Sonography of partial-thickness quadriceps tendon tears with surgical correlation.

OBJECTIVE: With the use of surgical findings as the reference standard, the purpose of this study was to describe the sonographic findings of partial-thickness and complete tears of the quadriceps tendon and to determine whether sonography can potentially aid diagnosis. METHODS: Three hundred eighty-nine consecutive sonographic reports (January 1996 to April 2001) of the knee/quadriceps tendon were reviewed retrospectively and assessed for subsequent surgery on the quadriceps tendon. Seven cases were thus identified. Findings at surgery (complete versus partial tears) were compared with the original sonography reports. RESULTS: All 4 partial tears and 1 of 2 complete tears were diagnosed correctly on the basis of sonography. One complete tear was described as a partial tear on the basis of sonography. In a seventh case, complete disruption of the extensor mechanism with osseous avulsion of the superior pole of the patella was identified correctly. Dynamic scanning was essential in diagnosing a partial quadriceps tendon tear in 1 case. CONCLUSIONS: Sonography, including the use of dynamic evaluation, was helpful in the diagnosis of partial-thickness tears of the quadriceps tendon and may aid in differentiation of such cases from complete quadriceps tendon tears, particularly in the acute setting. The presence of scar tissue in the setting of chronic injury may represent a potential pit-fall in the assessment of partial versus complete quadriceps tears. Further study is needed to define the accuracy of sonography for detecting quadriceps tendon tears.