Chondroprotective effects of zoledronic acid on articular cartilage in dogs with experimentally induced osteoarthritis.

OBJECTIVE: To assess effects of zoledronic acid on biomarkers, radiographic scores, and gross articular cartilage changes in dogs with induced osteoarthritis. ANIMALS: 21 purpose-bred hound-type dogs. PROCEDURES: The left stifle joint of each dog was examined arthroscopically to determine initial articular cartilage status, which was followed by cranial cruciate ligament (CrCL) transection to induce osteoarthritis. Dogs were assigned to 3 groups (control group, low dose [10 µg of zoledronic acid/kg], or high dose [25 µg of zoledronic acid/kg). Treatments were administered SC every 3 months for 1 year beginning the day after CrCL transection. Serum and synovial fluid samples and radiographs were obtained 0, 1, 3, 6, 9, and 12 months after transection. At 12 months, each joint was scored for cartilage defects. Serum and synovial fluid biomarkers of bone and cartilage turnover (bone-specific alkaline phosphatase, type I and II collagen, carboxy-propeptide of type II collagen, and chondroitin sulfate 846) were analyzed with ELISAs. RESULTS: The high-dose group had fewer total articular defects and lower severity scores in CrCL-transected stifle joints than did the control group. In addition, the high-dose group had significantly less change in collagenase cleavage of type I or II collagen in the synovial fluid at 1 and 3 months after CrCL transection than did the control group and also had greater changes in bone-specific alkaline phosphatase in synovial fluid at 3 months after CrCL transection than did the control group. CONCLUSIONS AND CLINICAL RELEVANCE: Zoledronic acid had a chondroprotective effect in dogs with a transected CrCL.

The effect of stem length on femoral component positioning in canine total hip arthroplasty.

OBJECTIVE: To determine the effects of femoral prosthesis stem length on positioning of the femoral component within the canine femur. STUDY DESIGN: An in vitro experimental study. SAMPLE POPULATION: Eleven adult, mixed breed, canine cadaver femurs. METHODS: Polymethylmethacrylate centralized Biomedtrix size 5, 6, and 7 standard and 1cm shortened implants were placed in specimens, manipulated to achieve maximal displacements of the implant tip in each plane, and radiographed. Measurements of the implant angle, tip offset, and minimal tip to endosteal surface distance were obtained with image processing software. The effects of implant length and size on implant positioning were evaluated with the use of Student's t, chi(2) exact, and 2-way ANOVA testing. RESULTS: Statistically significant increases were noted in tip to caudal cortex distance in the sagittal plane, and available angle variability and tip offset variability in the transverse plane for shortened size 6 and 7 stems relative to the standard stems. No significant differences were noted in size 5 stems. Statistically significant increases in tip to caudal cortex distance and transverse plane available angle variability for standard 6 compared to standard 7 stems were noted. CONCLUSIONS: Shortened stems result in statistical improvement of several variables of femoral component positioning. However, the improvement appears to be clinically negligible. CLINICAL RELEVANCE: Alteration of current stem lengths is not recommended. The use of undersized standard implants may improve femoral component positioning in total hip arthroplasty.