Patellofemoral pain syndrome (runner's knee)
Also known as runner's knee or jumper's knee, it often affects athletes and those who engage in running, basketball, and other sports.
However, patellofemoral syndrome can also affect non-athletes and is frequently seen in adolescents, young people, manual workers, and older adults.
The American Academy of Family Physicians report that patellofemoral syndrome is the most common cause of knee pain in the population. It can be caused by overuse of the knee joint, physical trauma, or misalignment of the kneecap.
- Patellofemoral pain syndrome occurs when nerves in the tendons, synovial tissue, and bone around the kneecap sense pain.
- The most obvious symptom of patellofemoral syndrome is a dull, aching pain in the front of the knee.
- A doctor will usually diagnose patellofemoral syndrome based on a physical examination and medical history.
- Surgery is considered the last resort for patellofemoral pain syndrome. It is only used in very severe cases and if other non-invasive treatments have failed.
What is it?
The onset of patellofemoral syndrome can be gradual or result from a single incident. A condition known as chondromalacia patella may also be present.
Chondromalacia is characterized by a wearing away and softening of the cartilage around the knee, which leads to inflammation and pain.
When a person has patellafemoral syndrome, their knee pain can become worse when they do any of the following movements:
Although athletes are most at risk, patellofemoral syndrome can also affect non-athletes.
- ascending or descending stairs
- sitting for long periods of time
Other symptoms they may have can include:
- mild swelling
- a sensation of grating or grinding when bending or extending the leg
- reduced thigh muscle strength if initial symptoms are left untreated
Causes and risk factors
Patellofemoral syndrome happens when the back of the kneecap comes into contact with the thigh bone. The exact reason this occurs is not entirely understood, but it is linked to:
- Overuse of the knee: Activities that involve running or jumping put a repetitive strain on the knee joint, which can lead to pain in the patella.
- Muscle imbalance: When certain muscles, such as those around the hip and knee, are weak, they fail to keep adjacent body parts, including the kneecap, properly aligned. This may eventually lead to injury.
- Trauma: Injury to the kneecap, or knee surgery, may increase the risk of experiencing patellofemoral pain syndrome.
Repetitive strain on the knee joint may be caused by running or jumping activities.
Factors which increase the likelihood of developing an illness or injury are known as risk factors.
Common risk factors for patellofemoral syndrome include:
- Age: Adolescents and young adults are at the highest risk of patellofemoral syndrome, although it may also affect older adults.
- Sex: Women are more likely than men to develop this condition, possibly due to greater risk of muscle imbalance and the wider angle of the female pelvis.
- High-impact activities: Engaging in high-impact or weight-bearing activities, including running, jumping, or squatting causes repetitive stress to the joints, and increases the risk of knee injury.
- Flat feet: People with flat feet may be at higher risk of patellofemoral syndrome as they place additional stress on their knee joints.
A doctor will inquire about symptoms and may ask a person to move their legs and knees in certain ways to check for instability and determine the range of motion.
In some cases, imaging tests, such as X-rays and MRI scans, may be ordered to confirm a diagnosis and rule out other conditions.
There are several treatments available when someone has patellofemoral syndrome, including:
For many cases of patellofemoral syndrome, simple measures, such as rest and ice, may be enough to alleviate pain and swelling.
The RICE protocol, standing for Rest, Ice, Compression, Elevation, involves resting the leg, applying ice packs regularly, using compression bandages, and elevating the knee above heart level. The RICE protocol is most effective when used within 72 hours of injury.
Over-the-counter anti-inflammatory medications (NSAIDs), such as acetaminophen and ibuprofen, can help to reduce the pain and swelling associated with patellofemoral syndrome. NSAIDs should not be taken on long-term basis due to the risk of gastrointestinal problems.
A therapist may recommend:
- exercises and stretches
- a brace
- patella taping
Working with a qualified physical therapist can help alleviate symptoms and speed up recovery time.
As overuse of the knee is a primary contributing factor to patellofemoral syndrome, activity modification is one way to reduce further damage to the knee and prevent a recurrence of the condition.
People who experience patellofemoral syndrome may wish to reduce or avoid activities that include repetitive high-impact actions, such as:
- going up and down stairs or other steep inclines
- sitting for long periods of time
Examples of low-impact exercises that put less strain on the knees include:
- water aerobics
- using elliptical machines
Surgery is usually carried out using an arthroscope, a thin tube containing a camera and light. The scope is inserted into the knee, and surgical tools are used to remove damaged cartilage.
This minimally invasive procedure can increase mobility and relieve tension.
Severe cases of patellofemoral syndrome may involve an operation on the knee to change the direction that the patella passes over and rubs against with the femur.
Warming up before exercise helps flexibility and may reduce the risk of patellofemoral syndrome.
Patellofemoral syndrome can be painful and debilitating.
While not all cases can be prevented, certain steps can be taken to reduce the risk of knee problems. These include:
- Keeping muscle balance: Strengthening the muscles in the knee and leg can reduce the risk of muscular imbalance and contribute to proper alignment of the knee.
- Correcting flat feet: Wearing supportive footwear and shoe inserts can treat flat feet and reduce additional stress on the knee joints.
- Having a healthy weight: Carrying around too much bodyweight puts stress on the joints, increasing the risk of patellofemoral syndrome. Maintaining a healthy weight can be achieved by eating a balanced diet and engaging in regular physical activity.
- Warming up before workouts: A person should always stretch and engage in light activities before exercising properly. This can promote flexibility and reduce injury.
- Changing training regimens gradually: Suddenly increasing the intensity, duration, or frequency of workouts can contribute to knee pain.
- Avoiding stress to the knee: Choosing low-impact activities, wearing supportive footwear, and using knee braces during workouts can help reduce the impact on the knees and legs.
Recovery time varies between individuals and depends on factors that include the severity of the symptoms and the treatments used.
However, most cases will heal within several weeks with the use of at-home and minimally invasive therapies. Employing the RICE protocol and engaging in low-impact activities improves the outlook for many people.
It may take up to 5 months to completely recover, especially if the patellofemoral syndrome was brought on by physical trauma.