Asymmetrical lower extremity biomechanics during squats and drop jumps in adolescents with MPFL reconstruction

Evidence describing movement strategies during bilateral functional tasks after medial patellofemoral ligament (MPFL) reconstruction is limited, highlighting the need for biomechanical assessments to better inform rehabilitation progression and clinical decision-making. The purpose of the study was to investigate lower extremity biomechanics during squats and drop vertical jumps (DVJs) in adolescent athletes with MPFL reconstruction.

Twenty patients with MPFL reconstruction and 20 uninjured controls were included. Lower extremity biomechanics during squats and DVJs were assessed using a three-dimensional (3D) motion capture system and synchronized force plates. Primary variables included positive and negative joint power at the hip, knee and ankle, and secondary variables included peak joint flexion angles. Limbs and groups comparisons were examined using linear mixed-effects models. Exploratory analyses examined associations between symmetry indices for joint power during squats and DVJs in subjects with MPFL reconstruction using Pearson correlation coefficients.

During squats, the surgical limb demonstrated greater hip positive and negative power and greater ankle positive and negative power, accompanied by lower knee positive (41% lower) and negative (33.3% lower) power (both p < 0.001) than the non-surgical limb. In between-group comparisons, the surgical limb exhibited lower knee and ankle positive and negative power compared with the uninjured controls. During DVJs, the surgical limb demonstrated lower knee positive and negative power and lower ankle positive and negative power compared with the non-surgical limb (p < 0.001 to 0.005) and uninjured controls (p < 0.001 to 0.044). Symmetry in hip and knee positive and negative power during squats was positively associated with symmetry during DVJs.

Adolescent patients with MPFL reconstruction exhibited altered squat and jumping mechanics during the return to sport phase. Greater symmetry during squatting was associated with greater symmetry during jumping, suggesting evaluation of squat mechanics may provide clinically meaningful insights into movement strategy relevant to jumping and help guide rehabilitation progression.

Level III, case-control study.