Modular hybrid total hip arthroplasty. Experimental study in dogs

Background: This prospective experimental study evaluated the surgical procedure and results of modular hybrid total hip arthroplasty in dogs.Methods: Ten skeletally mature healthy mongrel dogs with weights varying between 19 and 27 kg were used. Cemented modular femoral stems and uncemented porous-coated acetabular cups were employed. Clinical and radiographic evaluations were performed before surgery and at 30, 60, 90, 120, 180 and 360 days post-operation.Results: Excellent weight bearing was noticed in the operated limb in seven dogs. Dislocation followed by loosening of the prosthesis was noticed in two dogs, which were therefore properly treated with a femoral head osteotomy. Femoral fracture occurred in one dog, which was promptly treated with full implant removal and femoral osteosynthesis.Conclusions: The canine modular hybrid total hip arthroplasty provided excellent functionality of the operated limb

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

Determinants of passive hip range of motion in adult Greyhounds

Objective To determine the ranges of normal pelvic limb range of motion in adult Greyhound dogs, and to explore which factors influence hip range of motion in a population bred to meet the specific demands of racing. Design A cross-sectional study design. Method Thirty-two dogs (17 male and 15 female) 13 to 81 months old were randomly selected from a local pool of 160 Greyhounds. Goniometric measurements of hip, stifle and hock range of motion were recorded in triplicate. Signalment information collected included sex, weight and age of each Greyhound. The outcome factors for the study were range of hip flexion and hip extension. The theorised exposures, age, sex, weight, racing history and hock and stifle range of motion, were modelled against the outcome variables by linear regression analysis. Results Male dogs were significantly heavier (P < 0.001) and older (P < 0.002) than female dogs. Mean hip flexion was 71.75 degrees and mean hip extension 128.10 degrees. The determinants of hip flexion were sex (P = 0.008) and range of stifle flexion (P = 0.002). Race training did not influence the range of hip flexion in the sample. Determinants of hip extension included range of stifle extension (P = 0.015), history of race training (P = 0.004) and hock flexion. The mean hip extension of raced Greyhounds was 134.95 degrees compared with 121.25 degrees for unraced Greyhounds (mean difference -13.70, 95% confidence interval -18.12, -9.29; P < 0.001). Conclusions This study has reported isolated pelvic limb joint range of motion in the racing Greyhound. Hip range of motion was affected by stifle range of motion, sex and race training. Dogs that had received race training had greater flexibility, possibly due to training having an active stretching role on muscles, tendons and other structures limiting the hip range of motion