Chondromalacia Patellae

Knee anatomy and Mechanics:

Three bones meet in the knee: the thighbone (femur), the shinbone (tibia), and the kneecap (patella). When the leg moves, the kneecap slides along a shallow groove in the femur known as the trochlear groove. The joint is cushioned and made smooth by articular cartilage, which wraps around the ends of all the bones in the joint. Repeated abnormal stress of the joint, whether due to age, injury, abnormal alignment or muscle weakness, can weaken and soften the articular cartilage. Doctors estimate that about one-half of all non-injury knee pain complaints are due to this disorder.

When afflicted with the condition, the patient's knee rubs against the trochlear groove, instead of gliding smoothly across it. The damage may range from a slight abnormality of the surface of the cartilage to a surface that has been worn away completely to the bone. Anterior knee pain can present a diagnostic challenge because of the complex anatomy of the knee.

Note: There are other causes of anterior knee pain not considered here, which include scar tissue (plicae), patellar tendonitis and other soft tissue abnormalities.

Symptoms (Chondromalacia patellae):

  • Pain in the front of the knee, especially when using stairs or climbing up or down hills
  • Squatting, lunging
  • Pain may radiate toward back of knee
  • Cracking or grating in the knee
  • Knee seems to “catch”

Cause and Risk Factors:

  • Overuse when an abnormality exists
  • Chronic Injury
  • Muscle weakness (vastus medialis muscle)

Risk Factors:

  • Risk factors include participation in high-impact sports like running, skiing, soccer and high-impact aerobics when a previous abnormality exists. These sports do not cause chondromalacia themselves. Trauma to the front of the knee can cause a cartilage injury.
  • The Q-Angle, the angle formed by the thighbone and the patellar tendon, is also a major factor in the development of anterior knee pain syndrome.
  • Quickly growing teenage women most often have a more acute Q-angle than others, and are thus at the highest risk group for developing the condition.
  • Old age.
  • Knock-kneed or bow-legged stance also increase the risk for developing anterior knee pain syndrome. 

Treatment   (Immediate care):

  • Take aspirin or an anti-inflammatory medication, such as ibuprofen for a week.
  • Avoid kneeling, climbing too many stairs, or sitting too long.
  • Avoid jumping sports like basketball or volleyball.
  • At your doctor’s advice, do low-impact exercises to strengthen the knee muscles. S/he may refer you to a therapist for exercises.
  • Using knee supports can sometimes help avoid further injury.
  • Call your knee specialist doctor if the following does not cure the symptoms.

Injections: 

Cortisone injections can help reduce the inflammation within the joint capsule. It would be more beneficial to combine Physical therapy with injection therapy. Hyaluronate (often referred to as “Chicken shots”) injections can be helpful if the underlying cause is degenerative arthritis of the joint. 

Surgical Procedures:

Surgery may be necessary in some cases. Your surgeon or physician may recommend arthroscopy surgery to assess the extent of the injury and smooth the surface of the cartilage. Other procedures to correct alignment of the kneecap may be undertaken simultaneously.

Prevention:

Check with your doctor before beginning any sport or exercise routine. Also, stay away from activities that require deep knee bending especially if you are at risk for chondromalacia patellae or already have low-grade knee symptoms.  Physical therapy guided exercises are recommended.

Strengthening Exercises:

The best exercises for chondromalacia tend to be those that focus on the hip (gluteal exercises) and flexibility exercises. An exercise that directly put force through the knee, especially the knee extension exercise is not appropriate and usually painful. Swimming is a good overall exercise. Bicycling can sometimes be an irritant for chondromalacia in some people, but in others it can be a very good exercise. Do not do it or any exercise, if it reproduces your pain. A physical therapist can instruct the proper exercise program specific to your needs and other health factors.