Peter G Passias

NYU Langone Medical Center, New York City, New York, United States

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Publications (37)84.81 Total impact

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    ABSTRACT: The aim of this study is to report and quantify the associated factors for morbidity and mortality following surgical management of cervical spondylotic myelopathy (CSM). The Nationwide Inpatient Sample (NIS) database was use to retrospectively review all patients over 25 years of age with a diagnosis of CSM who underwent anterior and/or posterior cervical fusion or laminoplasty between 2001 and 2010. The main outcome measures were total procedure-related complications and mortality. Multivariate regression analysis was used to identify demographic, comorbidity, and surgical parameters associated with increased morbidity and mortality risk [reported as: OR (95 % CI)]. A total of 54,348 patients underwent surgical intervention for CSM with an overall morbidity rate of 9.83 % and mortality rate of 0.43 %. Comorbidities found to be associated with an increased complication rate included: pulmonary circulation disorders [6.92 (5.91-8.12)], pathologic weight loss [3.42 (3.00-3.90)], and electrolyte imbalance [2.82 (2.65-3.01)]. Comorbidities found to be associated with an increased mortality rate included: congestive heart failure [4.59 (3.62-5.82)], pulmonary circulation disorders [11.29 (8.24-15.47)], and pathologic weight loss [5.43 (4.07-7.26)]. Alternatively, hypertension [0.56 (0.46-0.67)] and obesity [0.36 (0.22-0.61)] were found to confer a decreased risk of mortality. Increased morbidity and mortality rates were also identified for fusions of 4-8 levels [morbidity: 1.55 (1.48-1.62), mortality: 1.80 (1.48-2.18)] and for age >65 years [morbidity: 1.65 (1.57-1.72), mortality: 2.74 (2.25-3.34)]. An increased morbidity rate was found for posterior-only [1.55 (1.47-1.63)] and combined anterior and posterior fusions [3.20 (2.98-3.43)], and an increased mortality rate was identified for posterior-only fusions [1.87 (1.40-2.49)]. Although revision fusions were associated with an increased morbidity rate [1.81 (1.64-2.00)], they were associated with a decreased rate of mortality [0.24 (0.10-0.59)]. The NIS database was used to provide national estimates of morbidity and mortality following surgical management of CSM in the United States. Several comorbidities, as well as demographic and surgical parameters, were identified as associated factors.
    European Spine Journal 05/2015; DOI:10.1007/s00586-015-4010-2 · 2.47 Impact Factor
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    ABSTRACT: Cervical Deformity (CD) is prevalent among patients with adult spinal deformity (ASD). The effect of baseline cervical alignment on achieving optimal thoracolumbar alignment in ASD surgery is unclear. This study assesses the relationship between pre-operative cervical spinal parameters and global alignment following thoracolumbar ASD surgery at 2-year follow up. A retrospective review of a multi-center, prospective database. Surgical ASD patients with 2-year follow-up and cervical x-rays. The outcome measure was radiographic parameters and self-reported HRQL measures (SF-36, ODI and SRS-22). Surgical ASD patients over the age of 18 with scoliosis ≥20° and one of the following radiographic parameters were included: SVA ≥5cm, pelvic tilt ≥25° or thoracic kyphosis >60°. SRS-Schwab sagittal modifiers (PT, GA, PI-LL) were assessed at 2-year post-op as either normal ("0") or abnormal ("+" or "++"). Patients were classified in the Aligned Group (AG) or Malaligned Group (MG) at 2-year follow-up if all 3 sagittal modifiers were normal or abnormal, respectively. Patients were assessed for CD based on the following criteria: C2-C7 SVA >4cm, C2-C7 SVA <4cm, cervical kyphosis (CL >0), cervical lordosis (CL <0), any deformity (C2-C7 SVA >4cm OR CL >0), and both CD (C2-C7 SVA >4cm AND CL >0). Univariate testing was performed using t-tests or chi square, looking at the following pre-op parameters: CD, C2-C7 SVA, C2-T3 SVA, CL, T1S, T1S-CL, C2-T3 angle, LL, TK, PT, C7-S1 SVA, and PI-LL. No study funding sources are related to this clinical study. The International Spine Study Group (ISSG) is funded through research grants from DePuy-Synthes and individual donations. 104 patients met initial inclusion criteria with 70 in the AG group and 34 in MG. Pre-op, patients in the MG group had a higher cervical lordosis (11.7 vs 4.9, p=0.03), higher C2-T3 angle (13.59 vs 4.9 p=0.01), higher PT (p<0.0001), higher SVA (p<0.0001), and higher PI-LL (p<0.0001) compared to the AG group. Interestingly, the prevalence of CD at baseline was similar for both groups. There was no statistically significant difference among groups in the amount of improvement over 2 years on the ODI or the SF-36 PCS. Patients with sagittal spinal mal-alignment associated with significant cervical compensatory lordosis are at increased risk of realignment failure at 2 year follow up. Assessment of the degree of cervical compensation may be helpful in preoperative evaluation to assist in realignment outcome prediction. Copyright © 2015 Elsevier Inc. All rights reserved.
