Chondromalacia Patella results from an inflammation of the articular cartilage on the back of the patella (kneecap), which becomes irritated as it rubs against the medial femoral condyle (inner bottom of the thighbone). As the condition advances, the articular cartilage can soften and wear away, resulting in extreme pain, although symptoms of CP generally tend to vary. In severe cases, the cartilage will wear away completely, and the bone will be exposed. This may occur in only a small area, or it can involve the entire surface of the patella.

While the knee is the largest joint in the human body, and is subject to gigantic amounts of stress, it relies almost entirely on soft tissue (i.e. ligaments, muscles, tendons) for support. These tissues are put under great stress every day, through commonplace activities such as walking, which exerts a patello-femoral force of approximately 1/2 the person's body weight, climbing stairs (which can exert of force ranging from 3-8 times the person's body weight), and rising from a crouching position, which can generate forces of up to 8 times the body weight.

Chondromalacia Patella can occur for a number of reasons. These include:

  • Overpronation- The lower leg rolls inward as a result of foot pronation. The knee is pushed to the outside, which causes increased pressure to be placed on the patella.
  • Trauma- Either direct or repeated trauma can cause CP, meaning it could arise as a result of a fall or a blow to the knee region, or from constant minor trauma, such as seen during weightlifting.
  • Muscle imbalances- This is most commonly seen when the muscles on the outside of the leg are stronger than those on the inside. This results in the patella being pulled to one side, which in turn can result in CP. This is more commonly seen in women, as their wider pelvis causes their thigh muscles to lean loward their knees at a wider angle than those of men.
  • Weak Quadriceps- The quadriceps are crucial to the proper tracking of the kneecap; weak quadriceps muscles can often contribute to the development of CP.
  • Running in the same direction- Runners who stick to only one side of the road often develop symptoms of CP. The tilt in the road can accentuate foot pronation, which is a cause of CP. CP is so common among runners that it is often referred to as Runner's Knee, and experts estimate that up to 30% of runners are afflicted by the condition to some degree.

The most noticable symptom of CP is pain, which is strongest when the affected person kneels down, climbs or descends stairs, or performs some sort of exercise invloving leg extension against resistance. Also, when the knee is extended, an affected person will often feel grinding under the kneecap, and will notice crackling and popping (crepitus) beneath or on both sides of the patella. Stiffness can also result after sitting for long periods of time, or descending stairs.

The pain will usually develop for about a year's time, until it gets so bad that the patient will seek medical help. CP is quite common, and accounts for 25% of the overuse injuries treated in sports clinics.

Once a person finds out they have the condition, they will generally be advised to decrease their activity level, and possibly take up some new modes of exercise which don't put weight on a bent knee. These include things like swimming and cross-country skiing. If the knee is painful and swollen, it is recommended the the patient cease all exercise and get some rest.

The knee(s) should be iced for 15 minutes twice daily, and anti-inflammatories (i.e. asprin, ibuprofen) are recommended to ease swelling and pain. Often, a neoprene brace can be helpful while exercising, to provide support to the quadriceps muscles and maintain normal patellar tracking. To prevent further damage to the knee, it is advisable to make sure that one always wears shoes with good support that haven't been worn out. Also, runners ought to stay away from uneven, hilly surfaces. If conservative methods of treatment prove uneffective, arthroscopic surgery is an option as a last resort.