Healing of the medial collateral ligament in unstable rat knees

Immobilization has been shown to be detrimental to healing ligaments while early motion and exercise increase healing ligament tensile strength. In order to take advantage of early motion and exercise without causing undesirable joint laxity in unstable rat knees we devised an internal joint restabilization procedure. The results in this well-established rat model were encouraging. Exercise in unstable rat knees caused increased medial collateral ligament laxity compared with a group allowed motion ad libitum. Joint laxity was significantly decreased in the restabilized groups and no adverse effects of exercise were noted. Tensile strength was increased in healing medial collateral ligaments of both exercise groups regardless of the stability of the joint. This study supports the use of early aggressive rehabilitation of injured joints considered stable and encourages the development of methods to provide secure dynamic internal or external stabilization of severely injured human joints.