Patellar tendon rupture

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Patellar tendon rupture
Patellar tendon rupture.JPG
Patellar tendon rupture showing a marked distance between the tibial tuberosity and the bottom of the patella.
Classification and external resources
ICD-10 S76.1
ICD-9 727.66
eMedicine article/1249472

Patellar tendon rupture is a rupture of the tendon that connects the patella to the tibia. The superior portion of the patellar tendon attaches on the posterior portion of the patella, and the posterior portion of the patella tendon attaches to the tibial tubercle on the front of the tibia. Above the patella are the quadriceps muscle (large muscles on the front of the thigh), the quadriceps tendon attaches to the top of the patella. This structure allows the knee to flex and extend, allowing use of basic functions such as walking and running.

There are three possible forms of patellar tendon rupture. The first form of rupture is a complete tear. In a complete tear, the tendon separates completely from the top of the tibia which results in the inability to straighten one's leg. When the tendon tears, it can break a piece of the bone off of the kneecap. The second form of rupturing the patellar tendon is a partial tear. A partial tear is when some of the fibers of the patellar tendon are torn but the majority of the tendon is still attached to the soft tissue located at the posterior end of the patella bone. The third form of rupture is caused by patellar tendinitis ("jumper's knee"). Patellar tendinitis causes the tendon to be torn in the middle due to the tissue damage it has been acquiring from over-use. Patellar tendonitis is inflammation of the tendon which results in the weakening of the tendon. Tendonitis is caused by excessive jumping or running without sufficient rest.

The tell-tale sign of a ruptured patella tendon is the movement of the patella further up the quadriceps. When rupture occurs, the patella loses support from the tibia and moves toward the hip when the quadriceps muscle contracts, hindering the leg's ability to extend. This means that those affected cannot stand, as their knee buckles and gives way when they attempt to do so.


Patellar tendon rupture can usually be diagnosed by physical examination and X-Ray. Partial tears may be visualized using MRI scans. Patellar tendon rupture is diagnosed by recognising that the patella has moved upward along the thigh compared to Blumensaat's line.


Patellar tendon rupture must be treated through surgery. In the surgery, an incision is made in the skin over the rupture, the site of which is identified. The tendons are retracted so surgeons may inspect the femur. The tendon ends are then sewn together.

A cast or brace is then put over where the operation took place. The cast or brace remains for at least 6 weeks followed by an unidentified time of rehabilitation of the knee.

The usual risks of surgery are involved, including: infection, stiffness, death, suture reaction, failure of satisfactory healing, risks of anesthesia, phlebitis, pulmonary embolus, and persistent pain or weakness after the injury and repair.

If the tendon rupture is a partial tear (without the two parts of the tendon being separated) then non-surgical methods of treatment may suffice. The future of non-surgical care for partial patella tendon ruptures is likely bioengineering. Ligament reconstruction is possible using mesenchymal stem cells and a silk scaffold.[1] These same stem cells have been shown to be capable of seeding repair of damaged animal tendons.[2]


  1. ^ Fan H, Liu H, Wong EJ, Toh SL, Goh JC (August 2008). "In vivo study of anterior cruciate ligament regeneration using mesenchymal stem cells and silk scaffold". Biomaterials 29 (23): 3324–37. doi:10.1016/j.biomaterials.2008.04.012. PMID 18462787. 
  2. ^ Long JH, Qi M, Huang XY, Lei SR, Ren LC (June 2005). "[Repair of rabbit tendon by autologous bone marrow mesenchymal stem cells]". Zhonghua Shao Shang Za Zhi (in Chinese) 21 (3): 210–2. PMID 15996290. 

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