Correlations between various lesions on the same articular surfaces and between lesions of opposing articular surfaces in the elbow and knee joints were observed. It was not obvious from the correlations which types of lesions preceded the other ones. However, because histology revealed erosions of the articular cartilage without ulcerations (Fig. 2a), it was most likely that erosions preceded ulcerations. An exception from this was in cases of osteochondritis dissecans, where ulceration was seen without erosion being present (Fig. 2b).
In accordance with results obtained in a previous study , a correlation between erosion in the articular cartilage of the lateral humeral condyle and the presence of marginal osteophytes on processus anconeus of ulna was observed. The presence of marginal osteophytes was always observed together with erosion of the articular cartilage. By contrast, erosions were often seen without marginal osteophytes. Therefore, it is likely that cartilage lesions precede the formation of marginal osteophytes. However, in humans osteophytes may be present without any affection of the cartilage , and it is assumed to be an adaptive and stabilizing reaction caused by instability of joints . Therefore, it could be speculated that both cartilage lesions and osteophytes in sows are caused by joint instability.
The positive association between forelegs that are turned out and stiff movements of the front and rear legs and cartilage lesions in the elbow joint is in agreement with the results obtained by Jørgensen . Weak pasterns on forelegs were both negatively and positively associated with lesions in the elbow and knee joints, but in particular marginal osteophytes on radius were positively associated (P < 0.001). The presence of weak pasterns on forelegs has previously been found to be positively associated with normal, brisk gait and negatively associated with osteochondrosis/osteoarthrosis . However, in contrast to a study by Jørgensen (9), in which only lesions in the knee joint had an impact on hind legs being turned out, it was found that also lesions in the elbow joint were associated with this abnormal posture.