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Spinal deformity in the adult is a common medical disorder with a significant and measurable impact on health-related quality of life. The ability to measure and quantify patient self-reported health status with disease-specific and general health status measures, and to correlate health status with radiographic and clinical measures of spinal deformity, has enabled significant advances in the assessment of the impact of deformity on our population, and in the evaluation and management of spinal deformity using an evidence-based approach. There has been a significant paradigm shift in the evaluation and management of patients with adult deformity. The paradigm shift includes development of validated, disease-specific measures of health status, recognition of deformity in the sagittal plane as a primary determinant of health status, and information on results of operative and medical/interventional management strategies for adults with spinal deformity. Since its inception in 1966, the Scoliosis Research Society (SRS) has been an international catalyst for improving the research and care for patients of all ages with spinal deformity. The SRS Adult Spinal Deformity Committee serves the mission of developing and defining an evidence-based approach to the evaluation and management of adult spinal deformity. The purpose of this overview from the SRS Adult Deformity Committee is to provide current information on the epidemiology and impact of adult deformity, and to provide patients, physicians, and policy makers a guide to the evidence-based evaluation and management of patients with adult deformity.

The KAST (Kiva Safety and Efficacy) investigation device exempt (IDE) study indicated that the majority of patients responded equally well to vertebral augmentation using either an implant-based approach or balloon kyphoplasty (BK). Additional investigation has suggested that a subset of patients may benefit further by avoiding repeated readmissions due to serious adverse events (SAEs) if they receive one vertebral augmentation approach over another.The primary aim was to assess the effect of 2 different augmentation procedures on readmission rates for SAEs.The KAST trial is a pivotal, multicenter, randomized, controlled trial conducted to evaluate an implant-based vertebral augmentation approach (implant) against BK. Post-hoc analysis was performed to evaluate SAEs and readmission rates.Twenty-one sites in North America and Europe.The treatment effect of vertebral implant versus BK on SAEs requiring unplanned readmission was evaluated by estimating the risk of SAEs associated with readmissions in KAST while controlling for key baseline covariates using multivariate Poisson regression modeling.Forty (27.8%) patients with implants had 69 SAEs associated with readmission compared to 44 (31.2%) patients with BK having 103 events. The risk for all SAEs leading to readmission was 34.4% lower with the implant than for BK (95% confidence interval = 11.1%, 51.7%; P0.01). Multivariate analysis showed that the risk of SAEs associated with readmission was decreased in subjects treated with the implant compared to BK, and increased in patients with prior histories of vertebral compression fractures (VCFs) or significant osteoporosis.The power of the KIVA study was based on clinical efficacy criteria to meet FDA requirements and recommendations for equivalency or noninferiority. The primary endpoint in this post-hoc analysis is SAEs associated with readmissions; as a result, the sample size is underpowered, although the results remain significant.The augmentation approaches compared here have similar pain relief and quality of life effects; the implant showed a lower risk of readmissions.ClinicalTrials.gov Identifier: NCT01123512. Key words: Vertebral compression fracture, kiva implant, balloon kyphoplasty, vertebroplasty, health economics, osteoporosis.

Background: Lateral mass screw fixation with plates or rods has become the standard method of posterior cervical spine fixation and stabilization for a variety of surgical indications. Despite ubiquitous usage, the safety and efficacy of this technique have not yet been established sufficiently to permit ‘‘on-label’’ U.S. Food and Drug Administration approval for lateral mass screw fixation systems. The purpose of this study was to describe the safety profile and effectiveness of such systems when used in stabilizing the posterior cervical spine.

