summary A quadriceps tendon rupture is a traumatic injury of the quadriceps insertion on the patella leading to a disruption in the knee extensor mechanism. Diagnosis is made clinically with a palpable defect 2 cm proximal to the superior pole of the patella with inability to perform a straight leg raise and presence of patella baja on knee radiographs. Treatment may be nonoperative in patients with partial tears and intact extensor mechanism. Operative repair is indicated if there is disruption of the extensor mechanism. Epidemiology Incidence quadriceps tendon rupture is more common than patellar tendon rupture Demographics usually occurs in patients > 40 years of age males > females (up to 8:1) occurs in nondominant limb more than twice as often Anatomic location usually at insertion of tendon to the patella Risk factors renal failure diabetes rheumatoid arthritis hyperparathyroidism connective tissue disorders steroid use intraarticular injections (in 20-33%) Etiology Pathophysiology mechanism eccentric loading of the knee extensor mechanism often occurs when the foot is planted and knee is slightly bent in younger patients the mechanism is usually direct trauma Classification Rupture classified as either partial complete Anatomy Quadriceps tendon has been described as having 2 to 4 distinct layers important when distinguishing between partial and complete tear and when repairing tendon Presentation History often report a history of pain leading up to rupture consistent with an underlying tendonopathy Symptoms pain Physical exam tenderness at site of rupture palpable defect usually within 2 cm of superior pole of patella unable to extend the knee against resistance unable to perform straight leg raise with complete rupture Imaging Radiographs recommended views AP and lateral of knee findings will show patella baja MRI indications when there is uncertainty regarding diagnosis helps differentiate between a partial and complete tear Treatment Nonoperative knee immobilization in brace indications partial tear with intact knee extensor mechanism patients who cannot tolerate surgery Operative primary repair with reattachment to patella indications complete rupture with loss of extensor mechanism Techniques Primary repair of acute rupture approach midline incision to knee repair longitudinal drill holes in patella nonabsorbable sutures in tendon in a running locking fashion with ends free to be passed through osseous drill holes repair with suture anchors has been shown to have decreased gap formation and increased ultimate loads to failure retinaculum is repaired with heavy absorbable sutures ideally the knee should flex to 90 degrees after repair postoperative care initial immobilization in brace, cast, or splint eventual progressive flexibility and strengthening exercises Primary repair of chronic rupture approach midline to knee repair often the tendon retracts proximally ruptures >2 weeks old can retract 5cm repaired with a similar technique to acute ruptures but a tendon lengthening procedure may be necessary Codivilla procedure (V-Y lengthening) auto or allograft tissue may be needed to secure quadriceps tendon to patella Complications Strength deficit 33%-50% of patients Stiffness Functional impairment 50% of patients are unable to return to prior level of activity/ sports Re-rupture Risk is increased in the setting of pre-existing inflammatory arthropathy