    The spine journal: official journal of the North American Spine Society 04/2015; DOI:10.1016/j.spinee.2015.04.007 · 2.80 Impact Factor
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    ABSTRACT: OBJECT Alignment changes in the cervical spine that occur following surgical correction for thoracic deformity remain poorly understood. The purpose of this study was to evaluate such changes in a cohort of adults with thoracic deformity treated surgically. METHODS The authors conducted a multicenter retrospective analysis of consecutive patients with thoracic deformity. Inclusion criteria for this study were as follows: corrective osteotomy for thoracic deformity, upper-most instrumented vertebra (UIV) between T-1 and T-4, lower-most instrumented vertebra (LIV) at or above L-5 (LIV ≥ L-5) or at the ilium (LIV-ilium), and a minimum radiographic follow-up of 2 years. Sagittal radiographic parameters were assessed preoperatively as well as at 3 months and 2 years postoperatively, including the C-7 sagittal vertical axis (SVA), C2-7 cervical lordosis (CL), C2-7 SVA, T-1 slope (T1S), T1S minus CL (T1S-CL), T2-12 thoracic kyphosis (TK), apical TK, lumbar lordosis (LL), pelvic incidence (PI), PI-LL, pelvic tilt (PT), and sacral slope (SS). RESULTS Fifty-seven patients with a mean age of 49.1 ± 14.6 years met the study inclusion criteria. The preoperative prevalence of increased CL (CL > 15°) was 48.9%. Both 3-month and 2-year apical TK improved from baseline (p < 0.05, statistically significant). At the 2-year follow-up, only the C2-7 SVA increased significantly from baseline (p = 0.01), whereas LL decreased from baseline (p < 0.01). The prevalence of increased CL was 35.3% at 3 months and 47.8% at 2 years, which did not represent a significant change. Postoperative cervical alignment changes were not significantly different from preoperative values regardless of the LIV (LIV ≥ L-5 or LIV-ilium, p > 0.05 for both). In a subset of patients with a maximum TK ≥ 60° (35 patients) and 3-column osteotomy (38 patients), no significant postoperative cervical changes were seen. CONCLUSION Increased CL is common in adult spinal deformity patients with thoracic deformities and, unlike after lumbar corrective surgery, does not appear to normalize after thoracic corrective surgery. Cervical sagittal malalignment (C2-7 SVA) also increases postoperatively. Surgeons should be aware that spontaneous cervical alignment normalization might not occur following thoracic deformity correction.
    Journal of neurosurgery. Spine 03/2015; DOI:10.3171/2014.10.SPINE14829 · 2.36 Impact Factor
  • Deng Zhao, Shenglin Wang, Peter G Passias, Chao Wang
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    ABSTRACT: Our clinical understanding of os odontoideum (OO) remains incomplete. Congenital and traumatic causes have been proposed and advocated. Clinical presentations range from asymptomatic to axial pain to myelopathy or vertebral-basilar ischemia. A consensus for surgical management exists for those found to have an unstable atlantoaxial complex or symptomatic cranial-vertebral junction compression. To evaluate the clinical presentation and surgical outcomes of patients with OO and an unstable atlantoaxial complex or symptomatic cranial-vertebral junction compression. Patients with a diagnosis of OO who underwent surgical management were included. Patients were excluded on the basis of previous C2 fracture, Fielding diagnostic criteria, and inadequate follow-up. History of trauma and presenting symptoms were assessed. Clinical and neurological improvements were measured with the use of patient satisfaction scores and the Japanese Orthopaedic Association scores. Fusion status was documented with the use of radiographs and computed tomographic imaging. Of 279 patients, 112 reported a history of cranial-vertebral junction trauma, whereas 28 were diagnosed with congenital malformations. Clinically, 84.9% of patients presented with myelopathy, with pain presented in 42.6%. Atlantoaxial fixation was performed in 240 patients, occiput-to-C2 fixation in 35 patients, and extended occipito-cervical fixation in 4 patients. Mean follow-up was 40.3 months. Complications were reported in 2.4% of patients. Japanese Orthopaedic Association scores improved from a preoperative mean of 12.4 to 14.8. Two hundred thirty-five patients (77.7%) improved, with 30 patients experiencing no change in symptoms and 14 patients deteriorating. Fusion was achieved in 96.8% of patients. Our data reveal that surgical treatment for OO using the indications and techniques delineated is associated with high satisfaction rates, improved functional scores, and high fusion rates with low complication rates. AAI, atlantoaxial instabilityJOA, Japanese Orthopaedic AssociationOO, os odontoideum.
