Acceleration of experimental lapine osteoarthritis by calcium pyrophosphate microcrystalline synovitis.

ABSTRACT

OBJECTIVE: To investigate the effects of chronic calcium pyrophosphate dihydrate (CPPD) synovitis on the development of osteoarthritic (OA) lesions in an animal model. METHODS: OA was induced in the right knees of 30 male New Zealand white rabbits by partial lateral meniscectomy and section of the fibular collateral and sesamoid ligaments (PLM/LS), followed by 8 weekly intraarticular (IA) injections of 1 mg (low-dose) or 10 mg (high-dose) of CPPD crystals in 3 sets of experiments (10 rabbits each). The contralateral left knees served as controls experiment 1 PLM/LS alone, experiment 2 8 weekly IA injections of CPPD crystals alone, and experiment 3 sham surgery plus 8 weekly IA injections of CPPD crystals. RESULTS: At 8 weeks, repeated IA injections of low-dose and high-dose CPPD crystals into meniscectomized right knees resulted in more severe OA than in meniscectomized but noninjected left knees (experiment 1) (P = 0.003 and P = 0.001, respectively). One-fourth of the meniscectomized knees (11 of 40), both CPPD-injected and noninjected, showed embedded synovial cartilage shards. CONCLUSION: The data demonstrate a worsening effect of chronic CPPD crystal-induced synovitis on experimental OA produced in the rabbit knees by PLM/LS, and support a possible role for CPPD microcrystalline inflammation in the progression of OA lesions in clinical CPPD crystal deposition disease.