Establishing case volume benchmarks for ACGME-accredited orthopedic surgery of the spine fellowship training.

BACKGROUND CONTEXT: There has been increasing scrutiny on the standardization of surgical training in the US. PURPOSE: This study provides case volume benchmarks for Accreditation Council for Graduate Medical Education (ACGME)-accredited orthopedic spine surgery fellowship training. STUDY DESIGN/SETTING: This was a retrospective cross-sectional study of fellows at ACGME-accredited orthopedic spine surgery fellowships (2017-2022). PATIENT SAMPLE: N/A. OUTCOME MEASURES: Reported case volume during fellowship training. METHODS: Case volume percentiles were calculated across ACGME-defined case categories and temporal changes assessed via linear regression. Variability between the highest and lowest deciles by case volume was calculated as fold-differences (90th percentile/10th percentile). Sensitivity analyses were performed to identify potential targets for case minimum requirements. RESULTS: A total of 163 spine surgery fellows were included in this study. Total mean reported spine surgery case volume increased from 313.2±122 in 2017 to 382.0±164 in 2022 (p=.19). Most cases were classified as adult (range, 97.2%-98.0%) over pediatric cases (range, 2.0%-2.8%). An average of 322.0 cases were reported and most were classified as laminectomy (32%), posterior arthrodesis (29%), and anterior arthrodesis (20%). Overall variability in total case volume was 2.4 and the greatest variability existed for posterior instrumentation (38.1), application of cage (34.6), anterior instrumentation (20.8), and fractures and dislocations (17.3). If case minimum requirements for total reported cases was assumed at 200 cases, then all spine fellows included in this study would achieve this requirement. However, if case minimum requirements were assumed at 250 total cases, then approximately thirty percent of fellows (n=49) would not achieve this requirement for graduation. CONCLUSIONS: Increasingly, national societies and accrediting bodies for surgical education recognize the need for standardized training. This study provides benchmarks to inform potential case minimum requirements and help reduce variability during spine fellowship training. Future studies are needed to establish case minimum requirements for spine surgery fellowship training across comprehensive and granular case categories that cover the full gamut of orthopedic spine surgery.

Energy Consumption and Substrate Utilization During Spinal Surgery.

INTRODUCTION: This study aims to measure surgeon physiologic stress and energy expenditure during adult spine surgery. Energy expenditures were assessed based on patient BMI, lead use, instrumentation/intraoperative navigation, primary/revision surgeries, tranexamic acid (TXA) use, and anatomic region involved. METHODS: The senior author wore a heart rate (HR) monitor and triaxial accelerometer during spinal surgeries, providing assessments of mean HR, maximum HR, calories consumed/minute, and calories as measured by a Polar device (P calories) and Fitbit device (F calories). RESULTS: One hundred sixty-two surgeries were included. Median patient age was 62 years. Median BMI was 29.02. Significant differences existed for BMI and estimated blood loss (P < 0.05). TXA use had a significant effect on case time, estimated blood loss, P calories, F calories, and Kcal/min (P < 0.05). Instrumentation use was significant for all variables (P < 0.05), except for mean HR and Kcal/min (P > 0.05). Lead use did not have a significant effect on max HR, P calories, F calories, and Kcal/min (P > 0.05). Navigation use was associated with significant differences for every variable tested (P ≤ 0.05). Differences were observed between primary and revision surgeries for case time, estimated blood loss, and F calories (P < 0.05). CONCLUSIONS: In spinal surgery, the use of navigation, instrumentation use, TXA use, and performing revision surgeries were associated with increased energy expenditure and can potentially increase surgeon fatigue.

Applications of SPECT/CT in the Evaluation of Spinal Pathology: A Review.

