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

Abstract

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. (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. 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. 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. 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. III.