the Short-form 36 to estimate health related quality of life (HRQoL) and the Oswestry disability index (ODI) to estimate function. Inclusion criterion was single level DS operated on with either decompression only (D) or decompression and instrumented posterolateral fusion (DF). Based on preoperative leg and back pain scores, the patients were assigned to one of two groups: Leg pain predominance or back pain predominance. The patients completed the outcome protocol at 1 and 2 year follow-up. Statistical analysis was performed using linear regression adjusting for multiple potential confounders. In the adjusted outcome at the 1 year follow-up, patients with predominant leg pain reported a 7.9 mm more improvement on the VAS for back pain with fusion, compared to decompression only (95%CI: 0.7-15.2), p=0.03. Despite more change in the fused group, the reported back pain levels remained similar in the decompressed only versus decompressed and fused at the 1 year follow-up (28 vs. 24, p=0.77). The patients with predominant back pain benefited from adding fusion in terms of back pain 7.1 (95%CI: 0.3-13.9, p=0.04), leg pain 8.8 (95%CI: 2-15.7, p=0.01), the ODI 5.7 (95%CI: 1.6-9.9, p=0.006) and the EQ-5D 0.09 (95%CI:1.7-0.02, p=0.02) at the 1 year follow-up as the DF group reported greater change in outcome compared to the D group. At the 2 year follow-up no significant differences were found between decompressed only and decompressed and fused in either the leg or back pain predominant groups. Patients with predominant back pain operated with DF report better outcomes in terms of pain, function and HRQoL than patients with only decompression. Although these differences are significant on a group level they may fail to reach minimal clinical significant difference. Patients with predominant leg pain report significantly more improvement in terms of back pain with DF compared to D but due to baseline differences in preoperative BP these improvements may not be explained by the added fusion per se. At the two year follow-up no significant differences were observed between the D and DF patients in either the PB or PL groups but greater loss to follow-up in the DF groups could potentially bias these findings. Copyright © 2014 Elsevier Inc. All rights reserved.

MRI issues for ballistic objects: Information obtained at 1.5-, 3- and 7-Tesla

April 2013


420 Reads

Background context: Few studies exist for magnetic resonance imaging (MRI) issues and ballistics, and there are no studies addressing movement, heating, and artifacts associated with ballistics at 3-tesla (T). Movement because of magnetic field interactions and radiofrequency (RF)-induced heating of retained bullets may injure nearby critical structures. Artifacts may also interfere with the diagnostic use of MRI. Purpose: To investigate these potential hazards of MRI on a sample of bullets and shotgun pellets. Study design: Laboratory investigation, ex vivo. Methods: Thirty-two different bullets and seven different shotgun pellets, commonly encountered in criminal trauma, were assessed relative to 1.5-, 3-, and 7-T magnetic resonance systems. Magnetic field interactions, including translational attraction and torque, were measured. A representative sample of five bullets were then tested for magnetic field interactions, RF-induced heating, and the generation of artifacts at 3-T. Results: At all static magnetic field strengths, non-steel-containing bullets and pellets exhibited no movement, whereas one steel core bullet and two steel pellets exhibited movement in excess of what might be considered safe for patients in MRI at 1.5-, 3- and 7-Tesla. At 3-T, the maximum temperature increase of five bullets tested was 1.7°C versus background heating of 1.5°C. Of five bullets tested for artifacts, those without a steel core exhibited small signal voids, whereas a single steel core bullet exhibited a very large signal void. Conclusions: Ballistics made of lead with copper or alloy jackets appear to be safe with respect to MRI-related movement at 1.5-, 3-, and 7-T static magnetic fields, whereas ballistics containing steel may pose a danger if near critical body structures because of strong magnetic field interactions. Temperature increases of selected ballistics during 3-T MRI was not clinically significant, even for the ferromagnetic projectiles. Finally, ballistics containing steel generated larger artifacts when compared with ballistics made of lead with copper and alloy jackets and may impair the diagnostic use of MRI.

