Knee cartilage injury after tibial lengthening. Radiographic and histological studies in rabbits after 3-6 months.

We investigated the effects of tibial lengthening by callotasis on the knee articular cartilage in 10 rabbits at 3 and 6 months after distraction. The distraction rate was 1 mm per day, until a 30 percent gain in length. On the right tibia, the daily distraction frequency was in 2 steps by hand, while on the left it was in 120 steps by an autodistractor. 5 animals were killed at 3 months and 5 at 6 months following distraction, and their knee joints were radiographically and histologically examined. On the 2-step side, arthrotic changes at 3 and 6 months after distraction were found in 3 of 5 and 4 of 5 knees, respectively. The severity of change increased with time. On the 120-step side, however, no arthrotic changes were found, except in one knee at 6 months. Our findings suggest that by increasing the frequency of distraction for limb lengthening one can prevent the onset of arthrosis in adjacent joints.