The effect of gracilis tendon harvesting in addition to semitendinosus tendon harvesting on knee extensor and flexor strength after anterior cruciate ligament reconstruction

Introduction Anterior cruciate ligament (ACL) reconstruction using hamstring tendons may involve harvesting of the gracilis tendon in addition to the semitendinosus tendon (ST) depending on the size of the ST graft. However, the effect of gracilis harvesting in addition to ST harvesting on muscle strength, such as the hamstring-to-quadriceps (HQ) ratio, remains unclear. Hence, this study aimed to investigate the effect of gracilis harvesting on subsequent knee muscle strength. Materials and methods Eighty-two patients who underwent ACL reconstruction were included in this retrospective study. They were divided into the following two groups depending on the tendon graft used for ACL reconstruction: the ST group (41 patients) and the semitendinosus tendon/gracilis tendon (STG) group (41 patients). The isokinetic peak torque of the knee extensor and flexor was measured using a BIODEX dynamometer at a velocity of 60 degrees/s and 180 degrees/s, respectively, 3 and 6 months after ACL reconstruction. The groups were compared in terms of the limb symmetry index (LSI) and HQ ratio. Results The significant difference in the knee flexor of the LSI at 6 months after ACL reconstruction was as follows: ST group, 120.3 +/- 28.3 vs STG group, 105.6 +/- 19.0 (p < 0.01) at 60 degrees/s and ST group, 122.9 +/- 35.2 vs STG group, 106.2 +/- 24.6 (p = 0.02) at 180 degrees/s. There were significant differences in the HQ ratio at 180 degrees/s as follows: ST group, 0.67 +/- 0.15 vs STG group, 0.60 +/- 0.13 (p < 0.01) at 3 months and ST group, 0.67 +/- 0.13 vs STG group, and 0.59 +/- 0.12 (p < 0.01) at 6 months after ACL reconstruction. Conclusions Gracilis tendon harvesting may contribute to a decrease in knee flexor strength and HQ ratio with fast contraction. Thus, the need for gracilis tendon harvesting in ACL reconstruction should be carefully considered.

Automated summary

This study aimed to investigate the effect of gracilis harvesting on subsequent knee muscle strength after ACL reconstruction. Results showed that harvesting the gracilis tendon may lead to a decrease in knee flexor strength and HQ ratio.