Kneecap Dislocation (MPFL Injury)

Knee Conditions

What is the MPFL (Medial patella-femoral ligament)?

The medial patellofemoral ligament is a broad structure located on the medial side (inside) of the knee joint. It connects the patella (kneecap) to the femur (thigh bone). It provides stability to the patella by acting as a restraint to any lateral displacement (outward directed force) to the patella during the early parts of knee flexion (the knee bending a few degrees from a straight position). 


How is MPFL injury diagnosed?

For patients suffering with recurrent dislocations of the patella or subluxations (almost dislocating) an MRI scan helps in confirming the diagnosis. An Xray may be useful to confirm an avulsion fracture of the medial edge of the patella (where the ligament has pulled of its bone attachment to the inner border of the kneecap). 


How is an MPFL injury treated?

An MPFL reconstruction is performed through a combination of arthroscopic (keyhole) surgery and small incisions to pass a single tendon graft (usually a single hamstring tendon ) either taken from the same patient or from a donor through a small bone tunnel in the patella and the femur where it is secured with a special mechanical device. In most cases, patients may be able to go home the same or next day partial weight bearing for between 2-4 weeks (taking some of their body weight but using crutches ) before progressing onto full weight bearing . Many patients return to their usual activities around three months after surgery.

Kneecap Dislocation Page