Obese Class III Patients at Significantly Greater Risk of Multiple Complications After Lumbar Surgery: An Analysis of 10,387 Patients in the ACS-NSQIP Database

December 2013


110 Reads

Prior studies on the impact of obesity on spine surgery outcomes have focused mostly on lumbar fusions, do not examine lumbar discectomies or decompressions, and have shown mixed results regarding complications. Differences in sample sizes as well as differences in the BMI thresholds for the definition of the obese vs. comparison cohorts could account for the inconsistencies in the literature. To analyze whether different degrees of obesity influence the complication rates in patients undergoing lumbar spine surgery. Retrospective cohort analysis of prospectively collected data using the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database from 2005 to 2010. Patients in the de-identified, risk-adjusted, and multi-institutional ACS-NSQIP database undergoing lumbar anterior fusion, posterior fusion, TLIF/PLIF, discectomy, or decompression. Primary outcome measures were 30-day post-surgical complications, including PE, DVT, death, system-specific complications (wound, pulmonary, urinary, CNS, cardiac), septic complications and having ≥ 1 complication overall. Secondary outcomes were time spent in the operating room, blood transfusions, length of stay, and re-operation within 30 days. Patients undergoing lumbar anterior fusion, posterior fusion, TLIF/PLIF, discectomy, or decompression in the ACS-NSQIP, 2005-2010 were categorized into 4 BMI groups: non-obese (18.5-29.9 kg/m(2)), obese I (30-34.9 kg/m(2)), obese II (35-39.9 kg/m(2)), obese III (≥40 kg/m(2)). Obese I-III patients were compared to patients in the non-obese category using χ(2) and ANOVA. Multivariate linear/logistic regression models were used to adjust for preoperative risk factors. The authors report no sources of funding or conflicts of interest related to this study. Data was available for 10,387 patients undergoing lumbar surgery. Of these, 4.5% underwent anterior fusion, 17.9% posterior fusion, 6.3% TLIF/PLIF, 40.7% discectomy, 30.5% decompression. Among all patients, 25.6% were obese I, 11.5% obese II, and 6.9% obese III. On multivariate analysis, obese I and III had a significantly increased risk of urinary complications and obese II and III patients had a significantly increased risk of wound complications. Only obese III patients, however, had a statistically increased risk of having increased time spent in the operating room, an extended length of stay, pulmonary complications and of having ≥ 1 complication (all p < .05). Patients with high BMI appear to have higher complication rates after lumbar surgery than patients who are non-obese. However, the complication rates seem to increase substantially for obese III patients. These patients have longer times spent in the operating room, extended hospitals stays and an increased risk for wound, urinary, pulmonary complications and for having at least one or more complication overall. Surgeons should be aware of the increased risk of multiple complications for patients with BMI ≥ 40 kg/m(2).

Alterations of the biomarker S-100B and NSE in patients with acute vertebral spine fractures

April 2014


53 Reads

Background Context Although several publications concerning the use of the biomarkers S100B and NSE in vertebral spine fractures in animal experimental studies have proven their usefulness as early indicators of injury severity, there are no clinical reports on their effectiveness as indicators in patients with spinal injuries. As these biomarkers have been examined–with promising results–in patients with traumatic brain injury (TBI), there is a potential for their implementation in patients with vertebral spine fractures. Purpose To investigate the early serum measurement of S100B and NSE in patients with vertebral spine fractures as compared to those in patients with acute fractures of the proximal femur. Study Design Prospective longitudinal cohort study. Patient Sample A cohort of 34 patients admitted over an 18-month period to a single medical center for suspected vertebral spine trauma. 29 patients were included in the control group. Outcome Measures S100B and NSE serum levels were assessed in different types of vertebral spine fractures. Methods We included patients over 16 years of age with vertebral spine fractures whose injuries were sustained within 24 hours prior to admission to the emergency room, and who had undergone a brief neurological examination. Spinal cord injuries were classified as being either paraesthesias, incomplete paraplegias or complete paraplegias. Blood serum was obtained from all patients within 24 hours after time of injury. Serum levels of S100B and NSE were statistically analyzed using Wilcoxon tests. Results S100B serum levels were significantly higher in patients with vertebral spine fractures (p=0.01). In these patients, the mean S100B serum level was 0.75 μg/L (SD 1.44) [95% CI 0.24; 1.25]. The mean S100B serum level in control group patients was 0.14 μg/L (SD 0.11) [0.10; 0.19]. The 10 patients with neurological deficits had significantly higher S100B serum levels when compared to the patients with vertebral fractures but without neurological deficits (p=0.02). The mean S100B serum level in these patients was 1.18 μg/L (SD 1.96). In the 26 patients with vertebral spine fractures but without neurological injury, the mean S100B serum level was 0.42 μg/L (SD 0.91) [95% CI 0.08; 0.76]. The analysis revealed no significant difference in NSE levels. Conclusions Not only did we observed a significant correlation between S100B serum levels and vertebral spine fractures, a significant correlation was also seen between S100B serum levels and spinal cord injuries with neurological deficit. These results may be meaningful in clinical practice, and to future studies as well.

