Limited Dorsiflexion Range Of Motion Alters Joint Kinematics During Walking In Chronic Ankle Instability Patients

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Limited dorsiflexion range of motion (DFROM) may be one of risk factors for lateral ankle sprains. Further, chronic ankle instability (CAI) patients consistently showed reduced DFROM during functional movements. Although DFROM seems to vary between CAI patients, it is unclear whether varied DFROM changes lower-limb joint kinematics during walking. PURPOSE: To examine the effects of varied DFROM on lower-limb kinematics during walking within the CAI population. METHODS: 100 CAI subjects were classified into 3 subgroups based on DFROM, measured by the weight-bearing lunge test: a Hypo (14 M, 10F; ≤ 40°; 35 ± 2.5°, 23 ± 2 yr, 176 ± 13 cm, 80 ± 13 kg), Normal (25 M, 32F; 40-50°; 46 ± 2.6°, 21 ± 2 yr, 174 ± 7 cm, 72 ± 14 kg), or Hyper DFROM group (11 M, 8F; ≥ 50°; 54 ± 3°, 22 ± 2 yr, 175 ± 11 cm, 74 ± 14 kg). Subjects performed 5 walking trials at a preferred speed while 3D joint kinematic data were collected using high-speed video (250 Hz) and a force plate (1000 Hz). Functional linear models were used to detect between-group differences. If 95% confidence intervals did not cross zero, differences were significant. RESULTS: Figure 1 shows that the Hypo-DFROM group showed increased ankle inversion and hip flexion and decreased hip abduction angles relative to the Normal-DFROM group. In addition, Hypo-DFROM group showed the lowest plantarflexion angle but greatest ankle inversion angle after heel contact among three groups. The Hyper-DFROM group showed the greatest plantar flexion and lowest inversion angles before and/or after heel contact. CONCLUSIONS:During gait, Hypo-DFROM group show increased ankle inversion angle relative to the Normal- and Hyper-DFROM groups, which may increase the risk for lateral ankle sprains. However, decreased plantarflexion and hip flexion angles in the Hypo-DFROM group may be compensatory patterns in effort to avoid further injuries. Future studies are needed to determine whether these kinematic compensations would reduce further injuries in the Hypo-DFROM group.