Associations between meniscal tears and various degrees of osteoarthritis among dogs undergoing TPLO for cranial cruciate ligament rupture.

OBJECTIVE: The aim of this study was to evaluate the association between meniscal lesions and severity of osteoarthritis (OA) among dogs that underwent Tibial Plateau Leveling Osteotomy (TPLO) for stabilization of cranial cruciate ligament rupture (CrCLR) at the University of Tennessee in 2011-2017. RESULTS: There were a total of 252 meniscal tears. Factors associated with diagnosis of medial meniscal tears (MMT) in dogs were severe OA in comparison to no OA (3.8 OR, 2.0-8.0 95% CI, 0.001 p-value), sporting and mixed breed group compared to other breed (3.6 OR, 1.7-7.6 95% CI, 0.004 p-value; 3.2 OR, 1.6-6.6 95% CI, 0.019 p-value, respectively), increasing age (1.1 OR, 1.0-1.2 95% CI, 0.018 p-value), complete CrCLR compared to partial (3.3 OR, 2.1-5.0 95% CI, < 0.001 p-value), and arthrotomy compared to arthroscopy (2.2 OR, 1.4-3.1 95% CI, 0.002 p-value). The factors that did not have significance in predicting MMT were weight, sex, lameness period, and side affected.

One-stage revision of an infected cementless total hip replacement.

A two-year-old, 44 kg dog with a right Helica cementless total hip replacement (THR) was radiographically diagnosed with implant loosening eight months after the index total hip replacement procedure. Subsequent synoviocentesis and synovial fluid culture revealed a methicillin-resistant coagulase-negative Staphylococcus spp infection of the right THR. A one-stage revision using a hybrid BFX cementless acetabular cup and CFX cemented femoral stem was performed. Vancomycin and micro-silver antimicrobial powder impregnated cement were used in the revision. At re-evaluation 27 months following the revision procedure, the patient did not exhibit any signs of lameness. Radiographic images confirmed stable implants, with bone ingrowth into the cup and no signs of implant loosening. Our report demonstrates the success of a one-stage THR revision when faced with a multi-drug resistant periprosthetic infection, when combined with the use of micro-silver antimicrobial powder and culture-based antibiotic impregnated cement therapy.

Biomechanical evaluation of polymethyl methacrylate with the addition of various doses of cefazolin, vancomycin, gentamicin, and silver microparticles.

OBJECTIVES: Numerous studies have examined the biomechanics of polymethyl methacrylate (PMMA) with added antibiotics, but direct comparison between studies is difficult. Our purpose was to evaluate the effects of the addition of antibiotic drugs and silver on compressive and bending strength of PMMA. Our null hypothesis was that there would be no significant difference in the compressive strength or bending strength of PMMA with the addition of silver or varying amounts of antibiotic drugs. METHODS: Polymethyl methacrylate was mixed with cefazolin, gentamicin, vancomycin, or silver; the control was PMMA alone. Antibiotic groups contained 20 g PMMA and 0.5 g, 1 g, 2 g, or 3 g of antibiotic. Silver groups had 0.25 g silver powder alone added to 20 g PMMA or silver with PMMA and 0, 0.5 g or 1 g of antibiotic. Samples underwent four-point bending and compression testing in air at room temperature and prevailing humidity. Pairwise comparisons between groups and to the ASTM and ISO standards were performed. RESULTS: Compression: All antibiotic and silver groups were weaker than the control. Samples with cefazolin tended to be stronger than other antibiotic groups with equivalent doses of antibiotic. All groups were above the ASTM standard, except 3 g vancomycin. Four-point bending: The addition of antibiotics did not significantly affect bending strength in groups with lower doses of antibiotics. The silver + PMMA group was weaker than the control. No groups were significantly below the ISO standard except the 3 g vancomycin group. CLINICAL SIGNIFICANCE: The addition of antibiotic or silver decreased the biomechanical strength in all samples, but not below the ASTM or ISO standard for most groups. The addition of cefazolin appears to affect strength the least, while high doses of vancomycin alter strength the most.