Pes planus in patients with posterior tibial tendon insufficiency: asymptomatic versus symptomatic foot.

Bilateral weightbearing anteroposterior and lateral radiographs were analyzed in 43 patients with a clinical diagnosis of posterior tibial tendon insufficiency by two independent observers. The radiographs of each patient's asymptomatic foot was considered to serve as the control for the preexistance of pes planus. The radiographs were assessed for the severity of flatfoot deformity, the degree of talonavicular coverage, the talometatarsal angle, the calcaneometatarsal angle, the cuneiform to ground height and the cuneiform to fifth metatarsal height. Interobserver correlations were assessed. Results indicated that there was a high interobserver correlation for the values measured, making these angles reproducible among observers. Strong correlations were found in the degree of severity of flatfoot deformity between the asymptomatic and symptomatic feet as well as the values used to assess pes planus (i.e., similar radiographic measurements on the opposite side). The data suggest that patients with posterior tibial tendon insufficiency often have a preexisting flatfoot. This substantiates our belief that a preexisting flexible flatfoot, although far from the determining factor, is one of several etiological factors in the development of posterior tibial tendon insufficiency.