Background: Individuals with a history of anterior cruciate ligament reconstruction (ACLR) represent altered knee joint mechanics in running. Hip joint can make subtle compensations in response to ACLR. Effects of ACLR on hip joint compensatory mechanisms is not well known. The aim of this study was to evaluate the hip join mechanics and asymmetry in individuals with ACLR history. We hypothesized that ACLR individuals’ hip exhibit altered mechanics which can increase the risk of hip overuse or osteoarthritis. Methods: Kinetic and kinematic data of 20 males with ACLR history and 20 healthy males were collected bilaterally while running at 3.3 m s 1. Hip and knee joints peak angles, peak moments, peak negative and positive power and negative and positive work in the sagittal plane were calculated. Also, asymmetry of the outcomes was calculated. A mixed design MANOVA was used to detect between-group and within-group (side-by-group interaction) effects of ACLR on outcomes. Results: Involved knee showed smaller flexion angle and negative work compared to uninvolved and control knee. In the hip joint, involved leg showed a higher flexion angle, extension moment, and peak positive and negative power as well as negative and positive work compared to uninvolved and control leg. ACLR group showed greater asymmetries in knee flexion angle, knee flexion moment, hip flexion angle, hip extension angle and hip negative power compared to healthy group. Conclusion: Hip and knee joints mechanics of involved and uninvolved sides of the ACLR individuals are different. These results show that ACLR affects hip joint as well as knee joint. When returning to activity and sport, mechanics of the hip joint as well as knee joint, must be considered in ACLR individuals.
