Patello-Femoral Syndrome

Patello-Femoral Syndrome or Chondromalacia Patella (of Greek origin meaning "softening of the cartilage") or "Runner's Knee"

Runners Knee refers to pain "primarily" on the inside of the knee, although pain on both sides or beneath the kneecap can also occur. It is more commonly seen in runners as opposed to walkers due to high level of activity, particularly mileage. The key element in this injury is due to over pronation causing a repeated stress of the patella bone moving abnormally from side to side over the groove of the thigh bone (femur), gradually softening the cartilage under the kneecap. The result is the surface of the joint can become rough. Pain may be just a prelude to further destruction of the surface (traumatic arthritis). This injury can be confused with "Patella tendonitis" which is usually pain beneath the patella bone. In either case it is the "tracking" of either the bone or tendon which needs to be addressed.

What is it?

Chondromalacia is a condition wherein the cartilage on the back of the patella (kneecap) is irritated and painful because it rubs against the medial femoral condyle.

What are the common symptoms/complaints?

Patients complain of pain felt under the kneecap on the medial side of the knee particularly while going up or down stairs and hills. Also pain and stiffness after prolonged sitting.

Causes of this injury can be:

  • Weak quads
  • Muscle imbalance
  • Direct or repeated trauma
  • An untreated ligament injury
  • Running on a banked surface (similar to ITB Syndrome)
  • History of trauma

During a normal gait cycle, the femur and the tibia rotate in unison (i.e. internally during pronation and externally during supination). However, Chondromalacia occurs when a person over-pronates because the tibia is locked into the Talus and therefore continues to rotate internally past the end of the contact phase (where supination starts at the beginning of midstance in a normal gait) while the femur receives its orders from the brain and begins to rotate externally at midstance. The resulting counter rotation of the femur and the tibia causes the patella to rub against the medial femoral condyle instead of moving smoothly up and down in its normal track, which causes the pain felt by the patient and the damage to the cartilage.

How is it treated?

Since the problem is caused by over-pronation, the patient should be fitted with orthotics and will likely experience pain relief within weeks and complete recovery within months (generally 2 - 3 months).

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