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

Abstract

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.

Acutely Normalizing Walking Speed Does Not Normalize Gait Biomechanics Post-Anterior Cruciate Ligament Reconstruction

“…The average of the 5 walking trials were calculated and utilized for the waveform analyses in which each averaged waveform was assumed to be an independent observation. Bayesian P-splines were fit to estimate the average gait waveforms for each group which were utilized to compute difference curves and corresponding 95% confidence intervals (CI) (5,12,13,28,34). Comparisons between conditions and groups were considered significantly different at each % of stance phase if the mean difference and corresponding 95% CI did not span zero for greater than 3% of stance phase (34).…”

“…The slow speed group comprised individuals who exhibited average habitual walking speeds that were less than one MDD from 1.3 m•s −1 . Next, the same functional waveform analyses described above (5,12,13,28,34) were completed to detect differences during stance phase between each subgroup's i) ACLR limb at habitual speed (n = 15 per subgroup) vs ACLR limb at 1.3 m•s −1 (n = 15 per subgroup), and ii) ACLR limb at 1.3 m•s −1 (n = 15 per subgroup) vs limb of uninjured controls at their habitual speed (n = 15 per subgroup).…”

“…Uninjured control participants. Thirty uninjured control participants were age-(±2 yr), BMI-(±3 kg•m −2 , and within same BMI category), and sex-(male, female) matched to an ACLR participant (28). Control participants were excluded if they were pregnant, diagnosed with inflammatory arthritis, had a history of knee injury or any other lower extremity joint injury (i.e., chronic ankle instability, hip labrum injury), or a history of any lower extremity orthopedic surgery (12,28).…”

“…Anterior cruciate ligament reconstruction gait biomechanics were assessed during a single session first while walking at their habitual speed (±5%) followed by walking at 1.3 m·s −1 (±5%). The uninjured controls were matched to the ACLR group based on age (±2 yr), sex (male, female), and BMI (±3 kg·m −2 ) (28). Gait biomechanics were collected at each control participant’s habitual walking speed during a single session, and dominant limb biomechanics of each control participant were analyzed as part of the current study (12,28).…”

“…The uninjured controls were matched to the ACLR group based on age (±2 yr), sex (male, female), and BMI (±3 kg·m −2 ) (28). Gait biomechanics were collected at each control participant’s habitual walking speed during a single session, and dominant limb biomechanics of each control participant were analyzed as part of the current study (12,28). Limb dominance was defined as the preferred leg to kick a soccer ball (29).…”