Association of Quadriceps Muscle Fatigue With Return to Preinjury Sports Following Primary Anterior Cruciate Ligament Reconstruction Using Hamstring Autograft and Tibialis Anterior Allograft

It is unclear whether patients who return to preinjury sports levels 2 years after primary anterior cruciate ligament reconstruction (ACLR) have better functional outcomes than those who do not. In particular, the specific factors among functional outcomes that influence the return to preinjury and postoperative sports levels remain controversial.

To compare functional outcomes such as muscle and functional performances and patient-reported outcomes (PROs) between patients who returned to preinjury sports levels 2 years after primary ACLR and those who did not, as well as identify functional outcomes associated with returning to either preinjury or postoperative sports levels at 2 years postoperatively.

Case-control study; Level of evidence, 3.

A total of 50 male patients (26 successfully returned vs 24 did not return) were included in this study. The criteria for study participants were general patients with a preoperative Tegner activity level ≥6. Patients who returned to their preinjury sports levels were classified using the Tegner activity level and sports activity rating scale after surgery. At the 2-year follow-up evaluation, functional outcomes such as knee muscle strength, work fatigue, single-leg hop distance (SLHD), limb symmetry index, Lysholm score, International Knee Documentation Committee (IKDC) score, Knee injury and Osteoarthritis Outcome Score (KOOS) Sport and Recreation subscale, and KOOS Quality of Life subscale were compared between the groups. Multiple linear regression analysis was performed to identify associated factors affecting return to preinjury and postoperative sports levels.

Work fatigue of quadriceps muscles (Cohen d = -0.86; 95% CI, -12.2 to -2.5; P = .004), SLHD (Cohen d = 1.21; 95% CI, 17.8 to 48.8; P < .001), IKDC score (Cohen d = 2.14; 95% CI, 6.4 to 27.2; P < .001), and KOOS Sport and Recreation subscale (Cohen d = 1.05; 95% CI, 6.6 to 22.0; P < .001) were better in patients who returned to preinjury sports levels than those who did not. Work fatigue of quadriceps muscles (R ² = 0.110; β = -0.332) and SLHD (R ² = 0.084; β = 0.290) were associated with preoperative Tegner activity level, whereas work fatigue of quadriceps muscles (R ² = 0.157; β = -0.397), SLHD (R ² = 0.283; β = 0.532), and IKDC score (R ² = 0.452; β = 0.672) were associated with postoperative Tegner activity level.

The work fatigue, SLHD, IKDC score, and KOOS Sport and Recreation subscale were better in patients who returned to preinjury sports levels than in those who did not. Work fatigue of the quadriceps muscle and SLHD were associated with return to preinjury sports levels, whereas work fatigue of the quadriceps muscle, SLHD, and IKDC score were associated with postoperative sports levels.