Altered Spinopelvic and Hip Kinematics During Deep Squatting in Asymptomatic Adolescent Soccer Players With Cam Morphology: A Two-Year Prospective Study.

INTRODUCTION: Cam morphology is prevalent in physically active adolescent males and is associated with the development of femoroacetabular impingement, yet the biomechanical factors associated with its development remain unclear. OBJECTIVES: (1) To investigate longitudinal changes in squat kinematics and their association with Cam morphology development; and (2) to compare kinematics between asymptomatic athletes with and without Cam morphology. METHODS: This prospective two-year study evaluated spinopelvic and hip kinematics in elite adolescent soccer players aged 12 to 16 years (baseline n=29; follow-up n=20), classified as having or not having Cam morphology based on skeletal maturity and an alpha angle >60° on hip radiographs. Three-dimensional motion capture was performed at both timepoints during standardized and unstandardized deep squats. Inverse kinematics of the trunk, lumbopelvic region, pelvis, and hip were analyzed. RESULTS: At baseline and follow-up, 58.5% of participants were classified as having Cam morphology (right hips=16; left hips=15). Statistical parametric mapping paired t-tests showed no statistically significant longitudinal changes in kinematic waveforms within either group. In the skeletally age-matched cross-sectional comparison, the Cam group demonstrated greater trunk flexion (17%-34%, p=0.032), lumbopelvic flexion (11%-30%, p=0.027), anterior pelvic tilt (35%-55%, p=0.012), and hip internal rotation (45%-55%, p=0.024) during the unstandardized squat compared with the No Cam group. Pelvic range of motion was also greater in the Cam group (28.0 ± 5.3° vs 20.5 ± 4.6°). No between-group differences were observed during the standardized squat. CONCLUSION: Asymptomatic adolescents with Cam morphology demonstrate distinct, task-dependent spinopelvic and hip kinematics during deep squatting, including greater pelvic motion. These patterns remain stable over time and are evident only under self-selected conditions, suggesting preferred movement strategies rather than fixed limitations in movement capacity. LEVEL OF EVIDENCE: III.