Serious Adverse Events Associated with Readmission Through One Year After Vertebral Augmentation with Either a Polyetheretherketone Implant or Balloon Kyphoplasty.

BACKGROUND: 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. OBJECTIVES: The primary aim was to assess the effect of 2 different augmentation procedures on readmission rates for SAEs. STUDY DESIGN: 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. SETTING: Twenty-one sites in North America and Europe. METHODS: 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. RESULTS: 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%; P < 0.01). 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. LIMITATIONS: 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. CONCLUSION: The augmentation approaches compared here have similar pain relief and quality of life effects; the implant showed a lower risk of readmissions. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01123512. Key words: Vertebral compression fracture, kiva implant, balloon kyphoplasty, vertebroplasty, health economics, osteoporosis.

Adult Spinal Deformity: Epidemiology, Health Impact, Evaluation, and Management.

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.

Multiexpandable cage for minimally invasive posterior lumbar interbody fusion.

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.

Results of the 2014 SRS Survey on PJK/PJF: A Report on Variation of Select SRS Member Practice Patterns, Treatment Indications, and Opinions on Classification Development.

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.

Proximal junctional kyphosis and failure after spinal deformity surgery: a systematic review of the literature as a background to classification development.

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.

Defining rates and causes of mortality associated with spine surgery: comparison of 2 data collection approaches through the Scoliosis Research Society.

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.

Lateral mass screw fixation in the cervical spine: a systematic literature review.

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 <1% of the screws inserted. Fusion was achieved in 97.0% of patients across nine case series. CONCLUSIONS: The risks of complications were low and the fusion rate was high when lateral mass screw fixation was used in patients undergoing posterior cervical subaxial fusion. Nerve root injury attributed to screw placement occurred in only 1% of 1041 patients. No cases of vertebral artery injury were identified in 758 patients. Screw or rod pullout, screw or plate breakage, and screw loosening occurred in <1% of the screws inserted.

NFlex Dynamic Stabilization System : Two-Year Clinical Outcomes of Multi-Center Study.

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.

Complications of spinal fusion for scheuermann kyphosis: a report of the scoliosis research society morbidity and mortality committee.

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 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

Early Clinical & Radiographic Results of NFix II Posterior Dynamic Stabilization System.

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.

Agreement between surgeons and an independent panel with respect to surgical site fusion after single-level anterior cervical spine surgery: a prospective, multicenter study.

STUDY DESIGN: Prospective multicenter cohort study. OBJECTIVE: To assess the: (1) agreement between surgeon and independent review of fusion after single-level anterior cervical decompression and fusion, and (2) influence of surgeon impression of patient status on agreement. SUMMARY OF BACKGROUND DATA: Failure to achieve fusion can lead to poor functional outcome. Visual inspection of plain radiographs is used to assess fusion, but this assessment's reliability is not well understood. METHODS: Of 668 participants in the Cervical Spine Research Society Outcomes Study, 181 underwent single-level procedures. Three independent reviewers and each surgeon assessed fusion (i.e., radiographic trabecular bridging of the graft-vertebral body gap and absence of spinous process motion) on plain radiographs at 3 and 6 months after surgery. Agreement was evaluated with an intraclass correlation coefficient (ICC). The influence of surgeon impression of patient status on agreement was assessed with logistic regression analysis. RESULTS: Agreement was high among reviewers (ICC 0.822 to 0.892) but poor between reviewers and surgeons (ICC 0.308 to 0.484); disagreement was higher when the surgeon reported medical (odds ratio [OR] = 0.19, 95%; confidence interval [CI] 0.12, 0.30; P < 0.001), neurologic (OR = 0.13, 95% CI: 0.09, 0.21, P < 0.001), or functional (OR = 0.19, 95% CI: 0.12, 0.29, P < 0.001) improvement than when the surgeon did not report this improvement. CONCLUSIONS: The finding that surgeons and independent reviewers disagreed on fusion assessment highlights the need for objective and reproducible measures of fusion.

Complications in spinal fusion for adolescent idiopathic scoliosis in the new millennium. A report of the Scoliosis Research Society Morbidity and Mortality Committee.

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.

Instrumented transforaminal lumbar interbody fusion with bioresorbable polymer implants and iliac crest autograft.

STUDY DESIGN: Twenty-seven patients underwent instrumented transforaminal lumbar interbody fusion (TLIF) procedures using bioresorbable implants as interbody spacers. The greater than 2-year clinical and radiographic results of this series are presented along with as a review of relevant preclinical and preliminary clinical studies of bioresorbables. OBJECTIVE: To determine the clinical suitability of bioresorbable implants used as interbody spacers in spinal fusion surgery applications, particularly in the TLIF procedure. SUMMARY OF BACKGROUND DATA: Bioresorbable technology has been in clinical use by surgeons of a variety of specialties for over 35 years. The use of bioresorbable implants in spine surgery, however, has only been widely investigated in the last several years. The use of slowly degrading bioresorbable implants has the potential for load sharing during fusion when used for interbody applications, retaining imaging quality after fusion, obviating later implant removal, providing biologic barriers as well as other various applications. Animal studies and early clinical series with the use of these materials for a variety of indications have been encouraging. METHODS: This study evaluates the use of bioresorbable polymer spacers manufactured with a 70:30 copolymer of poly-L-lactide and D,L-lactide as interbody spacers in 27 of 31 patients with 2 years or more follow-up who underwent instrumented TLIF for primarily degenerative indications. RESULTS: At a mean of 31.9 months follow-up, 25 patients (92.6%) were judged to have solid fusions and 22 patients (81.5%) had good to excellent results. Three patients (11.1%) experienced complications, none of which were directly or indirectly attributable to the use of the bioresorbable polymer implant. Only one implant in 1 patient (3.7%) demonstrated mechanical failure on insertion, and that patient exhibited no clinical sequelae. CONCLUSIONS: Bioresorbable implants have significant potential for use in spine surgery. This potential is realized in this first published clinical series using bioresorbable implants as interbody spacers with a minimum follow-up of 2 years, significantly exceeding the biologic "life expectancy" (12-18 months) of the implant material. Both the clinical and radiographic results of this study support the use of interbody devices manufactured from bioresorbable polymers for structural interbody support in the TLIF procedure.

Instrumented transforaminal lumbar interbody fusion with bioabsorbable polymer implants and iliac crest autograft.

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.

Resorbable polymer implants in unilateral transforaminal lumbar interbody fusion.

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.

Bioresorbable polymer implants in the unilateral transforaminal lumbar interbody fusion procedure.

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.