Abstract: This paper is on effect of mobilization on immobilized ligament.Eighteen rabbits were divided into three groups.Group Ⅰ,eight weeks of active movement;group Ⅱ,eight weeks of passive+active movement;group Ⅲ,age matched normal control.The biomechanical testing,histological and ultrastructural evaluation were used.Results:with mobilization,the structural properties of ligament bone complexs of MCL obviously improved but did not return to normal.The material properties of MCL was similar to those of contralateral and normal control.Arrangement of collagen fibers was similar to that of normal.Resorption of bone in ligament bone insertion sites was not significantly changed.Through mobilization following immobilization,failure location of MCL changed.Conclusion:The recovery of material properties of ligament substance was more quick than that of structural properties of ligament bone complexs.The effect of active movement and passive +active movement on recovery of structure of immobilized ligament was similar.

Key words: medial collateral ligament, mobilization, biomechanics, morphology