Poor Agreement Between Next-Generation DNA Sequencing and Bacterial Cultures in Orthopaedic Trauma Procedures.

BACKGROUND: Next-generation DNA sequencing (NGS) detects bacteria-specific DNA corresponding to the 16S ribosomal RNA gene and can identify bacterial presence with greater accuracy than traditional culture methods. The clinical relevance of these findings is unknown. The purpose of the present study was to compare the results from bacterial culture and NGS in order to characterize the potential use of NGS in orthopaedic trauma patients. METHODS: A prospective cohort study was performed at a single academic, level-I trauma center. Three patient groups were enrolled: (1) patients undergoing surgical treatment of acute closed fractures (presumed to have no bacteria), (2) patients undergoing implant removal at the site of a healed fracture without infection, and (3) patients undergoing a first procedure for the treatment of a fracture nonunion who might or might not have subclinical infection. Surgical site tissue was sent for culture and NGS. The proportions of culture and NGS positivity were compared among the groups. The agreement between culture and NGS results was assessed with use of the Cohen kappa statistic. RESULTS: Bacterial cultures were positive in 9 of 111 surgical sites (110 patients), whereas NGS was positive in 27 of 111 surgical sites (110 patients). Significantly more cases were positive on NGS as compared with culture (24% vs. 8.1%; p = 0.001), primarily in the acute closed fracture group. No difference was found in terms of the percent positivity of NGS when comparing the acute closed fracture, implant removal, and nonunion groups. With respect to bacterial identification, culture and NGS agreed in 73% of cases (κ = 0.051; 95% confidence interval, -0.12 to 0.22) indicating only slight agreement compared with expected chance agreement of 50%. CONCLUSIONS: NGS identified bacterial presence more frequently than culture, but with only slight agreement between culture and NGS. It is possible that the increased frequency of bacterial detection with molecular methods is reflective of biofilm presence on metal or colonization with nonpathogenic bacteria, as culture methods have selection pressure posed by restrictive, artificial growth conditions and there are low metabolic activity and replication rates of bacteria in biofilms. Our data suggest that NGS should not currently substitute for or complement conventional culture in orthopaedic trauma cases with low suspicion of infection. LEVEL OF EVIDENCE: Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Effect of Training Modules on Hip Fracture Surgical Skills Simulation Performance: Early Validation of the AAOS/OTA Simulator.

BACKGROUND: A preliminary validation study on a computer-based force-feedback simulation platform demonstrated the ability of the simulator to distinguish between novice and experienced users during a simulated hip-pinning procedure. The purpose of the present study was to further investigate whether the simulator and associated training modules are effective for improving user performance during simulated percutaneous hip-pinning procedures. METHODS: With institutional review board approval, 24 medical students at our institution were randomized to "Trained" and "Untrained" groups. After a basic introduction, the Untrained group placed 3 guidewires in a valgus-impacted femoral neck fracture with use of the simulator. The Trained group completed 9 simulator-based training modules before performing the same task. Measured outcomes included an overall performance score and the distance from the pin to various ideals on the femoral neck, femoral head articular surface, and lateral cortex. Performance parameters were compared between groups with the Mann-Whitney U test. RESULTS: The Trained group achieved a significantly higher overall score (median, 29) compared with the Untrained group (median, 6) (p < 0.01), outperformed the Untrained group in 4 specific performance metrics, and trended toward improvement over the Untrained group in 4 pin placement measures (p < 0.2). CONCLUSIONS: Completion of novel training modules for percutaneous hip pinning on this fluoroscopic surgery simulator improves skill performance on simulator-based objective measurements and a simulated orthopaedic procedure compared with non-simulator-trained surgically inexperienced users. Improvement in the overall score and on 4 of 13 specific performance parameters implies that the training modules more effectively teach only certain motor and 3-dimensional spatial skills. CLINICAL RELEVANCE: A valid platform such as the one described here has the potential to improve surgical education in orthopaedic trauma.

Construct Validation of a Novel Hip Fracture Fixation Surgical Simulator.

