Reliability analysis of the epidural spinal cord compression scale.

OBJECTIVE: The evolution of imaging techniques, along with highly effective radiation options has changed the way metastatic epidural tumors are treated. While high-grade epidural spinal cord compression (ESCC) frequently serves as an indication for surgical decompression, no consensus exists in the literature about the precise definition of this term. The advancement of the treatment paradigms in patients with metastatic tumors for the spine requires a clear grading scheme of ESCC. The degree of ESCC often serves as a major determinant in the decision to operate or irradiate. The purpose of this study was to determine the reliability and validity of a 6-point, MR imaging-based grading system for ESCC. METHODS: To determine the reliability of the grading scale, a survey was distributed to 7 spine surgeons who participate in the Spine Oncology Study Group. The MR images of 25 cervical or thoracic spinal tumors were distributed consisting of 1 sagittal image and 3 axial images at the identical level including T1-weighted, T2-weighted, and Gd-enhanced T1-weighted images. The survey was administered 3 times at 2-week intervals. The inter- and intrarater reliability was assessed. RESULTS: The inter- and intrarater reliability ranged from good to excellent when surgeons were asked to rate the degree of spinal cord compression using T2-weighted axial images. The T2-weighted images were superior indicators of ESCC compared with T1-weighted images with and without Gd. CONCLUSIONS: The ESCC scale provides a valid and reliable instrument that may be used to describe the degree of ESCC based on T2-weighted MR images. This scale accounts for recent advances in the treatment of spinal metastases and may be used to provide an ESCC classification scheme for multicenter clinical trial and outcome studies.

Thoracic pedicle subtraction osteotomy for fixed sagittal spinal deformity.

STUDY DESIGN.: A retrospective clinical study. OBJECTIVE.: To find the corrective capacity of a thoracic pedicle subtraction osteotomy (PSO), determine if segmental correction is dependent on level, and to compute the impact of thoracic PSO on regional and global spinal balance. SUMMARY OF BACKGROUND DATA.: PSO is a technique popularized in the lumbar spine primarily for the correction of fixed sagittal imbalance. Despite several studies describing the clinical and radiographic outcome of lumbar PSO, there is no study in literature reporting its application in the thoracic spine. METHODS.: We retrospectively analyzed patients with fixed thoracic kyphosis who underwent thoracic PSOs for sagittal realignment. Segmental pedicle screw instrumentation and intraoperative neurophysiologic monitoring was used in all patients. Data acquisition was performed by reviewing medical charts and radiographs to determine sagittal correction (segmental/regional/global) and complications. Clinical outcome using the Scoliosis Research Society-22 (SRS-22) instrument was determined by interview. RESULTS.: A total of 25 thoracic PSOs were performed (mean: 1.7 PSOs/patient, range: 1-3) in 15 patients (9 M/6 F). The study population had an average age of 56 years (range, 36-81 years) and was followed up after surgery for a mean of 3.5 years (range, 24-75 months). The osteotomies were carried out in the proximal thoracic spine (T2-T4, n = 6), midthoracic spine (T5-T8, n = 12), and distal thoracic spine (T9-T12, n = 7). Mean correction at the PSO for all 25 levels was 16.3 degrees +/- 9.6 degrees . Stratified by region of the spine, thoracic PSO correction was as follows: T2-T4 = 10.7 degrees +/- 15.8 degrees , T5-T8 = 14.7 degrees +/- 4.6 degrees , and T9-T12 = 23.9 degrees +/- 4.1 degrees . Mean thoracic kyphosis (T2-T12 Cobb angle) was improved from 75.7 degrees +/- 30.9 degrees to 54.3 degrees +/- 21.4 degrees resulting in a significant regional sagittal correction of 21.4 degrees +/- 13.7 degrees (P < 0.005). Global sagittal balance was improved from 106.1 +/- 56.6 to 38.8 +/- 37.0 mm yielding a mean correction of 67.3 +/- 54.7 mm (P < 0.005). One patient, in whom there was segmental translation during osteotomy closure, had a decline in intraoperative somatosensory-evoked potentials. No patient sustained a temporary or permanent neurologic deficit after surgery. The mean SRS-22 Questionnaire score at final follow-up was 82.4 +/- 10.2. CONCLUSION.: Thoracic PSO can be performed safely. Segmental sagittal correction appears to vary based on the region of the thoracic spine the PSO is performed. The distal thoracic segments, which more closely resemble lumbar segments in morphology, rendered the greatest sagittal correction after PSO, approximately 24 degrees . There was no case of neurologic injury associated with thoracic PSO, and clinical outcomes according to the SRS-22 instrument were generally favorable.