Jeffrey D Coe,1 James F Zucherman,2 Donald W Kucharzyk,3 Kornelis A Poelstra,4 Larry E Miller,5 Sandeep Kunwar,6 1Silicon Valley Spine Institute, Campbell, 2San Francisco Orthopaedic Surgeons, San Francisco, CA, 3Orthopaedic Pediatric and Spine, Crown Point, IN, 4Department of Surgery, Sacred Heart Hospital on the Emerald Coast, Miramar Beach, FL, 5Miller Scientific Consulting, Inc., Asheville, NC, 6Bell Neuroscience Institute, Washington Hospital Healthcare System, Fremont, CA, USA Abstract: The increasing adoption of minimally invasive techniques for spine surgery in recent years has led to significant advancements in instrumentation for lumbar interbody fusion. Percutaneous pedicle screw fixation is now a mature technology, but the role of expandable cages is still evolving. The capability to deliver a multiexpandable interbody cage with a large footprint through a narrow surgical cannula represents a significant advancement in spinal surgery technology. The purpose of this report is to describe a multiexpandable lumbar interbody fusion cage, including implant characteristics, intended use, surgical technique, preclinical testing, and early clinical experience. Results to date suggest that the multiexpandable cage allows a less invasive approach to posterior/transforaminal lumbar interbody fusion surgery by minimizing iatrogenic risks associated with static or vertically expanding interbody prostheses while providing immediate vertebral height restoration, restoration of anatomic alignment, and excellent early-term clinical results. Keywords: degenerative disc disease, expandable, low back pain, Luna

Objective : Pedicle-based dynamic stabilization systems, in which semi-rigid rods or cords are used to restrict or control spinal segmental motion, aim to reduce or eliminate the drawbacks associated with rigid fusion. In this study, we analyzed the two-year clinical outcomes of patients treated with the NFlex (Synthes Spine, Inc.), a pedicle-based dynamic stabilization system. Methods : Five sites participated in a retrospective study of 72 consecutive patients who underwent NFlex stabilization. Of these 72 patients, 65 were available for 2-year follow-up. Patients were included based on the presence of degenerative disc disease (29 patients), degenerative spondylolisthesis (16 patients), lumbar stenosis (9 patients), adjacent segment degeneration (6 patients), and degenerative lumbar scoliosis (5 patients). The clinical outcome measures at each assessment were Visual Analogue Scale (VAS) to measure back pain, and Oswestry Disability Index (ODI) to measure functional status. Radiographic assessments included evidence of instrumentation failure or screw loosening. Results : Sixty-five patients (26 men and 39 women) with a mean age of 54.5 years were included. Mean follow-up was 25.6 months. The mean VAS score improved from 8.1 preoperatively to 3.8 postoperatively, representing a 53% improvement, and the ODI score from 44.5 to 21.8, representing a 51% improvement. Improvements in pain and disability scores were statistically significant. Three implant-related complications were observed. Conclusion : Posterior pedicle-based dynamic stabilization using the NFlex system seems effective in improving pain and functional scores, with sustained clinical improvement after two years. With appropriate patient selection, it may be considered an effective alternative to rigid fusion.

Study Design. Retrospective review of a prospectively collected, multicentered database from the Scoliosis Research Society. Objectives. To evaluate incidences of complications in a series of spinal fusions for Scheuermann kyphosis (SK) and to assess whether the incidence of complications is associated with patient age and surgical approach. Summary of Background Data. Although there is some evidence that adolescents have lower complication rates for spinal deformity surgery, this has not been well-documented for SK. Moreover, there is a lack of consensus on surgical approach for the management of SK. Methods. The Scoliosis Research Society morbidity and mortality database was queried to identify cases of SK from 2001 to 2004. Complications rates were analyzed based on patient age and surgical approach. Pediatric and adult patients were defined as ≤19 and >19 year old, respectively. Results. A total of 683 procedures involving spinal fusion for SK were identified. Mean patient age was 21 years (range: 5–75 years), with the majority (73%) of patients ≤19 years old. Procedures included 338 (49%) posterior spinal fusions (PSF), 73 (11%) anterior spinal fusions (ASF), and 272 (40%) same-day ASF and PSF. Ninety-nine complications were reported (14%). The most common complication was wound infection (3.8%). The acute neurologic complication rate was 1.9%, including 4 spinal cord injuries (0.6%). The mortality rate was 0.6%. Complications were more common among adult (22%) compared with pediatric patients (12%) (P = 0.002). The overall incidence of complications did not differ significantly between the PSF (14.8%) and same-day ASF/PSF (16.9%) procedures (P = 0.5). Conclusion. The incidence of complications associated with spinal fusion for SK in adults is significantly greater than in pediatric patients. There were no significant differences in complication rates between PSF and same-day ASF/PSF procedures. These data may be used to counsel patients regarding complications associated with spinal fusion for SK in the hands of experienced spinal deformity surgeons.