INTRODUCTION: A surgical simulation platform has been developed to simulate fluoroscopically guided surgical procedures by coupling computer modeling with a force-feedback device as a training tool for orthopaedic resident education in an effort to enhance motor skills and potentially minimize radiation exposure. The objective of this study was to determine whether the simulation platform can distinguish between novice and experienced practitioners of percutaneous pinning of hip fractures. METHODS: Medical students, orthopaedic residents, orthopaedic trauma fellows, and attending surgeons completed in situ hip-pinning simulation that recorded performance measures related to surgical accuracy, time, and use of fluoroscopy. Linear regression models were used to compare the association between performance and practitioner experience. RESULTS: Notable associations were shown between performance and practitioner experience in 10 of the 15 overall measures (P < 0.05) and 9 of 11 surgical accuracy parameters (P < 0.05). CONCLUSION: This novel simulation platform can distinguish between novice and experienced practitioners and defines a performance curve for completion of simulated in situ hip pinning. This important first step lays the groundwork for subsequent validation studies, which will seek to demonstrate the efficacy of this simulator in improving clinical performance by trainees completing a sequence of skills-training modules.

How Should We Secure Our Transplanted Meniscus? A Meta-analysis.

BACKGROUND: Meniscal allograft transplant (MAT) is a salvage procedure for young patients with symptomatic meniscal deficiency. Although many studies report good outcomes, MAT remains controversial, and an optimal fixation technique for the meniscus roots is debated. PURPOSE: To assess the overall outcome of MAT and compare the results of different meniscal root fixation techniques. STUDY DESIGN: Meta-analysis. METHODS: Following specific guidelines, we systematically evaluated all current literature for studies reporting on the outcomes of patients who underwent MAT. Using random effect models of proportions, we determined the tear and failure rates. Standardized mean differences (SMDs) were calculated to determine the improvement in clinical outcomes and pain level. Data were then stratified by root fixation method into 2 groups: fixation that preserved the graft's root insertions on the allograft bone (bone fixation group) and suture fixation of the root soft tissue without the allograft bone (soft tissue suture group). RESULTS: A total of 38 studies (1637 MATs, 81% men) involving subjects with a mean age of 34 years (range, 20-48 years) and a mean follow-up of 60 months (range, 25-168 months) met inclusion criteria. This overall cohort had significant improvements in Lysholm scores (from 57.8 to 81.4 points; SMD 1.5, P < .001) and pain level (visual analog scale [VAS], from 56 to 21 points; SMD 1.8, P < .001). The cohort had a tear rate of 9% and a failure rate of 12.6%. No significant differences were found between the soft tissue suture (485 MATs) and bone fixation (489 MATs) groups in terms of meniscal allograft tear rates (13.4% vs 14.9%), failure rates (17.6% vs 18.8%), Lysholm scores (from 52.3 to 82.4, SMD 2.0, and from 60.7 to 82.9, SMD 1.7; respectively), and VAS scores (from 65 points to 18 points, SMD 2.6, and from 63 points to 13 points, SMD 3.1; both P < .001). Meniscal extrusion was similar, with a weighted mean percentage of extrusion of 40.2% in the soft tissue suture group and 43.1% in the bone fixation group. CONCLUSION: This meta-analysis demonstrated significant improvements in clinical outcomes for MAT patients with low tear and failure rates. The data do not demonstrate a difference between soft tissue suture and bone fixation for MAT root fixation. This suggests that the technique of root fixation may not have an appreciable influence on clinical outcome, pain reduction, extrusion, or MAT longevity. Further prospective trials are needed.

Operative management of acetabulum fractures in the obese patient: challenges and solutions.

In this review, we aim to increase our knowledge of the treatment of acetabular fractures in the obese patient population. The extremely high incidence of obesity in the USA is a looming health care concern that impacts aspects of health care in all medical specialties. There are specific concerns to the orthopedic surgeon when treating obese patients for acetabular fracture. Patients with body mass index ≥30 present particular challenges to the surgeon in terms of preexisting medical conditions, diagnostic imaging, and perioperative complications. Specifically, this patient population experiences worse functional outcomes and greater incidence of surgical site infection, intraoperative blood loss, deep venous thrombosis, post-traumatic osteoarthritis, heterotopic ossification, and increased hospital length of stay. These problems are further exacerbated in the morbidly obese, as a scaling effect exists between increasing body mass index and worsening complication profile. This is problematic given the current high incidence of morbid obesity in the USA and particularly worrisome in light of the projected increase in obesity rates for the future.

Heterotopic bone formation about the hip undergoes endochondral ossification: a rabbit model.

