Chondromalacia Patellae, CMP (Runner's Knee)
Runner’s knee is referred to as chondromalacia patellae or CMP. Chondromalacia refers to the softening of the cartilage. Runner’s knee is a degenerative condition affecting the articular cartilage at the back of the kneecap (the patella). It can be a chronic or an acute condition.
The Patella is a thick triangular shaped bone which sits above the knee joint. Its main functions are to protect the knee joint, which it covers, and knee extension. The patella articulates with the femur, and it is the biggest sesamoid bone (a bone located within a tendon) in the human body. The patella connects with the femoral groove to form the patella joint, a synovial gliding joint.
There are four ligaments (the medial and lateral collateral ligaments and the anterior and posterior cruciate ligament) which also strengthen the knee and prevent extreme movement of the knee joint. In addition, the meniscus (which is formed by the lateral and medial menisci) plays a crucial role in the anatomy of the knee. They are C shaped pads of fibrocartilage, located between the femur and the tibia and act as shock absorbers, protect the articulating cartilage of the femur and the tibia, and play a crucial role in preventing hyperextension of the knee.
As the knee bends the cartilage, which acts as a shock absorber, should glide smoothly over the femoral groove (the point where the Femur and Tibia connect). However, sometimes through overuse or muscular imbalance, the patella rubs against the knee joint, causing the cartilage to become irritated, inflamed and sore. As the cartilage wears away it becomes roughened and small pieces break off. Unlike arthritis chrondromalacia can repair itself. Cells called chrondrocytes regenerate cartilage. This process is referred to as chondroplasia.
Because the patella is a floating bone it relies on muscular balance to keep it central. Muscular imbalance or tightness of the quadriceps (vastus medialis, vastus lateralis) and the Illotibial band (ITB) can pull on the knee cap, bringing it out of alignment.
Runner’s knee can be an acute condition, as well as a chronic condition. An acute injury occurs as a direct impact or trauma to the knee, causing small tears of the cartilage.
Runner’s knee is common amongst runners, cyclists, skiers, snow boarders, football players and sports that involve jumping. It affects women more than men and is more common in younger athletes and individuals who have suffered a traumatic injury to the knee, such as a dislocation or fracture. It is more common in individuals who spend a lot of time sitting or having their knees bent.
- Over use; a repetitive action that causes continual wear and tear of the articular cartilage.
- Muscular imbalance of the quadriceps, and tight Illotibial band (ITB)
- Jumping or an explosive movement.
- A direct trauma to the knee, for example a blow or a fall.
Pain and discomfort is felt at the front of the knee, and can feel like a dull ache.
Pain is felt when pushing down on the knee cap when the leg is straight.
A sudden sharp pain in the knee when running, which disappears on rest.
Pain is particularly felt when walking down stairs, or up and down hill.
Pain can be more pronounced after sitting.
A cracking/crunching sound and sensation, as the cartilage wears away. The roughened edges of the cartilage rub against the patella causing it to create this sound.
Inflammation can occur but is not always present.
Uneven wear of shoes.
The Clarke’s test can be carried out to help the diagnosis of runner’s knee. In this test the doctor might ask the patient to slowly straighten their knee as they push the knee cap down towards their toes. Pain and a grating or crunching sound in the knee confirms diagnosis.
It is important to seek medical advice to help determine the nature and cause of chrondromalacia. An X-ray or an MRI scan can help confirm diagnosis.
Athletes often ignore runner’s knee, which can end up resulting in this sports injury becoming chronic, and requiring surgery. Treatment should focus on strengthening and improving flexibility of the muscles surrounding the patella and the hip.
With rest and appropriate treatment chrondromalacia is curable.
Rest: to prevent further damage.
It is important that training should be adapted to avoid jumping or any exercises that cause excessive wear and tear of the articular cartilage, such as squats. Exercise should be resumed gradually and it can take weeks before a full return to exercise is achieved
A physiotherapist osteopath, sports therapist or sports massage therapist can advise when exercise should be resumed and what exercise would be appropriate. Low impact exercise, such as swimming is a good alternative, however breaststroke should be avoided.
Ice, can be applied for 10-15 minutes, every 2-3 hours in the acute and sub- acute stage (frequency can be reduced according to recovery, and can be continued for as long as deemed necessary). Ice can help reduce inflammation. In the sub-acute stage (3days – 3 weeks) heat therapy can be applied.
Compression: To reduce swelling and restrict movement.
Elevation: Gravity will assist lymphatic drainage and aid venous return.
NSAIDS (anti-inflammatories) and paracetamol can be taken to aid pain relief, if necessary. Medical advice should be sought, in case of possible side effects.
Knee supports or a knee brace can help stabilise the knee and prevent the cartilage rubbing away. Zinc oxide tape and Kinesiology tape can be useful.
A physiotherapist or doctor might prescribe ultrasound or laser treatment to aid recovery; or advise key hole surgery. Surgery can help smooth out the jagged edges of the cartilages.
Massage can help aid recovery, and improve joint mobility and range of movement. It should not be administered during the acute stage. If there is any underlying medical condition, such as a heart condition, it is important to seek medical advice before receiving massage.
A physiotherapist can recommend strengthening, flexibility and proprioceptive exercises in the sub acute and the chronic stage of recovery.
Exercises should focus on eccentric strengthening; focusing on the quadriceps muscles, the intensity of the exercises should be increased gradually and in a measured way.
Foam rollers can be good for stretching the quadriceps and ITB band, which should help to prevent misalignment of the patella.
Orthotics can prevent overprontation. It is therefore, worth consulting a podiatrist, who can perform gait analysis and advise on appropriate foot wear.
Sophia Cross, BA (Hons) MA