Acute quadriceps tendon rupture: a pragmatic approach to diagnostic imaging

Introduction Quadriceps tendon ruptures are uncommon injuries, occurring most frequently in males over 40 years and associated with obesity, renal failure and steroids. Literature states that ultrasonography and magnetic resonance imaging have a role in diagnosis. We discuss the contrasting advantages and disadvantages of each imaging modality and establish their diagnostic value. Materials and methods A closed loop audit cycle was performed over 68 months by reviewing all patients presenting with a suspected acute quadriceps tendon ruptures to a Teaching Hospital. Results Sixty-six patients were included in the study; 4/47 patients in the initial audit period were inaccurately diagnosed, either clinically or by ultrasonography, leading to surgical exploration identifying an intact quadriceps tendon. This highlighted the need for improved pre-operative diagnosis and a recommendation to increase the use of magnetic resonance imaging. In the second cycle, the use of magnetic resonance imaging increased from 4 to 42 % ( p = 0.0004) and misdiagnosis fell from 4/47 (9 %) to 1/19 (5 %). Ultrasonography was shown to be highly sensitive (1.0) but the specificity of this modality was only 0.67 with a positive predictive value of 0.88. Magnetic resonance imaging displayed a sensitivity of 1.0, a specificity of 1.0 and a positive predictive value of 1.0. Conclusion We propose that all patients who have a suspected quadriceps tendon rupture after clinical examination and radiography should either proceed directly to magnetic resonance imaging or be initially assessed by ultrasound, and in those with positive findings, a supplementary magnetic resonance imaging to eliminate false positive diagnoses.