Effects of ankle angle changes on anterior talofibular ligament length and eversion strength in patients with ankle sprain

Abstract

Background

Recurrent lateral ankle sprains (LAS) with chronic ankle instability (CAI) frequently results in damage to the anterior talofibular ligament (ATFL). Eversion muscle strength is crucial for prevention; however, its relationship with ATFL length, an indicator of ankle instability, remains unclear.

Objective

To investigate the relationship and compare ATFL length and eversion muscle strength between the non-CAI and CAI sides.

Methods

Twenty-five adults (50 feet; 12 males; 13 females) with unilateral CAI, voluntarily participated. ATFL length was measured using ultrasonography. Eversion muscle strength was assessed using a handheld dynamometer during maximum isometric contraction. The measurement position was taken with the ankle in two positions: neutral and 20° plantar flexion (P/F).

Results

ATFL length was significantly greater on the CAI side than on the non-CAI side in the P/F position (p < 0.05). The ankle eversion muscle strength was significantly lower on the CAI side than on the non-CAI side in the P/F position (p < 0.01). Only the CAI side in the P/F position showed a moderate negative correlation between ATFL length and eversion muscle strength (r = −0.45, p = 0.02).

Conclusions

Highlighting decreases in eversion muscle strength in the P/F position may be related to the increased ATFL length observed in CAI.