BACKGROUND: Accurate identification of pain generators in the context of low back and spine-related pain is crucial for effective treatment. This review aims to evaluate the potential usefulness of single photon emission computed tomography with computed tomography (SPECT/CT) as an imaging modality in guiding clinical decision-making. METHODS: A broad scoping literature review was conducted to identify relevant studies evaluating the use of SPECT/CT in patients with spine-related pain. Studies were reviewed for their methodology and results. RESULTS: SPECT/CT appears to have advantages over traditional modalities, such as magnetic resonance imaging and CT, in certain clinical scenarios. It may offer additional information to clinicians and improve the specificity of diagnosis. However, further studies are needed to fully assess its diagnostic accuracy and clinical utility. CONCLUSIONS: SPECT/CT is a promising imaging modality in the evaluation of low back pain, particularly in cases where magnetic resonance imaging and CT are inconclusive or equivocal. However, the current level of evidence is limited, and additional research is needed to determine its overall clinical relevance. CLINICAL RELEVANCE: SPECT/CT may have a significant impact on clinical decision-making, particularly in cases in which traditional imaging modalities fail to provide a clear diagnosis. Its ability to improve specificity could lead to more targeted and effective treatment for patients with spinal pathology.

Allergic contact dermatitis to Dermabond Prineo after abdominal wound closure for anterior lumbar interbody fusion: case report.

Background: Dermabond Prineo is popular for wound closure due to its anti-microbial attribute, ease of application, and patient comfort. Reports of allergic contact dermatitis have increased, likely due to increased usage, mostly in breast augmentations and joint replacements. To the authors' knowledge, this is the first report of allergic contact dermatitis following spine surgery. Case Description: This case involved a 47-year-old male with a history of two posterior L5-S1 lumbar microdiscectomies. Dermabond Prineo was used in the revision microdiscectomy with no skin complications noted. Six weeks after revision microdiscectomy, the patient underwent discectomy and anterior lumbar interbody fusion of L5-S1, again closed with Dermabond Prineo. One week later, the patient presented with allergic contact dermatitis around his incision, which was treated with topical hydrocortisone and diphenhydramine. Around the same time, he was diagnosed with post-operative pneumonia. Conclusions: Previous studies have suggested that repeated usage and duplicate coverage with 2-octyl cyanoacrylate (Dermabond Prineo) correlate with an increased risk of allergic reaction. Type IV hypersensitivity reactions require an initial sensitization to the allergen and subsequent re-exposure for reaction. In this case, the revision microdiscectomy closed with Dermabond Prineo functioned as the sensitization and repeated usage in a subsequent discectomy caused an allergic reaction. Providers should be aware of the increased risk of allergic reaction when using Dermabond Prineo for repeat surgeries.

Mycobacteriumabscessus-associated vertebral osteomyelitis in an immunocompetent patient: a rare case report and literature review.

Introduction: Vertebral osteomyelitis (VO) is an uncommon infection with Staphylococcus aureus as the most commonly implicated organism. VO caused by nontuberculous mycobacteria (NTM) such as Mycobacteriumabscessus (M. abscesscus) is exceedingly rare with only eight cases reported in literature. Case presentation: We report a rare case of an 82-year-old male with a remote history of trauma who was diagnosed with NTM vertebral osteomyelitis. The patient initially underwent a vertebroplasty of T12 and kyphoplasty of L1 for pathologic compression fractures. Subsequent cultures revealed M. abscessus. The patient further underwent an anterior T12-L2 corpectomy and debridement with instrumented fusion, as well as a posterior T9-L4 instrumentation and fusion. He received multi-agent antibiotic therapy; however, was ultimately unable to tolerate the aggressive treatment regimen and his prolonged postoperative course. Discussion: Nontuberculous mycobacteria vertebral osteomyelitis is exceedingly rare. NTM vertebral osteomyelitis is challenging to treat. Surgical management plays a limited role in early VO, but is the mainstay treatment in chronic VO. Early recognition of the condition and shared patient management with multidisciplinary teams is key to successfully treating cases of NTM VO.

Surgeon Energy Expenditure and Substrate Utilization During Simulated Spine Surgery.

