Effects of additional gracilis tendon harvest on muscle torque, motor coordination, and knee laxity in ACL reconstruction

Purpose To evaluate muscle torque, lower extremity coordination, and knee laxity after ACL reconstruction comparing patients operated on with semitendinosus graft (ST) and patients with combined semitendinosus and gracilis (STGR) grafts. Methods Forty-six subjects who underwent ST ( n = 23) or STGR harvest ( n = 23) ACL reconstruction participated in this study. Quadriceps and hamstring torque were recorded using an isokinetic dynamometer. The anterior tibial translation was measured using the Kneelax 3 Arthrometer. The eccentric and concentric motor coordination was tested by multi-joint lower-limb tracking-trajectory test. All measurements were taken 12 months after surgery. Side-to-side differences were determined for all subjects. Results Side-to-side differences in extensor peak torque at 180°/s and 60°/s did not differ between semitendinosus (ST) and semitendinosus + gracilis (STGR) groups (n.s.). However, side-to-side differences in flexor peak torque were significantly higher at 60°/s for the STGR group than the ST group ( P = 0.002). Side-to-side differences in eccentric and concentric parts of tracking-trajectory test and anterior tibial translation did not differ between the STGR and the ST groups (n.s.). Conclusion The outcomes of this study suggested that additional harvest of gracilis did not influence lower extremity motor control, quadriceps muscle torque, and anterior tibial translation; however, it affected knee flexion isokinetic torque negatively at low angular velocity. This finding could be important for functional activity or sports with high demands on hamstring muscle strength. It is recommended that gracilis muscle should be preserved as possible during ACL reconstruction. Level of evidence Prospective comparative study, Level II.