    Neurosurgery 01/2015; 76(5). DOI:10.1227/NEU.0000000000000668 · 3.03 Impact Factor
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    ABSTRACT: Retrospective review of prospective multicenter database. Quantify the incidence of new onset cervical deformity (CD) after adult spinal deformity surgery of the thoracolumbar spine, identify predictors of development, and determine the impact on outcomes. High prevalence of residual CD has been identified after surgical treatment of adult spinal deformity. Development of new onset CD is less understood and its clinical impact unclear. A total of 215 patients with complete 2-year follow-up and full-length radiographs met inclusion criteria. CD was defined by T1 slope minus Cervical Lordosis (CL) more than 20°, C2-C7 sagittal vertical axis more than 40 mm, or C2-C7 kyphosis more than 10°. Univariate analysis was performed using t tests or tests of proportion. Multivariate logistic regression was used to determine independent predictors of new onset CD. The impact of CD on health-related quality of life and satisfaction was measured using repeated measures mixed models or logistic regression as appropriate, accounting for potential confounders. The overall rate of CD at 2 years after surgery was 63%. Univariate analysis revealed that patients who developed new onset CD postoperatively had higher incidence of diabetes (7.35% vs. 1.28%, P = 0.05), increased preoperative C2-C7 sagittal vertical axis (P = 0.04) and C2 slope (P = 0.038), and smaller diameter rods used at surgery (P = 0.032). Independent predictors of new onset CD at 2 years included: diabetes (odds ratio, 10.49; P = 0.046) and increased preoperative T1 slope minus cervical lordosis (odds ratio, 1.08/º; P = 0.022). Ending instrumentation below T4 was a negative predictor (odds ratio, 0.31; P = 0.019). Patients with and without CD experienced improvements in 2-year 36-Item Short Form Health Survey (P = 0.0001), Oswestry Disability Index (P = 0.0001), and Scoliosis Research Society (P = 0.0001). Rates and overall improvement were similar. CD was not associated with decreased satisfaction (P = 0.28). A total of 47.7% of patients without preoperative CD developed new onset postoperative CD after thoracolumbar surgery. Independent predictors of new onset CD at 2 years included diabetes, higher preoperative T1 slope minus cervical lordosis, and ending instrumentation above T4. Significant improvements in health-related quality of life scores occurred despite the development of postoperative CD. 2.
    Spine 01/2015; 40(5):283-291. DOI:10.1097/BRS.0000000000000746 · 2.45 Impact Factor
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    ABSTRACT: Study Design Literature review. Objective Atlantoaxial dislocation (AAD) is a rare and potentially fatal disturbance to the normal occipital-cervical anatomy that affects some populations disproportionately, which may cause permanent neurologic deficits or sagittal deformity if not treated in a timely and appropriate manner. Currently, there is a lack of consensus among surgeons on the best approach to diagnose, characterize, and treat this condition. The objective of this review is to provide a comprehensive review of the literature to identify timely and effective diagnostic techniques and treatment modalities of AAD. Methods This review examined all articles published concerning "atlantoaxial dislocation" or "atlantoaxial subluxation" on the PubMed database. We included 112 articles published between 1966 and 2014. Results Results of these studies are summarized primarily as defining AAD, the normal anatomy, etiology of dislocation, clinical presentation, diagnostic techniques, classification, and recommendations for timely treatment modalities. Conclusions The Wang Classification System provides a practical means to diagnose and treat AAD. However, future research is required to identify the most salient intervention component or combination of components that lead to the best outcomes.
    08/2014; 4(3):197-210. DOI:10.1055/s-0034-1376371
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    ABSTRACT: A high prevalence of residual cervical deformity (CD) has been identified following surgical treatment of adult spinal deformity (ASD). Development of new onset CD is less understood and its clinical impact unclear. This study quantifies the incidence of CD after ASD surgery, identifies predictors of development, and determines the impact outcomes.
