Patellofemoral pain syndrome

Patellofemoral pain syndrome

Chondromalacia Patella

Patellofemoral pain syndrome is the most commonly diagnosed cause of chronic knee pain. It results from damage to the cartilage on the under surface of the patella (the kneecap), following which the patella rubs over the femur during movement, leading to pain and inflammation. It is common among young adults, especially those involved in sports such as soccer, running, cycling or in ballet dancing. The problem is more prevalent in females.


 

The knee is formed by the union of four bones:

Femur (the thigh bone)
Tibia (the shin bone)
Fibula (a smaller leg bone)
Patella (the kneecap)

At the front of the knee, the femur articulates with the patella. The articulating end of the femur has two rounded heads separated by a small groove. When the knee is extended or flexed, the patella slides vertically up and down in this groove.


The articulating end of the femur is covered with cartilage. There is additional cartilage adhered to the posterior surface of the patella, interposed between the patella and the femur. This cartilage not only acts as a shock absorber, but also serves to reduce friction as the patella glides in the femoral groove during joint movement.


 

Femoral (Trochlear) groove

Cause:

Chondromalacia patella refers to an abnormal softening or degeneration of the patellar cartilage resulting from:

- Excessive stresses on the cartilage by repeated intense activity such as running, jumping, skiing, etc.
- Maltracking of the patella:

Normally the patella glides in the femoral groove, with articulating cartilage providing a smooth, almost frictionless movement. However, in some cases, for example due to muscle power imbalance, the patella slides outwards, leaving its normal track.

- Direct trauma to the knee damaging the cartilage
- Joint disease such as arthritis involving the cartilage
- Anatomical variations such as a very high patella, a large Q angle (as in females)
- Over-pronation, knock-knees

Symptoms:

  • Pain at the front and inside of the knee
  • Pain worsens after activity such as walking, running, and going up and down stairs, or after sitting for prolonged periods (as while watching a movie, hence it is sometimes known as “movie sign” or “theatre sign”)
  • A clicking or grinding sound when the knee is extended
  • Pressing on the extended knee elicits pain
  • Mild swelling, weakness and wasting of quadriceps (anterior thigh muscles)

Diagnosis:

Symptoms and physical examination usually reveal the problem. The kneecap is tender, especially when pressed while extending the knee. Bending the knee also elicits a painful grinding sensation inside the knee cap.

Patellar malalignment may be visible clinically.

X-rays carried out at a specific angle may reveal signs of inflammation of the patellar cartilage.

Treatment:

Early treatment involves relieving pain and preventing further deterioration.

Cessation of any painful activity, training modification or complete rest is recommended.

Ice application helps to alleviate pain

Gentle compression of the area, taping and knee-supporting braces all help to stabilise the knee and reduce discomfort.

Orthotic devices are recommended to correct any biomechanical abnormalities.

NSAIDs may be used to overcome severe pain.

Rehabilitation:

A proper rehabilitation program should be followed to:

  • Reduce pain and further damage to the joint
  • Correct any muscle imbalances (by strengthening weak muscles)
  • Compensate for weak or loose ligaments
  • Improve flexibility
  • Safely return to normal activity level, meanwhile reducing the risk of recurrence in the future

Taping:

Taping is applied to support the kneecap and prevent its maltracking. It also helps to stabilise the knee during movement, thus reducing pain and allowing one to keep up with the rehabilitation exercises.

It can be applied all day long if routine activities such as walking or climbing stairs are painful.

Stretching:

  • Care must be taken to resume activity gradually. Start with stretching the thigh muscles and iliotibial band. Stretching the structures on the outer aspect of the thigh helps to relax the lateral forces on the patella and limit its miss tracking, if present.
  • Stretch other leg muscles as well.
  • Stretch mildly to the extent that it remains painless. Hold the stretch for a few seconds, i.e,. up to 20 seconds or more if it doesn’t hurt.

Strengthening:

Strong quadriceps prevent patellar maltracking. The main focus is on the inner thigh muscle (vastus medialis oblique) as it exerts medial pull on the patella, keeping it inside the femoral groove during movement.


Action of the VM (Vastus medialis) on the knee cap

If the problem is a large Q angle, working on the hip abductors (Gluteus, Tenser fascia lata) helps.




Increased angulation of quadriceps in case of increased Q angle results in greater lateral force on patella

Sports massage not only aids in improving circulation to the area, but also helps relax the tense lateral thigh muscles. It should be started when the pain subsides and should be performed regularly.

Rehabilitation also involves correcting functional abnormalities such as overpronation.

Surgery:

The procedures used are:

  • Removing damaged cartilage through arthroscopy.
  • Correcting the alignment of the kneecap.

Surgery is rarely required as the problem usually resolves with strict adherence to the rehabilitation program.