creates a sling that supports the talar head between the calcaneus and the navicular. In patients with AAFD, the spring ligament is frequently attenuated or fully ruptured.
TABLE 1 Clinical Staging of Posterior Tibial Tendon Dysfunction
develops. The foot deformity may be flexible or rigid. Once AAFD has progressed to this stage, treatment becomes much more difficult. For this reason, weight-bearing anterior-posterior (AP) ankle radiographs should always be obtained in patients with AAFD to ensure ankle congruity and to assess for arthritis. Patients with ankle involvement may present with either isolated deltoid stretching or tearing, or frank arthritis in the ankle joint itself with lateral cartilage loss contributing to valgus talar tilt. The distinction between these two scenarios has important implications for surgical management.
TABLE 2 Clinical Classification System for Posterior Tibial Tendon
FIGURE 1 Weight-bearing CT sagittal image demonstrating first tarsometatarsal plantar gapping (arrow), representing instability, as well as degenerative arthritis.
shown to be an excellent predictor of PTTD confirmed with MRI. In a study of 49 patients, pitting edema in the distal PTT area had a sensitivity of 86% and specificity of 100% for PTT degeneration.13 Additional examination findings associated with AAFD include a callus that may develop under the medial column and a medial rocker-bottom deformity. Tenderness may be noted in the sinus tarsi, in the subfibular area, and over the peroneal tendons.