Increased inversion angle replication error in functional ankle instability

The inversion-angle replication error of the ankle joint was measured in subjects with a functionally stable or unstable ankle. Testing was performed as a passive set–active replication design. The absolute replication error on the unstable side of 23 unilaterally, functionally, and mechanically unstable subjects was found to be significantly greater (2.5°) than the error on the healthy contralateral side (2.0°; P < 0.05) and the error in a group of 40 ankle healthy controls (1.7°; P < 0.01). In 10 ankle-healthy high-level cross-country runners the replication error was reduced by 38% after warming up (P = 0.04).