The plantaris tendon graft: an ultrasound study

To assess the value of ultrasound in imaging the plantaris tendon, ultrasounds were done on 26 legs in 25 patients who had a variety of surgical procedures on the posterior leg. Eighteen ultrasounds were done and interpreted before operation and eight after operation by a radiologist. The sonographic results were compared with the status of the plantaris as determined at surgery. The plantaris was present in 21 of 23 patients for a prevalence of 91%. Eighteen plantaris tendons were well visualized on ultrasound for a sensitivity of 86%. Of the three false-negative results, two occurred with thinned plantaris tendons that were less than 2 mm thick and hence considered inadequate for grafting. Therefore, the sensitivity for detecting a tendon suitable for grafting was 95%. All patients with positive studies had a plantaris tendon present for a specificity of 100%. A learning curve for the radiologist was demonstrated. Ultrasound appears to be effective in the preoperative imaging of the plantaris tendon.