Comparing the Effectiveness of Sagittal Balance, Foraminal Stenosis, and Preoperative Cord Rotation in Predicting Postoperative C5 Palsy.

STUDY DESIGN: Retrospective cohort review. OBJECTIVE: To determine whether preoperative cord rotation is independently correlated with C5 palsy when analyzed alongside measures of sagittal balance and foraminal stenosis. SUMMARY OF BACKGROUND DATA: Postoperative C5 palsy is a well-documented complication of cervical procedures with a prevalence of 4%-8%. Recent studies have shown a correlation with preoperative spinal cord rotation. There have been few studies, however, that have examined the role of sagittal balance and foraminal stenosis in the development of C5 palsy. METHODS: A total of 77 patients who underwent cervical decompression-10 of whom developed C5 palsy-were reviewed. Sagittal balance was assessed using curvature angle and curvature index on radiographs and magnetic resonance image (MRI). Cord rotation was assessed on axial MRI. C4-C5 foraminal stenosis was assessed on sagittal MRI using area measurements and a grading scale. Demographics and information on surgical approach were gathered from chart review. Correlation with C5 palsy was performed by point-biserial, χ, and regression analyses. RESULTS: Point-biserial analysis indicated that only cord rotation showed significance (P<0.01). There was no statistical significance shown with surgical approach, sex, or age. In addition, changes in sagittal balance did not correlate with presence of C5 palsy. Logistic regression model yielded cord rotation as the only significant independent predictor of C5 palsy. For every degree of axial cord rotation, the likelihood ratio for suffering a C5 palsy was 3.93 (95% confidence interval, 2.01-8.66; P<0.05). CONCLUSIONS: This supports the independent capability of preoperative cord rotation to predict postoperative C5 palsy. Lack of correlation with measures of neuroforaminal stenosis potentially points to mechanisms other than direct compression as the etiology. In addition, the lack of correlation with postoperative changes in sagittal balance hints that measures of curvature angle and curvature index may not be appropriate to accurately predict this complication. LEVEL OF EVIDENCE: Level 3.

Magnetic Resonance Imaging of the Cervical Spine Under-Represents Sagittal Plane Deformity in Degenerative Myelopathy Patients.

BACKGROUND: In treating patients with cervical myelopathy, surgical approach may be dictated by sagittal balance, highlighting the need for accurate pre-operative assessment. Magnetic Resonance Imaging (MRI) is widely-recognized for its utility in the diagnosis and surgical planning of cervical myelopathy. Plain radiographs (X-rays) are a reliable tool to assess bony alignment. However, they may not always be included in standard pre-operative evaluation, especially in an era of restricted payer-environments. Failure to appropriately acknowledge a patients' preoperative kyphotic deformity may cause the surgeon to choose a posterior-only approach, which would provide suboptimal sagittal plane correction and decompression of anterior pathology. METHODS: 101 patients with cervical myelopathy with MRI and plain radiographs were identified. Cervical lordosis and kyphosis were measured using the Cobb method on standing lateral x-ray and sagittal T2-weighted MRI. CI (Ishihara) was also measured on standing lateral x-ray, and sagittal T2-weighted MRI. Bland-Altman plots were generated and used to compare subtle differences in measurement techniques and modalities. Odom's criteria were recorded. RESULTS: The average difference between plain radiograph and MRI measurements for curvature angle was 3.5± 7.2 degrees (p< 0.001), and the average difference between plain radiograph and MRI measurements for curvature index was 1.5± 5.9 degrees (p= 0.015). CONCLUSIONS: MRI may under-represent the respective sagittal plane deformity in patients with degenerative cervical myelopathy. CLINICAL RELEVANCE: We would recommend the use of standing x-rays when considering surgical planning in all myelopathy patients. This manuscript was reviewed and approved by an institutional review board. Informed consent was not obtained because patient specific identifying information was not used. It was performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments.

Predicting Postoperative C5 Palsy Using Preoperative Spinal Cord Rotation.

