Differences in Gait Biomechanics Between Adolescents and Young Adults With Anterior Cruciate Ligament Reconstruction

Context: Adolescents and adults are treated similarly in rehabilitation and research despite differences in clinical recovery after anterior cruciate ligament reconstruction (ACLR). Aberrant gait is a clinical outcome associated with poor long-term health post-ACLR but has not been compared between adolescents and adults.

Objective: To compare gait biomechanical waveforms throughout stance between adolescents (<18 years old) and young adults (≥18 years old) post-ACLR.

Design: Case-control study.

Setting: Laboratory.

Patients or other participants: Adolescents (n = 13, girls = 77%, age = 16.7 ± 0.6 years, height = 1.7 ± 0.1 m, weight = 22.2 ± 3.7 kg/m2) were identified from a cross-sectional cohort assessing clinical outcomes 6 to 12 months post-ACLR. Young adults (n = 13, women = 77%, age = 22.3 ± 4.0 years, height = 1.7 ± 0.1 m, weight = 22.9 ± 3.3 kg/m2) were matched based on sex, time since surgery (±2 months), and body mass index (±3 kg/m2).

Intervention(s): Participants performed 5 gait trials at their habitual speed.

Main outcome measure(s): Three-dimensional gait biomechanics and forces were collected. Vertical ground reaction force normalized to body weight (xBW), knee-flexion angle (°), knee-abduction moment (xBW × height), and knee-extension moment (BW × height) waveforms were calculated during the stance phase of gait (0%-100%). Habitual walking speed was compared using independent t tests. We used functional waveforms to compare gait biomechanics throughout stance with and without controlling for habitual walking speed by calculating mean differences between groups with 95% CIs.

Results: Adolescents walked with slower habitual speeds compared with adults (adolescents = 1.1 ± 0.1 m/s, adults = 1.3 ± 0.1 m/s, P < .001). When gait speed was not controlled, adolescents walked with less vertical ground reaction force (9%-15% of stance) and knee-abduction moment (12%-25% of stance) during early stance and less knee-extension moment during late stance (80%-99% of stance). Regardless of their habitual walking speed, adolescents walked with greater knee-flexion angle throughout most stances (0%-21% and 29%-100% of stance).

Conclusions: Adolescents and adults demonstrated different gait patterns post-ACLR, suggesting that age may play a role in altered gait biomechanics.