    Neurosurgery; 08/2014
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    ABSTRACT: Cervical drains have historically been used to avoid postoperative wound and respiratory complications such as excessive edema, hematoma, infection, re-intubation, delayed extubation, or respiratory distress. Recently, some surgeons have ceased using drains because they may prolong hospital stay, operative time, or patient discomfort. The objective of this retrospective case-control series is to investigate the effectiveness of postoperative drains following one- and two-level cervical fusions. A chart review was conducted at a single institution from 2010-2013. Outcome measures included operative time, hospital stay, estimated blood loss and incidence of wound complications (infection, hematoma, edema, and complications with wound healing or evacuation), respiratory complications (delayed extubation, re-intubation, and respiratory treatment), and overall complications (wound complications, respiratory complications, dysphagia, and other complications). Statistical analyses including independent samples t-test, chi-square, analysis of covariance, and linear regression were used to compare patients who received a postoperative drain to those who did not. The study population included 39 patients who received a postoperative drain and 42 patients who did not. There were no differences in demographics between the two groups. Patients with drains showed increased operative time (100.1 vs 69.3 min, p < 0.001), hospital stay (38.9 vs. 31.7 hrs, p = 0.021), and blood loss (62.7 vs 29.1 mL, p < 0.001) compared to patients without drains. The frequency of wound complications, respiratory complications, and overall complications did not vary significantly between groups. Cervical drains may not be necessary for patients undergoing one- and two-level cervical fusion. While there were no differences in incidence of complications between groups, patients treated with drains had significantly longer operative time and length of hospital stay. This could contribute to excessive costs for patients treated with drains, despite the lack of compelling evidence of the advantages of this treatment in the literature and in the current study.
    01/2014; 8:1-13. DOI:10.14444/1034
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    ABSTRACT: Study Design. Retrospective analysis.Objective. To determine patient demographics, incidence of comorbidities and procedure-related complications, and identify risk factors associated with morbidity and mortality after spinal surgery for cauda equina syndrome (CES).Summary of Background Data. To our knowledge, no study has provided nationwide estimates of patient characteristics and procedure-related complication rates after spinal surgery for CES relative to an unaffected population.Methods. Nationwide Inpatient Sample data collected between 2001 and 2010 was analyzed. Discharges with procedural codes for lumbar spinal fusion, decompression, or discectomy were included. The CES cohort included diagnoses of CES, and the unaffected cohort included lumbar spinal pathology diagnoses. Patient demographics, incidence of comorbidities and procedure-related complications, and risk factors associated with morbidity and mortality were compared.Results. Discharges for 11,207 CES and 689,799 unaffected patients were identified. Differences between cohorts were found for demographic and hospital data. Average comorbidity indices for the CES cohort were found to be increased (0.23 vs.0.13, p< 0.0001), as well as the incidence of total procedure-related complications (18.63% vs. 13.12%, p< 0.0001). In-hospital mortality rate was significantly increased for the CES cohort (0.30% vs. 0.08%, p< 0.0001). A number of comorbidities associated with additional risk for morbidity and mortality among the CES cohort were identified.Conclusion. Relative to an unaffected population undergoing similar treatment, CES patients were more likely to have increased associated comorbidities on presentation, as well as increased complication rates with a prolonged hospital course postoperatively. CES was found to carry an increased incidence of procedure-related complications as well as in-hospital mortality. A number of comorbidities associated with additional risk for morbidity and mortality among the CES cohort were identified. This study provides clinically useful data for surgeons to educate patients at risk for morbidity and mortality as well as direct future research to improve patient outcomes.
    Spine 12/2013; 39(6). DOI:10.1097/BRS.0000000000000170 · 2.45 Impact Factor
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    ABSTRACT: Object Lateral mass screws (LMS) have been used extensively with a low complication rate in the subaxial spine. Recently, cervical pedicle screws (CPS) have been introduced, and are thought to provide more optimal stabilization of the subaxial spine in certain circumstances. However, because of the concern for neurovascular injury, the routine use of CPS in this location remains controversial. Despite this controversy, however, there are no articles directly comparing screw-related complications of each procedure in the subaxial cervical spine. The purpose of this study was to evaluate screw-related complications of LMS and CPS in the subaxial cervical spine. Methods A PubMed/MEDLINE and Cochrane Collaboration Library search was executed, using the key words "lateral mass screw" and "cervical pedicle screw." Clinical studies evaluating surgical procedures of the subaxial cervical spine in which either LMS or CPS were used and complications were reported were included. Studies in which the number of patients who had subaxial cervical spine surgery and the number of screws placed from C-3 to C-7 could not be specified were excluded. Data on screw-related complications of each study were recorded and compared. Results Ten studies of LMS and 12 studies of CPS were included in the analysis. Vertebral artery injuries were slightly but statistically significantly higher with the use of CPS relative to LMS in the subaxial cervical spine. Although the use of LMS was associated with a higher rate of screw loosening, screw pullout, loss of reduction, pseudarthrosis, and revision surgery, this finding was not statistically significant. Conclusions Based on the available literature, it appears that perioperative neurological and late biomechanical complication rates, including pseudarthrosis, are similarly low for both LMS and CPS techniques. In contrast, vertebral artery injuries, although statistically significantly more common when using CPS, are extremely rare with both techniques, which may justify their nonroutine use in select cases. Given the paucity of well-designed studies available, this recommendation may be a reflection of deficiencies in the available studies. Surgeons using either technique should have intimate knowledge of cervical anatomy and an adequate preoperative evaluation for each patient, with the final selection based on individual case requirements and anatomical limitations.
