Impact of radiologic variables on item responses of ODI, SRS22 and SF-36. in adult spinal deformity patients: differential item functioning (DIF) analysis results from a multi-center database.

PURPOSE: To determine if responses given to each question of the Scoliosis Research Society-22 (SRS22), Oswestry disability index (ODI) and Short Form-36 (SF-36) questionnaires are influenced by the radiological parameters. METHODS: Patients enrolled in a multi-centre prospectively collected adult spinal deformity database who had complete SRS22, ODI and SF-36 data at baseline and at one-year follow-up were analysed. The presence of a differential item function of each question within each score in relation to radiological parameters was analysed using a mixed Rasch model with the radiological threshold value(s) determined. RESULTS: Of those patients analysed (n = 1745; 1406 female, average age 51.0 ± 19.8 years), 944 were surgically and 801 were non-surgically treated. For the SRS22, questions (Q) 3, 5 and 18 were sensitive to almost all radiological parameters and the overall score was found sensitive to the Cobb angle. For the ODI, Q3, 6, 9 and 10 were not sensitive to any radiologic parameters whereas Q4 and 5 were sensitive to most. In contrast, only 3 of the SF-36 items were sensitive to radiological parameters. CONCLUSIONS: 78% of the SRS-22, 60% of the ODI and 8% of the questions in the SF-36 are sensitive to radiological parameters. Sagittal imbalance is independently associated with a poor overall outcome, but affects mental status and function more than pain and self-image. The assembly of questions responsive to radiological parameters may be useful in establishing a connection between changes in radiologic parameters and HRQL.

Correction of rotational deformity and restoration of thoracic kyphosis are inversely related in posterior surgery for adolescent idiopathic scoliosis.

Adolescent Idiopathic Scoliosis (AIS) is a complex three dimensional deformity the treatment of which remains to be surgical correction of the deformity as it had progressed over certain thresholds. The main focus in surgical treatment had, for decades, been the amount of correction in the coronal plane whereas corrections in sagittal and rotational (axial) planes have also been recognized as almost as important as the coronal over the recent decades. The hypotheses presented and discussed in this study is the virtual adversity between the rates of correction in these two (sagittal and axial) planes. Namely, we are suggesting that due to an elongated anterior spinal column as an intrinsic component of AIS, posterior surgery cannot correct both the axial plane deformity and the thoracic hypokyphosis in the sagittal plane at the same time, unless the posterior spinal column is substantially lengthened. This hypothesis is supported by 3D modeling of the AIS spine as well as the relative inability in changing the sagittal alignment of the thoracic spine demonstrated by a literature search by us. Understanding and internalization of this hypothesis by AIS surgeons is important as it suggests that by posterior instrumentation, unless a riskier approach of substantially lengthening the spinal column is taken, surgeons need to make the choice of correcting the hypokyphosis OR axial rotation.

Validation of a Simplified SRS-Schwab Classification Using a Sagittal Modifier.

STUDY DESIGN: Multicenter, prospective study of consecutive adult spinal deformity (ASD) patients. OBJECTIVE: To Validate Schwab's classification accuracy for surgical indication, and to evaluate a simplified sagittal modifier. SUMMARY OF BACKGROUND DATA: The SRS-Schwab Radiologic Classification based on clinical impact parameters, offers 27 different sagittal classification possibilities regarding sagittal vertical alignment (SVA), pelvic tilt (PT), and pelvic incidence-lumbar lordosis (PI-LL). The high number of classification possibilities makes it complex to use. METHODS: Inclusion criteria were ASD patients, presenting at least 1 criteria: Cobb ≥ 20°, SVA ≥ 5 cm, thoracic kyphosis ≥ 60°, or PT ≥ 25°. A total of 1,004 patients (410 nonoperative and 594 operative) were classified regarding SVA, PT, and PI-LL (0, +, ++), and 27 possibilities were identified. Categories were formed by adding the number of + signs, considering PT, SVA, and PI-LL. Three specific categories were identified: Aligned: 0 +; Moderate deformity: 1 to 3+; and Severe deformity: 4 to 6+. A χ-square test was performed for surgical indication (operated or not) and an analysis of variance was performed to evaluate the relationship between categories and Oswestry Disability Index (ODI). Probability <.05 was considered significant. RESULTS: Significant differences for HRQoL scores and surgical indication were found in the 27 sagittal parameter possibilities. For nonoperative patients, 230 (56.1%) were classified as aligned, 145 (35.4%) as moderate, and 35 (8.5%) as severe. For operative patients, there were 200 (33.7%), 215 (36.2%), and 179 (30.1%) in each respective subgroup. For HRQoL scores and surgical indication, no significant differences were found within each category, but significant differences were found when comparing the subgroups. CONCLUSIONS: Despite the correlation between SRS-Schwab classification and surgical indication, it is complex to use, with a total of 27 possibilities regarding sagittal modifiers. This simplification into three categories offers more readability, without losing any significant information, and could replace Schwab sagittal modifiers. In association with other parameters, they could be used for decision-making. LEVEL OF EVIDENCE: Level II.

