Talofibular Bony Impingement in the Ankle.

BACKGROUND: Talofibular bony impingement has not previously been reported, since it is difficult to detect on plain radiograph, similar to the spur on the anterior border of the medial malleolus and anterior portion of the medial talar facet. We hypothesized that talofibular bony impingement can cause limited dorsiflexion of the ankle. The aim of this study was to evaluate talofibular bony impingement as a distinct form of impingement that limits dorsiflexion of the ankle.

METHODS: This study included 20 consecutive patients (21 ankles) with talofibular impingement and 19 consecutive patients (19 ankles) with lateral ankle instability without talofibular impingement. Presence or absence of talofibular impingement was confirmed under direct intraoperative visualization. Dorsiflexion before and after excision of the impinging spurs was measured. Findings on plain radiographs and computed tomography were compared between the groups. Pre- and postoperative clinical assessments were done with Foot Function Index, visual analog scale for pain, and American Orthopaedic Foot & Ankle Society ankle-hindfoot score at a mean follow-up of 1.4 years.

RESULTS: After removal of the bony impingement, the range of dorsiflexion increased by a mean 7.9 degrees (range, 2.5 to 11.0 degrees) in the impingement group. The mean distance between the fibula and lateral process of the talus on weight- bearing anteroposterior radiograph of the ankle was 1.2 mm (range, 0 to 4.5) in the impingement group and 3.2 mm (range, 1 to 4.5) in the control group. On axial computed tomography image, bony protrusion of the lateral process of the talus was frequently present in the impingement group, and the mean amount of protrusion was more than that of the control group. Clinical findings improved overall.

CONCLUSIONS: Talofibular impingement was a cause of limited dorsiflexion, and the diagnosis was confirmed intraoperatively.

LEVEL OF EVIDENCE: Level III, retrospective comparative study.