Classification of congenital scoliosis and kyphosis: a new approach to the three-dimensional classification for progressive vertebral anomalies requiring operative treatment.

STUDY DESIGN: We reviewed three-dimensional (3D) computed tomography (CT) images of congenital spinal deformities and proposed a new classification based on the information obtained. OBJECTIVES: The purposes of this article were to clearly illustrate the limitations of two-dimensional classification, to summarize the clinical significance of 3D analysis of congenital vertebral anomalies, and to propose a new 3D classification of congenital vertebral anomalies. SUMMARY OF BACKGROUND DATA: The classification of congenital scoliosis or kyphosis were based on radiographic findings of plain radiograph images of congenital vertebral anomalies, it is sometimes difficult in classifying the large variety of anomalous vertebrae or severely twisted 3D curves. METHODS: Three-dimensional CT images of more than 150 patients with congenital spinal deformities were analyzed and compared with plain radiograph images. By developing the algorithm for the evaluation of malformed vertebrae in terms of numbers of abnormal vertebrae, type of formation failure, and type of segmentation failure in separate steps, we attempted to revise the classification of congenital spinal deformities. RESULTS: The images of plain radiograph cannot demonstrate the spatial relationship of each structure of the vertebrae. Three-dimensional findings in congenital-deformed vertebrae included several types of laminae and clearer definitions of each type of anomalous vertebrae. By developing an algorithm for the evaluation of congenital spinal deformity, congenital spinal deformity could be mainly classified into 4 types of congenital vertebral abnormalities: Type 1: solitary simple, Type 2: multiple simple, Type 3: complex, Type 4: segmentation failure. CONCLUSION: The large volume of information that can be obtained by evaluating 3D CT images of congenitally deformed vertebrae can be a great help in developing a strategy for surgical treatment. We need to develop a new classification of congenital scoliosis based on the perspective of 3D imaging to understand the etiology and embryology, as well as to determine an operative strategy.

Reliability analysis for manual radiographic measures of rotatory subluxation or lateral listhesis in adult scoliosis.

STUDY DESIGN: Retrospective observational study. OBJECTIVE: To define the inter- and intraobserver reliability of 3 measures of rotatory subluxation (RS) in adult scoliosis (AS). SUMMARY OF BACKGROUND DATA: RS is a hallmark of AS. To accurately track this measure, one must know its reliability. Reliability testing has not been performed. METHODS: PA 36" films of 29 AS patients were collected from one surgeon's practice. Three observers on 2 separate occasions measured all levels with >or=3-mm RS (60 levels, 360 measurements) on the convexity of the involved segment using 3 different techniques-midbody (MB), endplate (EP), and centroid (C). These data were then analyzed to determine the intraclass correlation coefficient (ICC) for inter- and intraobserver reliability. RESULTS: The thoracolumbar/lumbar curve (average 58 degrees ) was the major curve for the majority (62%) of patients. RS at L3/4 was most common (35%). The overall inter- and intraobserver reliability was good-excellent for all methods, but the centroid method consistently had the highest ICC. ICC correlated with observer experience. Moderate-severe arthritic change (present in 55%) and poor image quality (52%) decreased ICC, but it still remained good-excellent for each measure. The reproducibility coefficient for each measure was 4 mm for MB and 2.8 mm for C and EP. CONCLUSION: MB, EP, and C are reliable techniques to measure RS even in elderly arthritic spines, but the methods inherently produce different values for a given level. The centroid method is most reliable and least influenced by experience. The EP method is easy to perform and very reliable. Spine surgeons should pick their preferred method and apply it consistently. Changes >3 mm suggest RS progression. RS may be a useful measure in addition to Cobb angle in AS. Having defined measurement reliability, the role of RS progression in surgical indications and patient outcomes can be evaluated.

Does superior-segment facet violation or laminectomy destabilize the adjacent level in lumbar transpedicular fixation? An in vitro human cadaveric assessment.