Table 1 Inclusion and exclusion criteria
Table 2 Overall sex life as reported using ODI item 8 
Table 3 Change in ODI 8 postoperatively 
101. Sex Life and Sexual Function in Men and Women before and after Total Disc Replacement Compared to Posterior Lumbar Fusion

October 2009


3,602 Reads

Sex life and sexual function may be affected by low back pain (LBP). Sexual dysfunction after anterior lumbar fusion is reported in both men and women, but focus is mainly on impaired male biological function (retrograde ejaculation) as this may cause infertility. This has led to concern as to whether anterior surgery should be employed in men, at least in younger age groups. To investigate how chronic low back pain (CLBP) of assumed discogenic origin affects sex life and sexual function in patients considered for surgical treatment, whether this is affected by surgical treatment (total disc replacement [TDR] or posterolateral fusion [PLF]/posterior lumbar interbody fusion [PLIF]), and if so, are there differences between the surgical procedures undertaken. A randomized controlled trial comparing TDR and instrumented lumbar spine fusion, performed either as a PLF or PLIF. One hundred fifty-two patients were included in this randomized controlled trial to compare the effect on CLBP of either TDR via an anterior retroperitoneal approach or instrumented posterior lumbar fusion, PLF or PLIF. Global assessment of back pain, back pain (visual analog scale [VAS] 0-100), function (Oswestry Disability Index [ODI] 0-100), quality of life (EQ5D [EuroQol] 0-1), and answers on specific sexual function. Outcome was assessed using data from the Swedish Spine Register (SweSpine). In ODI, one question, ODI 8, reflects the impact of back pain on sex life. This question was analyzed separately. Patients also answered a gender-specific questionnaire preoperatively and at the 2-year follow-up to determine any sexual dysfunction regarding erection, orgasm, and ejaculation. Follow-up was at 1 and 2 years. Before surgery, 34% reported that their sex life caused some extra LBP, and an additional 30% that their sex life was severely restricted by LBP. After surgery, sex life improved in both groups, with a strong correlation to a reduction of LBP. The gender-specific questionnaire used to measure sexual function after 2 years revealed no negative effect of TDR or Fusion in men regarding erection or retrograde ejaculation. However, 26% of all men in the Fusion group, compared with 3% in the TDR group, reported postoperative deterioration in the ability to achieve orgasm, despite a reduction of LBP. Impairment of sex life appears to be related to CLBP. An improvement in sex life after TDR or lumbar fusion was positively correlated to a reduction in LBP. Total disc replacement in this study, performed through an anterior retroperitoneal approach, was not associated with greater sexual dysfunction compared with instrumented lumbar fusion performed either as a PLF or as a PLIF. Sexual function, expressed as orgasm, deteriorated in men in the Fusion group postoperatively, in spite of this group reporting less LBP after 2 years.

Outcomes of percutaneous rupture of lumbar synovial cysts: A case series of 101 patients

September 2009


1,104 Reads

Lumbar facet joint synovial cysts are benign degenerative abnormalities of the lumbar spine. Previous reports have supported operative and nonoperative management. Facet joint steroid injection with cyst rupture is occasionally performed, but there has been no systematic evaluation of this treatment option. To profile the role of facet joint steroid injections with cyst rupture in the treatment of lumbar facet joint synovial cysts. Retrospective chart review and long-term follow-up of patients treated for lumbar facet joint synovial cysts. One hundred one patients treated for lumbar facet joint synovial cysts with fluoroscopically guided corticosteroid facet joint injection and attempted cyst rupture. Oswestry Disability Index and numeric rating scale score for back and leg pain. A retrospective review and a subsequent interview were conducted to collect pretreatment and posttreatment pain and disability scores along with details of subsequent treatment interventions. Group differences in pain and disability scores were assessed using paired t test. Multiple clinical factors were analyzed in terms of risk for surgical intervention using logistic regression modeling and Cox proportional hazards modeling. Successful cyst rupture was confirmed fluoroscopically in 81% of cases. Fifty-five patients (54%) required subsequent surgery over a period averaging 8.4 months because of inadequate symptom relief. All patients reported significant improvement in back pain, leg pain, and disability at 3.2 years postinjection, regardless of their subsequent treatment course (p<.0001 in all groups). There was no significant difference in current pain between patients who received injections only and those who underwent subsequent surgery. This study presents the largest clinical series of nonsurgical treatment for lumbar facet joint synovial cysts. Lumbar facet joint steroid injection with attempted cyst rupture is correlated with avoiding subsequent surgery in half of treated patients. Successful cyst rupture does not appear to have added benefit, and it was associated with worse disability 3 years postinjection. Long-term outcomes are similar, regardless of subsequent surgery.

