Comparison of knee extensor strength after anterior cruciate ligament reconstruction using either quadriceps tendon...

The aim was to assess the consequences of quadriceps tendon (QT) harvest on knee extensor strength after anterior cruciate ligament reconstruction (ACL-R) compared to hamstring tendon (HT) autograft. Secondary objectives were to evaluate flexor strength recovery and search for correlation between strength status and functional outcome.

This a retrospective cohort of 44 patients who underwent ACL-R using either QT (25) or HT (19). Median age was 31.1 years. We assessed thigh muscle strength thanks to concentric iso kinetic evaluation (peak torque) at 60°.s^-1, 180°.s^-1, 240°.s^-1 and eccentric at 30°.s^-1, 7 months on average after surgery. Muscle strength values were compared to the uninjured leg in order to calculate a percentage of deficit as well as unilateral hamstring/quadriceps (H/Q) ratios. KOOS score was obtained at a mean follow-up of 18 months.

Extensor strength deficit (concentric 60°.s^-1) was one average 33.1% in the QT group and 28.2% in the HT group (p = 0.42). Difference of flexor strength deficit (concentric 60°.s^-1) was close to be significant with 5% and 12% of deficit in the QT and HT group, respectively (p = 0.1), and statistically significant for high angular velocity (14% versus 3% at 240°.s^-1, p = 0.04). H/Q ratios were comparable in both groups ranging from 0.62 to 0.78. Quadriceps muscle strength deficit was negatively correlated with the KOOS score (Pearson coefficient = -0.4; p = 0.005).

QT autograft harvest does not yield significant quadriceps muscle weakness after ACL-R, which appear to be a pejorative factor for functional outcome.

IV, Retrospective study.