STUDY DESIGN: This is an in vitro biomechanical study. OBJECTIVE: The current investigation was performed to evaluate adjacent level kinematic change following unilateral and bilateral facet violation and laminectomy following 1-, 2-, and 3-level reconstruction. SUMMARY OF BACKGROUND DATA: The incidence of superior-segment facet violation with lumbar transpedicular fixation has been reported as high as 35%; however, its contribution to biomechanical instability at the supradjacent level is unknown. In addition, superior-segment laminectomy has been implicated as a risk factor for the development of adjacent level disease. The authors assess the acute biomechanical effects of proximal facet violation and subsequent laminectomy in an instrumented posterior fusion model in 10 cadaveric specimens. METHODS: Biomechanical testing was performed on 10 human cadaveric spines under axial rotation (AR), flexion-extension (FE), and lateral bending (LB) loading. After intact analysis, pedicle screws were inserted from L5-S1 and testing repeated with: (1) preserved L4-L5 facets, (2) unilateral facet breach, (3) bilateral breach, and (4) L5 laminectomy. Following biomechanical analysis, instrumentation was extended to L4, then L3 and biomechanical testing repeated. Full range of motion (ROM) at the proximal adjacent levels were recorded and normalized to intact (100%). RESULTS: Supradjacent level ROM was increased for all groups under all loading methods relative to intact (P < 0.05). However, AR testing revealed progressive instability at the adjacent level in groups 3 and 4, relative to group 1, following 1-, 2- and 3-level fixation (P < 0.05). During FE, supradjacent level ROM was significantly increased for group 4 specimens compared with group 1 after L5-S1 fixation (P < 0.05), and was greater than all other groups for L3-S1 constructs (P < 0.05). Interestingly, under lateral bending, facet joint destabilization did not change adjacent segment ROM. CONCLUSION: There were significant changes in proximal level ROM immediately after posterior stabilization. However, an additional increase in supradjacent segment ROM was recorded during AR after bilateral facet breach.Subsequent complete laminectomy at the uppermostfixation level further destabilized the supradjacent segment in FE and AR. Therefore, meticulous preservation of the cephalad-most segment facet joints-is paramount to ensure stability.

Intervertebral disc tissue engineering using a novel hyaluronic acid-nanofibrous scaffold (HANFS) amalgam.

Degeneration of the intervertebral disc (IVD) represents a significant musculoskeletal disease burden. Although spinal fusion has some efficacy in pain management, spine biomechanics is ultimately compromised. In addition, there is inherent limitation of hardware-based IVD replacement prostheses, which underscores the importance of biological approaches to disc repair. In this study, we have seeded multipotent, adult human mesenchymal stem cells (MSCs) into a novel biomaterial amalgam to develop a biphasic construct that consisted of electrospun, biodegradable nanofibrous scaffold (NFS) enveloping a hyaluronic acid (HA) hydrogel center. The seeded MSCs were induced to undergo chondrogenesis in vitro in the presence of transforming growth factor-beta for up to 28 days. The cartilaginous hyaluronic acid-nanofibrous scaffold (HANFS) construct architecturally resembled a native IVD, with an outer annulus fibrosus-like region and inner nucleus pulposus-like region. Histological and biochemical analyses, immunohistochemistry, and gene expression profiling revealed the time-dependent development of chondrocytic phenotype of the seeded cells. The cells also maintain the microarchitecture of a native IVD. Taken together, these findings suggest the prototypic potential of MSC-seeded HANFS constructs for the tissue engineering of biological replacements of degenerated IVD.

Biomechanical contribution of transverse connectors to segmental stability following long segment instrumentation with thoracic pedicle screws.

STUDY DESIGN: An in vitro biomechanical cadaver study of long segment thoracic pedicle screw constructs with transverse connectors (TC). OBJECTIVE: To determine the resultant degree of motion of the instrumented thoracic spine after segmental pedicle screw instrumentation with and without TC. SUMMARY OF BACKGROUND DATA.: TC are generally not thought to be necessary with thoracic pedicle screw constructs, yet to date no study has reported the effect of TCs after all pedicle screw long thoracic fusions. METHODS: Eight human cadaveric spines were potted and then instrumented from T4-T10 with bilateral 5.5 mm multiaxial titanium (Ti) pedicle screws and 5.5 mm contoured Ti rods. Specimens were tested with a six-degree-of-freedom spine stimulator in the intact condition, after instrumentation, after placement of 1 TC (3 different locations) and after placement of both TCs. Data were analyzed by loading modality (axial rotation, flexion-extension, and lateral bending) using one-way analysis of variance with an alpha of 0.05. Paired t tests were used for post hoc analysis with correction for multiple comparisons. RESULTS: There was no difference with the addition of 1 or 2 TCs in terms of flexion-extension or lateral bending when compared to the instrumented condition (P > 0.05). Biomechanical testing of the long-segment thoracic constructs in axial rotation (torsion) loading modes generated the most significant findings of this study. After instrumentation with thoracic pedicle screws, T4-T10 full ROM was significantly reduced from the intact condition (P < 0.05). On average, TPS alone resulted in a 65% decrease in ROM. However, the addition of a transverse connector at 1 of the 3 positions tested yielded another 20% improvement in axial segmental stability as represented by further ROM reduction. These differences were significant from the TPS only group (no TCs), regardless of the TC position (P < 0.05). Furthermore, 2 TCs placed at the proximal and distal ends of the construct provided the greatest biomechanical axial stability to the instrumented specimens (P < 0.05). This was highlighted by an average of 35% ROM reduction from the stability level achieved with the TPS only constructs (P < 0.05), or an additional 15% improvement in axial stability over a single TC. CONCLUSION: For long thoracic pedicle screw constructs, the addition of 1 or 2 TCs significantly decreases construct axial rotation, which is the primary plane of motion for the thoracic spinal region. A single TC contributed to a significant reduction of T4-T10 ROM (an additional 20%) relative to TPS fixation alone (P < 0.05), while the location of the TC within the construct was irrelevant. A second TC had an additive effect (an additional 15% reduction) on axial stability. (P < 0.05) Flexion-extension and lateral bending are not affected. Single TC significantly improves axial rotation stability in long thoracic pedicle screw constructs. Two crosslinks, however, are better than one.