    Journal of neurosurgery. Spine 09/2013; DOI:10.3171/2013.8.SPINE13136 · 2.36 Impact Factor
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    ABSTRACT: INTRODUCTION: Previous studies have reported that the alignments of the occipital-cervical and subaxial spine were closely interrelated in asymptomatic individuals; however, none have focused on a population with atlantoaxial dislocation. MATERIAL AND METHODS: From 2007 to 2011, 298 patients with atlantoaxial dislocation and atlas occipitalization were studied. Angles formed between Occiput-C2 and C2-C7 were measured. The relationship between the alignment of the occipital-cervical junction and the subaxial cervical spine was evaluated. RESULTS: The range of values for the angles measured was as followed: the Occiput-C2 angles were -35.2° to 44.8°, and the C2-C7 angles were -17.4° to 77.8°. Statistically significant negative correlations were observed between the Occiput-C2 and C2-C7 angles. CONCLUSION: Anterior dislocations of the atlas are associated with diminished lordosis or even kyphosis of the occipital-cervical junction, and result in compensatory hyperlordosis of the subaxial cervical spine, collectively presenting as a "swan neck" deformity. Atlantoaxial dislocation may influence the global cervical alignment.
    European Spine Journal 04/2013; 22(7). DOI:10.1007/s00586-013-2742-4 · 2.47 Impact Factor
  • Peter G Passias, Shaobo Wang, Shenglin Wang
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    ABSTRACT: PURPOSE: Spinal stenosis at the C2-3 segment is a rare occurrence, and when it occurs myelopathy infrequently results. Furthermore, only a handful of cases involving congenital abnormalities of the posterior arch of the axis have been described resulting in cervical myelopathy many of which described simultaneous congenital abnormalities at adjacent levels and none of which identified ossification of the posterior longitudinal ligament (OPLL) at the same level. We report a case of a previously undescribed combination of abnormalities at the C2-3 segment resulting in clinical myelopathy. METHODS: A 49-year-old Chinese male presented with a progressive cervical myelopathy (C-JOA score 11 immediately pre-op). Segmental OPLL at the C2-3 disk space was visible, together with invagination of the bilaterally hypoplastic C2 lamina into the spinal canal. Signal abnormalities of the spinal cord were evident on both T1 and T2 sequences. RESULTS: The patient underwent a posterior decompression and instrumented fusion at C2-3 using pars screws at C2 and lateral mass screws at C3. Following surgery there was a rapid and significant improvement in the neurological symptoms, with the C-JOA score improving to 14 at final follow-up. A successful fusion was evident. CONCLUSIONS: Deficiencies in the posterior arch of the axis are rare and have not previously been reported in conjunction with OPLL. Advanced imaging is helpful to define the abnormality and site of compression. In the setting of a progressive neurological dysfunction, surgical decompression and stabilization is a reasonable intervention and can be associated with neurological and symptomatic improvement.