The development of C5 nerve palsy after cervical decompression surgery has been well documented. The goal of this study was to determine whether preoperative spinal cord rotation could be used as a predictor of C5 palsy in patients who underwent posterior cervical decompression at C4-C6. The authors reviewed the records of 72 patients who had posterior decompression and 77 patients who had anterior decompression. With the patients undergoing anterior decompression used as a control group, magnetic resonance imaging scans were analyzed for area of the spinal cord, anterior-posterior diameter, and cord rotation relative to the vertebral body. The rate of C5 palsy was 7.3%. Average degrees of rotation were 3.83°±2.47° and 3.45°±2.23° in the anterior and posterior groups, respectively. A statistically significant association was detected between degree of rotation and C5 palsy. Point-biserial correlations were 0.58 (P<.001) and 0.60 (P<.001) in the anterior and posterior groups, respectively. With a diagnostic cutoff of 6°, the sensitivity and specificity of identifying patients with C5 palsy in the posterior group were 0.67 (95% confidence interval, 0.24-0.94) and 0.95 (95% confidence interval, 0.86-0.98), respectively. The results suggested that preoperative spinal cord rotation may be a valid predictor of C5 nerve palsy after posterior cervical decompression. With mild rotation defined as less than 6°, moderate rotation as 6° to 10°, and severe rotation as greater than 10°, the prevalence of C5 palsy in the posterior group was 2 of 65 for mild rotation, 3 of 6 for moderate rotation, and 1 of 1 for severe rotation.

Characterization of lumbar spinous process morphology: a cadaveric study of 2,955 human lumbar vertebrae.

BACKGROUND CONTEXT: Despite the interest in lumbar spinous process (SP)-based surgical innovation, there are no large published studies that have characterized the morphometry of lumbar SPs. PURPOSE: To provide accurate level-specific morphometric data with respect to human lumbar SPs using a human cadaveric lumbar spine model and to describe the morphometric variation of lumbar SPs with respect to gender, race, and age. STUDY DESIGN: An anatomic observational study. METHODS: This study used 2,955 cadaveric lumbar vertebrae from 591 adult spines at the Hamann-Todd Human Osteological Collection. Specimens were aged 20 to 79 years. Each vertebra was photographed in standardized positions and measured using ImageJ software. Direct measurements were made for the SP length, width, height, slope, and caudal morphology. Gender, race, and age were recorded and analyzed. RESULTS: Spinous process length was 24.8±4.6 mm (L5) to 33.9±3.9 mm (L3). Effective length varied from 19.5±2.6 mm (L1) to 24.6±3.3 mm (L4). Height was shortest at L5 (18.2±2.7 mm). Caudal width was greater than the cranial width. Slope, caudal morphology, and radius measures showed large interspecimen variation. Slope at L5 was steeper than other levels (23.7°±10.5°, p<.0001). Most specimens demonstrated convex caudal morphology. L4 had the highest proportion of convexity (80.7%). L1 was the only level with predominantly concave morphology. Measurements for female SPs were smaller, but the slope was steeper. Anatomic and effective SP lengths were longer for specimens from white individuals. Specimens from black individuals had larger width and height, as well as steeper slope. Black specimens had more convex morphology at L4 and L5. With increasing age, the SP length, effective length, and width increased. Height increased with age only at L4 and L5. Slope and caudal radius of curvature decreased with age, and increasingly convex morphology was noted at most levels. CONCLUSIONS: This large cadaveric study provides level-specific morphometric data regarding the osseous dimensions of lumbar SPs relevant to techniques and devices targeting the lumbar SPs or the interspinous space. Of particular importance is the recognition that L5 has relatively different morphology when compared with more cranial levels. Potentially important differences were noted comparing women with men, black with white, and aging populations.

Correlation of slipped capital femoral epiphysis with disk degeneration.

SUMMARY OF BACKGROUND DATA: Spinal osteoarthritis is greater in patients with known hip pathology secondary to alterations in spinopelvic geometry. To our knowledge, no study has investigated the long-term impact of slipped capital femoral epiphysis (SCFE) on the spine. OBJECTIVE: To evaluate the relationship between SCFE and the presence of degenerative disk disease and facet arthrosis. STUDY DESIGN: An anatomic study of disk degeneration in cadaveric lumbar spines with SCFE. METHODS: An observational study was performed on 25 cadaveric specimens with SCFE and 647 controls that were identified out of 3100 total cadaveric specimens in an osteological collection. The specimens were evaluated for disk degeneration and facet arthrosis at L1/2 to L5/S1 using the classification of Eubanks and colleagues. Linear regression analyses were then used to determine the relationship between SCFE and lumbar disk and facet degeneration at each level, correcting for confounding factors such as age, sex, and race. RESULTS: Linear regression demonstrated a significant association (P<0.01) that was found between SCFE and degenerative disk disease at all levels from L1/2 to L5/S1. In addition, a significant association (P<0.01) was found between SCFE and facet arthrosis at all levels from L1/2 to L5/S1. CONCLUSIONS: The findings of this study show a relationship between SCFE and lumbar disk degeneration and facet arthrosis. This relationship may prove useful in predicting the course of spinal osteoarthritis in patients with SCFE.

