Ankle Dorsiflexion Affects Hip and Knee Biomechanics During Landing.

Background: Restricted ankle dorsiflexion range of motion (DFROM) has been linked to lower extremity biomechanics that place an athlete at higher risk for injury. Whether reduced DFROM during dynamic movements is due to restrictions in joint motion or underutilization of available ankle DFROM motion is unclear.

Hypothesis: We hypothesized that both lesser total ankle DFROM and underutilization of available motion would lead to high-risk biomechanics (ie, greater knee abduction, reduced knee flexion).

Study Design: Cross-sectional study.

Level Of Evidence: Level 3.

Methods: Nineteen active female athletes (age, 20.0 ± 1.3 years; height, 1.61 ± 0.06 m; mass, 67.0 ± 10.7 kg) participated. Maximal ankle DFROM (clinical measure of ankle DFROM [DF-CLIN]) was measured in a weightbearing position with the knee flexed. Lower extremity biomechanics were measured during a drop vertical jump with 3-dimensional motion and force plate analysis. The percent of available DFROM used during landing (DF-%USED) was calculated as the peak DFROM observed during landing divided by DF-CLIN. Univariate linear regressions were performed to identify whether DF-CLIN or DF-%USED predicted knee and hip biomechanics commonly associated with injury risk.

Results: For every 1.0° less of DF-CLIN, there was a 1.0° decrease in hip flexion excursion ( = 0.21, = 0.05), 1.2° decrease in peak knee flexion angles ( = 0.37, = 0.01), 0.9° decrease in knee flexion excursion ( = 0.40, = 0.004), 0.002 N·m·N·cm decrease in hip extensor work ( = 0.28, = 0.02), and 0.001 N·m·N·cm decrease in knee extensor work ( = 0.21, = 0.05). For every 10% less of DF-%USED, there was a 3.2° increase in peak knee abduction angles ( = 0.26, = 0.03) and 0.01 N·m·N·cm lesser knee extensor work ( = 0.25, = 0.03).

Conclusion: Lower levels of both ankle DFROM and DF-%USED are associated with biomechanics that are considered to be associated with a higher risk of sustaining injury.

Clinical Relevance: While total ankle DFROM can predict some aberrant movement patterns, underutilization of available ankle DFROM can also lead to higher risk movement strategies. In addition to joint specific mobility training, clinicians should incorporate biomechanical interventions and technique feedback to promote the utilization of available motion.