Salvage of C2 pedicle and pars screws using the intralaminar technique: a biomechanical analysis.

STUDY DESIGN: Human cadaveric biomechanical analysis. OBJECTIVE: The purpose of this study is to evaluate the ability of using 1 of the remaining 2 methods of instrumenting C2, should the initial method fail. SUMMARY OF BACKGROUND DATA: Although 3 different methods of C2 fixation (pedicle, pars, and laminar screws) are possible, occasionally an attempt at screw insertion fails. In such cases, the surgeon needs a viable alternative to salvage/obtain fixation to obviate the need to instrument an additional motion segment. METHODS.: Eleven fresh-frozen cadaveric specimens (Occ-C4) were DEXA scanned for bone mineral density. On the left side, pedicle screws were first inserted, then pulled out. Then, "salvage" pars screws were inserted, then pulled-out, followed by laminar screws. On the right, a similar sequence was repeated, except that a pars screw was followed by a pedicle screw, then a laminar screw. All screws were placed by experienced cervical spine surgeons. Insertional torque (IT) was measured in Newton-meters (Nm). Tensile loading to failure was performed "in-line"with the screw axis at a rate of 0.25 mm/s using a MTS 858 MiniBionix II System with data recorded as peak pull-out strength (POS) in newtons "N". RESULTS: Pedicle screws generated statistically greater IT and POS than other techniques as the initial fixation type (P < 0.0001). Similar trends were observed with transpedicular fixation as a salvage procedure (P > 0.05). Laminar screws yielded consistently higher POS values than pars fixation when applied in a salvage scenario (POS range: LS = 146-707 N; PrS = 8-548 N); however, high standard deviation precluded statistical significance (P > 0.05). Significant predictive relationship was established between IT and POS for all screws using Pearson correlation coefficient and bivariate linear regression analysis (r = 0.75 and r = 0.511, respectively; P < 0.01). CONCLUSION: Our results suggest that pedicle screws provide the strongest fixation for both initial and salvage applications. If they should fail, lamina screws appear to provide stronger and more reproducible fixation than pars screws.

Osteoporosis and vertebral compression fractures-continued missed opportunities.

BACKGROUND CONTEXT: Untreated osteoporosis causes decreased bone mineral density, which predisposes to fragility fractures. Low-energy vertebral compression fractures are the most common type of osteoporotic fragility fracture. Prior studies have shown that only one-quarter of patients diagnosed with an osteoporotic fracture are referred or treated for osteoporosis. PURPOSE: To identify the rate of therapeutic interventions for patients aged 50 years and older within a capitated population who sustained low impact vertebral compression fractures over a 6-month period. STUDY DESIGN/SETTING: Retrospective observational study. PATIENT SAMPLE: The reports of all imaging studies of the chest, abdomen, and spine taken from July to December 2002 within a large military health-care system were queried on the Composite Health Computer System (CHCS). The sample included patients 50 years or older who had a low-energy vertebral compression fracture. OUTCOME MEASURES: The computerized medical records were examined for osteoporotic medication prescriptions, referrals to endocrinology, and to dual-energy X-ray absorptiometry (DEXA) scans. These results were compared with results obtained from a similar study on osteoporotic distal radius fractures. RESULTS: The records of 156 patients (average age: 77.3y; 78 women, 78 men) meeting the inclusion criteria were analyzed to determine what proportion was followed-up with osteoporosis interventions. Within 1 year after the fracture, 39% (37 females, 24 males) had undergone a DEXA scan, 35% (37 females, 18 males) had been referred to endocrinology, 38% (47 females, 12 males) were receiving active osteoporosis treatment, and 51% (55 females, 25 males) were receiving any form of osteoporosis-directed medication. The rate of medical intervention was similar to the rate of intervention after distal radius fragility fractures (n=111; 30% active medication; 47% any osteoporosis medication) (p>.21). The rate of all interventions was significantly greater for women than men. CONCLUSIONS: Although the likelihood of intervention is slightly greater after vertebral compression fractures than for distal radius fractures, orthopedic surgeons, emergency room physicians, and primary care providers continue to miss opportunities, especially in males, to diagnose and/or initiate active therapeutic interventions for osteoporosis in patients presenting with osteoporosis-related fragility fractures.

