A study of ligamentous growth.

Scant data are available on the growth of ligament. This study answers basic questions concerning mechanisms of ligament growth and determines the location of longitudinal ligament growth. Growing rabbits had metal marking sutures implanted, at measured intervals, along the length of their medial collateral ligament. Separate metal markers were inserted in the epiphysis and metaphysis of the femur and tibia. Changes in marker intervals were measured radiographically after growth. Measurements revealed that growth occurred throughout the length of the ligament, with somewhat greater growth occurring in the distal segment. Total ligament growth was much less than that occurring at the tibial physis (which the ligament crosses). The magnitude of total ligament growth was proportional to the enlargement of the joint itself, as measured by changes in the distance between epiphyseal markers. The most distal suture inserted in the ligament became incorporated in bone and moved rapidly away from the ligament insertion. This rapid displacement of the distal suture was not responsible for enlargement of the ligament itself, but rather a phenomenon of the maintenance of the position of the ligament insertion on the proximal metaphysis, as the epiphysis grows away from the original site of ligament insertion.