Dr. Beth Shubin Stein

A kneecap dislocation is startling. The knee gives way, the patella (kneecap) slips out of its groove, and it often pops back on its own or needs to be put back by a medical professional. For many people it happens once and never again. For others it keeps recurring, and that is where MPFL reconstruction often comes into the conversation. This guide covers what the MPFL is, who may need surgery, what the procedure involves, and what recovery typically looks like. What Is the MPFL? The medial patellofemoral ligament (MPFL) is a thin band of tissue on the inner side of the knee. It connects the kneecap to the thigh bone (femur). Its main job is to keep the patella tracking in the center of its groove, called the trochlea, as the knee bends and straightens. Of the structures that stabilize the kneecap, the MPFL is the main restraint against the patella sliding outward, especially in the first 20 to 30 degrees of knee bending. When the kneecap dislocates, the MPFL is almost always stretch...

  A kneecap dislocation is one of those injuries that looks worse than it sounds — until the kneecap slips back into place and the real question begins: how much damage was actually done? For most patients, that question comes down to the medial patellofemoral ligament, or MPFL, the primary soft-tissue structure holding the kneecap in its groove. Whether that ligament is merely stretched (a sprain) or fully torn changes everything about the recovery timeline, the treatment plan, and the risk of it happening again. Because the two injuries can feel almost identical in the first 48 hours — swelling, pain, a knee that doesn't feel "trustworthy" — patients often can't tell them apart on their own. Here's how physicians actually make that distinction. What the MPFL Does, and Why It Fails The MPFL is a thin band of tissue running from the inner edge of the kneecap to the femur. Its job is almost entirely passive: it acts like a checkrein, resisting the tendency of the p...