Factors associated with having an indication for surgery in adult spinal deformity: an international european multicentre study.

PURPOSE: The aim of this study was to evaluate factors that distinguish between patients with adult spinal deformity (ASD) with and without an indication for surgery, irrespective of their final treatment. METHODS: Baseline variables (demographics, medical history, outcome measures, coronal, sagittal and neurologic parameters) were evaluated in a multicentre, prospective cohort of patients with ASD. Multivariable analyses were carried out for idiopathic and degenerative patients separately with the dependent variable being "indication for surgery" and baseline parameters as independent variables. RESULTS: In total, 342 patients with degenerative ASD and 624 patients with idiopathic ASD were included in the multivariable models. In patients with degenerative ASD, the parameters associated with having an indication for surgery were greater self-rated disability on the Oswestry Disability Index [odds ratio (OR) 1.04, 95% confidence interval (CI) 1.02-1.07] and a lower thoracic kyphosis (OR 0.97 95% CI 0.95-0.99), whereas in patients with idiopathic ASD, it was lower (worse) SRS self-image scores (OR 0.45 95% CI 0.32-0.64), a higher value for the major Cobb angle (OR 1.03 95% CI 1.01-1.05), lower age (OR 0.96 95% CI 0.95-0.98), prior decompression (OR 3.76 95% CI 1.00-14.08), prior infiltration (OR 2.23 95% CI 1.12-4.43), and the presence of rotatory subluxation (OR 1.98 95% CI 1.11-3.54) and sagittal subluxation (OR 4.38 95% CI 1.61-11.95). CONCLUSION: Specific sets of variables were found to be associated with an indication for surgery in patients with ASD. These should be investigated in relation to patient outcomes for their potential to guide the future development of decision aids in the treatment of ASD. These slides can be retrieved under Electronic Supplementary Material.

Factor analysis of the SRS-22 outcome assessment instrument in patients with adult spinal deformity.

PURPOSE: Designed for patients with adolescent idiopathic scoliosis, the SRS-22 is now widely used as an outcome instrument in patients with adult spinal deformity (ASD). No studies have confirmed the four-factor structure (pain, function, self-image, mental health) of the SRS-22 in ASD and under different contexts. Factorial invariance of an instrument over time and in different languages is essential to allow for precise interpretations of treatment success and comparisons across studies. This study sought to evaluate the invariance of the SRS-22 structure across different languages and sub-groups of ASD patients. METHODS: Confirmatory factor analysis was performed on the 20 non-management items of the SRS-22 with data from 245 American English-, 428 Spanish-, 229 Turkish-, 95 French-, and 195 German-speaking patients. Item loading invariance was compared across languages, age groups, etiologies, treatment groups, and assessment times. A separate sample of SRS-22 data from 772 American surgical patients with ASD was used for cross-validation. RESULTS: The factor structure fitted significantly better to the proposed four-factor solution than to a unifactorial solution. However, items 14 (personal relationships), 15 (financial difficulties), and 17 (days off work) consistently showed weak item loading within their factors across all language versions and in both baseline and follow-up datasets. A trimmed SRS (16 non-management items) that used the four least problematic items in each of the four domains yielded better-fitting models across all languages, but equivalence was still not reached. With this shorter version there was equivalence of item loading with respect to treatment (surgery vs conservative), time of assessment (baseline vs 12 months follow-up), and etiology (degenerative vs idiopathic), but not age (< vs ≥50 years). All findings were confirmed in the cross-validation sample. CONCLUSION: We recommend removal of the worst-fitting items from each of the four domains of the SRS-instrument (items 3, 14, 15, 17), together with adaptation and standardization of other items across language versions, to provide an improved version of the instrument with just 16 non-management items.

