Harvesting hamstring tendons for ACL reconstruction influences postoperative hamstring muscle performance

Introduction. Anterior cruciate ligament (ACL) reconstruction using hamstring tendons has recently received attention because of less donor site morbidity. It has been reported that harvesting hamstring tendons has little effect on postoperative hamstring muscle performance based on the peak torque value of the hamstring strength. However, recent studies have clarified some adverse effects of harvesting hamstring tendons. There is still argument about the influences of harvesting hamstring tendons on postoperative hamstring muscle performance. The purpose of this study was to evaluate the postoperative hamstring muscle performance measured by various parameters after harvesting hamstring tendons for ACL reconstruction.Patients and methods. We evaluated the postoperative hamstring muscle performance after harvesting hamstring tendons in 58 patients who underwent ACL reconstruction. We assessed peak torque value, total work, and peak torque angle in the isokinetic hamstring strength test and active knee flexion angle. We classified the patients into three groups according to the type of hamstring used for ACL reconstruction: 1) the autologous semitendinosus tendon (ST); 2) the autologous ST and the gracilis tendon, which were harvested from the ipsilateral knees; and 3) allogeneic fascia lata. Results. This study clearly demonstrated that the peak torque value and total work in the patients in each group compared to preoperative normal knees were not statistically different; however, the more hamstring tendons were harvested, the more loss of active knee flexion angle was observed and the more the peak torque angle was shifted to a shallow angle, suggesting that the hamstring strength might be weaker at the deep flexion angle.Conclusion. Physicians should recognize that the ACL reconstruction using autologous hamstring tendons is not appropriate for sportsmen or women who are required to flex their knees deeply or powerfully in their performance.