INTRODUCTION: Orthopaedic surgery can be a physically demanding occupation with high rates of fatigue and burnout. Fatigue has been shown to affect surgeon performance with higher rates of errors in fatigued surgeons. The metabolic cost of performing surgery has yet to be quantified. A better understanding of these costs may provide insights into surgeon fatigue and its effect on patient safety. METHODS: Eight subjects performed a one-level lumbar laminectomy and fusion on cadavers. Oxygen consumption (VO2) was measured via indirect calorimetry and used to calculate energy expenditure (EE). Substrate utilization was estimated from measurements of inspired and expired gases (ie, O2 and CO2, respectively). EE was also measured with the use of triaxial accelerometers. RESULTS: The peak VO2 was 11.3 ± 0.4 mL/kg/min. The EEtotal was 132 ± 6 kcal corresponding to the EEtotal/hr of 142 ± 7 kcal/hr. Upper arm accelerometers (154.8 ± 9.8 kcal; r = 0.54) accurately estimated total EE. Subjects used, on average, 53% ± 4% CHO versus 47% ± 7% fat, with peak utilization of 65% ± 5% CHO versus 35% ± 15% fat. DISCUSSION: Simulated orthopaedic spine surgery elicited modest but significant increases in EE over resting. Surgeons used a higher percentage of carbohydrate than would be expected for the intensity of the activity.

Computer Assisted Cobb Angle Measurements: A novel algorithm.

BACKGROUND: The standard for evaluating scoliosis is PA radiographs using Cobb angle to measure curve magnitude. Newer PACS systems allow easier Cobb angle calculations, but have not improved inter/intra observer precision of measurement. Cobb angle and its progression are important to determine treatment; therefore, angle variability is not optimal. This study seeks to demonstrate that a performance equivalent to that achieved in the manual method is possible using a novel computer algorithm with limited user input. The authors compared Cobb angles from predetermined spinal levels in the average attending score versus the computer assisted approach. METHODS: Retrospective analysis of PA radiographs from 58 patients previously evaluated for scoliosis was collected. Predesignated spinal levels (e.g., T2-T10) were assigned for different curves and calculated by Cobb method. Four spine surgeons evaluated these Cobb angles. Their average scores were measured and compared to formulated values using the novel computer-based algorithm. Literature reports inter-observer reliability is 6.3-7.2degrees. Limits of accuracy were set at 5 degrees of average orthopedic surgeons' score. RESULTS: The computer-based algorithm calculated Cobb angles within 5 degrees of orthopedic surgeons' average with a standard deviation of 3.2 degrees. This result was based on a 95% confidence interval with p values <0.001. The computer algorithm was plotted against average angle determined by the surgeons, with individual determinations and linear regression (r2 =0.90). The average difference between surgeons' measures and computer algorithm was 0.4 degrees(SD= 3.2degrees, n=79). There was a tendency for the computer algorithm program to overestimate the angle at larger angles, but difference was small with r2 = 0.09. CONCLUSIONS: Our study showed the novel computer based algorithm was an efficient and reliable method to assess scoliotic curvature in the coronal plane with the possibility of expediting clinic visits, ensuring reliability of calculation and decreasing patient exposure to radiation. Level of Evidence: III.

ISSLS Prize Winner: Dynamic Loading-Induced Convective Transport Enhances Intervertebral Disc Nutrition.

STUDY DESIGN: Experimental animal study of convective transport in the intervertebral disc. OBJECTIVE: To quantify the effects of mechanical loading rate on net transport into the healthy and degenerative intervertebral disc in vivo. SUMMARY OF BACKGROUND DATA: Intervertebral disc degeneration is linked with a reduction in transport to the avascular disc. Enhancing disc nutrition is, therefore, a potential strategy to slow or reverse the degenerative cascade. Convection induced by mechanical loading is a potential mechanism to augment diffusion of small molecules into the disc. METHODS: Skeletally mature New Zealand white rabbits with healthy discs and discs degenerated via needle puncture were subjected to low rate axial compression and distraction loading for 2.5, 5, 10, 15, or 20 minutes after a bolus administration of gadodiamide. Additional animals with healthy discs were subjected to high-rate loading for 10 minutes or no loading for 10 minutes. Transport into the disc for each loading regimen was quantified using post-contrast-enhanced magnetic resonance imaging. RESULTS: Low-rate loading resulted in the rapid uptake and clearance of gadodiamide in the disc. Low-rate loading increased net transport into the nucleus by a mean 16.8% and 12.6% in healthy and degenerative discs, respectively. The kinetics of small molecule uptake and clearance were accelerated in both healthy and degenerative discs with low-rate loading. In contrast, high-rate loading reduced transport into nucleus by a mean 16.8%. CONCLUSION: These results illustrate that trans-endplate diffusion can be enhanced by forced convection in both healthy and degenerative discs in vivo. Mechanical loading-induced convection could offer therapeutic benefit for degenerated discs by enhancing uptake of nutrients and clearance of by-products. LEVEL OF EVIDENCE: 4.