Global tilt: a single parameter incorporating spinal and pelvic sagittal parameters and least affected by patient positioning.

PURPOSE: Regarding the close interaction between the spinal alignment and the pelvis orientation, no parameter is routinely used to describe and to evaluate the global spinopelvic balance, taking into account simultaneously the spinal part and the pelvic part of the global alignment. We described the global tilt (GT) that could analyze malalignment considering the spine and the pelvis simultaneously. From a geometrical point of view, the global tilt is the sum of the pelvic tilt (PT) and the C7 vertical tilt (angular value of sagittal vertical axis). The aim of this study is to evaluate the global tilt with comparison to PT and sagittal vertical axis (SVA), with the hypothesis that GT would be the least sensitive to positional changes. METHODS: A cohort of 22 patients with sagittal malalignment was identified from a multicentric database of adult spinal deformities (ASD). Inclusion criteria were age >30 years, SVA > 40 mm and/or PT > 20°. All patients had full spine EOS radiographs in positions 1 and 2 (P1 and P2), in which the patient was asked to stand and put his hands on his shoulders without any effort (P1), or to make an effort to be as straight as possible (P2). PT, SVA and GT were measured in both positions and changes between P1 and P2 were calculated and compared using Student's t test with significance level at p < 0.05. RESULTS: No significant changes were observed for GT; SVA and PT were significantly influenced by patient positioning. SVA decreased and PT increased for all cases in P2 whereas the changes in GT were in either direction. The average increase in PT was 7.1° (±5.4) or 30.8 % (±24.9); decrease in SVA was 45.1 mm (±25.6) or 60.0 % (±44.2) while the change in GT was 4.4° (±3.3) or 12.6 % (±9.3). DISCUSSION: GT appears to be less affected by the patient's position compared to SVA and PT. This seems logical because GT contains both spinal alignment and pelvic compensation; it is not affected by their changes in opposing directions. CONCLUSION: GT appears to be the most reliable single sagittal plane parameter in ASD. It is the least affected by patient position and incorporates both the pelvic and the spinal alignment within one measure.

The Core Outcome Measures Index (COMI) is a responsive instrument for assessing the outcome of treatment for adult spinal deformity.

INTRODUCTION: The Core Outcome Measures Index for the back (COMI-back) is a very brief instrument for assessing the main outcomes of importance to patients with back problems (pain, function, symptom-specific well-being, quality of life, disability). However, it might be expected to be less responsive than a disease-specific instrument when evaluating specific pathologies. In patients with adult spinal deformity, we compared the performance of COMI-back with the widely accepted SRS-22 questionnaire. METHODS: At baseline and 12 months after non-operative (N = 121) and surgical (N = 83) treatment, patients (175 F, 29 M) completed the following: COMI-back, SRS-22, Oswestry Disability Index (ODI) and SF-36 PCS. At 12 months' follow-up, patients also indicated on a 15-point Global Rating of Change Scale (GRCS) how their back problem had changed relative to 1 year ago. Construct validity for the COMI-back was assessed by the correlation between its scores and those of the comparator instruments; responsiveness was assessed with receiver operating characteristics (ROC) analysis of COMI-back change scores versus the criterion 'treatment success' (dichotomized GRCS). RESULTS: Baseline values for the COMI-back showed significant (p < 0.0001) correlations with SRS-22 (r = -0.85), ODI (r = 0.83), and SF-36 PCS (r = -0.82) scores; significantly worse scores for all measures were recorded in the surgical group. The correlation between the change scores (baseline to 12 months) for COMI and SRS-22 was 0.74, and between each of these change scores and the external criterion of treatment success were: COMI-back, r = 0.58; SRS-22, r = -0.58 (each p < 0.0001). The ROC areas under the curve for the COMI-back and SRS-22 change scores were 0.79 and 0.82, respectively. CONCLUSION: Both baseline and change scores for the COMI-back correlated strongly with those of the SRS-22, and differed significantly in surgical and non-operative patients, suggesting good construct validity. With the "change in the back problem" serving as external criterion, COMI-back showed similar external responsiveness to SRS-22. The COMI-back was well able to detect important change. Coupled with its brevity, which minimizes patient burden, these favourable psychometric properties suggest the COMI-back is a suitable instrument for use in registries and can serve as a valid instrument in clinical studies emerging from such data pools.

