The clinical diagnosis of subcutaneous tear of the Achilles tendon. A prospective study in 174 patients.

A study to determine the sensitivity, specificity, and positive and negative predictive values of several clinical diagnostic tests of subcutaneous Achilles tendon rupture was performed during a 13-year period. There were 174 patients with clinical diagnosis of unilateral complete subcutaneous Achilles tendon tear and 28 patients with unilateral suspected but no actual Achilles tendon tear. The following tests were used: palpation, calf squeeze, Matles, Copeland, and O'Brien. Palpation of the gap was the least sensitive clinical test with the patient awake (0.73), increasing to 0.81 when the test was performed under anesthesia; the Copeland and O'Brien tests showed a sensitivity of 0.8. Both the calf squeeze and Matles tests were significantly more sensitive than the other tests (0.96 and 0.88, respectively; 0.022 < P < 0.05). All tests showed a high positive predictive value, with no statistically significant difference between the various tests. In the 28 patients with no evidence of a subcutaneous Achilles tendon tear on imaging, the tests showed a high capability to detect that the Achilles tendon was intact (gap palpation specificity, 0.89; calf squeeze test specificity, 0.93; Matles test specificity, 0.85). Whichever tests were performed, at least two of them were positive for a subcutaneous tear of the Achilles tendon in all patients in this study.