Background Complications associated with rigid posterior instrumented fusions of the lumbar spine include pseudarthrosis, accelerated adjacent-segment disease, hardware failure, and iatrogenic fixed sagittal imbalance. Posterior pedicle screw/rod-based dynamic stabilization systems, in which semirigid rods or cords are used to restrict or control, rather than completely eliminate spinal segmental motion, aim to reduce or eliminate these fusion-associated drawbacks. In this study, we analyzed the early radiographic and clinical outcomes of patients treated with the NFix II System (N Spine, Inc., San Diego, California), a novel pedicle screw/ rod-based system used as a nonfusion posterior dynamic stabilization system, and compared our results to those of similar systems currently in use. Methods Seven sites participated in a retrospective assessment of 40 consecutive patients who underwent dynamic stabilization of the lumbar spine with the NFix II System at a single level. (One patient underwent 2 single-level dynamic constructs at noncontiguous levels (L3-4 and L5-S1).) Patients were included based on the presence of spinal stenosis, degenerative spondylolisthesis, adjacent segment degeneration, recurrent disc herniation, symptomatic degenerative disc disease, and degenerative scoliosis requiring dynamic stabilization at 1 level with or without instrumented rigid fusion at a contiguous level. Participants were evaluated preoperatively, with planned postoperative assessments at 3 and 6 weeks (1 center assessed patients at 4 weeks), 3 months, 6 months, and 12 months. The primary clinical outcome measures at each assessment were visual analogue scale (VAS) scores to measure back pain, and Oswestry Disability Index (ODI)1 scores to measure function. Radiographic outcome measurements included evidence of instrumentation failure and range of motion (ROM) based on postoperative flexion-extension radiographs at 3, 6, and 12 months. Results Forty patients (15males, 25 females) with a mean age of 55 years (range 21–81) were included. Average follow-up was 8.1 months (range 6–12). The mean VAS score improved from 7.6 preoperatively to 3.3 postoperatively (P < .001), and the ODI score from 47.3 to 22.8 (P < .001). Eighty percent of patients were severely disabled or worse (ODI ≥ 41) preoperatively, which was reduced to 13% postoperatively. Of the 10 patients with more than 6 months’ follow-up, only 4 demonstrated adequate flexion/extension effort. ROM measurements in those 4 patients showed that on average 53% of preoperative segmental motion was retained at the dynamically stabilized level 6 months postoperatively. There were no instrumentation-related complications. Conclusions Results of this limited study indicate that the NFix II System when used as a nonfusion device for dynamic stabilization produces significant improvements in pain and function at short-term follow-up with outcomes comparable to other dynamic stabilization systems. The use of this system was not associated with an increased risk of instrumentation failure. The small number of patients with postoperative severe disability or worse compares favorably to long-term published data on posterolateral fusion. Lastly, in this small sample, ROM was preserved at 6-month follow-up. Clinical Relevance Posterior pedicle screw/rod dynamic stabilization using the NFix II System seems very effective in improving pain and function scores, at least in the short term (mean postoperative ODI of 22.8). Preservation of ROM is also possible. Longerterm follow-up is necessary to assess sustained clinical improvement, hardware complications, and maintenance in segmental ROM. The NFix II System may be considered an effective alternative to existing dynamic stabilization systems. This device is cleared by the US Food and Drug Administration for use as an adjunct to fusion and has the European CE Marking for use in both fusion and nonfusion applications.