Does transverse apex coincide with coronal apex levels (regional or global) in adolescent idiopathic scoliosis?

STUDY DESIGN: Cross-sectional. OBJECTIVES: To identify the regional and global apexes of curves in adolescent idiopathic scoliosis and to compare the levels of those with the most rotated vertebral levels on computed tomography scans. SUMMARY OF BACKGROUND DATA: The terminology regarding the terms and definitions had been arbitrary until being refined and standardized by the Scoliosis Research Society Working Group on Three-Dimensional Terminology of Spinal Deformity. Apical vertebra or disc is defined as the most laterally deviated vertebra or disc in a scoliosis curve, but the most rotated vertebra (or disc) has not been included in this terminology. One study suggested that the most rotated vertebral level was always located at the apex. METHODS: Thirty-three structural curves of 25 consecutive patients scheduled for surgery for thoracic or thoracolumbar scoliosis were analyzed with standing anteroposterior radiographs and computed tomography scans covering the curve apexes and pelvis. Thoracic and lumbar curves were evaluated separately for all Type II curves. Vertebral rotations were normalized by the rotation of the pelvis. The most rotated vertebral (or disc) levels (transverse apex) were compared with the regional and global apex levels (vertebra or disc) (coronal apexes) of the corresponding curves separately. RESULTS: Regional and global apexes were at the same level in 18 (54.5%) curves, and within half a level in another 15 (45.4%), and the regional apex was one level higher in two curves (95% confidence levels: -0.82, +0.88). Comparison of the most rotated levels with regional and global apex levels revealed a higher variability, extending up to two levels for the global apex (95% confidence levels: -1.19, +1.54 levels for the global and -1.0, +1.41 levels for the regional apexes). CONCLUSION: This study demonstrated that the regional or global apex of a given curve is the most rotated level in only a minority of the curves. The most rotated level may be as far as two levels from the global apex and one level from the regional apex.

Four-level noncontiguous fracture of the vertebral column: a case report.

The case of a patient with four-level fractures of the vertebral column, located at the cervical, thoracic, lumbar, and sacral regions, three of which were unstable, is reported. There were no injuries in the appendicular skeleton. Neurological involvement was potentially caused by multilevel compressions. This patient was treated aggressively with early surgical stabilization of all unstable levels, which facilitated early expeditious rehabilitation.

Measurement of vertebral rotation in standing versus supine position in adolescent idiopathic scoliosis.

Thirty-three structural curves of 25 patients with adolescent idiopathic scoliosis were evaluated using computed tomography (CT) scans and plain radiography. The average Cobb angle on standing radiographs was 55.72 degrees and was observed to be corrected spontaneously to 39.42 degrees while the patients were in supine position (29.78% correction). Average apical rotation according to Perdriolle was 22.75 degrees on standing radiographs and 16.78 degrees on supine scanograms. The average rotation according to Aaro and Dahlborn on CT scans was 16.48 degrees. Radiographic measurements were significantly different from axial CT slice or scanogram measurements (p = 0.000), but the two latter measurements, both obtained in the supine position, did not appear to be different (p = 0.495). Deformities on the transverse plane as well as on the coronal plane are influenced by patient positioning. If the patient lies supine, the scoliosis curve corrects spontaneously to some degree on both planes. Measurements obtained from the scanograms by the Perdriolle method in the supine position are very similar to those obtained by CT. Perdriolle's is a simple, convenient, and reliable method to measure rotation on standing radiograms.

Short-segment pedicle instrumentation of thoracolumbar burst fractures: does transpedicular intracorporeal grafting prevent early failure?

