Observations of abnormalities and age-related changes in the anconeal processes of swine.

Abnormalities and age-related changes in the anconeal processes of 60 boars were studied. Postmortem examination of both cubitus joints from 25 lame adolescent boars and from 5 of their nonlame contemporaries revealed cartilaginous tissue (termed cartilage plate) of varying size between the anconeal process and the ulnar diaphysis in 8 of the lame animals. The cartilage plate was fractured in both joints from 7 of these 8 animals, and joints from 6 animals with cartilage plate were associated with lesions of the semilunar articular cartilage and bone in the proximal portion of the ulna. Postmortem examination of the joints from 30 boars (ranging in age from 1 month before birth to 1.5 years) indicated that during growth, bone developed from the ulnar diaphysis toward the cranial tip of the anconeal process. Separate ossification centers were not observed in any of the clinically normal anconeal processes studied in this group. However, microscopic observations of 1 abnormal anconeal process from a 13-week-old boar indicated that trauma may be involved in morphogenesis of a cartilage plate. Age-dependent changes were also observed in the composition of the anconeal process.