Surgical treatment of vertebral osteomyelitis with recombinant human bone morphogenetic protein-2.

STUDY DESIGN: A retrospective clinical study. OBJECTIVE: To evaluate the use of recombinant human bone morphogenetic protein-2 (rhBMP-2) as the primary graft material for the surgical treatment of vertebral osteomyelitis. SUMMARY OF BACKGROUND DATA: The clinical and radiographic results using allograft, autograft, and vascularized bone flaps for the surgical treatment of osteomyelitis have been previously reported. Despite an expanding body of literature documenting the value of rhBMP-2 in spinal fusion, its application to the management of spinal infection has never before been analyzed. METHODS: Twenty patients underwent surgical treatment of vertebral osteomyelitis using rhBMP-2 and were analyzed with a mean follow-up of 40 months (range, 24-53 months). All patients were treated with anterior column debridement and instrumented reconstruction. Four (20%) patients were treated with an anterior approach alone while the remaining 16 (80%) patients underwent circumferential spinal reconstruction. Clinical outcomes were assessed by Frankel grade and Odom criteria. Radiographic fusion was characterized based on thin-section computerized tomography (CT) analysis. RESULTS: Pathogens responsible for infection included Staphylococcus aureus (11; 55%), S. epidermidis (6; 30%), Bacteroides (1; 5%), and polymicrobial species (1; 5%). Infected segments of the spinal column based on region were found to be: thoracic (1; 5%), thoracolumbar (5; 25%), lumbar (11; 55%), and lumbosacral (3; 15%). The mean number of anterior and posterior segments fused was 3.3 (range, 2-5) and 6.5 (range 2-16), respectively. Forty-five percent of the subjects underwent multilevel corpectomies and fusion. All patients demonstrated clinical and radiographic evidence of spinal fusion at the time of follow-up. Patients had stable (14 patients) or improved (6 patients) Frankel grades after surgery. Odom criteria at final follow-up were: excellent (3; 15%), good (12; 60%), fair (4; 20%), and poor (1; 5%). There was no case of persistent or recurrent infection requiring revision surgery. CONCLUSION: rhBMP-2 is a valuable graft option for the surgical treatment of vertebral osteomyelitis. When dosed in the manner reported, very high rates of fusion are achievable as is eradication of infection.

Effect of multilevel lumbar disc arthroplasty on the operative- and adjacent-level kinematics and intradiscal pressures: an in vitro human cadaveric assessment.

BACKGROUND CONTEXT: With lumbar arthroplasty gaining popularity, limited data are available highlighting changes in adjacent-level mechanics after multilevel procedures. PURPOSE: Compare operative- and adjacent-segment range of motion (ROM) and intradiscal pressures (IDPs) after two-level arthroplasty versus circumferential arthrodesis. STUDY DESIGN: Cadaveric biomechanical study. METHODS: Ten human cadaveric lumbar spines were used in this investigation. Biomechanical testing was performed according to a hybrid testing protocol using an unconstrained spine simulator under axial rotation (AR), flexion extension (FE), and lateral-bending (LB) loading. Specimens were tested in the following order: 1) Intact, 2) L3-L5 total disc replacement (TDR), 3) L3-L5 anterior interbody cages+pedicle screws. IDP was recorded at proximal and distal adjacent levels and normalized to controls (%intact). Full ROM was monitored at the operative and adjacent levels and reported in degrees. RESULTS: Kinematics assessment revealed L3-L5 ROM reduction after both reconstructions versus intact controls (p < .05). However, global quality of segmental motion distributed over L2-S1 was preserved in the arthroplasty group but was significantly altered after circumferential fixation. Furthermore, adjacent-level ROM was increased for the arthrodesis group under LB at both segments and during AR at L2-L3 relative to controls (p < .05). FE did not reveal any intergroup statistical differences. Nonetheless, after arthrodesis IDPs were increased proximally under all three loading modalities, whereas distally a significant IDP rise was noted during AR and LB (p < .05). No statistical differences in either biomechanical parameter were recorded at the adjacent levels between intact control and TDR groups. CONCLUSIONS: Our results indicate no significant adjacent-level biomechanical changes between arthroplasty and control groups. In contrast, significant alterations in ROM and IDP were recorded both proximally (ROM=LB & AR; IDP=AR, FE, LB) and distally (ROM=LB; IDP=AR & LB) after circumferential arthrodesis. Therefore, two-level lumbar arthroplasty maintains a more favorable biomechanical environment at the adjacent segments compared with the conventional transpedicular fixation technique. This, in turn, may have a positive effect on the rate of the transition syndrome postoperatively.