STUDY DESIGN: A prospective, randomized study comparing two treatment methods for thoracolumbar burst fractures: short-segment instrumentation with transpedicular grafting and the same procedure without transpedicular grafting. OBJECTIVE: To evaluate the efficacy of transpedicular grafting in preventing failure of short-segment fixation for the treatment of thoracolumbar burst fractures. SUMMARY OF BACKGROUND DATA: Short-segment pedicle instrumentation for thoracolumbar burst fractures is known to fail early because of the absence of anterior support. Additional transpedicular grafting has been offered as an alternative to prevent this failure. However, there is controversy about the results of transpedicular grafting. METHODS: Twenty patients with thoracolumbar burst fractures were included in the study. The inclusion criterion was the presence of fractures through the T11-L3 vertebrae without neurologic compromise. The patients were randomized by a simple method into two groups. Group 1 patients were treated using short-segment instrumentation with transpedicular grafting (TPG) (n = 10), and Group 2 patients were treated by short-segment fixation alone (NTPG) (n = 10). Clinical (Likert's questionnaire) and radiologic (sagittal index, percentage of anterior body height compression, and local kyphosis) outcomes were analyzed. RESULTS: The two groups were similar in age, follow-up period, and severity of the deformity and fracture. The postoperative and follow-up sagittal index, percentage of anterior body height compression, and average correction loss in local kyphosis in both groups were not significantly different. The failure rate, defined as an increase of 10 degrees or more in local kyphosis and/or screw breakage, was also not significantly different (TPG = 50%, NTPG = 40%, P = 0.99). CONCLUSIONS: Short-segment transpedicular instrumentation of thoracolumbar burst fractures is associated with a high rate of failure that cannot be decreased by additional transpedicular intracorporeal grafting.

The effect of transpedicular intracorporeal grafting in the treatment of thoracolumbar burst fractures on canal remodeling.

Short-segment posterior instrumentation for the treatment of thoracolumbar burst fractures has been reported with a high rate of failure. Transpedicular intracorporeal grafting in combination with short-segment instrumentation has been offered as an alternative to prevent failure. However, concern still remains about the potential complication of further canal narrowing or failure of remodeling with this technique. The purpose of this prospective, randomized, controlled study is to evaluate the effect of transpedicular intracorporeal grafting on spinal canal restoration and remodeling in a group of patients treated with short-segment instrumentation for thoracolumbar burst fractures. Twenty-one patients with thoracolumbar burst fractures were randomised into transpedicular grafting (TPG) (n=11) and non-transpedicular grafting (NTPG) (n=10) groups, and were prospectively followed for an average of 50 months (range 25-85 months). Groups were similar in age, type of fracture, load sharing classification and kyphotic deformity. Preoperative, postoperative and follow-up computed tomographic (CT) images through the level of pedicles were obtained, corrected for differences in magnification, and digitized. Areas of the spinal canals were measured and normalized by the estimated area at that level (average of adjacent levels). Average kyphosis was 19.7 degrees+/-6.2 degrees at presentation, was corrected to 1.9 degrees+/-4.9 degrees by operation, but was found to have deteriorated to 9.1 degrees+/-6.4 degrees at final follow-up. There were no differences between groups regarding the evolution of sagittal deformity. Spinal canal narrowing was 38.5+/-18.2% at presentation, 22.1+/-19.8% postoperatively, and it further improved to -2.5+/-16.7% at follow-up, similar for both groups. Our results demonstrate that transpedicular intracorporeal grafting in the treatment of burst fractures does not have a detectable effect on the rate of reconstruction of the canal area or on remodeling. Spinal canal remodeling was observed to occur in all patients regardless of grafting.

Traumatic L1-L2 dislocation without fracture in a 6-year-old girl. Incomplete neurologic deficit and total recovery.

STUDY DESIGN: A report of a rare complete dislocation of the first lumbar vertebra without fracture in a 6-year-old girl. OBJECTIVES: To describe a rare traumatic lesion in children. SUMMARY OF BACKGROUND DATA: Although there has been a report of posterior dislocations of vertebra without fracture accompanied by anterior apophyseal splitting in young cadavers, all in the cervical region, to date, there has not been a reported clinical case of vertebral dislocation in the thoracolumbar region in a child. METHODS: A 6-year-old girl, while playing on a farm, had her hair caught in the wheel of a sugar beet harvesting machine. She was referred with incomplete paraplegia. Radiologic examination showed an L1-L2 dislocation with no fracture. She was treated surgically using a modified Luque frame with sublaminar wires. RESULTS: Six months after injury, the patient had no neurologic deficit and was living an entirely normal life. Radiographs showed a perfect alignment of the thoracolumbar spine. At the 26-month follow-up, no radiologic abnormalities were observed, other than minimal end-plate sclerosis. Magnetic resonance images obtained after the removal of the implants showed no structural abnormalities in the vertebral column except disc narrowing at all instrumented levels, secondary to posterior fusion. CONCLUSION: To date, this is the first case of dislocation of the thoracolumbar spine in children. It is further notable because the neurologic deficit was incomplete, although there were striking radiologic abnormalities.

