Patellofemoral syndrome, also known as Chondromalacia Patella or runners’ knee, is a common condition of the knee and describes pain due to degeneration or abnormal changes of the cartilage under the knee cap (patella). This is often due to poor alignment of the knee cap as it slides over the lower end of the femur (thigh bone) with knee movement.
Causes of Injury
When the knee bends or straightens the quadriceps muscle pulls the knee cap over the end of the femur in a straight line. Commonly, abnormal patella tracking towards the lateral (outer) side of the femur will result in the under surface of the patella to wear away on the femur. This can cause chronic inflammation and frequently pain. There are a number of factors that can increase a person’s risk of developing patellofemoral pain. These include:
- Abnormal biomechanics of the knee or feet (knock-knee, flat feet)
- Tightness of the ITB (Iliotibial Band)- outer thigh
- Muscle weakness, especially of the muscle on the inside of the thigh (VMO) and the gluteals
- Repetitive activities involving a lot of bending of the knee while it is loaded, including stairs, walking on uneven surfaces, hills, jogging, squatting or prolonged sitting with the knee bent.
- Inappropriate footwear or training surface
- Poor training technique
There is generally no specific event or injury causing patella-femoral pain. Occasionally, however, it may follow an incident such as a fall onto or over-straightening (hyperextension) of the knee.
- Pain at the front of the knee and around or under the knee cap. Usually a dull ache but can become sharp with activity
- Aggravated by activities such as going down stairs or hills, squatting, running or jumping.
- Occasionally clicking or grinding sound when bend and straighten the knee
The primary aim of treatment is to reduce pain and any inflammation that may be present. Gradual progression of a rehabilitation program by a physiotherapist is important to correct contributing factors and ensure return to full activity. Treatment and management options include:
- Sufficient rest from any aggravating activity or activities which place large amounts of stress through the patellofemoral joint.
- Low impact exercise, such as swimming or stationary cycling, can allow fitness to be maintained without causing further injury
- Reduce inflammation through rest, ice, physiotherapy. Anti-inflammatory medication as recommended by a doctor or pharmacist may also assist in the healing process.
- Pain free strengthening exercises, particularly of the VMO muscle
- Regular stretching of tight muscle groups, particularly ITB (muscle on the outside of the leg), hamstrings, calf and hip muscles
- Taping of the knee cap may help to alter the ‘tracking’ of the knee cap and bring it back to alignment
- Correction of any abnormalities in lower limb biomechanics through the use of arch supports and orthotics
Return to Sport/Activity
Complete rest will lead to weakness of the thigh muscles, which is undesirable. Swimming is a great form of exercise that does not place excessive load on the knee joint. Exercises such as this can be used to maintain fitness while allowing the knee time to recover fully. A physiotherapist can guide you through an individual exercise program, including a gradual increase to normal activity. Provided the person is compliant with exercises provided, the expected outcome is very good.
Further treatment is rarely required and would be considered only as a last resort with severe or persistent cases. Arthroscopic surgery to smooth the surface under the knee cap, or a ‘lateral release’ to reduce pull on the knee cap are the two most common surgery options.