Disc bulge bubble: Spine economics 101

November 2004


44 Reads

The spine market is a complex economic model that does not conform to many classical economic theories. The outlook for the spine market is, however, very optimistic. One important factor contributing to this optimistic growth is its multidisciplinary nature. Spinal procedures are performed by orthopedists, neurosurgeons, anesthesia pain management interventionalists, interventional radiologists and physiatrists. These physicians, however, must be aware of premium implant pricing and minor design or cosmetic changes marketed and associated with premium pricing. The benefits of premium implants or devices may not be appropriate for all patients. Programs to define which patients would benefit from premium implants or devices can help keep costs in check. Physicians drive demand, medical device manufacturers drive supply and hospitals are frequently left to shoulder the escalating costs. Controlling implant costs will be critical to maintaining the level of service available. Implant costs can be controlled by fair negotiation between vendors and hospitals, by limiting vendors, by avoiding premium implants and by involving the physicians in the purchasing process. If all parties involved in the spine market are vigilant in not letting the spine market turn into a cancer, then the "disc bulge bubble" will not burst.

No difference in long-term trunk muscle strength, cross-sectional area, and density in patients with chronic low back pain 7 to 11 years after lumbar fusion versus cognitive intervention and exercises

August 2011


118 Reads

Reduced muscle strength and density observed at 1 year after lumbar fusion may deteriorate more in the long term. To compare the long-term effect of lumbar fusion and cognitive intervention and exercises on muscle strength, cross-sectional area, density, and self-rated function in patients with chronic low back pain (CLBP) and disc degeneration. Randomized controlled study with a follow-up examination at 8.5 years (range, 7-11 years). Patients with CLBP and disc degeneration randomized to either instrumented posterolateral fusion of one or both of the two lower lumbar levels or a 3-week cognitive intervention and exercise program were included. Isokinetic muscle strength was measured by a Cybex 6000 (Cybex-Lumex, Inc., Ronkonkoma, NY, USA). All patients had previous experience with the test procedure. The back extension (E) flexion (F) muscles were tested, and the E/F ratios were calculated. Cross-sectional area and density of the back muscles were measured at the L3-L4 segment by computed tomography. Patients rated their function by the General Function Score. Trunk muscle strength, cross-sectional area, density, and self-rated function. Fifty-five patients (90%) were included at long-term follow-up. There were no significant differences in cross-sectional area, density, muscle strength, or self-rated function between the two groups. The cognitive intervention and exercise group increased trunk muscle extension significantly (p<.05), and both groups performed significantly better on trunk muscle flexion tests (p<.01) at long-term follow-up. On average, self-rated function improved by 56%, cross-sectional area was reduced by 8.5%, and muscle density was reduced by 27%. Although this study did not assess the morphology of muscles likely damaged by surgery, trunk muscle strength and cross-sectional area above the surgical levels are not different between those who had lumbar fusion or cognitive intervention and exercises at 7- to 11-year follow-up.

Ischemic Stroke after Cervical Spine Injury: Analysis of 11,005 Patients Using the Japanese Diagnosis Procedure Combination Database.

