This page is educational and is not a substitute for professional medical advice, diagnosis, or treatment.
Please ask a qualified health professional about symptoms, treatment decisions, or concerns about your own condition.
Emergency? If symptoms are severe, rapidly worsening, or you think it may be an emergency, call your local emergency number or go to the nearest emergency department.
Bones & Joints
Patellar tendon rupture is a complete tear of the tendon connecting the kneecap (patella) to the shin bone (tibia), causing sudden severe knee pain, inability to straighten the leg, and loss of the extensor mechanism—a devastating injury that requires emergency surgical repair to restore knee function. These ruptures typically occur during forceful eccentric quadriceps contraction (landing from a jump, sudden deceleration, stumbling down stairs) in adults 30-50 years old, often with predisposing tendon weakening from chronic patellar tendinopathy, corticosteroid use, systemic diseases (diabetes, chronic kidney disease, rheumatoid arthritis), or prior knee surgery. Clinically, patients present with inability to lift the leg straight (positive straight leg raise test), palpable gap below the kneecap, high-riding patella on X-ray (patella alta), and large hemarthrosis (blood in joint). Treatment is almost always surgical—early repair within 2 weeks critical as delayed surgery has worse outcomes due to tendon retraction, muscle shortening, and scar tissue formation. Surgical repair involves reattaching torn tendon to patella with strong sutures, augmentation with wire or suture anchors, and often requiring tissue augmentation in chronic cases (allograft, synthetic graft, hamstring autograft). Recovery timeline: 4-6 months to regain full knee function, 6-12 months to return to high-level activities, with 75-85% achieving good functional outcomes if repaired early, though many have residual quadriceps weakness (10-20% weaker than uninjured leg).
What it is and why it happens
Patellar tendon rupture is a complete tear of the tendon connecting the kneecap (patella) to the shin bone (tibia), causing sudden severe knee pain, inability to straighten the leg, and loss of the extensor mechanism—a devastating injury that requires emergency surgical repair to restore knee function. These ruptures typically occur during forceful eccentric quadriceps contraction (landing from a jump, sudden deceleration, stumbling down stairs) in adults 30-50 years old, often with predisposing tendon weakening from chronic patellar tendinopathy, corticosteroid use, systemic diseases (diabetes, chronic kidney disease, rheumatoid arthritis), or prior knee surgery. Clinically, patients present with inability to lift the leg straight (positive straight leg raise test), palpable gap below the kneecap, high-riding patella on X-ray (patella alta), and large hemarthrosis (blood in joint). Treatment is almost always surgical—early repair within 2 weeks critical as delayed surgery has worse outcomes due to tendon retraction, muscle shortening, and scar tissue formation. Surgical repair involves reattaching torn tendon to patella with strong sutures, augmentation with wire or suture anchors, and often requiring tissue augmentation in chronic cases (allograft, synthetic graft, hamstring autograft). Recovery timeline: 4-6 months to regain full knee function, 6-12 months to return to high-level activities, with 75-85% achieving good functional outcomes if repaired early, though many have residual quadriceps weakness (10-20% weaker than uninjured leg).