Object The purpose of this study was to evaluate the clinical and radiographic results in 31 patients from one center who underwent instrumented transforaminal lumbar interbody fusion (TLIF) for primarily degenerative indications. Methods Bioabsorbable polymer spacers manufactured with a copolymer of 70:30 poly(L-lactide-co-D,L-lactide) and filled with iliac crest autograft bone were used for the TLIF procedure. In this paper the details of this procedure, intermediate (1- to 2-year) clinical and radiographic outcomes, and the basic science and rationale for the use of bioabsorbable polymers are discussed. At a mean of 18.4 months of follow up, 30 patients (96.8%) were judged to have attained solid fusions and 25 patients (81%) had good to excellent results. Three patients (9.7%) experienced complications, none of which were directly or indirectly attributable to the use of the bioabsorbable polymer implant. Only one implant in one patient (3.2%) demonstrated mechanical failure on insertion, and that patient experienced no clinical sequelae. Conclusions This is the first clinical series to be published in which the mean follow-up duration equals or exceeds the biological life expectancy of this material (12–18 months). Both the clinical and radiographic results of this study support the use of interbody devices manufactured from biodegradable polymers for structural interbody support in the TLIF procedure.

Study design An electronic survey administered to Scoliosis Research Society membership. Objective To characterize surgeon views regarding proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) management providing the framework in which a PJK/PJF classification system and treatment guidelines could be established. Summary of background data PJK/PJF are common complications of adult spinal deformity surgery. To date, there is no consensus on PJK/PJF definitions, classification, and indications for revision surgery. There is a paucity of data on deformity surgeon practice pattern variations and consensus opinion on treatment and prevention. Methods An electronic 19-question survey regarding PJK/PJF was administered to members of the Scoliosis Research Society who treat adult spinal deformity. Determinants included the surgeons' type of practice, number of years in practice, agreement with given PJK/PJF definitions, importance of key factors influencing prevention and revision, prevention methods currently used, and the importance of developing a classification system. Results A total of 226 surgeons responded (38.8% response rate). Both 44.4% of surgeons selected "extremely important" and 40.8% selected "very important" that PJK in adult spinal deformity surgery is a very important issue and that a Scoliosis Research Society PJK/PJF classification system and guidelines for detection and prevention of PJK/PJF is a "must have" (18.1%) and "very likely helpful" (31.9%). Both 86.2% and 90.7% of surgeons agreed with the provided definitions of PJK and PJF, respectively. Top 5 revision indications included neurological deficit, severe focal pain, translation or subluxation fracture, a change in kyphosis angle of greater than 30°, chance fracture, spondylolisthesis greater than 6 mm, and instrumentation prominence. The majority of respondents use a PJK/PJF prevention strategy 60% of the time or more, the most common were terminal rod contour, preoperative bone mineral density testing, and frequent radiographical studies during first 3 months postoperative, preoperative bone mineral density medication for low bone mineral density. Conclusion The results of this study provide insight from the practicing surgeons' perspective of the management of PJK and PJF that may aid in the validation of current definitions and consensus-based treatment decisions and prevention guidelines. Level of evidence 5.

Object. Sixty patients underwent instrumentation-assisted posterior transforaminal lumbar interbody fusion (TLIF) with resorbable polymer cages and autograft bone for degenerative disease. This article discusses the technique of TLIF and its early outcomes. Methods. Although the follow-up period is short and results are preliminary, no adverse events or complications were attributed to the resorbable polymer. Conclusions. Further multicenter clinical studies are underway with a minimum 2-year follow-up period chosen as an endpoint to provide insight as to the future of biodegradable polymers as spinal interbody devices.

