Treatment Outcomes of Chronic Lateral Ankle Instability Associated with Mild Cavovarus Deformity

Abstract

Category: Ankle Introduction/Purpose: Chronic lateral ankle instability (CLAI) has shown significant relationship with cavovarus deformity in prior studies. Isolated lateral ankle ligament reconstruction in patients who have CLAI with cavovarus deformity has been shown poor outcome if the deformity had not been corrected. Traditionally, cavovarus foot has been associated with neuromuscular conditions, however, nowadays it occurs in a less severe form even in the normal population. Mild cavovarus deformity is thought to be an anatomical risk factor for CLAI, but there are still debates on the correction of the mild deformity. The purpose of the current study was to evaluate clinical and radiographic outcomes of the modified Broström operation (MBO)s with additional procedures for the CLAI with mild cavovarus deformity. Methods: We reviewed total 12 patients who underwent MBOs with additional procedures for CLAI with mild cavovarus deformity between August 2009 and September 2013. Patients were evaluated by visual analogue scale (VAS) for pain, the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score and the Karlsson-Peterson (KP) ankle score. The talar tilt angle and the anterior displacement of the talus on ankle stress radiographs and the first metatarsal- talus angle, the arch height between cuneiform and fifth metatarsal base and the calcaneal pitch angle on foot lateral standing radiographs were examined. Results: The mean follow-up period was 31.5 months. Calcaneal lateral closing wedge osteotomy was performed in 6 patients to correct fixed hindfoot varus, and first metatarsal dorsiflexion osteotomy in 9 patients to correct remnant plantarflexion of the first ray. Three of 12 patients underwent both calcaneal and first metatarsal osteotomies. The mean VAS score decreased from 5.5 to 1.7 at last follow-up (p=0.002). The mean AOFAS score and the mean KP ankle score were significantly improved (61.0 to 85.3 (p< 0.001), 56.8 to 83.1 (p < 0.001)) and there was no recurrence of instability. Radiographically, the mean talar tilt angle and the anterior displacement of the talus were decreased (p=0.001, p=0.007), and the first metatarsal- talus angle and the arch height were decreased at last follow-up (p=0.001, p=0.003). Conclusion: Concomitant correction of mild cavovarus deformity with MBO for CLAI improves clinical outcomes and prevents recurrent instability. A comprehensive evaluation and cautious approach for deformity should be followed when treating patients with chronic ankle instability.