    European Spine Journal 01/2013; DOI:10.1007/s00586-012-2654-8 · 2.47 Impact Factor
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    ABSTRACT: Study Design. Prospective case series and radiographic analysis.Objective. This study aimed to characterize the changes in subaxial alignment following surgical correction of occipitoaxial (OA) kyphosis, establish normal parameters, and report on clinical outcomes in a population of chronic atlantoaxial dislocation (AAD) patients presenting with swan neck deformities,.Summary of Background Data. Swan neck deformity of the cervical spine is a term used to describe the simultaneous development of both abnormal kyphosis and hyperlordosis malalignments. Currently, there are no published series that discuss their outcomes following treatment and, more specifically, the subsequent changes that occur in the subaxial spine following the correction of the primary deformity in cases of chronic hyper-kyphosis at the OA segment.Methods. This was a prospective clinical and radiographic study in a population of chronic AAD patients presenting with swan neck deformities. C0-C2 and C2-C7 angles were measured using plain radiographs pre- and post-surgery. The relationship between the alignment of the OA joint and the subaxial cervical spine was evaluated. Japanese Orthopaedic Society (JOA) scores were used to assess functional outcomes.Results. C0-2 improved from a mean of -14.4º (SD 9.5º) pre-operatively to a mean of 7.8º (SD 1.0º) postoperatively (p = 0.02). C2-7 changed from a mean of 43º (SD 2.8°) to a mean of 18.6º (SD 11.2°) post-operatively (p = 0.02). A significant correlation was detected between the changes that occurred in the upper and lower cervical alignments (R = 0.133; p<0.01). Clinically, JOA scores improved significantly from pre- to post-op (p<0.01).Conclusions. This study reports the novel auto-correction of subaxial abnormalities following treatment of the primary upper cervical deformity and delineates the relationship between these two occurrences, thus demonstrating the reversibility of such complex abnormalities. Furthermore, the clinical outcomes following surgical treatment of swan neck deformities secondary to AAD are favorable and associated with a low complication rate.
    Spine 01/2013; DOI:10.1097/BRS.0b013e31828625e4 · 2.45 Impact Factor
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    ABSTRACT: : Controlled experimental study. : To evaluate the kinematical effects of X-Stop device on the spinal process at the operated and the adjacent segments before and after X-Stop surgeries during various weight-bearing postures in elderly patients with lumbar spine stenosis. : The mechanism of interspinous process (ISP) devices is to directly distract the ISP of the implanted level to indirectly decompress the intervertebra foramen and spinal canal. Few studies have investigated the changes of ISP gap caused by X-Stop implantation using magnetic resonance imaging or radiography, but the effect of X-Stop surgery on the kinematics of spinous processes during functional activities is still unclear. : Eight patients were tested before and, on average, 7 months after surgical implantation of the X-Stop devices using a combined computed tomography/magnetic resonance imaging and dual fluoroscopic imaging system during weight-bearing standing, flexion-extension, left-right bending, and left-right twisting positions of the torso. The shortest distances of the ISPs at the operated and the adjacent levels were measured using iterative closest point method and was dissected into vertical (gap) and horizontal (lateral translation) components. : At the operated levels, the shortest vertical ISP distances (gap) significantly (P<0.05) increased by 1.5 mm during standing, 1.2 mm during left twist, 1.3 mm during extension, and 1.1 mm during flexion, whereas they also increased yet not significantly (P>0.05) in right twist, left bend, and right bend after the X-Stop implantation. The lateral translations were not significantly affected. At both cephalad and caudad adjacent levels, the ISP distances (vertical and horizontal) were not significantly affected during all postures after X-Stop implantation. : The findings of this study indicate that implantation of the X-Stop devices can effectively distract the ISP space at the diseased level without causing apparent kinematic changes at the adjacent segments during the studied postures.
    Journal of spinal disorders & techniques 10/2011; 25(7):374-8. DOI:10.1097/BSD.0b013e318227eb84 · 1.89 Impact Factor
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    ABSTRACT: Study DesignRetrospective case control series
    The Spine Journal 10/2011; DOI:10.1016/j.spinee.2011.06.010 · 2.80 Impact Factor
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    ABSTRACT: STUDY DESIGN:: Prospective radiographic analysis. OBJECTIVE:: This study aimed to characterize the relationship between the alignment of the occipitoaxial (OA) and the subaxial spine, establish normal parameters, and to determine the influence of upper cervical spine alignment on subaxial degenerative disc disease (DDD) and clinical outcomes in this population. SUMMARY OF BACKGROUND DATA:: Previous studies reported that the alignments of the upper and lower cervical spine are closely interrelated in patients with atlantoaxial dislocations of a rheumatoid etiology. None have focused on congenital etiologies or included patients with OA kyphosis. The influence of the upper cervical alignment on subaxial (DDD) and outcomes is also unclear. METHODS:: Fifty-eight patients with congenital AAD undergoing surgical reduction and fusion were included. C0-C2 and C2-C7 angles were measured and DDD was assessed using plain radiographs. The relationship between the alignment of the OA joint and the subaxial cervical spine was evaluated, as well as the relationships between the cervical alignment, outcomes, and cervical DDD. RESULTS:: C0-2 improved from a mean of 1.59±17.3 degrees preoperatively to a mean of 15±9.8 degrees postoperatively (P<0.001). C2-7 changed from a mean of 25.55±19.6 degrees to a mean of 14.2±14.4 degrees postoperatively (P<0.001). The OA and subaxial alignment were negatively correlated in this population both before (r=-0.84; P<0.001) and after (r=-0.64; P<0.001) surgical treatment. There was an increased incidence of DDD postoperatively (P<0.01), which was positively correlated with the postoperative C0-2 angle (r=0.54; P<0.001), but negatively correlated with the postoperative C2-7 angle (r=-0.79; P<0.001). CONCLUSIONS:: Changes in OA alignment before and after surgery are associated with changes in the subaxial spine. There is a high incidence of postoperative DDD in the subaxial spine that seems to be related to sagittal alignment after surgery.