The Spinal Appearance Questionnaire: results of reliability, validity, and responsiveness testing in patients with idiopathic scoliosis.

STUDY DESIGN: Prospective, sequential enrollment. OBJECTIVE: We report the development and testing of the Spinal Appearance Questionnaire (SAQ) for reliability, validity, and responsiveness in patients with idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: The SAQ was designed to measure patients' and their parents' perception of their spinal deformity's appearance using standardized drawings and questions. This study was designed to test the instrument's psychometric properties. METHODS: The SAQ was administered as a test-retest to idiopathic scoliosis patients and parents for reliability and initial validity assessment (Group I). It was then administered to patients before surgery and 1 year after surgery (Group II) for responsiveness and further validity testing. Finally, both the SAQ and SRS instruments were administered to adolescent idiopathic patients before surgery and 1 year after surgery (Group III) for comparison of the 2 instruments. RESULTS: Group I: The individual scale items had good to excellent reliability (Spearman's rho, 0.57-0.99) and high internal scale consistency (Cronbach's alpha >0.7). The mean scale scores differentiated between curves greater than 30 degrees and lesser curves (P < 0.01). Surgery improved scores compared with those with "surgery recommended." Group II: The domains correlated with clinical and radiographic aspects of the deformity before surgery. All of the domains showed significant difference after surgery (P < 0.0001) and large effect size for all domains except for the patient chest domain. Group III: Both the SAQ and the SRS instruments had significant improvement in all of their domains except for the SRS Activity scale. The relative efficiency of the SAQ domains to the SRS appearance domain (the most responsive SRS domain) was greater for 5 SAQ domains. CONCLUSION: The SAQ is reliable, responsive to curve improvement, and shows strong evidence of validity. It provides more detail than the SRS in the appearance domain, and provides explanation of spinal deformity's concerns and improvements.

Neural complications in the surgical treatment of adolescent idiopathic scoliosis.

STUDY DESIGN: Multicenter, prospective, consecutive clinical series. OBJECTIVE: To report on neural complications in a prospective cohort study of 1301 children undergoing spinal fusion and instrumentation for adolescent idiopathic scoliosis (AIS). SUMMARY OF BACKGROUND DATA: The incidence of neural complications for spinal deformity surgery has been reported to be 0.26% to 17%. However, most studies have relied on retrospective voluntary reporting of nonconsecutive cases. METHODS: A review of 1301 consecutive surgical cases was conducted using the Prospective Pediatric Scoliosis Study database, which is maintained by the Spinal Deformity Study Group. RESULTS: There were 9 neural complications. There were 3 thecal penetrations, none of which required repair, and none of which demonstrated intraoperative neural monitoring changes or postoperative clinical sequelae. There were 2 nerve root injuries. In 1 nerve root injury, a positional compression femoral neurapraxia resolved over 6 months. The other was an L4 neurapraxia despite lowest instrumented vertebra L1, and resolved spontaneously by 3 months' follow-up. There were 4 spinal cord injuries. One required removal of implants and fusion in situ, 1 required relaxation of correction and in situ fusion with instrumentation, while the other 2 were observed after fusion and instrumentation with reduction. All resolved spontaneously within 3 months after operation. CONCLUSION: The neural complication rate was 0.69%. Two thecal penetrations were due to medial placement of pedicle screws, and 1 was due to dissection during spine exposure. If these are eliminated, as they imply intraspinal entry but not direct neural injury, together with 1 positional neurapraxia, which is remote from the surgical field, our complication rate is 0.38%. This is consistent with other studies in the North American Literature, including multiple reports from the Scoliosis Research Society. Common themes are significant curve correction producing neural stretch and the use of sublaminar wires. None of the neural injuries was permanent. These results reaffirm that surgical treatment of adolescent idiopathic scoliosis has a low but real neural complication rate.

