Healing of the medial collateral ligament in rats. The effects of repair, motion, and secondary stabilizing ligaments.

The effects of repair, motion, and the integrity of the secondary ligamentous restraints on healing of the medial collateral ligament were studied in a rat model. Healing was assessed by measuring ligamentous laxity and tensile strength. All healing ligaments were weaker and more lax than their controls. Repair did not have a statistically significant effect on the laxity or the strength of the medial collateral ligament. Allowing active motion had a statistically significant beneficial effect on the strength of the medial collateral ligament. Stability was adversely affected by active motion if the secondary restraints had been transected; however, when the secondary ligamentous restraints were intact, active motion was beneficial and immobilization was harmful.