Patellar Instability and MPFL Reconstruction

A kneecap dislocation is violent and memorable: the knee buckles, the patella visibly shifts, and the joint swells impressively. For some, it is a one-time event. But for many, especially teenagers and young adults, the first dislocation is the beginning of a pattern, because the initial injury tears the medial patellofemoral ligament (MPFL), the checkrein that holds the kneecap centered. Each subsequent dislocation risks shearing off cartilage, which is why recurrent instability is worth treating rather than enduring.

Some knees are simply built with more dislocation risk: a shallow groove (trochlear dysplasia), a kneecap that sits high (patella alta), or alignment that pulls the patella outward. Add a sports pivot or a direct blow, and the MPFL tears as the kneecap escapes the groove. Understanding each patient’s specific anatomy, through exam, X-rays, and often MRI or CT with standardized measurements, is the foundation of good treatment, because the operation should match the anatomy.

Most first-time dislocations without a loose cartilage fragment are treated nonoperatively: a short period of protection, then dedicated therapy to rebuild quadriceps and hip control. Surgery after a first dislocation is generally reserved for cases with a loose body, a cartilage injury needing treatment, or anatomy that makes recurrence very likely. This is also the visit where risk gets discussed honestly, because recurrence rates in young patients with risky anatomy are substantial.

For recurrent instability, MPFL reconstruction rebuilds the torn checkrein using a small tendon graft anchored between the kneecap and femur. It restores the passive restraint that keeps the patella tracking in its groove. When imaging shows significant underlying malalignment, Dr. Lyons may recommend combining the MPFL with a tibial tubercle osteotomy, repositioning the attachment of the patellar tendon, or addressing the groove itself, so that the reconstruction is not asked to fight the skeleton for the rest of your life.

MPFL reconstruction typically allows early motion and weight-bearing in a brace, with progressive strengthening over the following months and return to cutting sports once strength and control criteria are met. Most patients describe the biggest change simply: the knee stops feeling like it is about to go.