Summary A traumatic rupture of the patellar tendon caused by a tension overload during activity in a patient at risk. Diagnosis can be confirmed by physical exam and radiographs for complete tears. Partial tears may need an MRI to confirm the diagnosis. Treatment for complete tears is timely surgical repair to optimize the chance of healing. Partial tears with an intact extensor mechanism may be treated with immobilization. Epidemiology Incidence rare affects < 1 per 100,000 people annually Demographic most commonly in 3rd and 4th decade male > female Anatomic location quadriceps tendon rupture is more common than patella tendon rupture (2:1 ratio) Risk factors may see weakening of collagen structure systemic diseases login to view 5 more bullets local login to view 3 more bullets other login to view 1 more bullet Etiology Pathophysiology mechanism of injury tensile overload of the extensor mechanism login to view 1 more bullet most ruptures occur with knee in flexed position login to view 3 more bullets pathoanatomy 3 patterns of injury login to view 4 more bullets pathobiology rupture is usually the result of end stage or long-standing chronic tendon degeneration Associated conditions orthopedic conditions tibial tubercle avulsion patella fractures TKA extensor mechanism rupture Anatomy Extensor mechanism of the knee quadriceps tendon patella patellar tendon tibial tubercle Blood supply infrapatellar fat pad retinacular structures (medial and lateral inferior geniculate arteries) Biomechanics Forces in patellar tendon ascending stairs is 3x body weight to rupture a normal tendon is 17x body weight Classification Anatomic incomplete tear intact extensor mechanism in some cases can be treated noperatively complete tear patella alta with palpable defect treated with surgical repair Presentation History history of jumping event with sudden quadriceps contraction with knee in a flexed position (e.g., jumping sports, missing step on stairs) patient will often hear/feel a popping sensation Symptoms infrapatellar pain immediate swelling difficulty weight-bearing Physical exam inspection elevation of patella height usually associated with a large hemarthrosis and ecchymosis localized tenderness palpable gap below the inferior pole of the patella motion reduced ROM of knee (and difficulty bearing weight) due to pain login to view 1 more bullet provocative tests straight leg raise login to view 1 more bullet Imaging Radiographs recommended views AP and lateral of the knee login to view 1 more bullet optional views merchant or skyline findings patella alta seen in complete rupture various measurements indicating patella alta login to view 6 more bullets MRI indications differentiate partial from complete tendon rupture most sensitive imaging modality findings site of disruption, tendon degeneration, patellar position, and associated soft tissue injuries Ultrasound indications suspected acute and chronic injuries findings effective at detecting and localizing disruption operator and user-dependent Diagnosis Complete tears can be confirmed by physical exam and radiographs for complete tears. Partial tears partial tears may need an MRI to confirm the diagnosis. Treatment Nonoperative immobilization in full extension indications login to view 1 more bullet modalities login to view 4 more bullets Operative primary repair indications login to view 2 more bullets techniques login to view 3 more bullets rehabilitation login to view 2 more bullets outcomes login to view 2 more bullets tendon reconstruction indications login to view 2 more bullets techniques login to view 3 more bullets Techniques Nonoperative Treatment - Immobilization protocol similar to post-operative protocol below Direct primary repair approach longitudinal midline incision expose rupture and adjacent retinacula debride the ends of the rupture for subacute tears (> 2 weeks out from injury) login to view 1 more bullet technique end-to-end technique login to view 2 more bullets transosseous tendon repair login to view 3 more bullets suture anchor tendon repair login to view 3 more bullets postoperative rehabilitation weight bearing login to view 2 more bullets early motion login to view 6 more bullets return to sport login to view 1 more bullet Tendon reconstruction approach retracted patella may require extensive surgical release login to view 2 more bullets technique graft sources login to view 3 more bullets technique login to view 1 more bullet Complications Knee stiffness incidence most common complication risk factors delay in surgical treatment delay in initiating post-operative range of motion treatment manipulation under anesthesia (MUA) login to view 1 more bullet lysis of adhesions login to view 1 more bullet Re-tear incidence ~8% with transosseous direct primary repair login to view 1 more bullet treatment primary repair login to view 1 more bullet reconstruction login to view 2 more bullets Infection incidence ~2% following surgery Quadriceps atrophy incidence 2nd most common complication login to view 1 more bullet treatment physical therapy Prognosis Outcome with treatment excellent outcomes seen with early repair Prognostic variables most important prognostic factor for complete tears is timing of repair