BACKGROUND: The acquired adult flatfoot deformity (AFFD) is a potentially debilitating foot condition with a prevalence thought to be between 3 %-10 %. To the authors' best knowledge, no association has been described between severity of AFFD and degree of pre-existing ankle or foot arthritis. The degree and pattern of preexisting ipsilateral arthritis of the foot and ankle was investigated in those with symptomatic AFFD presenting to hospital.
METHODS: Retrospective observational study between May 2015 and May 2018, of patients who presented to our tertiary clinic with symptomatic AFFD. Radiographs of one hundred and forty-eight (n=148) patients were reviewed, excluding those with charcot arthropathy, previous trauma or coalition. The primary outcome measure was severity of OA in the ankle, subtalar, talonavicular and calcaneocuboid joints. Secondary outcome was severity of radiographic planovalgus deformity. The independant variables used were age and severity of planovalgus deformity as measured by the Meary angle, calcaneal pitch and medial cuneiform-fifth metatarsal height. A linear regression model was carried out on the outcomes.
RESULTS: Median age was 60.0 years (IQR 22). There were 56 males to 92 females, with 75 left sided deformities observed and 73 right sided. With increasing severity of planovalgus measurements, there was no significant association observed in severity of arthritis in the ankle joint (p = 0.766), subtalar joint (p = 0.090), talonavicular joint (p = 0.256) and calcaneocuboid joint (p = 0.091). With increasing age, there was significance observed in degree of ankle arthritis, subtalar, talonavicular and calcaneocuboid joints (p = 0.001). There was no significant correlation observed with age for the angular break of Meary's line (p = 0.73), calcaneal pitch (0.262) and medial cuneiform-fifth metatarsal height (p = 0.937).
CONCLUSION: This observational study shows no significant association between severity of radiographic planovalgus deformity and pre-existing arthritis of the ankle, hindfoot and midtarsal joints.