Surgical revision rates of hooks versus hybrid versus screws versus combined anteroposterior spinal fusion for adolescent idiopathic scoliosis.

STUDY DESIGN: Multi-institution retrospective review. OBJECTIVE: To determine the surgical revision rates of hook, hybrid, anteroposterior, and total pedicle screw constructs for adolescent idiopathic scoliosis (AIS). SUMMARY OF BACKGROUND DATA: Much debate continues on the safety, efficacy, and cost of thoracic pedicle screws. Nonetheless, there are no large series that have evaluated the revision rate of various constructs in AIS to determine the need for repeat surgery, and therefore, the added indirect costs and risks of additional procedures. METHODS: We retrospectively reviewed the surgical case logs of 1428 patients with AIS at 2 institutions from 1990 to 2004, and the clinical records and radiographs of revision cases. Patients were classified into 1 of 4 groups: hook, hybrid hook and screw, all pedicle screw, and combined anteroposterior fusion constructs. Overall, there were 65 (4.6%) returns to the operating room, or 55 (3.9%) cases after excluding infections without concomitant pseudarthrosis. RESULTS: Of the 65 revision cases, there were 52 females and 13 males, at an average age at first surgery of 13.9 years (range, 9-18 years), and an average age at revision of 14.7 years (range, 12-23 years). For the revision cases, the average initial Cobb was 61.9 degrees (range 44 degrees -110 degrees ), and this was not statistically different within the cohorts (P > 0.05). In terms of revision rate, all hook constructs had a higher revision rate secondary to instrumentation failure when compared with screws, while both hook and hybrid constructs had an overall higher surgical revision rate when compared with screw constructs or anteroposterior constructs (all P

Neurologic deficit following percutaneous vertebral stabilization.

STUDY DESIGN: A retrospective review. OBJECTIVE: The purpose of this study is to document a series of cases of neurologic deficit following percutaneous vertebral stabilization, to identify patterns of neurologic injury, and to describe potential methods for avoiding these injuries. SUMMARY OF BACKGROUND DATA: Percutaneous vertebral stabilization procedures, including vertebroplasty and kyphoplasty, have become a widely used for the treatment of osteoporotic vertebral compression fractures, primary and metastatic vertebral tumors, and traumatic burst fractures. Despite an increasing array of indications, there have been few reports of adverse events. Neurologic complications associated with vertebroplasty and kyphoplasty have been described previously as case reports and have generally been considered as infrequent and minor in severity. METHODS: The clinical course of 14 patients with documented loss of neurologic function following percutaneous vertebral cement augmentation was retrospectively reviewed. RESULTS: The average patient age was 74.9 years (range, 46-88 years) with 3 male and 11 female patients. Four patients underwent a vertebroplasty procedure while 10 were treated with kyphoplasty. Six patients developed neurologic deficits acutely (<24 hours of procedure). The remaining 8 patients developed neurologic symptoms at an average of 37.1 days (range, 3-112 days) postprocedure. Neurologic deficits were recorded as ASIA A in 4 patients, ASIA B in 2 patients, ASIA C in 1 patient, and ASIA D in 7 patients. Twelve of 14 patients (85.7%) required revision open surgical intervention for treatment of their neurologic injury. CONCLUSION: Percutaneous vertebroplasty and kyphoplasty have been reported to be safe options for the treatment of painful osteoporotic vertebral fractures. Although complications are infrequent, there remains the potential for catastrophic neurologic injury. Physicians performing these procedures need to be aware of these potential complications and be prepared to respond in an emergent manner (surgically) if a need arises.

Radiographic evaluation of spinal deformity.

A complete radiographic evaluation is inherent in the management of the spinal deformity patient; however, a complete evaluation is often not obtained or fully appreciated. This article reviews the proper radiographic methodology for obtaining consistent reproducible radiographs for spinal deformity. In addition, standard radiographic measurements are reviewed, and the reliability and validity of these measurements are reported. Regional curve flexibility and end, neutral, and stable vertebra selection are also included.

Fluoroscopic video to identify aberrant lumbar motion.

