It is also known as chondromalacia patellae.
The knee consists of moving parts, including the thigh bone (femur), shin bone (tibia), and the kneecap (patella). As these parts move, cartilage cushions them and prevents them from being worn away by friction.
However, if this cartilage gets worn or damaged, the knee loses some of this protective cushion, resulting in a painful condition known as chondromalacia.
What is chondromalacia?
A description of symptoms and habits and a physical examination can help make clear the cause of chondromalacia.
Chondromalacia may lead to a dull pain when bending the knee or when the knee straightens right after bending it.
Activities that might cause pain include:
- walking down hills or stairs
- climbing stairs
- straightening the knee while it is bearing weight
This is why the knees often hurt when a person is going up or down the stairs. This deeper movement means that the kneecap is forced to slide up and down over the femur more than usual.
If the cartilage is worn down, or the kneecap isn't sliding in its groove, a person may feel pain as the knees bend and straighten, and the bones rub on rough cartilage. The pain may go away when walking, however, because the knees do not have to move as much.
Squatting, kneeling, or sitting with the knees bent greater than 90 degrees may also cause pain with this condition. These activities all involve deep bending of the knee.
Even a slight swelling of the cartilage can be enough to trigger pain during these activities. Some people may also notice a cracking or grinding sensation after exercise or heavy use of the legs and knees.
Symptoms of chondromalacia include:
- pain in or around the knee, especially on climbing stairs, during intense activity, or after staying in one position for a length of time
- crepitus, or cracking as you bend the knee
The thigh bone, shin, and kneecap are the three main bones in the knee.
Common causes include injury, overuse, and misalignment.
Many people are surprised to find that their cartilage is damaged because they have never directly injured their knees.
However, chondromalacia can result from other factors, not only an injury or accident.
The most common causes include:
Excessive use of the knees: This can result from running, jumping, or any activity that requires heavy use of the knees. Chondromalacia is often called "runner's knee" for this reason. It occurs in people of any age and is common in young, active athletes.
A kneecap that is out of alignment: If the kneecap is not in the proper position, the cartilage will not be able to protect it from rubbing. Some people are born with a misalignment of the knee that can cause this issue.
Weak muscles in the thighs or calves: The leg muscles help support the knee and keep it in place. If they are not strong enough, the knee may slip out of alignment. Even a slight misalignment can gradually wear down the cartilage and cause pain over time.
A knee injury: An accident, fall, or blow to the knee can throw the kneecap out of proper alignment, damage the cartilage, or both.
Chondromalacia is more likely to develop in:
- athletes and others who put strain on their knees through exercise and other activities
- adolescents, due to a temporary muscle imbalance as the body grows, which normally corrects over time
- women, as they tend to have less muscle mass around the knee
- people who have a previous knee injury, such as dislocation
- those with a tight hamstring, flat feet, difference in leg length, or joint laxity
- people with patellar hypermobility, where the kneecap moves more than it should
It can also be a symptom of arthritis. It can be made worse by activities such as climbing stairs, squatting, jumping, cycling, skiing, running, sitting with the knees flexed for a long time, or a combination of these.
Another cause is muscles that are not balanced. Strong thigh muscles combined with weaker calf muscles can also push the kneecap out of place. Similarly, strong outer thigh muscles and weak inner thigh muscles can cause misalignment.
People who have knee pain or symptoms of chondromalacia should see their doctor. Early treatment can prevent further damage to the cartilage and alleviate pain.
Typically, noninvasive treatments for chondromalacia are successful. They include:
Low-impact exercise: Walking and swimming are good options to strengthen the legs and keep the muscles strong without stressing the knee. It can also enhance mood and sleep quality.
Orthotics, or shoe inserts: These can support the foot arch, if necessary.
Avoiding activities that cause pain: Many people must avoid stairs if climbing them causes pain. Instead, they should do exercises that are comfortable. This may help avoid further damage to the cartilage.
Diet: Following a varied diet can ensure a balance of nutrients and help maintain a healthy weight. Excess weight can damage the knee cartilage and put stress on the knee joint.
Sleep hygiene: Get enough sleep, as this will help reduce pain and fatigue.
Pain relief: Over-the-counter pain relief medication, such as ibuprofen, can help control discomfort.
Knee support straps: There is a lack of evidence that these are of use. Some people have reported adverse effects, such as discomfort and abrasion. One review of studies, published by Cochrane in 2015, in calls for further research before recommending these devices.
Orthotics and knee support devices are available for purchase online. A doctor can advise you on whether or not to use a knee support device.
Physical therapy can help strengthen muscles and prevent the problem from worsening.
If a physical examination reveals a muscle imbalance, certain exercises may help balance the muscles and put the kneecap back in alignment.
If the outside of the muscle is stronger than the inside, for example, a health professional may recommend exercises to strengthen the weaker muscles.
A physical therapist works with patients to perform special exercises and stretches. They will suggest specific exercises, depending on the cause of the problem and the muscle that needs strengthening.
Depending on the underlying cause of the problem, a health professional may recommend a series of exercises.
Examples of exercises to stretch and strengthen the quadriceps muscle include:
Semi-squats: Stand with the feet hip-distance apart and bend the knees to 40 degrees.
Step-ups: Put one foot on a 10-centimeter (cm) step, then the other foot, then step down with the first foot and then with the other.
Straight leg rise: Sit with the legs straight out in front, raise one leg and lower it slowly, then do the same with the other leg.
Sitting leg lift: Sit on a chair or bed with the feet on the floor and the back of the knee against the chair or bed. Slowly raise and lower each leg in turn.
Do each of these 3 times and rest, then repeat 10 times.
After doing these each day for 6 weeks, your health worker may recommend increasing the difficulty.
Other exercises may be recommended to stretch other parts of the body.
Medications and surgery
Ibuprofen or naproxen may help relieve pain and inflammation in the cartilage.
Surgery will only be necessary if the pain is severe and other treatments have not helped.
This may involve removing the rough surface of cartilage to reduce pain. The surgeon may also be able to release tight tendons and ligaments. This can help to align the kneecap.
Without treatment, chondromalacia can lead to patella-femoral arthritis. This occurs when the cartilage gets severely worn away by damage.
Once the cartilage is lost, it cannot grow back. In severe cases, the bones may directly rub together. If this happens, the pain may be debilitating, and the person may feel it while resting.
A healthful lifestyle, combined with exercise, is good for the knees and all the joints. It is important not to ignore knee pain. Pain during certain activities may be a warning sign of chondromalacia or another condition.
Some people wear kneepads when gardening, scrubbing floors, or other activities. Shoes with proper support are also helpful for the knees.
Keeping both feet in alignment can help the leg muscles remain balanced, and quality shoes can help absorb shock from walking and running.
People who have a diagnosis of chondromalacia can still lead healthy, active lives.
Early treatment can help prevent further irritation or damage to the cartilage. With proper treatment, many people get relief from pain and can do many of their favorite activities again.