Talar positional fault in persons with chronic ankle instability.

Objective: To determine whether sagittal plane talar position differs between uninjured controls and individuals with chronic ankle instability (CAI) using lateral ankle radiographs.

Design: Single-blind case control.

Setting: University-based sports medicine research laboratory.

Participants: University students (N=48) volunteered to participate. Twenty-four uninjured controls (12 men, 12 women; mean +/- SD, 21.8+/-2.6y; 170+/-10cm; 73+/-16kg), and 24 adults with CAI (12 men, 12 women; 21.7+/-2.8y; 175+/-13cm; 71+/-13kg) participated.

Intervention: A single nonweight-bearing lateral radiograph was taken of each ankle. Subjects were positioned side lying with the hip and knee in a neutral position in the transverse plane and the ankle joint in a neutral position (90 degrees of dorsiflexion, 0 degrees of inversion/eversion).

Main Outcome Measure: The sagittal plane talar position was calculated as the distance between the most anterior margin of the inferior tibia and the most anterior margin of the talar dome in millimeters for each radiograph.

Results: Talar position was significantly more anterior in the involved CAI limb (3.69+/-1.37mm) than the uninvolved CAI limb (2.98+/-1.61mm; P=.03). Additionally, an anterior talar position was significantly greater in the involved CAI limb than the matched control limb (2.65+/-1.24cm; P<.01). No differences were found between the uninvolved CAI limb and the matched control group limb (P=.57) or between the limbs of the uninjured control group (P=.75). Intratester reliability was found to be .90, while intertester reliability was .78.

Conclusions: An anterior talar positional fault is present in the involved limb of individuals with CAI relative to their uninvolved limb and compared with the matched limb of a control group. The talar position measurement technique has excellent intratester and intertester reliability.