January 2014


84 Reads

The incidence and relevant risk of ischemic stroke following cervical spine trauma remain unknown. To examine the incidence of ischemic stroke during hospitalization in patients with cervical spine injury and analyze the impact of different types of cervical spine injury on the occurrence of ischemic stroke. Study Design/Setting: Retrospective analysis of data abstracted from the Diagnosis Procedure Combination database, a nationally representative database in Japan. We included all patients hospitalized for any of the following traumas: fracture of cervical spine (International Classification of Diseases, 10th Revision codes: S120, S121, S122, S127, S129); dislocation of cervical spine (S131, S133); cervical spinal cord injury (S141). Outcome measures included all-cause in-hospital mortality and incidence of ischemic stroke (I63) during hospitalization. We analyzed the effects of age, sex, comorbidities, smoking status, spinal surgery, consciousness level at admission, and type of cervical spine injury on outcomes. This study was funded by a research grant from the Ministry of Health, Labour, and Welfare and the Council for Science and Technology Policy. There were no potential conflicts of interest to disclose. We identified 11,005 patients with cervical spine injury (8,031 men, 2,974 women; mean [standard deviation] age, 63.5 [18] years). According to the types of cervical spine injury, we stratified the patients into three groups: 1) cervical fracture and/or dislocation without spinal cord injury (SCI) (2,363 patients); 2) cervical fracture and/or dislocation associated with SCI (1,283 patients); and 3) cervical SCI without fracture and/or dislocation (7,359 patients). Overall, ischemic stroke occurred in 115 (1.0%) patients during hospitalization (median length of stay, 26 days). In-hospital death occurred in 456 (4.1%) patients. Multivariate analyses showed that ischemic stroke after cervical spine injury was significantly associated with age, diabetes, and consciousness level at admission. The highest in-hospital mortality was observed in patients with cervical fracture and/or dislocation associated with SCI (7.6%), followed by cervical SCI without fracture and/or dislocation (4.0%), and cervical fracture and/or dislocation without SCI (2.6%). Unlike mortality, risks of stroke did not vary significantly among the three groups. This analysis revealed that ischemic stroke following cervical spine injury was not uncommon and was associated with increased mortality and morbidity. Occurrence of ischemic stroke was significantly associated with age, comorbidities such as diabetes, and consciousness level at admission, but not with type of spine injury.

Assessment of pedicle screw placement accuracy in thoracolumbosacral spine using freehand technique aided by lateral fluoroscopy: Results of postoperative computed tomography in 114 patients

December 2014


54 Reads

Pedicle screw fixation is currently widely used in spine surgery for various pathologies. Increasing screw placement accuracy would improve outcomes. To determine the accuracy rate of screw placement in a group of patients who underwent pedicle screw fixation with conventional techniques. Study Design/Setting: Case series. Patients undergoing posterior spinal fixation with pedicle screw insertion. Outcome measures: The accuracy of screw placement in pedicles defined by post-operative CT. After surgery, an axial thin cut CT scan was performed in all patients. Screw position was classified as correct when the screw was completely surrounded by the pedicle cortex, and incorrect when any part of the screw was outside the pedicle boundaries. The study had no specific funding source and the authors had no conflict of interest. 770 screws were inserted at vertebral levels T7 to S1 of 114 patients between March 2012 and December 2012. There were 3 wound infections and one death. 18 screws were diagnosed as having an incorrect position (2.3%). The highest accuracy was observed in levels L4 and L5 (0.8% inaccuracy rate for each), while the highest inaccuracy rate was observed in T9. The mean inaccuracy rate was 10.5% for levels T7-T9, 3.5% for levels T10-L2, and 0.9% for levels L3-S1. The differences were statistically significant. Only 1 screw (5%) needed revision. The results of our study show that conventional methods for pedicle screw placement remain safe and accurate, with best results obtained in the lumbosacral spine, followed by the thoracolumbar junction. Nonetheless, results are less accurate in the mid thoracic spine. Copyright © 2014 Elsevier Inc. All rights reserved.

Quality of Life in Normal and Idiopathic Scoliosis Adolescents before diagnosis: reference values and discriminative validity of the SRS-22. A cross-sectional study of 1205 pupils.

December 2014


152 Reads

The Scoliosis Research Society (SRS) SRS-22 Questionnaire has shown to worsen with increasing deformity in Adolescents with Idiopathic Scoliosis (AIS). However, all studies have been performed on patients who have already been diagnosed and in relatively small samples. To evaluate a large sample of consecutive patients before diagnosis to develop reference values, and to check the discriminative validity and correlation with deformity of the SRS-22. Cross-sectional study, specialized outpatients scoliosis rehabilitation institute. 1,205 consecutive adolescents, 75% females (13.7±1.9 years), before their first scoliosis evaluation. Five subgroups: 0-10° Cobb (normals), and 11-20°, 21-30°, 31-40°, and >40°. SRS-22 questionnaire. The SRS-22 was used to examine the differences between the domains of the 5 subgroups and total scores, and it was correlated with Cobb degrees and curve location. We used one way ANOVA and Spearman's rho test. Apart from the Self-image domain in both genders and all subgroups, all other scores were above 4 points with small standard deviations. Females showed significant differences among groups for all domains and total score (p<0.05). In males, Function, Pain and Mental Health did not show statistically significant differences among groups (p>0.1). All differences found were below the minimally clinically significant change (0.5 points). The correlations with the severity of deformity measures were very low (rs<0.289). According to our results, deformity is apparently not a real issue for AIS before diagnosis made, treatment planned and/or specialists interfere with their everyday life. SRS-22 demonstrated some discriminative validity between small and large curves, but the differences found were small. Copyright © 2014 Elsevier Inc. All rights reserved.