Effects of deamino-8-D-arginin vasopressin on blood loss and coagulation factors in scoliosis surgery. A double-blind randomized clinical trial.

STUDY DESIGN: A double-blind, randomized, prospective clinical study was performed to evaluate the efficacy of deamino-8-D-arginin vasopressin in reducing blood loss in major scoliosis surgery. OBJECTIVES: To evaluate whether desmopressin has any effect on reducing blood loss in spinal surgery, to identify the probable mechanisms of effectiveness via blood coagulation factors, and to outline any adverse effect associated with the use of deamino-8-D-arginin vasopressin. SUMMARY OF BACKGROUND DATA: Scoliosis surgery is known to be associated with major blood loss. Because of major drawbacks of homologous blood transfusion, many alternative methods have been used to counter the blood loss. Only a few studies exist, with controversial results, on the use of deamino-8-D-arginin vasopressin. METHODS: The study population included 40 operations on 35 consecutive patients undergoing reconstructive surgery for either idiopathic (n = 26) or congenital (n = 9) scoliosis. Operations were randomized into deamino-8-D-arginin vasopressin (0.3 microgram/kg body weight; maximum, 20 micrograms) (n = 18) or placebo (n = 22) groups and stratified according to the diagnosis and the type of surgery performed (i.e., anterior versus posterior versus anterior and posterior sequential). Parameters of blood loss, serum levels of blood coagulation factors at different time intervals, and urinary output were measured. RESULTS: Findings indicated that blood loss per kilogram of body weight, blood loss per surgically treated spinal level, urinary output per kilogram of body weight and serum levels of fibrinogen, von Willebrand factor (vWF) activity, tissue type plasminogen activator activity, and plasminogen activator inhibitor activity were not sensitive to the administration of deamino-8-D-arginin vasopressin at any time interval during surgery or at 24 hours after surgery (P > 0.05). Only factor VIII:C levels exhibited significant elevations at 30 minutes and at 24 hours (P < 0.05). CONCLUSIONS: This study could not demonstrate any significant effect of deamino-8-D-arginin vasopressin on the amount of blood loss in a group of patients with idiopathic or congenital scoliosis. Findings indicate that for most of the coagulation factors, any changes in serum levels induced by deamino-8-D-arginin vasopressin were much like those expected from surgery itself. This study also failed to demonstrate any significant effects altering the urinary output that may be attributed to the use of deamino-8-D-arginin vasopressin.

A study of adenosine treatment in experimental acute spinal cord injury. Effect on arachidonic acid metabolites.

STUDY DESIGN: A prospective, randomized, blinded experimental trauma study. STUDY OBJECTIVE: The effect of adenosine on arachidonic acid metabolites and lipid peroxidation was investigated in induced spinal cord injury. SUMMARY OF BACKGROUND DATA: Effects of adenosine in ischemia-reperfusion models have been studied, but no studies of adenosine's effect on direct trauma to the spinal cord have been reported. METHODS: Thirty-seven adult Wistar albino rats were randomly divided into four groups and underwent laminectomy. Group 1 underwent a sham operation. Group 2 received an intravenous adenosine infusion of 100 micrograms/kg per minute for 30 minutes. In Group 3, a standard spinal cord trauma of 50 g.cm strength was established at the lower thoracic level with a "weight-drop" technique, and Group 4 received an infusion of adenosine (100 micrograms/kg per minute) for 30 minutes after the trauma. RESULTS: Tissue prostaglandin E2 activity was significantly higher in adenosine-treated trauma groups when compared with that in other groups (P < 0.0001). The difference in tissue leukotriene C4 activity between control and trauma groups was significant (P < 0.05). Adenosine infusion after trauma limited the increases in lipid peroxidation, with the difference approaching significance at P = 0.06. The structure of myelin was well preserved in the adenosine-treated trauma group. However, the changes were irreversible in severely damaged areas. CONCLUSION: After acute spinal cord trauma, intravenous adenosine infusion of 100 micrograms/kg per minute could attenuate progression to secondary injury, but adenosine alone was not effective yet.