Low rate loading-induced convection enhances net transport into the intervertebral disc in vivo.

BACKGROUND CONTEXT: The intervertebral disc primarily relies on trans-endplate diffusion for the uptake of nutrients and the clearance of byproducts. In degenerative discs, diffusion is often diminished by endplate sclerosis and reduced proteoglycan content. Mechanical loading-induced convection has the potential to augment diffusion and enhance net transport into the disc. The ability of convection to augment disc transport is controversial and has not been demonstrated in vivo. PURPOSE: To determine if loading-induced convection can enhance small molecule transport into the intervertebral disc in vivo. STUDY DESIGN: Net transport was quantified via postcontrast enhanced magnetic resonance imaging (MRI) into the discs of the New Zealand white rabbit lumbar spine subjected to in vivo cyclic low rate loading. METHODS: Animals were administered the MRI contrast agent gadodiamide intravenously and subjected to in vivo low rate loading (0.5 Hz, 200 N) via a custom external loading apparatus for either 2.5, 5, 10, 15, or 20 minutes. Animals were then euthanized and the lumbar spines imaged using postcontrast enhanced MRI. The T1 constants in the nucleus, annulus, and cartilage endplates were quantified as a measure of gadodiamide transport into the loaded discs compared with the adjacent unloaded discs. Microcomputed tomography was used to quantify subchondral bone density. RESULTS: Low rate loading caused the rapid uptake and clearance of gadodiamide in the nucleus compared with unloaded discs, which exhibited a slower rate of uptake. Relative to unloaded discs, low rate loading caused a maximum increase in transport into the nucleus of 16.8% after 5 minutes of loading. Low rate loading increased the concentration of gadodiamide in the cartilage endplates at each time point compared with unloaded levels. CONCLUSIONS: Results from this study indicate that forced convection accelerated small molecule uptake and clearance in the disc induced by low rate mechanical loading. Low rate loading may, therefore, be therapeutic to the disc as it may enhance the nutrient uptake and waste product clearance.

Drug-induced changes to the vertebral endplate vasculature affect transport into the intervertebral disc in vivo.

Intervertebral disc health is mediated in part by nutrient diffusion from the microvasculature in the adjacent subchondral bone. Evidence suggests that a reduction in nutrient diffusion contributes to disc degeneration, but the role of the microvasculature is unclear. The purpose of this study was to induce changes in the endplate microvasculature in vivo via pharmaceutical intervention and then correlate microvasculature characteristics to diffusion and disc health. New Zealand white rabbits were administered either nimodipine (to enhance microvessel density) or nicotine (to diminish microvessel density) daily for 8 weeks compared to controls. Trans-endplate diffusion and disc health were quantified using post-contrast enhanced magnetic resonance imaging (MRI). Histology was utilized to assess changes to the subchondral vasculature. Results indicate that nimodipine increased vessel area and vessel-endplate contact length, causing a significant increase in disc diffusion. Surprisingly, nicotine caused increases in vessel number and area but did not alter diffusion into the disc. The drug treatments did affect the microvasculature and diffusion, but the relationship between the two is complex and dependent on multiple factors which include vessel-endplate distance, and vessel-endplate contact length in addition to vessel density. Our data suggest that drugs can modulate these factors to augment or diminish small molecule transport.

Immunogenicity of osteogenic protein 1: results from a prospective, randomized, controlled, multicenter pivotal study of uninstrumented lumbar posterolateral fusion.

