Abstract: The mechanism most correlated with anterior cruciate ligament (ACL) tears is the simultaneous valgus and external rotation of the knee. This study investigated if ACL reconstruction with a hamstring tendon autograft predisposes to “knee-in & toe-out” compared to ACL reconstruction with a patellar tendon autograft and to healthy individuals during a vertical jump. A threedimensional markerless motion capture was used to conduct a case control study, collecting data from 11 healthy participants and 14 participants who underwent ACL reconstruction, 8 with a hamstring tendon autograft and 6 with a patellar tendon autograft, while performing a bilateral vertical jump. Joint kinematic variables such as angular positions, moments and velocities were obtained by processing video recordings with the Theia Markerless system and Visual3D. Differences between groups were calculated using the independent Sample T-test and One-Way ANOVA with Bonferroni post hoc adjustments. No significant differences were found at the peak knee valgus for the maximum valgus (mean difference (md): -2.14   1.57 deg, t (23): 0.171, p = 0.187, d = 0.548), rotation (md: 1.04   1.97 , t (23): 0.001, p = 0.601, d = 0.214) and flexion (md: ?10.29   11.82 , t (23): 0.917, p = 0.393, d = 0.351) of the knee, when comparing healthy participants with those who underwent ACL reconstruction. Vertical ground reaction forces were significantly higher in the healthy group when compared to the ACL reconstruction group (md: 20.11   6.29 N/Kg, t (23): 1.264, p = 0.049, d = 0.836). The knee extension angular moment and angular velocity were significantly higher for the healthy participants, when compared to participants who underwent ACL reconstruction with a patellar tendon autograft (md: 0.65   0.18 Nm/kg, F (2.22): 7.090, p = 0.004, d = 0.804; md: -111.51   38.31 /s, F (2.22): 4.431, p = 0.024, d = 1.000, respectively). ACL reconstruction with a hamstring tendon autograft does not increase the risk of a valgus knee alignment movement on initial contact during landing. Differences found in various parameters may justify the evaluation of the quality movement with a motion capture system while performing the vertical jump for the creation of specialized rehabilitation programs.

 

Keywords: anterior cruciate ligament injury; vertical jump test; valgus knee alignment