Patellar Tendon Rupture with Intact Overlying Prepatellar Quadriceps Continuation: A Case Report

Abstract

Introduction: The prepatellar quadriceps continuation is an aponeurotic layer and arises downwards anteriorly over the patella originating from the rectus femoris tendon. A wide variance in thickness of the prepatellar quadriceps continuation has been described. This continuation could potentially remain intact following a patellar tendon rupture mimicking an intact patellar tendon during diagnostic ultrasonography. Case presentation: We report a 43-year-old female patient with an injured knee after a direct blow during soccer. The patient was unable to actively extend her leg. After physical and conventional X-ray examination, a patellar tendon rupture was suspected. However, ultrasound demonstrated an elongated course of the patellar tendon without evidence of a rupture. An additional MRI scan revealed a complete patella tendon rupture with an intact overlying prepatellar quadriceps continuation as a normal variant. Conclusion: A dysfunctional extensor mechanism and patella alta on conventional radiographs is pathognomonic for a ruptured patellar tendon. MRI is the preferred imaging method in case of discrepancy between the clinical presentation and ultrasound findings since there are normal variants of the extensor mechanism. Introduction: The prepatellar quadriceps continuation is an aponeurotic layer and arises downwards anteriorly over the patella originating from the rectus femoris tendon. A wide variance in thickness of the prepatellar quadriceps continuation has been described. This continuation could potentially remain intact following a patellar tendon rupture mimicking an intact patellar tendon during diagnostic ultrasonography. Case presentation: We report a 43-year-old female patient with an injured knee after a direct blow during soccer. The patient was unable to actively extend her leg. After physical and conventional X-ray examination, a patellar tendon rupture was suspected. However, ultrasound demonstrated an elongated course of the patellar tendon without evidence of a rupture. An additional MRI scan revealed a complete patella tendon rupture with an intact overlying prepatellar quadriceps continuation as a normal variant. Conclusion: A dysfunctional extensor mechanism and patella alta on conventional radiographs is pathognomonic for a ruptured patellar tendon. MRI is the preferred imaging method in case of discrepancy between the clinical presentation and ultrasound findings since there are normal variants of the extensor mechanism.