OBJECT: The aim in this study was to detect and quantify antibody responses against recombinant human osteogenic protein 1 (OP-1) and to compare these responses to patient clinical outcomes and safety information. METHODS: A controlled, open-label, randomized, prospective, multicenter pivotal study was performed in which patients with single-level Grade I or II degenerative lumbar spondylolisthesis (Meyerding classification) and spinal stenosis underwent decompression and uninstrumented posterolateral spinal arthrodesis. Three hundred thirty-six patients were randomized in a 2:1 fashion to receive either OP-1 Putty or autogenous iliac crest bone graft. Patients were evaluated at regular postoperative intervals for radiographic results, clinical outcomes, and safety parameters for more than 36 months. Serum samples were collected over this period and evaluated for the presence of anti­OP-1 antibodies and neutralizing activity by using a battery of in vitro binding assays (including enzyme-linked immunosorbent assay [ELISA]) and cell-based bioassays, respectively. RESULTS: Antibodies were predominantly seen in the OP-1­treated patients, although some responses were recorded preoperatively and in patients receiving autograft alone. Antibody production peaked in the 6-week to 3-month postoperative time frame and diminished thereafter. Neutralizing antibodies (Nabs) were detected at 1 time point at least in 25.6% of the patients treated with OP-1 Putty, but were not found in any patient following the 24-month postoperative time period. A single autograft patient (1.2%) also presented with OP-1 Nabs. An anti­OP-1 antibody status did not correlate with any measure of patient outcomes or adverse events. CONCLUSIONS: Recombinant human OP-1 (bone morphogenetic protein 7), like many recombinant human proteins, induces an immune response following its use as a bone graft alternative. This response was transient and diminished over time, and there was no statistical evidence to suggest an association between Nab status and any of the efficacy or safety criteria that were examined.

A systematic review of occipital cervical fusion: techniques and outcomes.

OBJECT Numerous techniques have been historically used for occipitocervical fusion with varied results. The purpose of this study was to examine outcomes of various surgical techniques used in patients with various disease states to elucidate the most efficacious method of stabilization of the occipitocervical junction. METHODS A literature search of peer-reviewed articles was performed using PubMed and CINAHL/Ovid. The key words "occipitocervical fusion," "occipitocervical fixation," "cervical instrumentation," and "occipitocervical instrumentation" were used to search for relevant articles. Thirty-four studies were identified that met the search criteria. Within these studies, 799 adult patients who underwent posterior occipitocervical fusion were analyzed for radiographic and clinical outcomes including fusion rate, time to fusion, neurological outcomes, and the rate of adverse events. RESULTS No articles stronger than Class IV were identified in the literature. Among the patients identified within the cited articles, the use of posterior screw/rod instrumentation constructs were associated with a lower rate of postoperative adverse events (33.33%) (p < 0.0001), lower rates of instrumentation failure (7.89%) (p < 0.0001), and improved neurological outcomes (81.58%) (p < 0.0001) when compared with posterior wiring/rod, screw/plate, and onlay in situ bone grafting techniques. The surgical technique associated with the highest fusion rate was posterior wiring and rods (95.9%) (p = 0.0484), which also demonstrated the shortest fusion time (p < 0.0064). Screw/rod techniques also had a high fusion rate, fusing in 93.02% of cases. When comparing outcomes of surgical techniques depending on the disease status, inflammatory diseases had the lowest rate of instrumentation failure (0%) and the highest rate of neurological improvement (90.91%) following the use of screw/rod techniques. Occipitocervical fusion performed for the treatment of tumors by using screw/rod techniques had the lowest fusion rate (57.14%) (p = 0.0089). Traumatic causes of occipitocervical instability had the highest percentage of pain improvement with the use of screw/plates (100% improvement) (p < 0.0001). CONCLUSIONS Based on the existing literature, techniques that use screw/rod constructs in occipitocervical fusion are associated with very favorable outcomes in all categories assessed for all disease processes. For patients requiring occipitocervical arthrodesis for the treatment of inflammatory diseases, screw/rod constructs are associated with the most favorable outcomes, while posterior wiring and onlay in situ bone grafting is associated with the least favorable outcomes. Occipitocervical arthrodesis performed for the diagnosis of tumor is associated with the lowest rate of successful arthrodesis using screw/rod techniques, while posterior wiring and rods have the highest rate of arthrodesis. The nonspecified disease group had the lowest rate of surgical adverse events and the highest rate of neurological improvement.