Risk factors associated with corrective surgery in congenital scoliosis with tethered cord.

Severe neglected congenital scoliosis with tethered cord presents major difficulties in management. The primary objective of this study was to identify the risk factors associated with corrective scoliosis surgery in neglected cases presenting with severe deformity. Six patients who presented with such problems draw attention to the importance of a staged anterior and posterior approach in order to obtain satisfactory functional results. However, corrective surgery is associated with major neurologic and systemic complications, and every effort should be made to intervene with the progression of the deformity before corrective measures becomes necessary.

Simultaneous anterior and posterior approaches for correction of late deformity due to thoracolumbar fractures.

Thirty-one patients with an average age of 27 years were included in this study to analyze the short-term results of simultaneous anterior and posterior approaches in the treatment of late complications of thoracolumbar fractures. The complications treated were pseudoarthrosis and malunion resulting in neurologic compromise and pain. There were 20 burst fractures, 2 fracture/dislocations, and 9 compression fractures in this group. Average preoperative Sagittal Index was 35 degrees, which improved to an average of 4 degrees after surgical treatment. The average Motor Index Score improved from 90 to 98 after surgery. Average follow-up was 16 months. Average estimated blood loss was 2000 ml and average operation time was 5 h. It was concluded that the late problems associated with thoracolumbar fractures can be addressed quite adequately with simultaneous anterior and posterior approaches. The simultaneous anterior and posterior approach is associated with decreases in operating time, blood loss, and hospital stay. Technical advantages of the simultaneous technique include elimination of acute instability between the stages, protection against dislodgment of the graft, and application of the posterior instrumentation under complete visualization of the anterior graft.

Degeneration and aging affect the tensile behavior of human lumbar anulus fibrosus.

STUDY DESIGN: Samples of human lumbar (L3-L4) anulus fibrosus from four different anatomic sites (anterior outer, posterolateral inner), ranging from normal to severely degenerate, were studied in uniaxial tension and measured for water content. OBJECTIVES: To evaluate the effects of aging and degeneration on the tensile properties and hydration of the anulus fibrosus in a site-specific manner. The relationship between hydration and parameters of the tensile behavior were investigated. SUMMARY OF BACKGROUND DATA: Degeneration and aging have been shown to be related to dramatic changes in the composition and structure of the anulus fibrosus. The associated changes in the tensile, compressive, and shear properties of the anulus fibrosus have not been documented. Numerical studies using finite element models have attempted to simulate the degenerative process by incorporating estimated mechanical properties meant to represent the degenerate anulus fibrosus. Their results present findings that suggest that altered material properties of the anulus fibrosus affect the mechanics of the entire intervertebral disc. METHODS: Samples of human lumbar anulus fibrosus were classified by grade of degeneration based on a morphologic grading scheme. Multiple layer anulus specimens from four sites in the disc were tested in uniaxial tension under quasistatic conditions in a physiologic saline bath. The tensile modules, Poisson's ratio, failure stress and strain, the strain energy density to failure, and the corresponding hydration were determined for each sample. RESULTS: The Poisson's ratio, failure stress, and strain energy density of the anulus fibrosus were found to be affected significantly by degeneration, with some evidence of a sensitivity of the tensile modulus to grade of degeneration. All material properties were found to exhibit a significant and greater dependence on site within the disc than on degenerative grade. Weak correlations between aging and the Poisson's ratio and strain energy density were observed. Water content of anulus fibrosus tissue was not affected by degeneration or aging, although correlations with tensile properties were observed. CONCLUSIONS: The dramatic changes in morphology, composition, and structure that occur in anulus fibrosus with aging and degeneration are accompanied by specific variations in the tensile properties, which were generally small in magnitude. Position of the anulus fibrosus within the intervertebral disc, particularly in the radial direction, appeared to be the most important variable affecting anulus fibrosus tensile properties. This dependence on position did not change with either aging or degeneration. Results from the present study may be useful in future finite element models to assess how altered material properties of the anulus fibrosus during degeneration and aging may affect the mechanics of the entire intervertebral disc.