- OBJECTIVE: The purpose of this study was to determine whether sonography is as accurate as magnetic resonance (MR) imaging for depicting abnormalities of the spring ligament in patients with symptomatic posterior tibial tendon (PTT) dysfunction. METHODS: Sixteen patients (18 ligaments) with symptomatic PTT dysfunction were prospectively evaluated with sonography and MR imaging. RESULTS: Magnetic resonance imaging showed spring ligament tears in 8 of 18 feet, including 6 incomplete tears and 2 complete tears. Sonography showed spring ligament tears in 7 of 18 feet, including 6 incomplete tears and 1 complete tear. The findings of sonography and MR imaging were concordant in 17 of 18 feet (94%). Six of the 8 spring ligament tears on MR imaging were associated with posterior tibial tendinosis or tears. CONCLUSIONS: Sonography is an effective imaging option in assessing spring ligament abnormalities in patients with symptomatic PTT dysfunction.