Long-Term Postoperative Total Knee Arthroplasty Flexion Scores in Relation to Body Mass Index.

Knee range of motion (ROM) is an important postoperative measure of total knee arthroplasty (TKA). There is conflicting literature whether patients who are obese have worse absolute ROM outcomes than patients who are not obese. This study analyzed whether preoperative body mass index (BMI) influences knee ROM after patients' primary TKA. A retrospective investigation was performed on patients, who underwent primary TKA at an academic institution, by one of three fellowship-trained adult reconstruction surgeons. Patients were stratified according to their preoperative BMI into nonobese (BMI < 30.0 kg/m2) and obese (BMI ≥ 30.0 kg/m2) classifications. Passive ROM was assessed preoperatively as well as postoperatively at patients' most recent follow-up visit that was greater than 2 years. Mann-Whitney U tests were performed to determine statistical significance at p-value <0.05 for ROM outcomes. No statistically significant differences were observed when ROM in the nonobese group was compared with ROM in the obese group both preoperatively (105.73 ± 11.58 vs. 104.14 ± 13.58 degrees, p-value = 0.417) and postoperatively (105.83 ± 14.19 vs. 104.49 ± 13.52 degrees, p-value = 0.777). Mean follow-up time for all patients was 4.49 ± 1.92 years. In conclusion, long-term postoperative ROM outcomes were similar between patients who were nonobese and patients who were obese.

Autonomous lumbar spine pedicle screw planning using machine learning: A validation study.

INTRODUCTION: Several techniques for pedicle screw placement have been described including freehand techniques, fluoroscopy assisted, computed tomography (CT) guidance, and robotics. Image-guided surgery offers the potential to combine the benefits of CT guidance without the added radiation. This study investigated the ability of a neural network to place lumbar pedicle screws with the correct length, diameter, and angulation autonomously within radiographs without the need for human involvement. MATERIALS AND METHODS: The neural network was trained using a machine learning process. The method combines the previously reported autonomous spine segmentation solution with a landmark localization solution. The pedicle screw placement was evaluated using the Zdichavsky, Ravi, and Gertzbein grading systems. RESULTS: In total, the program placed 208 pedicle screws between the L1 and S1 spinal levels. Of the 208 placed pedicle screws, 208 (100%) had a Zdichavsky Score 1A, 206 (99.0%) of all screws were Ravi Grade 1, and Gertzbein Grade A indicating no breech. The final two screws (1.0%) had a Ravi score of 2 (<2 mm breech) and a Gertzbein grade of B (<2 mm breech). CONCLUSION: The results of this experiment can be combined with an image-guided platform to provide an efficient and highly effective method of placing pedicle screws during spinal stabilization surgery.

Local Versus Systemic Antibiotics for Surgical Infection Prophylaxis in a Rat Model.

BACKGROUND: The purpose of this study was to compare the local application of a variety of antimicrobial agents with intravenous (IV) antibiotics for infection prophylaxis in a rat model. METHODS: A total of 120 adult male Sprague-Dawley rats were implanted with an expanded polytetrafluoroethylene (ePTFE) vascular graft in a submuscular position and challenged with 2 × 10 colony-forming units of methicillin-sensitive Staphylococcus aureus (MSSA). Twenty rats received pretreatment with IV cefazolin and 20 rats were pretreated with IV vancomycin. The remaining 80 rats had application of local antimicrobials in the wound at the conclusion of the procedure: 20 rats received vancomycin powder; 20 rats, cefazolin powder; and 20 rats, tobramycin powder; 20 rats underwent dilute 0.35% Betadine (povidone-iodine) lavage for 3 minutes. One week after surgery, the grafts were retrieved and cultured. RESULTS: Twenty (100%) of 20 rats in each of the IV cefazolin, IV vancomycin, and dilute Betadine lavage groups had grossly positive cultures for MSSA (95% confidence interval [CI], 84% to 100%). Eighteen (90%) of 20 rats in the cefazolin local powder group demonstrated positive cultures for MSSA (95% CI, 77% to 100%). Four (20%) of 20 rats in the tobramycin local powder and vancomycin local powder groups demonstrated positive cultures for MSSA (95% CI, 3% to 38%). The infection rates for the local application of vancomycin and tobramycin powder were significantly lower compared with Betadine lavage, IV vancomycin, IV cefazolin, and local cefazolin powder (p < 0.000001). CONCLUSIONS: Local antimicrobial prophylaxis with vancomycin and tobramycin powder for infections in the rat model was statistically superior to systemic prophylaxis with IV antibiotics, local cefazolin powder, and Betadine lavage. CLINICAL RELEVANCE: This study supports the findings of prior clinical reports that intrawound vancomycin powder reduces the risk of surgical site infection. Local application of tobramycin powder was equivalent to vancomycin powder in this model. Additionally, the superiority of local antibiotic surgical prophylaxis suggests that clinical studies should be considered to determine the relative efficacy of local versus systemic antibiotics for surgical infection prophylaxis in humans.

Comparison of metal ion levels in patients with hip resurfacing versus total hip arthroplasty.

Mechanical wear at the articular surface and corrosive processes at modular junctions, such as the trunnion, are responsible for metal ions production. We retrospectively reviewed 64 patients who underwent THA with a metal on metal bearing surface and 34 patients with hip Resurfacing. Metal ion measurements, six-week post-op radiographs, and functional scores were included in the analysis. Cobalt ion levels were significantly elevated in THA patients, 2.95 µg/L as compared to resurfacing patients, (2.95 versus 1.30 µg/L, p < 0.0005). Chromium levels were not significantly different between THA patients and resurfacing patients (1.05 versus 1.00 µg/L, p = 0.529).