Ruptures of the patellar and/or quadriceps tendon are rare injuries requiring immediate repair to re-establish knee extensor continuity and to allow early motion. Ultrasound is extensively used as a diagnostic tool before surgery on acute traumatic tears of the patellar tendon and quadriceps tendons.

Our aim was to re-evaluate the value/role of sonography in diagnosing quadriceps and patellar tendon rupture and in differentiating partial from complete tears. To correlate the intra operative findings with the ultrasound report.

A retrospective review of 32 consecutive patients who had a surgical intervention for suspected acute quadriceps and patellar tendon rupture over the last 3 years. Intra-operative findings, clinical, x-ray, ultrasound and MRI reports were correlated.

Seventeen patients had a suspected patellar tendon rupture on clinical examination and 15 patients had suspected quadriceps tendon rupture. Diagnosis was confirmed by clinical examination and x-rays alone in 9 patients, with additional ultrasound in 18 patients and with MRI scan in 5 patients. There were 6 false positives out of 18 [33.3%] in the ultrasound proven group and 1 false positive out of 9 [11.1%] in the clinical examination and x-ray only group. MRI was 100% accurate [n=5].

This is a small, but important study. Ultrasound offers a low degree of sensitivity and specificity in diagnosing acute quadriceps and patellar tendon ruptures. As a result, patients are being exposed to the risks of surgery unnecessarily. We recommend MRI scan as a first line of investigation in patients where the diagnosis is clinically ambiguous. Ultrasound assessment should not be relied upon in when making the decision to operate.