Immunogenicity of bone morphogenetic proteins.

OBJECT: The object of this paper is to review the immunogenicity of bone morphogenetic proteins (BMPs) and to compare the results of the immunogenicity characterization and clinical consequences between recombinant human (rh)BMP-2 and recombinant human osteogenic protein-1 (rhOP-1/BMP-7). METHODS: The immunogenicity of therapeutic proteins and its clinical effects were reviewed. The characteristics of BMPs were also described in terms of immunogenicity. The methods and results of antibody detection in various clinical trials of rhBMP-2 and rhOP-1 were compared, including the most recent studies using a systematic characterization strategy with both a binding assay and bioassay. RESULTS: Similar to all recombinant human proteins, rhBMPs induce immune responses in a select subgroup of patients. Adverse effects from this response in these patients, however, have not been reported with antibody formation to either rhBMP-2 or rhOP-1. Overall, the incidence of antibody formation was slightly higher in rhOP-1 trials than in rhBMP-2 trials. CONCLUSIONS: Although they occur in a subgroup of patients, the immune responses against rhBMPs have no correlation with any clinical outcome or safety parameter. Clinicians, however, must be aware of the potential complications caused by the immunogenicity of BMPs until more studies clearly elucidate their safety.

The management of spinal injuries in patients with ankylosing spondylitis or diffuse idiopathic skeletal hyperostosis: a comparison of treatment methods and clinical outcomes.

STUDY DESIGN: A retrospective review of 12 patients with ankylosing spondylitis (AS) and 18 patients with diffuse idiopathic skeletal hyperostosis (DISH) treated at a single institution for spinal injuries between the years 2000 and 2006. OBJECTIVE: To independently evaluate patients with these diagnoses who sustained spinal injuries and directly compare their treatment methods and clinical outcomes. SUMMARY OF BACKGROUND DATA: AS and DISH are disorders characterized by abnormal ossification of the spinal column, which predisposes these patients to spinal injuries with potentially devastating consequences. METHODS: Patient and surgical data were obtained from medical records and appropriate imaging studies. Neurologic status was recorded using the American Spinal Injury Association (ASIA) impairment scale for spinal cord injuries, and clinical outcomes were assessed using Odom criteria. RESULTS: Most of these injuries involved the subaxial cervical spine between C5 and C7. In all, 41.2% of AS patients were considered to be ASIA A, whereas 44.4% of DISH patients were classified as ASIA E. Surgery was performed in 83.3% of AS patients and 66.7% of DISH patients, and the overall complication rates were 41.7% and 33.3%, respectively. There were no statistically significant differences between the survivorship and outcomes of the AS and DISH groups and 81.3% of all respondents were classified as having excellent or good outcomes. There were 4 deaths, all of which were considered to be related to the use of halo-vest immobilization. CONCLUSIONS: Although the rate of neurologic injury was high for both groups, AS patients were more likely to exhibit neurologic deficits and undergo operative management. Although the majority of these spinal injuries were treated surgically, stable fractures without any associated neurologic deficits were often successfully managed with immobilization. Complications were observed with both operative and nonoperative treatments, although all of the deaths occurred in conjunction with the use of the halo-vest orthosis.

Effects of recombinant human bone morphogenetic protein 2 on surgical infections in a rabbit posterolateral lumbar fusion model.

