MR imaging findings in spring ligament insufficiency.

Abstract

Spring ligament insufficiency is associated with chronic posterior tibial tendon dysfunction, and may constitute an indication for surgical repair or reconstruction. This study examines the accuracy of MRI for the diagnosis of insufficiency of the spring ligament. Two experienced musculoskeletal radiologists independently scored the MRI findings in 13 cases of surgically proven spring ligament insufficiency and in 18 control subjects, using a standardized scoring system. Insufficiency of the spring ligament was associated with increased signal heterogeneity on short TE spin echo images, and an increase in the thickness of the medial portion of the ligament. The sensitivity of MRI for the diagnosis of spring ligament insufficiency was 54-77%, while the specificity was 100%. MRI assessment of the plantar portion of the spring ligament was unreliable (kappa=0.33), but the assessment of global ligament integrity was substantially reproducible (kappa=0.76). The medial portion of the spring ligament can be reliably assessed on routine MRI. The findings of spring ligament insufficiency on MRI are only moderately sensitive but highly specific.