KNEE IMMOBILIZATION INHIBITS BIOMECHANICAL MATURATION OF THE RABBIT MEDIAL COLLATERAL LIGAMENT

In this investigation, the effect of immobilization on the structural biomechanical properties of the immature rabbit medial collateral liga ment (MCL) was quantified. The right hindlimbs of ten, three-month-old female New Zealand White rabbits were immobilized. The hindlimbs of t he first group (n = 5) were immobilized for one month, until the rabbi ts were four months of age. The hindlimbs of the second group (n = 5) were immobilized for three months, until the rabbits were six months o f age. Left hindlimbs were not surgically treated and served as contra lateral controls. Fifteen normal animals were kept in similar cages un til they were killed in subgroups at three, four, or six months of age . Biomechanical investigations after the animals were killed included the testing of a number of MCL. structural properties, including prefa ilure and strength tests. Results showed that the maturation of MCL st ructural properties were inhibited during immobilization with signs of structural degradation becoming more obvious at the longer period of immobilization. Results also demonstrated that the structural mechanic al properties of the contralateral MCLs were significantly altered. Th ese results suggest that knee mobility is essential to the normal matu ration of MCL mechanical properties and that contralateral MCLs cannot be used as normal controls in this immature rabbit model of immobilit y.