A Mouse Model of Post-Arthroplasty Staphylococcus aureus Joint Infection to Evaluate In Vivo the Efficacy of Antimicrobial Implant Coatings

Post-arthroplasty infections represent a devastating complication of total joint replacement surgery, resulting in multiple reoperations, prolonged antibiotic use, extended disability and worse clinical outcomes. As the number of arthroplasties in the U.S. will exceed 3.8 million surgeries per year by 2030, the number of post-arthroplasty infections is projected to increase to over 266,000 infections annually. The treatment of these infections will exhaust healthcare resources and dramatically increase medical costs.To evaluate novel preventative therapeutic strategies against post-arthroplasty infections, a mouse model was developed in which a bioluminescent Staphylococcus aureus strain was inoculated into a knee joint containing an orthopaedic implant and advanced in vivo imaging was used to measure the bacterial burden in real-time. Mice inoculated with 5x10(3) and 5x10(4) CFUs developed increased bacterial counts with marked swelling of the affected leg, consistent with an acute joint infection. In contrast, mice inoculated with 5x10(2) CFUs developed a low-grade infection, resembling a more chronic infection. Ex vivo bacterial counts highly correlated with in vivo bioluminescence signals and EGFP-neutrophil fluorescence of LysEGFP mice was used to measure the infection-induced inflammation. Furthermore, biofilm formation on the implants was visualized at 7 and 14 postoperative days by variable-pressure scanning electron microscopy (VP-SEM). Using this model, a minocycline/rifampin-impregnated bioresorbable polymer implant coating was effective in reducing the infection, decreasing inflammation and preventing biofilm formation.Taken together, this mouse model may represent an alternative pre-clinical screening tool to evaluate novel in vivo therapeutic strategies before studies in larger animals and in human subjects. Furthermore, the antibiotic-polymer implant coating evaluated in this study was clinically effective, suggesting the potential for this strategy as a therapeutic intervention to combat post-arthroplasty infections

Interspinous process device versus standard conventional surgical decompression for lumbar spinal stenosis: randomised controlled trial

STUDY QUESTION Is interspinous process device implantation more effective in the short term (eight weeks) than conventional surgical decompression for patients with intermittent neurogenic claudication due to lumbar spinal stenosis? SUMMARY ANSWER The use of interspinous implants did not result in a better outcome than conventional decompression, but the reoperation rate was significantly higher. WHAT IS KNOWN AND WHAT THIS PAPER ADDS Bony decompression and treatment with interspinous process devices are superior to conservative and non-surgical treatment for intermittent neurogenic claudication due to lumbar spinal stenosis. Interspinous implants surgery is not superior to bony decompression, and the reoperation rate is significantly higher

IPD without bony decompression versus conventional surgical decompression for lumbar spinal stenosis: 2-year results of a double-blind randomized controlled trial

Interspinous process devices (IPDs) are implanted to treat patients with intermittent neurogenic claudication (INC) based on lumbar spinal stenosis. It is hypothesized that patients with lumbar spinal stenosis treated with IPD have a faster short-term recovery, an equal outcome after 2 years and less back pain compared with bony decompression. A randomized design with variable block sizes was used, with allocations stratified according to center. Allocations were stored in prepared opaque, coded and sealed envelopes, and patients and research nurses were blind throughout the follow-up. Five neurosurgical centers (including one academic and four secondary level care centers) included participants. 211 participants were referred to the Leiden-The Hague Spine Prognostic Study Group. 159 participants with INC based on lumbar spinal stenosis at one or two levels with an indication for surgery were randomized into two groups. Patients and research nurses were blinded for the allocated treatment throughout the study period. 80 participants received an IPD and 79 participants underwent spinal bony decompression. The primary outcome at long-term (2-year) follow-up was the score for the Zurich Claudication Questionnaire. Repeated measurement analyses were applied to compare outcomes over time. At two years, the success rate according to the Zurich Claudication Questionnaire for the IPD group [69 % (95 % CI 57-78 %)] did not show a significant difference compared with standard bony decompression [60 % (95 % CI 48-71 %) p value 0.2]. Reoperations, because of absence of recovery, were indicated and performed in 23 cases (33 %) of the IPD group versus 6 (8 %) patients of the bony decompression group (p < 0.01). Furthermore, long-term VAS back pain was significantly higher [36 mm on a 100 mm scale (95 % CI 24-48)] in the IPD group compared to the bony decompression group [28 mm (95 % CI 23-34) p value 0.04]. This double-blinded study could not confirm the advantage of IPD without bony decompression over conventional 'simple' decompression, two years after surgery. Moreover, in the IPD treatment arm, the reoperation rate was higher and back pain was even slightly more intense compared to the decompression treatment arm

Clinical analysis following lumbar interspinous devices implant: where we are and where we go

lumbar interspinous device