Repeated Regeneration of a Meniscus in the Knee.

Experimental work in animals (Walmsley and Bruce 1938) has shown that the menisci of the knee joint can regenerate after surgical removal. There have been several reports of regenerated cartilages in the human knee joint (Mandl 1929, M#{246}ller 1930, Fisher 1936, Bruce and Walmsley 1937). Smillie (1944) described the characteristics of the regenerated meniscus. It is in general appearance similar to the normal meniscus but is narrower, thinner and whiter. It is composed of fibrous tissue without cartilage cells. It has a dense attachment to the capsule, and is therefore less mobile than the normal meniscus. Because it projects less into thejoint and is more fixed, the regenerated meniscus is less vulnerable to injury. Tears of these fibrous menisci are therefore rare, and are invariably associated with ligamentous damage, which renders the joint abnormally lax. A search of the literature has failed to reveal a report of regeneration of a meniscus a second time, and the following case, in which a torn lateral meniscus and two torn regenerated menisci have been removed from the same knee compartment in the course of two years, is thought to be unique.