Recombinant human bone morphogenetic proteins (rhBMPs) are often used during spine surgery, but their effects on postoperative infections have not been well elucidated. Long-bone studies suggest that BMPs may limit local infection and facilitate bone formation. Until now, rhBMP-2 had not been evaluated in the setting of infected spinal arthrodesis. In the study reported here, we evaluated the safety and efficacy of rhBMP-2 and autograft in inducing fusion in the setting of surgically acquired infection. Sixty rabbits underwent fusion with autograft or rhBMP-2 with coadministration of Staphylococcus aureus or sterile saline. In the noninoculated groups, 4/15 autograft and 13/13 rhBMP-2 rabbits fused (P<.001). In the inoculated groups, 0/14 autograft and 3/12 rhBMP-2 rabbits fused (P = .085). There were 4/14 early deaths caused by infection in the autograft group and 0/12 in the rhBMP-2 group (P = .1). Although the difference in fusion rates and early deaths from infection for rhBMP-2 and autograft did not reach our predetermined alpha error threshold, the data were trending toward significance. Our results demonstrated no increase in morbidity or mortality associated with use of rhBMP-2 in the setting of local infection. Although BMP use with infections remains controversial, these results indicate that rhBMP- 2 could be used in a contaminated environment.

The safety and efficacy of OP-1 (rhBMP-7) as a replacement for iliac crest autograft in posterolateral lumbar arthrodesis: a long-term (>4 years) pivotal study.

STUDY DESIGN: Randomized controlled trial comparing OP-1 (rhBMP-7) with iliac crest autograft in patients with symptomatic degenerative spondylolisthesis and spinal stenosis treated with decompression and uninstrumented posterolateral arthrodesis. OBJECTIVE: To determine the safety and the clinical and radiographic efficacy of OP-1 (rhBMP-7) Putty as compared with an iliac crest bone autograft control in uninstrumented, single-level posterolateral spinal arthrodesis. SUMMARY OF BACKGROUND DATA: Preclinical and preliminary clinical data have demonstrated successful fusion and clinical outcomes with the use of OP-1 Putty in posterolateral spinal arthrodesis. No prior randomized controlled trial with adequate study power has been performed. METHODS: A total of 335 patients were randomized in 2:1 fashion to receive either OP-1 Putty or autograft in the setting of an uninstrumented posterolateral arthrodesis performed for degenerative spondylolisthesis and symptomatic spinal stenosis. Patients were observed serially with radiographs, clinical examinations, and appropriate clinical indicators, including ODI, Short-Form 36, and visual analog scale scores. Serum samples were examined at regular intervals to assess the presence of antibodies to OP-1. The primary end point, Overall Success, was analyzed at 24 months. The study was extended to include additional imaging data and long-term clinical follow-up at 36+ months. At the 36+ month time point, CT scans were obtained in addition to plain radiographs to evaluate the presence and location of new bone formation. Modified Overall Success, including improvements in ODI, absence of retreatment, neurologic success, absence of device-related serious adverse events, angulation and translation success, and new bone formation by CT scan (at 36+ months), was then calculated using the 24-month primary clinical endpoints, updated retreatment data, and CT imaging and radiographic end points. RESULTS: OP-1 Putty was demonstrated to be statistically equivalent to autograft with respect to the primary end point of modified overall success. The use of OP-1 Putty when compared to autograft was associated with statistically lower intraoperative blood loss and shorter operative times. Although patients in the OP-1 Putty group demonstrated an early propensity for formation of anti-OP-1 antibodies, this resolved completely in all patients with no clinical sequelae. CONCLUSION: OP-1 Putty is a safe and effective alternative to autograft in the setting of uninstrumented posterolateral spinal arthrodesis performed for degenerative spondylolisthesis and symptomatic spinal stenosis.

Anterior tibial artery and deep peroneal nerve entrapment in spiral distal third tibia fracture.

The rate of injury to arterial structures following long bone injuries is low. The rate in tibial diaphyseal fractures is similarly low. This rate increases with open fractures, likely reflective of the higher energy nature of open fractures. The possibility of iatrogenic injury to neurovascular structures during fracture fixation is more concerning. Consequently, the clinician must be aware of the location of neurovascular structures and the possible distortion of the normal anatomy when treating fractures. The anterior tibial artery is in proximity to the distal tibia. Typically, the neurovascular bundle lies directly on the anterolateral tibia between the tibialis anterior and the extensor hallucis longus in the distal third of the tibia. After fracture, this normal relationship may be disrupted.

rhBMP-2 (ACS and CRM formulations) overcomes pseudarthrosis in a New Zealand white rabbit posterolateral fusion model.