    Journal of spinal disorders & techniques 09/2011; 26(1). DOI:10.1097/BSD.0b013e31823097f9 · 1.89 Impact Factor
  • Peter G Passias, Michal Kozanek, Kirkham B Wood
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    ABSTRACT: The ideal surgical treatment for adult low-grade isthmic spondylolisthesis (ALIS) remains unknown. Isolated anterior and posterior procedures are popular but have resulted in equivocal outcomes, whereas combined anterior and posterior procedures are associated with higher complication rates despite improved outcome. To evaluate the clinical and radiographic outcomes following the treatment of ALIS using a 1-stage posterior approach with posterior decompression and posterolateral arthrodesis combined with an interbody fibular allograft strut. Fifteen patients underwent fusion by a single surgeon using our modified technique. Seven patients were female and 8 were male, with a mean age of 48 years. All patients were classified as Meyerding grade II slips and underwent a posterior approach only, a decompressive laminectomy, and a circumferential fusion with the use of a transsacral fibular allograft and a posterolateral instrumented fusion. Postoperative clinical and radiographic evaluations were performed at 3, 6, and 12 months, and then on an annual basis. The average follow-up interval was 61 months. Three complications were seen: a single dural tear, an L5 radiculopathy secondary to a malpositioned pedicle screw, and one patient with urinary retention. The spines of all patients were determined to be fused by the 6-month postoperative visit. All patients returned to their normal activities of daily living. Significant improvements in the visual analog score were seen at all follow-up intervals. Transsacral interbody fibular allograft can be used successfully to supplement a posterolateral instrumented fusion in selected patients with low-grade ALIS.
    Neurosurgery 08/2011; 70(3):758-63. DOI:10.1227/NEU.0b013e3182338b2b · 3.03 Impact Factor
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    ABSTRACT: Controlled laboratory study. To evaluate the effect of lumbar degenerative disc diseases (DDDs) on motion of the facet joints during functional weight-bearing activities. It has been suggested that DDD adversely affects the biomechanical behavior of the facet joints. Altered facet joint motion, in turn, has been thought to associate with various types of lumbar spine pathology including facet degeneration, neural impingement, and DDD progression. However, to date, no data have been reported on the motion patterns of the lumbar facet joint in DDD patients. Ten symptomatic patients of DDD at L4-S1 were studied. Each participant underwent magnetic resonance images to obtain three-dimensional models of the lumbar vertebrae (L2-S1) and dual fluoroscopic imaging during three characteristic trunk motions: left-right torsion, left-right bending, and flexion-extension. In vivo positions of the vertebrae were reproduced by matching the three-dimensional models of the vertebrae to their outlines on the fluoroscopic images. The kinematics of the facet joints and the ranges of motion (ROMs) were compared with a group of healthy participants reported in a previous study. In facet joints of the DDD patients, there was no predominant axis of rotation and no difference in ROMs was found between the different levels. During left-right torsion, the ROMs were similar between the DDD patients and the healthy participants. During left-right bending, the rotation around mediolateral axis at L4-L5, in the DDD patients, was significantly larger than that of the healthy participants. During flexion-extension, the rotations around anterioposterior axis at L4-L5 and around craniocaudal axis at the adjacent level (L3-L4), in the DDD patients, were also significantly larger, whereas the rotation around mediolateral axis at both L2-L3 and L3-L4 levels in the DDD patients were significantly smaller than those of the healthy participants. DDD alters the ROMs of the facet joints. The rotations can increase significantly not only at the DDD levels but also at their adjacent levels when compared to those of the healthy participants. The increase in rotations did not occur around the primary rotation axis of the torso motion but around the coupled axes. This hypermobility in coupled rotations might imply a biomechanical mechanism related to DDD.