Summary of study results
Accuracy of Fluoroscopically Assisted Pedicle Screw Placement: Analysis of 1218 Screws in 198 Patients

April 2014


90 Reads

We retrospectively analyzed a total of 1218 pedicle screws for accuracy, with postoperative computed tomography, in 198 patients who were operated on between March of 2004 and September of 2012. The purpose of this study was to determine the incidence of screw misplacement in patients who received a transpedicular screw fixation with intraoperative fluoroscopy in the lateral and lateral with anteroposterior positions. The results are compared between two groups. Retrospective comparative study of accuracy of pedicle screw placement in thoracal and lumbar spine. The sample consists of 198 consecutive patients who underwent transpedicular screw fixation. Accuracy of screw placement was evaluated by postoperative CT scan. Misplacement was defined in cases where more than 25% of the screw size was residing outside of the pedicle. The indications for hardware placement, radiologic studies, patient demographics, and reoperation rates were recorded. Five hundred and twenty-eight screws (Group A, n=81) were inserted into the vertebral body with the assistance of lateral fluoroscopy only, whereas six hundred and ninety screws (Group B, n=117) were inserted with the assistance of lateral fluoroscopy, and the final positions of the screws were checked with anteroposterior fluoroscopy. A total of 1218 screws were analyzed, with 962 screws having been placed at the lumbosacral region, and 256 screws at the thoracal region. According to the postoperative CT-scan, twenty-seven screws (2.2%) were identified as breaching the pedicle. Nineteen of them (3.6%) were in Group A, whereas eight of them (1.16%) were in Group B. The rate of pedicle breaches was significantly different between Group A and Group B (p=0.0052). In Group A, the lateral violation of the pedicle was seen in 10 screws (1.9%), whereas the medial violation was seen in 9 screws (1.7%). In Group B, the lateral violation of the pedicle was seen in 6 screws (0.87%), whereas the medial violation was seen in 2 screws (0.29%). The medial and lateral penetration of screws was significantly different between Groups A and B (p<0.05). A pedicle breach occurred in 21 patients, and 15 of them underwent a revision surgery to correct the misplaced screw. Of these patients 11 of them (13.6%) were in Group A, and 4 of them (3.4%) were in Group B (p=0.0335). In this study we evaluated and clarified the diagnostic value of intra-operative fluoroscopy in both the lateral and anteroposterior imaging, which have not yet been evaluated in any comparative study. We concluded that the intraoperative use of fluoroscopy, especially in the anteroposterior position, significantly decreases the risk of screw misplacement and the results are comparable with other advanced techniques.

Anatomical considerations for cervical pedicle screw insertion: The use of multiplanar computerized tomography measurements in 122 consecutive clinical cases

September 2009


127 Reads

Successful placement of pedicle screws in the cervical spine requires a sufficient three-dimensional understanding of pedicle morphology to allow accurate identification of the screw axis. The goal of the present study was to assess morphologic trends from one level to the next with respect to linear and angular parameters associated with the subaxial cervical pedicles. We evaluated the pedicle morphology of cervical spine using axial and sagittal computed tomography (CT) imaging. The C3-C7 vertebrae in 122 patients (610 vertebrae) were evaluated (age range, 14-93; mean, 48 years). Thin cut (2.5mm thickness) axial CT images were measured. Sagittal reconstructions were obtained using 1.25-mm thickness slices. The following pedicle parameters were assessed: pedicle width (PW, the mediolateral diameter of the pedicle isthmus, perpendicular to the pedicle axis), pedicle height (PH, rostro-caudal dimension of the pedicle determined on the sagittal image), maximal screw length (MSL, distance from the posterior cortex of the lateral mass to the anterior wall of the vertebral body along the pedicle axis), and pedicle transverse angle (PTA, angle between the pedicle axis and the midline vertebral body). The overall mean PW and PH ranged from 4.7 to 6.5mm and 6.4 to 7.0mm, respectively. For both these parameters there was a trend toward increasing size proceeding caudally in the cervical spine. The mean PW and PH was greater in males than in females, and this difference was statistically significant at all levels (p<.0001). The overall mean MSL ranged from 29.9 to 32.9 mm. All intersections of the pedicle axis and the posterior cortex of the lateral mass were located at the most lateral portion of the lateral mass for the C3-C6 vertebrae. The overall mean PTA ranged from 37.8 degrees to 45.3 degrees . The overall mean PTA was approximately 44 degrees from C3 to C6 and 37.8 degrees at C7. The findings of our radiological anatomical study suggest that the preoperative CT scans of patients undergoing cervical transpedicular fixation should be thoroughly analyzed and close attention paid to the pedicle size and its angulation. The placement of cervical pedicle screws should be individualized for each patient and based on detailed preoperative planning.

