The fate of intraarticular loose bodies of meniscus origin in canine species.

A potential risk of arthroscopic meniscectomy is the retention of debris of meniscus origin in the knee joint. This prospective study analyzes the fate of loose bodies of meniscus origin placed into the canine knee joint. At 12 weeks, 16.7% of the free fragments were completely degraded, 16.7% were absorbed by the synovium, and 66.6% were loose, located between synovial folds. At 12 weeks, 93.3% of the fragments had disappeared, and the remaining fragments had decreased 70% in length and 50% in width. A focus of calcification was present in one fragment at 12 weeks. By three weeks, all loose bodies had a pseudocapsule composed of cells with intense fibroblastic activity, occasional mitoses, and a loss of connective tissue matrix at the periphery. A mononuclear leucocytic response was present in the synovium at 12 weeks in four of the five dogs. Free fragments of meniscus origin are most commonly degraded completely by 12 weeks. Enzymatic digestion, mechanical abrasion, and synovial phagocytosis are processes that may contribute to this phenomenon.