Study design Systematic review of literature. Objective To perform a comprehensive English language systematic literature review of proximal junctional kyphosis (PJK) and proximal junctional failure (PJF), concentrating on incidence, risk factors, health related quality of life impact, prevention strategy, and classification systems. Summary of background data PJK and PJF are well described clinical pathologies and are a frequent cause of revision surgery. The development of a PJK classification that correlates with clinical outcomes and guides treatment decisions and possible prevention strategies would be of significant benefit to patients and surgeons. Methods The phrases "proximal junctional," "proximal junctional kyphosis," and "proximal junctional failure" were used as search terms in PubMed for all years up to 2014 to identify all articles that included at least one of these terms. Results Fifty-three articles were identified overall. Eighteen articles assessed for risk factors. Eight studies specifically reviewed prevention strategies. There were no randomized prospective studies. There were 3 published studies that have attempted to classify PJK. The reported incidence of PJK ranged widely, from 5% to 46% in patients undergoing spinal instrumentation and fusion for adult spinal deformity. It is reported that 66% of PJK occurs within 3 months and 80% within 18 months after surgery. The reported revision rates due to PJK range from 13% to 55%. Modifiable and nonmodifiable risk factors for PJK have been characterized. Conclusion PJK and PJF affect many patients after long segment instrumentation after the correction of adult spinal deformity. The epidemiology and risk factors for the disease are well defined. A PJK and PJF scoring system may help describe the severity of disease and guide the need for revision surgery. The development and prospective validation of a PJK classification system is important considering the prevalence of the problem and its clinical and economic impact. Level of evidence N/A.

Study design A prospective evaluation of the clinical and radiographic outcomes of 71 patients who underwent lumbar fusion, with or without transpedicular instrumentation. The patients completed a questionnaire that determined pain relief, medication use, return to work, and overall satisfaction with surgery. Objectives To explore the effect, if any, of instrumentation on the outcome of lumbar fusion surgery, according to reports of the patients, and whether there is a correlation between the radiographic determination of a solid fusion and the same patient-reported outcome. Summary of background data The literature on this topic reports pseudarthrosis rates from 0% to 57% and good to excellent results from 56% to 95%. These studies provide no clear-cut recommendations concerning the effect of added lumbar instrumentation on patient-reported outcome in a prospective manner using concurrent control subjects. Methods The patients were randomized to groups with and without instrumentation after deciding to undergo a lumbar fusion and consenting to enter the study. Radiographs were obtained and questionnaires filled out at 6 weeks, 6 months, 1 year, and 2 years after surgery. Results There was no statistical difference in patient-reported outcome between the two groups. There was a slight nonsignificant trend toward increased radiographic fusion rate in the group with instrumentation that did not correlate with an increased patient-reported improvement rate. Conclusions These results do not provide data that indicate a benefit in outcome from added instrumentation in elective lumbar fusions.

STUDY DESIGN Retrospective review of prospectively collected databases. OBJECTIVE To compare 2 approaches for assessment of mortality associated with spine surgery. SUMMARY OF BACKGROUND DATA The Scoliosis Research Society collects morbidity and mortality data from its members. Previously, this included details for all spine cases and all complications. To reduce time burden and improve compliance, collection was changed to focus on a few major complications (death, neurological deficit, and blindness) for specific deformity diagnoses (scoliosis, spondylolisthesis, and kyphosis) and only for cases with complications. METHODS Data were extracted from the Scoliosis Research Society from 2004-2007 (detailed system) and 2009-2011 (simplified system). As an anchor for comparison, mortality rates were compared between the systems. RESULTS Between 2009 and 2011, the number of deformity cases reported were 87,162, with 131 deaths (1.50/1000 cases). The mean age of these 131 patients was 50, mean American Society of Anesthesiologists grade was 2.8, 10% were smokers, and 18% had diabetes. Rates of death (per 1000 cases) were: idiopathic scoliosis (0.4), congenital scoliosis (1.3), neuromuscular scoliosis (3.6), other scoliosis (3.1), spondylolisthesis (0.6), and kyphosis (4.7). Common causes of mortality included respiratory (48), cardiac (32), sepsis (12), organ failure (9), and blood loss (7). Compared with the detailed system, the simplified system had greater surgeon compliance (79% vs. 62%, P < 0.001), greater number of deformity cases per reporting surgeon per year (139 vs. 90, P < 0.001), and modest but significantly lower mortality rates (1.50 vs. 1.80/1000 cases; P < 0.001). Causes of death were comparable between the 2 systems. CONCLUSION On the basis of the simplified collection system, the rate of mortality for spinal deformity surgery was 1.50 per 1000 cases. Compared with the detailed system, the simplified system had significantly improved compliance and similar mortality rates. Although the simplified system is limited by less data collected, it achieves better compliance and may prove effective, especially if supplemented with focused data collection modules.

