Diagnosis of tears of the quadriceps tendon of the knee: value of sonography.

OBJECTIVE: The purpose of the study was to evaluate the role of sonography in diagnosing traumatic tears of the quadriceps tendon. More specifically, it was intended to determine the value of sonography in differentiating complete from partial tears and thus in directing therapy. Knees of asymptomatic volunteers and patients' contralateral knees were used as normal standards.

SUBJECTS AND METHODS: Sonography was performed in 29 patients with injuries of the quadriceps tendon in a 3-year period. As the control, 59 normal knees were examined: both knees of 15 healthy subjects and 29 contralateral knees of the injured patients. In all cases, longitudinal and transverse sonograms were obtained. In five cases (four complete and one partial rupture), the sonographic diagnosis was confirmed surgically. Those remaining patients who had a partial tendon tear were treated conservatively. Follow-up sonograms were obtained in 10 cases (three treated with surgery and seven not) and showed integrity of the affected tendon.

RESULTS: Among the 29 patients, sonograms showed a partial rupture (focal hypoechoic defect in the tendon) in eight and a complete rupture (complete disruption of the tendon fibers) in four. In the remaining 17 cases, the tendon was intact. The high sensitivity and specificity of sonography (100% or four of four in our sample) in the diagnosis of complete tears of the quadriceps tendon were confirmed by surgery. As only one partial tear was confirmed by surgery (the remaining seven were treated conservatively), the sensitivity and specificity of sonography with respect to partial tears could not be determined.

CONCLUSION: Results of this study, albeit obtained from a limited sample, indicate that sonography offers a high degree of sensitivity and specificity in the evaluation of quadriceps tendon rupture. This noninvasive and easily available imaging technique should be considered in the diagnostic workup and treatment planning of patients with suspected tears of the quadriceps tendon.