124. The Minimum Clinically Important Difference in Lumbar Spine Surgery Patients: A Choice of Methods Using the Oswestry Disability Index, MOS Short Form-36, and Pain Scales

February 2008


1,456 Reads

Background context: The impact of lumbar spinal surgery is commonly evaluated with three patient-reported outcome measures: Oswestry Disability Index (ODI), the physical component summary (PCS) of the Short Form of the Medical Outcomes Study (SF-36), and pain scales. A minimum clinically important difference (MCID) is a threshold used to measure the effect of clinical treatments. Variable threshold values have been proposed as MCID for those instruments despite a lack of agreement on the optimal MCID calculation method. Purpose: This study has three purposes. First, to illustrate the range of values obtained by common anchor-based and distribution-based methods to calculate MCID. Second, to determine a statistically sound and clinically meaningful MCID for ODI, PCS, back pain scale, and leg pain scale in lumbar spine surgery patients. Third, to compare the discriminative ability of two anchors: a global health assessment and a rating of satisfaction with the results of the surgery. Study design: This study is a review of prospectively collected patient-reported outcomes data. Patient sample: A total of 454 patients from a large database of surgeries performed by the Lumbar Spine Study Group with a 1-year follow-up on either ODI or PCS were included in the study. Outcome measures: Preoperative and 1-year postoperative scores for ODI, PCS, back pain scale, leg pain scale, health transition item (HTI) of the SF-36, and Satisfaction with Results scales. Methods: ODI, SF-36, and pain scales were administered before and 1 year after spinal surgery. Several candidate MCID calculation methods were applied to the data and the resulting values were compared. The HTI of the SF-36 was used as the anchor and compared with a second anchor (Satisfaction with Results scale). Results: Potential MCID calculations yielded a range of values: fivefold for ODI, PCS, and leg pain, 10-fold for back pain. Threshold values obtained with the two anchors were very similar. Conclusions: The minimum detectable change (MDC) appears as a statistically and clinically appropriate MCID value. MCID values in this sample were 12.8 points for ODI, 4.9 points for PCS, 1.2 points for back pain, and 1.6 points for leg pain.

Spinal Epidural Abscesses: Risk Factors, Medical vs Surgical Management, A Retrospective Review of 128 Cases.