Background: Lateral mass screw fixation with plates or rods has become the standard method of posterior cervical spine fixation and stabilization for a variety of surgical indications. Despite ubiquitous usage, the safety and efficacy of this technique have not yet been established sufficiently to permit “on-label” U.S. Food and Drug Administration approval for lateral mass screw fixation systems. The purpose of this study was to describe the safety profile and effectiveness of such systems when used in stabilizing the posterior cervical spine. Methods: A systematic search was conducted in MEDLINE and the Cochrane Collaboration Library for articles published from January 1, 1980, to December 1, 2011. We included all articles evaluating safety and/or clinical outcomes in adult patients undergoing posterior cervical subaxial fusion utilizing lateral mass instrumentation with plates or rods for degenerative disease (spondylosis), trauma, deformity, inflammatory disease, and revision surgery that satisfied our a priori inclusion and exclusion criteria. Results: Twenty articles (two retrospective comparative studies and eighteen case series) satisfied the inclusion and exclusion criteria and were included. Both of the comparative studies involved comparison of lateral mass screw fixation with wiring and indicated that the risk of complications was comparable between treatments (range, 0% to 7.1% compared with 0% to 6.3%, respectively). In one study, the fusion rate reported in the screw fixation group (100%) was similar to that in the wiring group (97%). Complication risks following lateral mass screw fixation were low across the eighteen case series. Nerve root injury attributed to screw placement occurred in 1.0% (95% confidence interval, 0.3% to 1.6%) of patients. No cases of vertebral artery injury were reported. Instrumentation complications such as screw or rod pullout, screw or plate breakage, and screw loosening occurred in

Autologous bone graft harvested from remote locations has been used to fuse the human spine for the treatment of disease, degeneration, or injury for over a century1. For the latter half of the twentieth century, autologous bone harvested from the iliac crest was the “gold standard” bone graft used for spinal fusion. Donor-site morbidity, particularly pain lasting more than a year, has been reported in >30% of patients who have undergone spinal fusion with autologous iliac crest bone graft (ICBG)2. This morbidity led many investigators to search for alternatives to ICBG. Research began to focus on recombinant forms of a variety of bone morphogenetic proteins (BMPs) as a potential bone-graft substitute. BMPs, discovered by Marshall Urist in the early 1960s3, are a subclass of a somewhat inhomogeneous group of proteins known as cytokines that have cell signaling as a common feature. BMPs were found to be osteoinductive; that is, they induce osteoblastic activity in the formation of bone. BMPs, in their natural form, are very difficult to generate in quantity. Recombinant forms that could be produced in quantity were developed, but manufacturing them was expensive and required substantial investment by industry. This investment appeared to show fruit as animal studies demonstrated efficacy of BMPs as a bone-graft substitute. These studies were followed by human clinical trials, in which two classes of BMPs (recombinant human [rh] BMP-7 and rhBMP-2) demonstrated non-inferiority compared with ICBG for achieving spinal …

