Introduction: Deficits in quadriceps strength following anterior cruciate ligament reconstruction (ACLR) are common and can be associated with biomechanical asymmetries during landing tasks. The relationship between quadriceps strength and knee function during ACLR recovery is well established. However, less is known regarding the role of hamstring strength in functional recovery after ACLR. We examined movement patterns during a drop-landing task in three patients following ACLR with different levels of quadriceps and hamstring strength. Methods: Three participants were assessed for quadriceps and hamstrings strength, functional performance, and lower-extremity biomechanics captured by a 3D motion analysis 6 months after ACLR. Results: Participant one, who presented with relatively recovered quadriceps and hamstring strength of the operated limb, demonstrated the highest limb symmetry indices across multiple tests compared to the other two participants. Participant two, who had insufficient recovery in quadriceps strength yet preserved hamstring strength, demonstrated similar recovery in drop-landing mechanics than participant one and a lower overall hop performance than participant one. Participant three, who had residual deficits in both quadriceps and hamstring strength, exhibited the largest asymmetries in overall hop performance, vertical ground reaction force, and knee flexion angle upon bilateral landing. Conclusion: This study suggests that quadriceps strength alone does not account for variability in functional recovery and altered biomechanics following ACLR. It is important to evaluate both quadriceps and hamstring strength as indicators for functional recovery and readiness for return to sport after ACLR.

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