Cervical endplate and facet arthrosis: an anatomic study of cadaveric specimens.

STUDY DESIGN: An anatomic, epidemiologic study of cervical endplate and facet arthrosis in cadaveric spines. OBJECTIVE: To determine the prevalence of cervical endplate and facet arthrosis and the relationship between these 2 entities in a large population sample. SUMMARY OF BACKGROUND DATA: Cervical endplate and facet arthrosis are common radiographic findings, which have both been linked to pain. However, the prevalence and relationship between cervical endplate and facet arthrosis has not been clearly defined. METHODS: The cervical vertebrae from 234 cadaveric spines were examined by a single investigator for evidence of endplate and facet arthrosis. Arthrosis at each endplate and facet was graded on a continuum from 0 to IV. Race, age at death, and sex of each specimen were also recorded. Stepwise multiple linear regression was used to analyze any association between race, age, sex, endplate arthrosis, and facet arthrosis. Factors with P values <0.05 remained in the analysis. Two-tailed t tests for matched samples were used to analyze any difference between mean endplate and facet arthrosis severity scores among patients within the same decades of life. RESULTS: Concurrent cervical endplate and facet arthrosis was present in 77% of the study population. Stepwise multiple linear regression revealed significant (P<0.01) associations between endplate and facet arthrosis and between age and facet arthrosis. Race and sex did not correlate with facet arthrosis. In addition, patients in age groups 30 to 39, 40 to 49, 50 to 59, 60 to 69, 70 to 79, and 80 to 89 demonstrated more severe (P<0.01) endplate arthrosis in comparison with facet arthrosis. CONCLUSIONS: Concurrent cervical endplate and facet arthrosis is a common condition. Cervical endplate arthrosis and advancing age are associated with cervical facet arthrosis independent of race and sex. Cervical endplate arthrosis precedes facet arthrosis.

Correlation of sacropelvic geometry with disc degeneration in spondylolytic cadaver specimens.

STUDY DESIGN: An anatomic study of sacral inclination, pelvic incidence, pelvic lordosis, and disc degeneration in cadaveric lumbar spines. OBJECTIVE: To evaluate the relationship between sacropelvic parameters and disc degeneration in subjects with bilateral spondylolysis at L5. SUMMARY OF BACKGROUND DATA: L5-S1 disc degeneration is greater in patients with spondylolytic defects (L5-S1) than with an intact pars interarticularis secondary to the instability caused by spondylolysis. Sacral inclination, pelvic incidence, and pelvic lordosis affect sagittal balance and axial forces on the L5-S1 disc. METHODS: An observational study was performed on 120 cadaveric specimens with spondylolysis (L5-S1) identified of 3100 total cadaveric specimens. Nine specimens were excluded because of incomplete or degraded skeletal elements; 10 were excluded for having unilateral defects only. The specimens were evaluated for sacral inclination, pelvic incidence, and pelvic lordosis. Disc degeneration and facet arthrosis at L4-L5 and L5-S1 were measured by the classification of Eubanks et al. Linear regression analyses were then used to determine the relationship between sacropelvic parameters and degeneration at the L5-S1 segment, correcting for confounding factors such as age, sex, and race. RESULTS: Linear regression demonstrated a significant association between sacral inclination and disc degeneration at L5-S1 (P = 0.018). Specimens were then divided into two groups, those in the highest quarter of pelvic incidence, and the remainder. Spearman rank correlation demonstrated a significant association between disc degeneration at L5-S1 and the highest quarter of pelvic incidence (P = 0.017). Increasing pelvic lordosis was also associated with an increase in facet arthrosis at L4-L5 (P = 0.006). CONCLUSION: The findings of this study show a relationship between the sacropelvic geometry and the degree of L5-S1 disc degeneration as well as L4-L5 facet degeneration in spondylolytic specimens. This relationship may prove useful in predicting the course of disc degeneration in patients with spondylolysis.