Posteriorly directed load to failure testing of four different types of spinal implants was performed in individual T5 to S1 vertebra harvested from seven fresh-frozen human cadaveric spines. The implants tested were: 1) Drummond spinous process wires, 2) Harrington laminar hooks, 3) Cotrel-Dubousset transpedicular screws, and 4) Steffee VSP transpedicular screws. The ultimate failure of each implant was compared with the bone mineral density of each vertebra to determine which implants, if any, were particularly advantageous in osteoporotic vertebrae. Before biomechanical testing, the spines were analyzed in vitro by dual photon absorptiometry to determine the bone mineral densities (gm/cm2) of each vertebra. The mean tensile loads to failure for each of the implants tested were as follows: Cotrel-Dubousset transpedicular screws: 345 Newtons; spinous process wire/button: 382 Newtons; Steffee transpedicular screws: 430 Newtons; and laminar hooks: 646 Newtons. The difference between the loads to failure for laminar hooks and the other implants was significant (P less than 0.05) using one-way analysis of variance. The overall correlation coefficient for bone mineral density with ultimate load to failure was 0.30 (P less than 0.001). The correlation coefficients were 0.47 (P less than 0.001) for spinous process wires alone; 0.096 (not significant) for laminar hooks alone; 0.37 (P less than 0.001) for Cotrel-Dubousset pedicle screws; and 0.48 (P less than 0.001) for Steffee pedicle screws. Of the four different implants tested, laminar hooks were most resistant to failure from posteriorly directed forces.(ABSTRACT TRUNCATED AT 250 WORDS)

STUDY DESIGN The Morbidity and Mortality database of the Scoliosis Research Society (SRS) was queried as to the incidence and type of complications as reported by its members for the treatment of adolescent idiopathic scoliosis (AIS) with spinal fusion and instrumentation procedures regarding surgical approach (anterior, posterior, or combined anterior-posterior) during a recent 3-year period. OBJECTIVE To evaluate the incidence of surgeon-reported complications in a large series of spinal fusions with instrumentation for a single spinal deformity diagnosis and age group regarding surgical approach. SUMMARY OF BACKGROUND DATA The SRS has been collecting morbidity and mortality data from its members since its formation in 1965 with the intent of using these data to assess the complications and adverse outcomes (death and/or spinal cord injury) of surgical treatment for spinal deformity. Surgical approaches to the management of treatment of AIS have a measurable impact on efficacy of correction, levels fused, and operative morbidity. However, there is a lack of consensus on the choice of surgical approach for the treatment of spinal deformity. METHODS Of the 58,197 surgical cases submitted by members of the SRS in the years 2001, 2002, and 2003, 10.9% were identified as having had anterior, posterior, or combined spinal fusion with instrumentation for the diagnosis of AIS, and comprised the study cohort. All reported complications were tabulated and totaled for each of the 3 types of procedures, and statistical analysis was conducted. RESULTS Complications were reported in 5.7% of the 6334 patients in this series. Of the 1164 patients who underwent anterior fusion and instrumentation, 5.2% had complications, of the 4369 who underwent posterior instrumentation and fusion, 5.1% had complications, and of the 801 who underwent combined instrumentation and fusion, 10.2% had complications. There were 2 patients (0.03%) who died of their complications. There was no statistical difference in overall complication rates between anterior and posterior procedures. However, the difference in complication rates between anterior or posterior procedures compared to combined procedures was highly significant (P < 0.0001). The differences in neurologic complication rates between combined and anterior procedures, as well as combined and posterior procedures were also highly statistically significant (P < 0.0001), but not between anterior and posterior procedures. CONCLUSIONS This study shows that complication rates are similar for anterior versus posterior approaches to AIS deformity correction. Combined anterior and posterior instrumentation and fusion has double the complication rate of either anterior or posterior instrumentation and fusion alone. Combined anterior and posterior instrumentation and fusion also has a significantly higher rate of neurologic complications than anterior or posterior instrumentation and fusion alone.

Sixty patients from two centers have undergone instrumented transforaminal posterior lumbar interbody fusion (TLIF) with bioresorbable polymer cages and autograft bone for degenerative indications. This article discusses the technique of TLIF and its early outcomes. Although follow-up is short and results are preliminary, no adverse events or complications may be attributed to the bioresorbable polymer. Further multicenter clinical studies are underway with a minimum of 2 years of follow-up chosen as an endpoint to provide insight as to the future of biodegradable polymers as spinal interbody devices.

