Tibiofemoral Joint Contact Force Profiles of Pediatric Patients After Anterior Cruciate Ligament Reconstruction.

BACKGROUND Incidence rates of pediatric anterior cruciate ligament (ACL) injuries and ACL reconstruction (ACLR) are increasing. In adult patients with ACLR, limb-level loading profiles are less dynamic compared with uninjured controls (ie, lesser peaks and minimal offloading during midstance) early post-ACLR, and less dynamic profiles are associated with deleterious knee tissue changes. However, joint-level loading magnitudes during gait in the pediatric ACLR population are unknown. PURPOSE/HYPOTHESIS The purpose of this study was to compare medial and lateral tibiofemoral joint contact force profiles between pediatric patients with ACLR and pediatric matched controls. It was hypothesized that pediatric patients with ACLR would demonstrate less dynamic medial and lateral joint contact force profiles compared with matched uninjured pediatric controls. STUDY DESIGN Cross-sectional study; Level of evidence, 2. METHODS Pediatric patients 6 to 24 months post-ACLR (n = 25) and matched pediatric controls (n = 25; Tanner stage category, sex, Tegner activity score ±3) underwent a gait biomechanical assessment at a single time point, where ground-reaction forces and 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 limb and pediatric matched control limb. A functional linear model was utilized to determine differences in joint contact force profiles throughout stance phase (0%-100%). RESULTS Pediatric patients with ACLR demonstrated a high occurrence of concomitant injuries (80% meniscal pathology; 13% chondral injuries) and walked with greater medial tibiofemoral joint contact forces in midstance (42%-63% of the stance phase; 339-N maximal difference) and greater lateral joint contact forces in the late stance compared with pediatric controls (69%-80%; 288 N). CONCLUSION Pediatric patients with ACLR may demonstrate a less dynamic tibiofemoral joint contact force loading profile in the medial compartment, as evidenced by greater loading during midstance, compared with matched pediatric controls.