Hemi-Castaing ligamentoplasty is a treatment for chronic ankle instability, accused of weakening a powerful stabilizing muscle: the peroneus brevis.

To assess proprioceptive and muscular impairment following hemi-Castaing and impact on postural control.

A retrospective series of 21 patients underwent clinical (Karlsson, AOFAS) and proprioceptive assessment with isokinetic assessment (evertors and invertors) on a Con-Trex^® dynamometer and postural assessment on a Win-Posturo^® force platform, at a minimum 6 months postsurgery.

At a mean 18 months’ follow-up, mean Karlsson score was 84 and AOFAS score 88. Ankle joint position sense error was less on the operated than on the healthy side. Evertor strength deficit with respect to the healthy side was 4.7% (ns) at 30°/s and 5.7% (ns) at 120°/s in concentric mode and 6.6% (ns) in excentric mode. After surgery, the evertor/invertor ratio was >1 (in favor of the evertors). Postural values were significantly higher for the operated ankle.

Hemi-Castaing ligamentoplasty provided excellent clinical and functional results. It did not disturb the agonist/antagonist balance of the ankle muscles, and harvesting a half peroneus brevis did not impair evertor isokinetic force. Joint position sense was not impaired; indeed, deficits with respect to the contralateral side showed improvement.

Retrospective study.