Patella Instability Surgery

Patellar (or kneecap) dislocations are common injuries and affect mainly adolescents and young adults. In this condition, the patella moves out of its usual location in the front of the knee to the lateral or outer side of the knee. This can occur because of direct trauma or a twisting injury of the knee. 

The risk factors for patella dislocations include generalized ligamentous laxity, a valgus (or knock-knee) deformity of the knee and a shallow trochlea (groove for the patella) in the front of the knee. ​The diagnosis of a patella dislocation is made after a thorough clinical assessment of the knee. MRI scans are done to confirm the diagnosis and to look for concomitant knee injuries and anatomical risk factors. First-time acute patella dislocations are usually treated with a period of immobilization of the knee. Surgery is usually not required unless there is a significant cartilage injury that needs to be addressed. 

In patients who have recurrent patella dislocations and symptoms of patella instability, reconstructive surgery is needed to improve patella stability. The most common surgical procedure that is performed is called a medial patellofemoral ligament (MPFL) reconstruction. The surgery involves drilling two bone tunnels in the inner or medial side of the patella and another bone tunnel in the medial or inner side of the knee. A hamstring tendon graft is then passed through and secured within these tunnels to serve as a check-rein to prevent further lateral or outward dislocation of the patella. 

Sometimes additional concomitant procedures may need to be carried out to ensure patella stability. These include tibial tubercle (or shin bone) transfers and trochlea (or thigh-bone groove) reshaping. An overnight stay in hospital is usually required after such reconstructive surgery and 1-2 weeks of crutch-assisted ambulation may be advised. 


The rehabilitation process after the surgery consists of progressive knee range of motion and muscle strengthening exercises, as well as functional recovery. It may last up to 6-9 months following the procedure. The success rate of patella instability surgery has been reported to be about 80-90%. The complications of this procedure include infection, knee stiffness and recurrent patella instability.

For more information, please contact us.

 

The MRI image on the left shows lateral tilting of the patella (arrowed), which is sometimes seen in patients with patella instability. The Xray image on the right shows the tunnels that are created in the patella (kneecap) and femur (thigh bone) during MPFL reconstruction.

Patella Instability MRI copy.jpg
MPFL Recon Xray copy.jpg
 

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