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MPFL Reconstruction

What is patellar instability?

Patellar instability is a condition where the kneecap bone dislocates out of its joint either completely or partially. It often results from a combination of factors including acute trauma, chronic ligament laxity, bone malalignment, or other anatomical problems. Most acute patellar dislocations occur because of a non-contact twisting injury to the knee, or a direct blow to the inside of the knee.

Most patellar dislocations occur in young females ages 10-17. Over time, patients with patellar instability can have pain, limited function, and in the long-term develop post-traumatic osteoarthritis. Patellar dislocations account for 3% of all knee injuries.

The medial patellofemoral ligament (MPFL) is damaged after a patellar dislocation. If the patella dislocates for the first time, treatment is usually conservative. However, this can increase the risk of continuous symptoms including recurrent dislocations. Recurrent kneecap dislocations are a high as 44% after conservative treatment. Conservative treatment also increases the risk of patellar osteoarthritis. Moreover, a single previous dislocation is associated with the highest risk of persistent patellar instability later in life.

The primary indication for patellar stabilization surgery is recurrent kneecap dislocation. Recurrent dislocation often leads to chronic instability of the patellofemoral joint, causing pain, functional limitations, and damage to the articular surfaces of the knee joint. Candidates for this procedure typically have a history of multiple patellar dislocations or subluxations and have not responded to conservative treatments.

The most common procedure to correct patellar instability is a MPFL reconstruction. Ligament reconstruction involves removing the damaged ligament and replacing it with a tissue graft. In terms of graft choice, a hamstring graft from the patient’s knee or a donor tendon (allograft) can be used.  When an individual has additional risk factors such a high riding patella (patella alta) or an increase Q ankle (a measure of rotational alignment), an additional procedure such as a tibial tubercle osteotomy may also be necessary. The tibial tubercle is a bony bump on the shin bone where the patellar ligament attaches to patella.  A separate incision is made, and the tibial tubercle is carefully cut and repositioned to improve patellar alignment. It is fixed in place with screws.

The goal of MPFL reconstruction with or without tibial tubercle osteotomy is to reduce the risk of recurrent patellar dislocations and improve knee function. Patients often experience decreased pain and improved knee stability, enabling them to return to their daily activities and sports. A well-executed MPFL reconstruction restores stability while the TTO serves to unload the lateral and/or inferior patellar cartilage and correct osseous malalignment. Many studies report good clinical outcomes with MPFL with tibial tubercle osteotomy.

Schedule a knee consultation

Medial Patellofemoral Ligament (MPFL) reconstruction +/-tibial tubercle osteotomy is an important knee stabilizing procedure. The selection of an experienced surgeon is essential. Contact HyperRegen Sports Medicine in Toronto Canada to learn more.

At a Glance

Dr. Jas Chahal

  • Head of Orthopaedic Surgery, Women’s College Hospital
  • Team Physician Toronto FC and University of Toronto Varsity Blues
  • Associate Professor, University of Toronto Orthopaedic Sports Medicine Program
  • Has more than 100 peer-reviewed publications
  • Learn more

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