Background Previous studies revealed that the patient with chronic ankle instability (CAI) has postural control deficit. However, it is unclear that if CAI patients rely more on plantar cutaneous sensation or other compensation strategy such as proximal joint postural control strategy.

Objective To investigate the alteration of lower extremity movement pattern to maintain balance in CAI patients as compared to healthy group with and without plantar cutaneous sensation (PCS).

Design Case controlled study.

Setting Laboratory.

Patients (or Participants) Nine healthy subjects (age: 23.75±1.98 years; height: 164.10±6.90 cm; weight: 57.76±9.14 kg) and 10 CAI patients (age: 23.57±2.72 years; height: 166.14±7.74 cm; weight: 67.84±12.60 kg) with normal foot arch type (5 mm∼9 mm; 5.78±2.44 mm) were recruited.

Interventions (or Assessment of Risk Factors) Subjects immersed both feet in an ice water for 10 minutes and performed three trials of a single-leg stance balance test with their eyes closed on a force plate for 10 s.

Main Outcome Measurements Three-dimensional lower extremity kinematics (Vicon Inc, Oxford, UK) were analysed. The kinematic data were analysed by ensemble curves and 95% confidential interval (CI). Group (healthy and CAI) by time (plantar sensation) mixed model two-way repeated measures of ANOVA was performed to analyse differences of maximum joint kinematics.

Results With diminished PCS, CAI group showed greater knee internal rotation (mean difference=−9.21±0.39°) and greater hip external rotation (mean difference=15.89±0.27°) throughout 10 seconds balance task. However, there were no significant main effects and interactions between group and time.

Conclusions Since PCS is intact before ice immersion, CAI patients rely more on PCS in order to maintain balance and revealed similar joint kinematics. However, once PCS diminished CAI patients utilize proximal joint compensatory mechanism such as leaning toward the injured side at the hip joint through external rotation of the hip joint and internally rotating the knee joint to prevent inversion at the ankle joint.