The Fixed Patella Test: A Reliable and Accurate Test for Detecting Quadriceps Tendon Rupture

Delayed diagnosis of quadriceps tendon rupture can compromise outcomes, particularly when standard clinical tests are limited by pain, swelling, or compensatory muscle activation. The fixed patella test is a novel, non-invasive clinical manoeuvre designed to assess tendon continuity. This service evaluation aimed to assess its diagnostic performance in routine clinical practice.

A prospective service evaluation was conducted at a major UK trauma centre across multiple sites. Patients presenting with suspected extensor mechanism injury underwent routine clinical evaluation, including the fixed patella test. During the test, patients performed an isometric quadriceps contraction while the examiner assessed mediolateral patellar mobility. A mobile patella indicated a ruptured tendon. All participants underwent confirmatory imaging with ultrasound and/or MRI. Surgical findings were used where available.

Thirty patients (31 knees) were included. The fixed patella test demonstrated a sensitivity of 100%, a specificity of 50%, a positive predictive value of 93.1%, a negative predictive value of 100%, and an overall accuracy of 93.5%. All patients with a positive test were confirmed to have a complete or high-grade partial rupture on imaging or at surgery.

The fixed patella test is a simple, highly sensitive, and well-tolerated clinical tool for detecting quadriceps tendon rupture. It requires no additional equipment and may expedite diagnostic confirmation and surgical intervention. Ongoing data collection will help further validate its use in larger cohorts.