Tibiofemoral Joint Contact Force Profiles Of Sexually-immature Pediatric Patients Following Anterior Cruciate Ligament Reconstruction

Incidence rates of pediatric anterior cruciate ligament injury and reconstruction (ACLR) surgery are increasing. In adult ACLR patients, limb-level and joint-level loading magnitudes are altered early post-ACLR and are associated with knee joint tissue changes consistent with osteoarthritis development. However, joint-level loading magnitudes during gait in pediatric ACLR patients remain unknown. PURPOSE: To compare medial and lateral tibiofemoral joint contact force profiles between sexually-immature pediatric ACLR patients (Tanner Stage I-IV) and pediatric matched controls (i.e., Tanner Stage category and sex). METHODS: We enrolled pediatric patients 6-24 months post-ACLR (n = 25; 60% female; 15 ± 1 yrs.; 10 ± 5 months post-ACLR) and matched, pediatric controls (n = 25; 60% female; 15 ± 1 yrs.). All participants underwent a gait biomechanics assessment at a single timepoint, where ground reaction forces and 3D marker trajectories were collected. The concurrent optimization of muscle activation and kinematics algorithm was utilized to estimate medial and lateral compartment tibiofemoral joint contact forces in the ACLR and control limbs. A functional linear model was utilized to compare joint contact force profiles throughout the stance phase of gait (0-100%). RESULTS: Pediatric ACLR participants walked with greater medial tibiofemoral joint contact forces in midstance (42-63% stance; 339 N maximal difference) and greater lateral joint contact forces in late stance compared to pediatric controls (69-80% stance; 288 N; Figure 1). CONCLUSIONS: Pediatric ACLR patients demonstrated greater tibiofemoral joint contact force magnitudes in both the medial and lateral compartments compared to matched pediatric controls. Future work should determine if greater knee joint loading leads to deleterious changes in joint tissue and increases the risk of osteoarthritis in pediatric ACLR patients. Supported by: Research reported in this abstract was supported by the American College of Sports Medicine (22-01803).