Plantar cutaneous sensitivity and balance in individuals with and without chronic ankle instability

Abstract

Objective: To determine if plantar cutaneous sensation and postural control differ between individuals with and without chronic ankle instability (CAI).

Design: Case-control.

Setting: Laboratory.

Participants: Ten subjects with CAI and 10 subjects with no ankle sprain history participated.

Interventions: Light touch was evaluated at 3 sites (heel, base of fifth metatarsal, and head of first metatarsal) on the plantar aspect of the foot using Semmes-Weinstein Monofilaments (SWMs). Postural control was assessed using the single leg firm and foam conditions of the Balance Error Scoring System (BESS) and during eyes open and eyes closed static postural control on a force plate.

Main outcome measures: Semmes-Weinstein Monofilament detection thresholds, BESS errors, and the mean of time-to-boundary (TTB) minima (TTB-mean) and the SD of TTB minima (TTB-SD) in the anterior-posterior (AP) and medial-lateral directions were evaluated for each subject.

Results: Subjects with CAI demonstrated increased SWM detection thresholds at the heel (P = 0.009), head of the first (P = 0.01), and base of the fifth metatarsal (P < 0.001) and postural control deficits on the BESS firm (P = 0.04) and foam (P = 0.001) conditions and with eyes open TTB-mean AP (P = 0.007) and TTB-SD AP (P = 0.02). When combining groups, a negative moderate correlation was observed between the base of the fifth metatarsal detection threshold and eyes open TTB-mean AP (r = -0.50; P = 0.03).

Conclusions: Light touch and postural control deficits were observed in individuals with CAI. The correlation between light touch over the base of the fifth metatarsal and eyes open TTB-mean AP suggests that there may be a relevant relationship between these measures.

Clinical relevance: Individuals with CAI demonstrated deficits in light touch over the plantar aspect of the foot. The relationship between base of the fifth metatarsal sensation and TTB-mean AP may provide a starting point to link plantar cutaneous sensory deficits to changes in other aspects of sensorimotor function.