Hamstring weakness after surgery for anterior cruciate injury.

The purpose of this study was to measure the effects of surgery and immobilization on the isometric strength of the hamstrings. Fifteen male volunteers were measured for isometric hamstring torque prior to surgery for correction of anterior cruciate ligament (ACL) insufficiency. After surgery the subjects were casted for 6 weeks and did not perform exercises specific to the hamstrings. Subjects were retested immediately after cast removal and the hamstring output was compared to the preoperative hamstring output. A 43% decrease in hamstring torque was noted which is statistically significant (p < 0.001). It is suggested that exercise of the hamstring, a muscle group of great importance to the ACL-injured knee, during immobilization may be helpful in limiting hamstring strength loss during the immobilization period. J Orthop Sports Phys Ther 1986;7(6):310-313.