The knee joint is made up of 2 joints; the tibia-femoral joint and the patellofemoral joint. Patella femoral pain comes from irritation of structures in the front of the knee. Symptoms occur during activities such as running, squatting, kneeling or sitting with a bent knee for an extended period of time. This can present as clicking or a dull ache in the front of the knee. Sometimes symptoms can produce a feeling of instability in the knee.
The knee cap floats in a groove on top of the femur. It can move up, down, tilt and rotate. With all these motions there are various points of contact between the under surface of the knee cap and the groove on the femur. Repetitive contact combined with maltracking of the patella is the likely mechanism of Patellofemoral Pain Syndrome (PFPS). The etiology of PFPS are biomechanical, muscular, or overuse.
Repeated weight bearing in activities that involve bending the knee such as running, cause an increase pressure under the knee cap. As the pressure builds, it can lead to irritation of the joint. Stairs, hills, and uneven surfaces can exacerbate the pain as well as prolonged sitting.
Biomechanical factors such as flat feet, rigid arches, and a large “Q” angle ( angle from the hip to the knee) can cause patellofemoral pain. Any of these factors can alter the way the knee cap fits in the groove. The groove can also be too shallow and cause knee cap pain.
Muscular causes are causes by an imbalance between the quadricep and hamstring as well as a weakness in the hip external rotators and tightness of the hip flexors.
Physical Therapy is the primary treatment option for patients suffering from PFPS. Exercises that focus on strengthening the quadriceps, hip external rotators and the core without aggravating the injury are prescribed. Treatment consists of strengthening, stretching, neuromuscular re-education, anti-inflammatory modalities, soft tissue mobilization and joint mobilization.
When extensive conservative treatment does not reach expected outcomes or the patients biomechanics are severe, surgical intervention is necessary. Surgery is done to normalize the tracking of the patella. There are 2 surgeries which can change the biomechanics of the joint. one is Medial Patellofemoral Ligament reconstruction. This surgery is more for patients who repeatedly dislocate their patella. The other procedure is a a high tibial osteotomy which is the anteromedialization of the tibial tubercle. Both procedures require extensive rehabilitation and take 6 months to a year to return to full activity.