Full- versus partial-thickness Achilles tendon tears: Sonographic accuracyand characterization in 26 cases with surgical correlation

PURPOSE: To determine the accuracy of the use of sonography for differentia tion of full- from partial-thickness tears or tendinosis of the Achilles te ndon by using surgical findings as the standard of reference and to identif y sonographic characteristics of full-thickness tears that can be used to d ifferentiate the two types of tears. MATERIALS AND METHODS: In part A of this study, sonographic findings (based on reports) in 26 consecutive cases of tears of the Achilles tendon were c ompared with surgical findings. In part B, the sonograms were blindly and r etrospectively evaluated with respect to six sonographic characteristics po ssibly related to pathologic findings in the tendon, and the characteristic s were correlated with surgical findings. RESULTS: In part A, statistical data regarding the use of sonographic findi ngs to distinguish full- from partial-thickness tears were as follows: sens itivity, 100%; specificity, 83%; accuracy, 92%; positive predictive value, 88%; and negative predictive value, 100%. In part B, tendon thickness (P < .001), posterior acoustic shadowing (P = .007), and tendon retraction (P < .001) were correlated with full-thickness tears. Visualization of fat herni ation (P = .051) and of the plantaris tendon (P = .098) demonstrated margin al correlation with full-thickness tears. Echogenicity at the site of the p athologic finding in the tendon showed no significant correlation. CONCLUSION: Sonography can be used to differentiate full- from partial-thic kness tears or tendinosis of the Achilles tendon with 92% accuracy. Undetec table tendon at the site of injury, tendon retraction, and posterior acoust ic shadowing demonstrate statistically significant correlation with full-th ickness tears.