    Spine 05/2011; 36(10):E629-37. DOI:10.1097/BRS.0b013e3181faaef7 · 2.45 Impact Factor
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    ABSTRACT: Case-control study. To evaluate the effect of lumbar degenerative disc disease (DDD) on the disc deformation at the adjacent level and at the level one above the adjacent level during end ranges of lumbar motion. It has been reported that in patients with DDD, the intervertebral discs adjacent to the diseased levels have a greater tendency to degenerate. Although altered biomechanics have been suggested to be the causative factors, few data have been reported on the deformation characteristics of the adjacent discs in patients with DDD. Ten symptomatic patients with discogenic low back pain between L4 and S1 and with healthy discs at the cephalic segments were involved. Eight healthy subjects recruited in our previous studies were used as a reference comparison. The In Vivo kinematics of L3-L4 (the cephalic adjacent level to the degenerated discs) and L2-L3 (the level one above the adjacent level) lumbar discs of both groups were obtained using a combined magnetic resonance imaging and dual fluoroscopic imaging technique at functional postures. Deformation characteristics, in terms of areas of minimal deformation (defined as less than 5%), deformations at the center of the discs, and maximum tensile and shear deformations, were compared between the two groups at the two disc levels. In the patients with DDD, there were significantly smaller areas of minimal disc deformation at L3-L4 and L2-L3 than the healthy subjects (18% compared with 45% of the total disc area, on average). Both L2-L3 and L3-L4 discs underwent larger tensile and shear deformations in all postures than the healthy subjects. The maximum tensile deformations were higher by up to 23% (of the local disc height in standing) and the maximum shear deformations were higher by approximately 25% to 40% (of the local disc height in standing) compared with those of the healthy subjects. Both the discs of the adjacent level and the level one above experienced higher tensile and shear deformations during end ranges of lumbar motion in the patients with DDD before surgical treatments when compared with the healthy subjects. The larger disc deformations at the cephalic segments were otherwise not detectable using conventional magnetic resonance imaging techniques. Future studies should investigate the effect of surgical treatments, such as fusion or disc replacement, on the biomechanics of the adjacent segments during end ranges of lumbar motion.
    Spine 04/2011; 36(9):E574-81. DOI:10.1097/BRS.0b013e3181f79e93 · 2.45 Impact Factor
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    ABSTRACT: Analysis of population-based national hospital discharge data collected for the Nationwide Inpatient Sample. To study perioperative outcomes of circumferential spine surgery performed on either the same or different days of the same hospitalization. Circumferential spine fusion surgery has been linked to an increased adjusted risk in perioperative morbidity and mortality compared with procedures involving only 1 site. To minimize these risks, some surgeons elect to perform the 2 components of this procedure in separate sessions during the same hospitalization. The value of this approach is uncertain. Data collected between 1998 and 2006 for the Nationwide Inpatient Sample were analyzed. Hospitalizations during which a circumferential noncervical spine fusion was performed were identified. Patients were divided into those who had their anterior and posterior portion performed on the same and those performed on different days of the same hospitalization. The prevalence of patient and health care system-related demographics was evaluated. Frequencies of procedure-related complications and mortality were determined. Multivariate regression models were created to identify whether timing of procedures was associated with an independent increase in risk for adverse events. We identified a total of 11,265 entries for circumferential spine fusion. Of those, 71.2% (8022) were operated in 1 session. Complications were more frequent among staged- versus same-day surgery patients (28.4% vs. 21.7%, P < 0.0001). The incidence of venous thrombosis and adult respiratory distress syndrome also increased among staged candidates, while the trend toward higher mortality (0.5% vs. 0.4%) did not reach significance. In the regression model, staged circumferential spine fusions were associated with a 29% increase in the odds morbidity and mortality compared with same-day procedures. Staging circumferential spine surgery procedures during the same hospitalization offers no mortality benefit and may even expose patients to increased morbidity.
    Spine 02/2011; 37(3):247-55. DOI:10.1097/BRS.0b013e31821350d0 · 2.45 Impact Factor

Publication Stats

259 Citations
84.81 Total Impact Points

Institutions

  • 2011–2014
    • NYU Langone Medical Center
      • Department of Orthopaedic Surgery
      New York City, New York, United States
  • 2009–2013
    • Harvard University
      Cambridge, Massachusetts, United States
    • Harvard Medical School
      • Department of Orthopaedic Surgery
      Boston, Massachusetts, United States
  • 2010–2011
    • Cornell University
      • Department of Orthopaedic Surgery
      Итак, New York, United States
    • Hospital for Special Surgery
      • Department of Orthopaedic Surgery
      New York City, New York, United States
  • 2009–2011
    • Massachusetts General Hospital
      • • Bioengineering Laboratory
      • • Department of Orthopaedic Surgery
      Boston, Massachusetts, United States