STUDY DESIGN: The study design consisted of a New Zealand white rabbit model of pseudarthrosis repair. Study groups consisting of no graft, autograft, or recombinant human bone morphogenetic protein-2 (rhBMP-2) with absorbable collagen sponge (ACS) or compression resistant matrix (CRM) were evaluated. OBJECTIVE: To evaluate the relative efficacy of bone graft materials (autograft, ACS, and CRM). SUMMARY OF BACKGROUND DATA: rhBMP-2 has been shown to have a 100% fusion rate in a primary rabbit fusion model, even in the presence of nicotine, which is known to inhibit fusion. METHODS: Seventy-two New Zealand white rabbits underwent posterolateral lumbar fusion with iliac crest autograft. To establish pseudarthroses, nicotine was administered to all animals. At 5 weeks, the spines were explored and all pseudarthroses were redecorticated and implanted with no graft, autograft, rhBMP-2/ACS, or rhBMP-2/CRM. At 10 weeks, fusions were assessed by manual palpation and histology. RESULTS: Eight rabbits (11%) were lost to complications. At 5 weeks, 66 (97%) had pseudarthroses. At 10 weeks, attempted pseudarthrosis repairs were fused in 1 of 16 of no graft rabbits (6%), 5 of 17 autograft rabbits (29%), and 31 of 31 rhBMP-2 rabbits (with ACS or CRM) (100%). Histologic analysis demonstrated more mature bone formation in the rhBMP-2 groups. CONCLUSIONS: The 2 rhBMP-2 formulations led to significantly higher fusion rates and histologic bone formation than no graft and autograft controls in this pseudarthrosis repair model.

Back pain in athletes.

The athlete with back pain presents a clinical challenge. Self-limited symptoms must be distinguished from persistent or recurrent symptoms associated with identifiable pathology. Athletes involved in impact sports appear to have risk factors for specific spinal pathologies that correlate with the loading and repetition demands of specific activities. For example, elite athletes who participate in longer and more intense training have higher incidence rates of degenerative disk disease and spondylolysis than athletes who do not. However, data suggest that the recreational athlete may be protected from lumbar injury with physical conditioning. Treatment of athletes with acute or chronic back pain usually is nonsurgical, and symptoms generally are self-limited. However, a systematic approach to the athlete with back pain, involving a thorough history and physical examination, pertinent imaging, and treatment algorithms designed for specific diagnoses, can facilitate symptomatic improvement and return to play. There are no reliable studies examining the long-term consequences of athletic activity on the lumbar spine.

Effect of daily parathyroid hormone (1-34) on lumbar fusion in a rat model.

BACKGROUND CONTEXT: Despite numerous studies evaluating the anabolic effects of intermittent administration of parathyroid hormone (PTH) on bone, there are no published studies examining its effect on spinal fusion outcomes. PURPOSE: To determine the effect of daily injection of human recombinant PTH(1-34) on posterolateral lumbar fusions in a rat model. STUDY DESIGN: Prospective, case-controlled, preclinical animal study. OUTCOME MEASURES: Manual palpation and serum osteocalcin. METHODS: Single-level, intertransverse process spinal fusions were performed with iliac crest autograft in 56 Sprague-Dawley rats. Animals received daily injections of placebo or PTH(1-34). At 6 weeks, fusion masses were assessed by manual palpation. Serum osteocalcin levels were assessed in a subset of the animals. RESULTS: Manual palpation revealed the control group to have a fusion rate of 37% (10/27) and the PTH(1-34)-treated group to have a fusion rate of 52% (15/29). Mean serum osteocalcin levels were 59.8 and 88.6 ng/L for the control and PTH(1-34) groups, respectively. CONCLUSIONS: There was a trend towards greater fusion rate in the PTH(1-34) group as compared with the placebo group. Further, PTH(1-34) administration was associated with a significant increase in osteocalcin levels. Certainly, further investigations are warranted, as an injectable agent capable of increasing fusion rates would be of great clinical value.