Chondromalacia patella (CMP) involves damage to the articular cartilage which is the smooth hard cartilage under the kneecap. Symptoms are similar to patellofemoral pain as the kneecap rubs on the bone underneath causing swelling and pain. Here we explain the injury as well as treatment, strapping and exercises.
Symptoms are similar to that of patellofemoral pain syndrome with pain and swelling at the front of the knee especially over and around the kneecap or patella. It is often worse when walking downstairs or after sitting for long periods, known as movie-goers knee or theatre knee. A grinding or clicking feeling called crepitus can be felt when bending and straightening the knee.
What is chondromalacia patella?
CMP results from damage to the cartilage which covers the back of the patella or kneecap. This smooth hard cartilage is known as hyaline cartilage or articular cartilage and its purpose is to allow smooth movement of the patella over the femur or thigh bone in the knee. There are different stages or grades of injury depending on how much of the surface has been damaged.
The cause can be either acute from a sudden impact or from a long-standing overuse injury. Acute injuries normally occur when the front of the kneecap suffers an impact, such as falling directly onto it or being hit from the front. This results is small tears or roughening of the cartilage. In overuse cases, the cause of the damage is usually repetitive rubbing of part of the cartilage against the underlying bone.
In a healthy knee, the movement of the Patella across the knee is a smooth gliding movement. In individuals with CMP, the kneecap rubs against the part of the joint behind it, resulting in inflammation, degeneration and pain.
This can be for a number of reasons but is usually due to the position of the patella itself. The most common feature of CMP is patella mal-tracking. Usually, the patella moves sideways towards the outside of the knee due to muscle imbalances. The quadriceps muscles and other tissues such as the retinaculum are too tight on the outside of the knee and the vastus medialis oblique muscle is weak on the inside of the knee.
Other structural problems include Patella Alta, which refers to a high patella and patella Baja which refers to a low patella.
Chondromalacia patellae are common in young athletes who are often otherwise injury free. Its incidence is also highest in women due to their higher Q angle. It is also more common in those who have experienced previous traumatic knee injuries such as fractures and dislocations.
CMP is often confused with PatelloFemoral Pain Syndrome (PFPS) as CMP is often a result of PFPS. However, they can both occur in isolation.
Other than rest and applying ice and compression to reduce swelling there is not much the athlete can do themselves to cure Chondromalacia patella. The causes need to be identified and corrected if possible. A sports medical professional will advise on treatment and rehabilitation program consisting of the following:
Knee joint assessment - Assessing the knee joint to confirm the diagnosis and rule out other injuries is important. Swelling, range of movement and pain levels as well as look at any muscle wasting or tight structures in the knee which may be contributing to the Chondromalacia patella can be determined. They will also look at biomechanical factors such as over pronation where the foot rolls in or flattens causing the lower leg to rotate and knee to twist.
You may be referred for x-rays to help confirm the diagnosis. However, standard x-rays are often normal in this condition, although they may rule out other injuries. An MRI scan may be ordered instead of an x-ray as this is more likely to confirm the diagnosis.
Reducing pain and inflammation - Rest and application of cold therapy and compression wraps can help reduce pain and swelling in the knee joint. A doctor may prescribe anti-inflammatory medication such as ibuprofen.This will help reduce pain, inflammation and swelling. Check with a doctor before taking medication as Ibuprofen should not be taken if you have asthma.
Patella taping to encourage correct tracking of the kneecap is often done and can instantly reduce pain by preventing the kneecap constantly rubbing on the sore spot. We demonstrate two different patella taping techniques. This first patella taping technique is done to control the position of the patella and is often applied for performing CMP exercises. The second general patella taping technique is ideal for returning to sport as it encourages correct patella tracking but is not restrictive. A patella knee support can help support the patella and relieve pain.
Exercises - A full knee rehabilitation program with specific exercises should be done. Exercises are usually aimed at increasing the strength of the vastus medialis muscle on the inside of the knee and stretching the lateral quadricep muscle on the outside of the knee. Sports massage can help relax the lateral structures of the knee.
Surgery is not common although can be a last resort if exercise rehabilitation has not worked. Surgery is via an arthroscopy or keyhole surgery where the damaged cartilage is removed or shaved off.