summary A rectus femoris strain is a traumatic injury caused by overstretching of the muscle which results in tearing of the muscle fibers of the rectus femoris. Diagnosis is made clinically with tenderness over the rectus femoris made worse with resisted hip flexion or extension. Treatment is conservative with NSAIDs, rest and stretching. Epidemiology Demographics seen more commonly in soccer and football players Etiology Pathophysiology mechanism sudden, forceful eccentric contraction of the muscle sprinting from standing position kicking soccer ball with great force pathoanatomy acute injuries usually more distal on the thigh chronic injuries usually occur closer to the muscle origin Associated conditions avulsion of anterior inferior iliac spine (AIIS) adolescent athletes may have proximal bony avulsion of anterior inferior iliac spine (AIIS) occurs at insertion site of direct head of rectus femoris Anatomy Osteology anterior inferior iliac spine (AIIS) origin of direct head of rectus femoris muscle Muscles rectus femoris crosses hip and knee joint flexes hip and extends knee Presentation Symptoms pain in the anterior aspect of the hip strain or avulsion at insertion on AIIS pain midthigh strain in muscle fibers pain distally most common finding Physical exam inspection and palpation tenderness to palpation in the injured area proximally at origin of rectus femoris muscle muscle belly midthigh region distally at knee feel for defect in muscle indicating a full tear (unusual finding) provocative maneuvers pain elicited with resisted hip flexion or extension Imaging MRI Ultrasound Radiographs indications concern for avulsion at insertion site on anterior inferior iliac spine in adolescent athletes findings normal in most cases Treatment Nonoperative NSAIDS, rest, ice, stretching/strengthening indications definitive treatment for vast majority outcomes usually resolves within 4-6 weeks