Patellofemoral Dysfunction (PDF)

What is PFD?


Do you ever have pain or aching in your knees that you can’t quite describe? One day the pain appears in one area of your knee and the next day maybe even your other knee hurts. Do you knees ache, pop or grind when walking up or down stairs? Have you asked your doctor about this hard to describe knee pain and they have told you “there is nothing I can do for you, just stop doing the activity that makes your knee(s) hurt”… Are you frustrated and at a loss as to what to do next? If so, and if this sounds all too familiar you are not alone.


Patellofemoral Dysfunction or PFD is a common orthopedic challenge experience by both men and women of all ages. Every year approximately 2.4 million Americans are treated for pain in the front of the knee and around the kneecap. In a great number of these cases, the cause of knee pain is a malaligned kneecap. The medical term for kneecap is patella. PFD can also be caused by insufficient strength of an important muscle on the inside of the upper leg called the Vastus Medialis Obliqus, or the VMO muscle.

Patellofemoral Dysfunction

When the kneecap is functioning correctly, it glides smoothly in the bony notch of the thighbone or femur without causing irritation. When the kneecap is malaligned, irritation can occur on the various surfaces of the knee joint, especially when the patella comes in contact with the femur. You may have one or more of the following four patellar malalignments. They are tilt, glide, rotation, and anterior/posterior which is also referred to as A/P.


Patellar tilt is typically toward the outside, or lateral side of the leg. When lateral tilt occurs, the surface of the kneecap is at an abnormal angle at the end of the femur. As a result, the kneecap rides over the outside edge of the bony prominence of the femur resulting in wearing down of the kneecap cartilage. One of the symptoms of tilt is a weakened Vastis Medialis Obliques muscle. Since the VMO is essential to keeping the patella tracking correctly, its lack of strength will contribute to an even greater malalignment.


With a glide condition, the entire kneecap is shifted to the outside of the joint. Glide can be seen by comparing the inside and outside portions of the kneecap to its position relative to the femur. Once again, any malalignment will cause irritation to the underside of the patella and the surface of the femur bone.


In a knee with a rotation malalignment, the kneecap’s midline is not parallel to the axis of the femur. Rotation of the kneecap can result in wear and tear on the patellar cartilage and a disadvantaged kneecap position which will inhibit the VMO muscles ability to contract.


Anterior/Posterior malalignment occurs when the lower edge of the kneecap is tilted downward toward the lower leg bone or tibia. The lower edge of the kneecap becomes buried in the fat pad below the patella and puts pressure on the major kneecap tendon. This can result in pain centered at the lower edge of the kneecap, irritation of the fat pad and inflammation of the kneecap tendon.

Treatment for PFD

Please follow to theTreatment Section

© OrthoRx, Inc. 2007         Site made by Novowebsoft