Operation Just Cause was until recently the largest American combat operation since Vietnam, and remains the largest nighttime parachute operation since World War II. All 252 casualties were airlifted to San Antonio, Texas, for medical treatment. Greater than 80% sustained orthopedic injuries. Sixteen patients were admitted for injuries to the back or neck. Three of the four patients with significant fractures or fracture-dislocations were paraplegic. Two of the three patients with gunshot wounds to the back required extensive reconstruction for wound management. In addition to the 252 casualties, there were 23 fatalities, among whom 7 suffered major injuries to the spine. Spine injuries represented the most significant source of long-term morbidity among those soldiers wounded in combat in Panama, and were common among the fatalities. Noteworthy in these cases was the high percentage of severe neurologic injuries in patients with significant fractures (75%), particularly fractures associated with gunshot wounds. Also of interest were the cases of major soft tissue injury associated with high-velocity gunshot wounds (66%) and the extensive soft tissue surgery needed to treat these injuries. Language: en

Surgery of the Lumbar Spine. Sanford J. Larson and Dennis J. Maiman. New York, Thieme Medical, 1999. $139.00, 334 pp. It is refreshing to see a clinical text that has as strong a foundation in the basic sciences as this book has. The authors, professors of neurosurgery at the Medical College of Wisconsin (Dr. Larson is also department chairman), have written a very readable, well referenced, and largely comprehensive text on the lumbar spine. This book reflects the sound biomechanical background of the authors, which is further represented in the cover illustration of a finite-element model of lumbar vertebrae. The text begins with chapters on lumbar anatomy, biomechanics of the spine, and vertebral instability; …

The authors have previously reported in vitro testing of various posterior and anterior constructs (sublaminar, Rogers', and Bohlman's triple-wire wiring; AO hook plate fixation; and Caspar anterior plate fixation) in a bovine model with multiaxial biomechanical testing. This study was undertaken to evaluate the above constructs and other constructs in human cadaveric spines. Six subaxial human cervical spine specimens were biomechanically tested at the C5-C6 motion segment both intact and with a simulated distractive-flexion Stage 3 injury created at the C5-C6 level with complete disruption of the supraspinous ligament, interspinous ligament, ligamentum flavum, posterior longitudinal ligament, and facet joint capsules; with sufficient disruption of the intervertebral disc to allow a bilateral C5-C6 facet dislocation. The specimens were tested with a six-channel Bionix MTS 858 materials tester (M.T.S., Minneapolis, Minnesota) using cyclic loads to simulate cervical compression, flexion, extension, and rotation with measurements of axial load, axial displacement, torque, rotation, and anterior and posterior strains. Eight constructs were tested nondestructively: the intact spinal segment, sublaminar wiring, Rogers' wiring, Bohlman's wiring method (triple-wire technique), Roy-Camille posterior plate fixation, AO posterior hook-plate fixation, Caspar anterior plate fixation, and AO posterior hook-plate with Caspar anterior plate fixation. There was no significant difference in flexural stiffness and torsional stiffness between any of the constructs tested; however, there was a significant (P less than 0.05) increase in the posterior strain during flexion and axial loading tests between the Caspar plate construct and all other tested constructs, including the combined posterior and anterior plating construct. These differences persisted after cyclic testing of 100 cycles. Biomechanical testing demonstrated no significant differences between any of the posterior stabilization methods tested. Caspar anterior plating is clearly an inferior method of treating distractive flexion injuries of the cervical spine when compared with all posterior fixation techniques. Also, there is little biomechanical justification for the use of potentially dangerous sublaminar wire fixation and posterior plating methods in these injuries (with intact bony posterior elements), since the relatively safe interspinous wiring methods (Rogers' and Bohlman) are just as rigid as these other posterior fixation techniques.