STUDY DESIGN: A prospective, case-control design. OBJECTIVES: To develop a kinematic model that characterizes frequently observed movement patterns in patients with low back pain (LBP). SUMMARY OF BACKGROUND DATA: Understanding arthrokinematics of lumbar motion in those with LBP may provide further understanding of this condition. METHODS: Digital fluoroscopic video (DFV) was used to quantify the magnitude and rate of attainment of sagittal plane intersegmental angular and linear displacement from 20 individuals with LBP and 20 healthy control subjects during lumbar flexion and extension. Three fellowship-trained spine surgeons subsequently qualitatively analyzed the DFVs to determine normality of movement. Final classification was based on agreement between their symptom and motion status (11 with LBP and aberrant motion and 14 healthy controls without aberrant motion). Independent t tests, receiver operator characteristic curves, and accuracy statistics were calculated to determine the most parsimonious set of kinematic variables able to distinguish patients with LBP. RESULTS: Eight kinematic variables had a positive likelihood ratio > or = 2.5 and entered the model. Six of the variables described a disruption in the rate of attainment of angular or linear displacement during midrange postures. When 4 or more of these variables were present, the positive likelihood ratio was 14.0 (confidence interval 3.2-78.5), resulting in accurately identifying 96% of participants. CONCLUSIONS: DFV was useful for discriminating between individuals with and without LBP based on kinematic parameters. Disruptions in how the motion occurred during midrange motions were more diagnostic for LBP than range of motion variables. Cross validation of the model is required.

Stabilizing potential of anterior, posterior, and circumferential fixation for multilevel cervical arthrodesis: an in vitro human cadaveric study of the operative and adjacent segment kinematics.

STUDY DESIGN: This is an in vitro biomechanical study. OBJECTIVE: The current investigation was performed to evaluate the stabilizing potential of anterior, posterior, and circumferential cervical fixation on operative and adjacent segment motion following 2 and 3-level reconstructions. SUMMARY OF BACKGROUND DATA: Previous studies reported increases in adjacent level range of motion (ROM) and intradiscal pressure following single-level cervical arthrodesis; however, no studies have compared adjacent level effects following multilevel anterior versus posterior reconstructions. MATERIALS AND METHODS: Ten human cadaveric cervical spines were biomechanically tested using an unconstrained spine simulator under axial rotation, flexion-extension, and lateral bending loading. After intact analysis, all specimens were sequentially instrumented from C3 to C5 with: (1) lateral mass fixation, (2) anterior cervical plate with interbody cages, and (3) combined anterior and posterior fixation. Following biomechanical analysis of 2-level constructs, fixation was extended to C6 and testing repeated. Full ROM was monitored at the operative and adjacent levels, and data normalized to the intact (100%). RESULTS: All reconstructive methods reduced operative level ROM relative to intact specimens under all loading methods (P < 0.05). However, circumferential fixation provided the greatest segmental stability among 2 and 3-level constructs (P < 0.05). Moreover, anterior cervical plate fixation was least efficient at stabilizing operative segments following C3-C6 arthrodesis (P < 0.05). Supradjacent ROM was increased for all treatment groups compared to normal data during flexion-extension testing (P < 0.05). Similar trends were observed under axial rotation and lateral bending loading. At the distal level, flexion-extension and axial rotation testing revealed comparable intergroup differences (P < 0.05), while lateral bending loading indicated greater ROM following 2-level circumferential fixation (P < 0.05). CONCLUSIONS: Results from our study revealed greater adjacent level motion following all 3 fixation types. No consistent significant intergroup differences in neighboring segment kinematics were detected among reconstructions. Circumferential fixation provided the greatest level of segmental stability without additional significant increase in adjacent level ROM.

Missed opportunities in patients with osteoporosis and distal radius fractures.

Low-energy wrist (distal radius) fractures are hallmarks of osteoporosis. Prompt diagnosis and treatment of osteoporosis reduce refracture rates. We retrospectively determined the type and frequency of osteoporosis-related interventions rendered to patients 50 years and older in the year after a wrist fragility fracture. In addition, we compared the rates of intervention between men and women. Data were collected from the computerized medical record of one military healthcare system. We identified 111 patients who sustained wrist fragility fractures between July and December 2002. Endocrinology referrals, dual-energy xray absorptiometry scans, and osteoporosis medication prescriptions in the year after their fracture were recorded. Overall, 28 patients (25%) were referred to endocrinology, 22 patients (20%) had a dual-energy xray absorptiometry scan, 33 patients (30%) were prescribed an approved medication for treatment of osteoporosis, and 52 patients (47%) were prescribed one of these medications and/or vitamin D and calcium. Sixty percent of patients received at least one intervention. All diagnostic and medical interventions were more likely ordered for women than men. Orthopaedic surgeons continue to miss opportunities to initiate diagnostic and therapeutic interventions for patients, especially men, presenting with fragility fractures.