November 2013


167 Reads

Spinal epidural abscess (SEA) is a rare, serious and increasingly frequent diagnosis. Ideal management (medical vs surgical) remains controversial. The purpose of this study is to assess the impact of risk factors, organisms, location and extent of SEA on neurological outcome after medical management or surgery in combination with medical management. Retrospective electronic medical record (EMR) review PATIENT SAMPLE: 128 consecutive spontaneous SEA from a single tertiary medical center, Jan 05-Sept 11, 79 male, 49 female, age 22-83 years (mean 52.9) OUTCOME MEASURES: Patient demographics, presenting complaints, radiographic features, pre/post-treatment neurological status (ASIA motor score (MS) 0-100), treatment (medical vs. surgical) and clinical follow-up were recorded. Neurological status was determined before treatment and at last available clinical encounter. Imaging studies reviewed location/extent of pathology. Inclusion criteria: diagnosis of a bacterial SEA based on radiographs and/or intra-op findings, age >18 years, and adequate EMR. Exclusion criteria: post interventional infections, Pott's disease, isolated discitis/osteomyelitis, treatment initiated at an outside facility, and imaging suggestive of a SEA but negative intra-op findings/cultures. Mean follow-up 241 days. Presenting chief complaint: site-specific pain (100%), subjective fevers (50%), weakness (47%). 54.7% had lumbar, 39.1% thoracic, 35.9% cervical, and 23.4% sacral involvement spanning an average of 3.85 disc levels. 36% ventral, 41% dorsal, 23% circumferential. Risk factors: history of IV drug abuse (39.1%), diabetes mellitus (21.9%), and no risk factors (22.7%). Pathogen: MSSA (40%), MRSA (30%). Location, SEA extent and pathogen did not impact MS recovery. 51 patients were treated with antibiotics alone (group 1), 77 with surgery and antibiotics (group 2). Within group 1, 21 patients (41%) failed medical management (progressive MS loss or worsening pain) requiring delayed surgery (group 3). Irrespective of treatment, MS improved 3.37 points. 30 patients had successful medical management (MS: pre-treatment 96.5, post-treatment 96.8). 21 patients failed medical therapy (41%), (MS: pre-treatment 99.86, decreasing to 76.2 (mean change -23.67 points), post-surgery improvement to 85.0, net deterioration of -14.86 points). This is significantly worse than the mean improvement of immediate surgery (group 2) (MS: pre-treatment 80.32, post-treatment 89.84, recovery of 9.52 points). Diabetes mellitus, CRP >115, WBC >12.5 and positive blood cultures predict medical failure; 0 of 4 parameters: 8.3% failure; 1 parameter: 35.4% failure; 2 parameters: 40.2% failure; 3 or more parameters: 76.9% failure. Early surgery improves neurological outcomes compared with surgical treatment delayed by a trial of medical management. Over 41% of patients treated medically failed management and required surgical decompression. Diabetes, CRP >115, WBC >12.5, and bacteremia predict failure of medical management. If a SEA is to be treated medically, great caution and vigilance must be maintained. Otherwise, early surgical decompression, irrigation, and debridement should be the mainstay of treatment. LEVEL OF EVIDENCE: III.

128. Two Year Fusion and Clinical Outcomes in 224 Patients Treated with a Single-level Instrumented Posterolateral Fusion with ICBG

June 2009


50 Reads

Reported fusion rates for spine fusions using iliac crest bone graft (ICBG) vary between 40% and 100% because of different fusion techniques, patient comorbidity, diagnosis and assessment criteria. We report two-year results of single-level instrumented posterolateral fusions evaluated with radiographs, fine-cut computed tomography (CT) scans with reconstructions and outcome measures. STUDY DESIGN/ SETTING: Retrospective analysis of data from a prospective multicenter randomized clinical controlled trial. Patients with various degenerative diagnoses enrolled in the control arm of a Food and Drug Administration (FDA)-regulated, multicenter trial of single-level decompression and posterolateral fusion for degenerative lumbar disease. Short Form-36 (SF-36), Oswestry Disability Index (ODI), Numeric Rating Scales (0-20) for back, leg, and graft site pain, CT scans, anteroposterior and lateral flexion/extension radiographs. Patients enrolled in an FDA-regulated, multicenter trial at 29 sites with degenerative lumbar disease treated with single-level instrumented posterolateral fusion with ICBG were included in the analysis. Demographic and surgical data were collected. Clinical outcomes were followed using standard metrics. Fusion was assessed by independent radiologists at 6, 12, and 24 months postoperatively. Two fusion criteria were compared: anteroposterior and flexion/extension radiographs to assess motion and bridging bone, with CT scans as needed to confirm bridging bone; and CT scan assessment for bridging bone only. One hundred ninety-four of 224 subjects (86.6%) completed the study. The mean operative time was 2.9 hours with a blood loss of 448.6 mL. The average graft volume was 36.3 mL. There were 21 (9.4%) wound infections, 18 (8.0%) incidental durotomies, 3 (1.3%) implant displacements, 2 (0.9%) malpositioned implants, and 17 (7.6%) graft-related complications. Twenty-seven patients (13.9%) required reoperation, the majority for nonunions. Fusion rates based on radiographs with selective CTs at 6, 12, and 24 months were 65.3%, 82.5%, and 89.3%, respectively. Fusion rates based on bridging bone on CT scans were 56.1%, 71.5%, 83.9%, respectively. Two-year improvement for all outcome measures was significant (p<.001)-ODI 25.3, SF-36 Physical Component Score (PCS) 12.2, back pain 7.9, and leg pain 7.1. Two years postoperatively, 60% of patients complained of graft site pain (mean pain score=8.5). In a large series of patients who had primary single-level instrumented posterolateral fusion with ICBG, evidence of bridging bone on fine-cut CT scans improved with time to 83.9% at 24 months. Significant improvement from baseline was noted in all clinical outcome measures at all time intervals with 75% achieving minimum clinically important difference (MCID) for ODI and 66% achieving MCID for SF-36 PCS.

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