Methicillin-resistant Staphylococcus aureus (MRSA) reinfection following revision surgery remains a major orthopaedic problem. Toward the development of immunotherapy with anti-glucosaminidase monoclonal antibodies (anti-Gmd), we aimed to: (i) develop a murine 1-stage exchange model of bioluminescent MRSA (USA300LAC::lux) contaminated femoral implants; and (ii) utilize this model to demonstrate the synergistic effects of combination vancomycin and anti-Gmd therapy on reinfection and bone healing. Following an infection surgery, the original plate and two screws were removed on day 7, and exchanged with sterile implants. Mice were randomized to five groups: (i) no infection control; (ii) infected placebo; (iii) anti-Gmd; (iv) vancomycin; and (v) combination therapy. Bioluminescent imaging (BLI) was performed on days 0, 1, 3, 5, 7, 8, 10, 12, and 14. Mice were euthanized on day 14 (day 7 post-revision), and efficacy was assessed via colony forming units (CFU) on explanted hardware, micro-CT, and histology. As monotherapies, anti-Gmd inhibited Staphylococcus abscess communities, and vancomycin reduced CFU on the implants. However, only combination therapy prevented increased BLI post-revision surgery, with a significant 6.5-fold reduction on day 10 (p < 0.05 vs. placebo), and achieved sterile implant levels by day 12. Synergistic effects were also apparent from reduced osteolysis and increased new bone formation around the screws only observed following combination therapy. Taken together, we find that: (i) this murine femoral plate 1-stage revision model can efficiently evaluate therapies to prevent reinfection; and (ii) immunotherapy plays a distinct role from antibiotics to reduce reinfection following revision surgery, such that synergy to achieve osseointegration is possible. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1590-1598, 2018.

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Abstract:Introduction: Multilevel total en bloc spondylectomy (TES) is required to secure oncologically adequate resection margins. However, no useful information has been reported for spinal reconstruction after multilevel TES. Therefore, this study set out to assess the clinical and radiological outcomes of spinal reconstruction after multilevel TES. Methods: Forty-eight patients treated with multilevel TES at our institute were included in the analysis. Reconstruction was achieved with posterior pedicle screw fixation and an anterior titanium mesh cage filled with iliac autograft in all cases. Spinal shortening was performed to increase spinal stability from the reconstruction. Instrumentation failure and radiological findings were evaluated with radiography and computerized tomography (CT). Results: After excluding one patient whose general condition was deteriorating, radiological evaluations of 47 patients were performed over a period of more than a year. The follow-up time was 17 to 120 months (mean: 70.2 months). Instrumentation failure occurred in one patient (5.9%) after thoracic multilevel TES, in 4 patients (25.0%) after thoracolumbar multilevel TES, and in 3 patients (42.9%) after lumbar multilevel TES. No instrumentation failure was observed in cervicothoracic cases. Cage subsidence (>2 mm) occurred in 30 patients (63.8%). In 22 of them, subsidence appeared on the CT one month after surgery. The risk factors of instrumentation failure included a multilevel TES below the thoracolumbar level and a long span of vertebral resection. There was no instrumentation failure in any of the 11 "disc-to-disc cutting" cases. Conclusions: This study identified the risk factors of instrumentation failure after multilevel TES. There is a high risk of instrumentation failure in cases of long vertebral resection below the thoracolumbar level. On the other hand, our reconstruction method can be successful for multilevel TES above the thoracic level.

Background Previous studies have indicated that trunk muscle strength decreases with chronic low back pain, and is associated with poor balance, poor functional performance, and falls in older adults. Strengthening exercises for chronic low back pain are considered the most effective intervention to improve functional outcomes. We developed an innovative exercise device for abdominal trunk muscles that also measures muscle strength. The correlation between muscle weakness, as measured by our device, the presence of chronic low back pain, and decreased physical ability associated with a risk of falling were evaluated in older women. Methods Thirty-eight elderly women, who could walk without support during daily activities and attended our outpatient clinic for treatment of chronic low back pain, knee or hip arthritis, or osteoporosis, were included in this study. Anthropometric measurements were performed. Grip power and one-leg standing time with eyes open were measured, and abdominal trunk muscle strength was measured using our device. History of falling in the previous 12 months was noted. Subjects with chronic low back pain (visual analog scale score ≥ 20 mm) for over 3 months were assigned to the low back pain group ( n = 21). The remaining subjects formed the non-low back pain group ( n = 17). Results Abdominal muscle strength of subjects in the low back pain group, and with history of falling, was significantly lower compared with that of subjects in the non-low back pain group, and in subjects without a history of falling, respectively. There was a moderate positive correlation between abdominal trunk muscle strength and one-leg standing time with eyes open. Conclusion We measured abdominal muscle strength in older women with chronic low back pain using our device, and it was significantly lower than that of those without chronic low back pain. Muscle weakness was associated with a history and risk of falling.