What is the role of the medial patellofemoral ligament (MPFL)?

The medial fin is a fibrous structure that joins the medial (inner) edge of the patella to the femur. The medial patellofemoral ligament (MPFL) plays a key role in patella stability.
Its role is to limit the lateral movement of the patella. Thus, it prevents it from dislocating towards the outside. It participates in the control of the passive stability of the patella, like a rope it tenses when requested. We can, for example, compare it to a dog’s leash attached to a tree. It only tenses up if the dog moves away from the tree, but it tenses up immediately. The muscles do not react immediately, there is a latency time.

What happens if the MPFL is torn or stretched?

During a sudden or rapid movement, the vastus medialis muscle is “surprised”. That is to say, he does not have time to react before the kneecap has strayed to the outer part of the knee. It’s too late, the kneecap has dislocated again.

Certainly, rehabilitation and training improve this reactivity but not to the point of providing the safety necessary for the practice of sport, with pivot or contact. Sometimes instability manifests itself as simple apprehension that limits your activities.
Additionally, one question helps highlight apprehension and lack of confidence in your knee: can you run down the stairs? If so, there is a good chance that your knee is perfectly stable.

MPFL reconstruction

It has become almost systematic in surgery for episodic patellar dislocation. The medial patellofemoral ligament is much more often reconstructed than repaired (sutured). To do this, we use a tendon graft which is transferred and fixed to the femur and the patella, where the medial patellofemoral ligament is inserted. It is uncommon to associate an advancement (retension) of the vastus medialis muscle.