Description
Induction
Early surgical repair for ruptured quadriceps tendon is recommended yet there is frequently delay in obtaining an accurate diagnostic confirmation. In the acute setting, tendon functional assessment is limited by pain, the recruitment of the iliotibial band can result in false negative findings when relying on straight leg raise test. The authors report the accuracy of a novel clinical test to determine continuity of tendon attachment to the patella.
Materials and method
A prospective analysis of patients suspected of extensor mechanism injury having presented to a single institution was carried out. The study adhered to the Standards for Reporting Diagnostic accuracy studies (STARD) criteria. Patients received a routine clinical evaluation plus the ‘fixed patella test’. Participants were asked to perform a sustained isometric contraction of the quadriceps muscles. The examiner moves the patella from side to side. A fixed patella indicates an intact tendon, a mobile patella indicates a ruptured tendon. Patients with neuromuscular disease, chronic ruptures >6weeks, or established muscle inhibition were excluded. All participants received further imaging in the form of ultrasound scan (USS) and/or magnetic resonance (MRI). Those who had confirmation of complete rupture went on to have surgical repair. Findings were compared to determine the sensitivity, specificity and diagnostic accuracy of the test in detecting quadriceps tendon rupture.
Results
26 knees in 24 consecutive patients were included. All patients presented with severe pain in an acutely swollen knee with loss of range of motion following an eccentric loading mechanism of injury. Age of patients ranged from 43-85 with only 2 patients being female. Quadriceps tendon confirmation on USS and/or MRI was followed by surgical findings confirmation. The Fixed patella test had a sensitivity of 100%, a specificity of 50% and an accuracy of 92.3%. Surgical confirmation of a complete or high grade partial rupture was identified in all cases with a positive fixed patella test. The latter group had both positive fixed patella test and confirmation on further imaging.
Conclusion
The Fixed Patella test can accurately detect quadriceps tendon rupture. The test was proven to be easy, reliable and very well tolerated by patients even acutely since no knee movement is required. The authors continue to collect data to expand the sample size and further validate the interim accuracy detected. Nonetheless present results recommend the use of this easy clinical test to help expedite urgent imaging and surgical treatment of ruptured quadriceps tendon.
