Ultrasound assessment of the spring ligament complex.

This study was conducted to document the normal ultrasound anatomy of the spring ligament in asymptomatic subjects and to prospectively determine the frequency of ultrasound abnormality of the spring ligament in patients with suspected posterior tibial tendinopathy. The superomedial calcaneonavicular ligament (CNL) of 10 healthy volunteers was examined by ultrasound. Nineteen patients with a clinical diagnosis of suspected posterior tibial tendinopathy and/or chronic pain along the course of the tendon were examined by ultrasound. The superomedial CNL thickness was measured. Normal anatomy of the superomedial CNL could be demonstrated in all the volunteers. The mean of the combined proximal measurements was 4 mm and of the distal measurements 3.6 mm. Sixteen patients with posterior tibial tendinopathy had increased thickness of the spring ligament, which was more evident on its distal portion over the talar head. One patient had superomedial CNL insufficiency with normal posterior tibial tendon. The mean proximal measurement in the study group was 5.1 mm and the distal measurement 6.1 mm. The differences between the measurements in the study group and controls were highly significant (proximal site P < 0.01, distal site P < 0.001). Spring-ligament laxity or tear is characterised by thickening. There is a strong association between posterior tibial tendinopathy and abnormality of the spring ligament.