BACKGROUND: Heterotopic ossification (HO) occurs most commonly after trauma and surgery about the hip and may compromise subsequent function. Currently available animal models describing the cellular progression of HO are based on exogenous osteogenic induction agents and may not reflect the processes following trauma. QUESTIONS/PURPOSES: We therefore sought to characterize the histologic progression of heterotopic bone formation in an animal model that recapitulates the human condition without the addition of exogenous osteogenic material. METHODS: We used a rabbit model that included intramedullary instrumentation of the upper femur and ischemic crush injury of the gluteal muscle. Bilateral surgical induction procedures were performed on 30 animals with the intention of inciting the process of HO; no supplemental osteogenic stimulants were used. Three animals were sacrificed at each of 10 predetermined times between 1 day and 26 weeks postoperatively and the progression of tissue maturation was graded histologically using a five-item scale. RESULTS: Heterotopic bone reliably formed de novo and consistently followed a pathway of endochondral ossification. Chondroid elements were found in juxtaposition with immature woven bone in all sections that contained mature osseous elements. CONCLUSIONS: These results establish that HO occurs in an animal model mimicking the human condition following surgical trauma about the hip; it is predictable in its histologic progression and follows a pathway of endochondral bone formation. CLINICAL RELEVANCE: By showing a consistent pathway of endochondral ossification leading to ectopic bone formation, this study provides a basis for understanding the mechanisms by which HO might be mitigated by interventions.

Capacitive coupling reduces instrumentation-related infection in rabbit spines: a pilot study.

BACKGROUND: Postoperative spine infections cause considerable morbidity. Patients are subjected to long-term antibiotic regimens and may require further surgery. Delivery of electric current through instrumentation can detach biofilm, allowing better antibiotic penetration and assisting in eradicating infection. QUESTION/PURPOSES: We asked (1) whether capacitive coupling treatment in combination with a single dose of antibiotics would reduce infection rates when compared with antibiotics alone in a rabbit spine infection model, (2) whether it would decrease the overall bacterial burden, and (3) whether there was a time-dependent response based on days treated with capacitive coupling. METHODS: Thirty rabbits were subjected to a well-established spine infection model with a single dose of intravenously administered systemic ceftriaxone (20 mg/kg of body weight) prophylaxis. Two noncontiguous rods were implanted inside dead space defects at L3 and L6 challenged with 10(6) colony-forming units of Staphylococcus aureus. Rabbits were randomly treated with a capacitive coupling or control device. Instrumentation and soft tissue bacterial growth were assessed after 7 days. RESULTS: Sites treated with capacitive coupling showed a decrease in the incidence of positive culture: 36% versus 81% in the control group. We observed no difference in the soft tissue's infectious burden. Overall bacterial load was not decreased with capacitive coupling. CONCLUSIONS: Capacitive coupling in conjunction with antibiotics reduced the instrumentation-related infection rate compared with antibiotics alone. CLINICAL RELEVANCE: Capacitive coupling noninvasively delivers an alternating current that may detach biofilm from instrumentation. Treatment of infection may be successful without removal of instrumentation, allowing for improved stability and overall decreased morbidity.

Heterotopic ossification after extremity blast amputation in a Sprague-Dawley rat animal model.

OBJECTIVE: To create an animal survival model for heterotopic ossification (HO) in the residual limb of the rat after extremity blast amputation. The hypothesis was that extremity blast amputation spontaneously stimulates development of HO in the residual limb. METHODS: Twelve Sprague-Dawley rats underwent localized exposure to a controlled, high-energy blast. Seven rats were designated for hind limb amputation and five for forelimb amputation. Our protocol produced extremity amputation through detonation of an explosive while protecting the animal proximal to the specified amputation level. Immediately after injury, the rat underwent wound management and primary surgical closure. Radiographs of the amputated limbs were obtained every 2 weeks. Heterotopic bone was radiographically classified as periosteal growth (Type A) or noncontiguous growth (Type B). A kappa statistic was calculated for interobserver strength of agreement on the presence of HO. Fisher exact test was conducted to assess the significance of the difference in hind limb and forelimb HO rates. RESULTS: Nine of 12 animals survived the procedure. The three nonsurvivors were all hind limb amputees, and each died of various related causes. All four surviving hind limb amputees exhibited Type A HO, and three of four also exhibited Type B HO within the injured stump. One of five forelimb amputees exhibited Types A and B HO. CONCLUSIONS: We have developed a reproducible model for HO in the residual limbs of blast-amputated rats without addition of exogenous osteogenic stimulus. Hind limb amputation demonstrated a predilection for HO formation in comparison with forelimb amputation (P < 0.05).