Cement augmentation of refractory osteoporotic vertebral compression fractures: survivorship analysis.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: To compare survivorship after cement augmentation of refractory osteoporotic vertebral compression fractures (OVCFs) with traditional inpatient pain management and bracing. SUMMARY OF BACKGROUND DATA: OVCFs can cause debilitating pain and functional decline necessitating prolonged bed rest and high-dose narcotics. Vertebroplasty and kyphoplasty are cement augmentation procedures used to control pain and restore function in patients with OVCF's that are refractory to conservative treatment. Early mobilization is associated with improved survival after other fractures in elderly patients. METHODS: A university hospital database was used to identify all participants treated with primary diagnosis of OVCF between 1993 and 2006. Chart review and imaging studies were used to confirm demographics, comorbidities, diagnosis, and treatment. Survival time was determined using hospital data, national death indices and patient follow-up. Exact Fisher tests, Mann-Whitney tests, and proportional hazards regression models with Kaplan-Meier plots compared patients treated with cement augmentation with controls treated with inpatient pain management and bracing. Patients with high-energy trauma, tumors or age more than 60 years were excluded. RESULTS: Within the past 12 years, 46 patients treated with cement augmentation and 129 matched controls met inclusion criteria. They did not differ with respect to age, sex, and comorbidities. A significant survival advantage was found after cement augmentation compared with controls (P < 0.001; log rank), regardless of comorbidities, age, or the number of fractures diagnosed at the start date (P = 0.565). Controlling simultaneously for covariates, the estimated hazard ratio associated with cementation was 0.10 (95% confidence interval [CI] = 0.02-0.43; P = 0.002) for year 1, 0.15 (95% CI = 0.02-1.12; P = 0.064) for year 2, and 0.95 (95% CI = 0.32-2.79; P = 0.919) for subsequent follow-up. The number of OVCFs at the start time of treatment did not affect survival benefit of cementation (P = 0.44). CONCLUSION: Cement augmentation of refractory OVCF improves survival for up to 2 years when compared with conservative pain management with bed rest, narcotics, and extension bracing, regardless of age, sex, and number of fractures or comorbidities. Therefore, aggressive management should be considered for refractory OVCFs with intractable back pain.

Prevalence of concurrent lumbar and cervical arthrosis: an anatomic study of cadaveric specimens.

STUDY DESIGN: An anatomic, epidemiologic study of lumbar and cervical arthrosis in cadaveric spines. OBJECTIVE: Determine the prevalence of combined lumbar and cervical arthrosis in a large population sample and examine its association with age, sex, and race. SUMMARY OF BACKGROUND DATA: Lumbar and cervical arthrosis are common radiographic findings, which have both been linked to pain. However, the prevalence of and temporal relationship between combined lumbar and cervical arthrosis has not been defined. METHODS: The lumbar and cervical segments from 234 cadaveric spines were examined by a single investigator for evidence of endplate and facet arthrosis. Arthrosis at each endplate and facet was graded on a continuum from 0 to IV. Race, age at death, and sex of each specimen was recorded.Stepwise multiple linear regression was used to analyze any association between race, age, sex, lumbar arthrosis, and cervical arthrosis. Factors with P-values <0.05 remained in the analysis. T tests for matched samples were used to analyze any difference between the mean lumbar and cervical arthrosis severity among patients within the same decades of life. RESULTS: Concurrent lumbar and cervical arthrosis was present in 80% of the study population. Stepwise multiple linear regression revealed significant (P < 0.01) associations between lumbar arthrosis and cervical arthrosis and between age and cervical arthrosis. Race and sex did not correlate with lumbar or cervical arthrosis. In addition, patients in age groups 20 to 29, 30 to 39, 40 to 49, 50 to 59, 60 to 69, 70 to 79, and 80 to 89 demonstrated more severe (P < 0.01) lumbar arthrosis in comparison to cervical arthrosis. CONCLUSION: Concurrent lumbar and cervical arthrosis is a common condition. Lumbar arthrosis and advancing age are associated with cervical arthrosis independent of race and sex. Lumbar arthrosis precedes cervical arthrosis. These findings suggest an underlying systemic component for spinal osteoarthritis.