MENISCAL OSSIFICATION .2. THE NORMAL PATTERN IN THE TIGER KNEE

Examination of knee menisci of Bengal tigers revealed ossicles within the cartilaginous anterior horn of each medial meniscus. This ossifica tion was not evident in the neonatal animal, but was present in animal s aged 20 months or older. The ossicle appeared prior to the completio n of skeletal maturation at the knee, and was composed of normal remod eling trabecular bone. While most animals had a single, variably sized ossicle, multiple ossicles also occurred. The meniscal cartilage appo sed to the femoral articulation exhibited a distinct columnar pattern in the region of the ossicle, in contrast to the non-columnar pattern throughout the bulk of the meniscus, including the ossicle side appose d to the tibial plateau. In this particular large mammalian species me dial meniscal ossification appears to be a normal anatomical variation that progressively develops following birth, and may serve as a model for the phylogenetic (developmental) theory of etiology.