Kneecap pain and chondromalacia patella: what causes it and how does it settle?

What is kneecap pain and what causes it?

As the knee bends and straightens, the kneecap (patella) glides in a groove at the end of the thigh bone ^[1]. Pain felt at the front of the knee, around or behind the kneecap, is called patellofemoral pain; it is also known as "runner's knee" and "anterior knee pain" ^[1][4].

The two main factors are overuse and the kneecap not gliding properly in its groove ^[1]. Activities that put repeated stress on the knee, such as running, squatting and climbing stairs, or a sudden increase in activity, can start the pain; problems with the alignment of the leg, and weakness of the muscles, especially the muscle at the front of the thigh (the quadriceps), can also disturb the way the kneecap glides ^[1].

What does "chondromalacia patella" on an MRI report mean, and what are its grades?

Chondromalacia patella is softening and breakdown of the joint cartilage on the back surface of the kneecap; it is present in some people with kneecap pain ^[1]. Cartilage has no nerves, so damage to the cartilage does not cause pain directly, but it can lead to inflammation of the joint lining and pain in the underlying bone ^[1].

Chondromalacia in the report describes how the cartilage looks; on its own it does not decide the treatment ^[2][6]. In a study that compared the MRI scans of 64 patients with those of 70 people who had no pain, minor cartilage defects of the kneecap were seen in 23% of the patients and 21% of the people without pain, and none of the structural changes was associated with pain; no one in the study had full-thickness cartilage loss ^[6]. The source reviewed likewise does not divide treatment by grade ^[2].

MRI is the method of choice for assessing cartilage; the change is divided into four grades ^[2]:

• Grade 1: the cartilage surface is intact, but the cartilage is soft and swollen
• Grade 2: fissures and fragmentation of the surface in an area half an inch (about 1.3 centimetres) or less in diameter
• Grade 3: loss involving part of the thickness of the cartilage, in an area more than half an inch in diameter
• Grade 4: full-thickness loss down to the underlying bone

What are the symptoms and who gets it?

It particularly affects adolescents and young adults ^[4]; it is common in people who play sport and in women, but it can also occur in people who do not play sport ^[1].

The most common symptom is a dull, aching pain at the front of the knee; it can come on gradually or appear suddenly ^[1][3]. Swelling, locking, or a hot and red knee are not among the symptoms listed by the American Academy of Orthopaedic Surgeons (AAOS) ^[1]. The typical features are ^[1][3]:

• Pain when going up or down stairs, squatting, running and jumping
• Pain after sitting for a long time with the knees bent
• Difficulty kneeling
• Crackling sounds from the knee when climbing stairs or when standing up after sitting for a long time

Which specialty should you see and how is it diagnosed?

Kneecap pain is assessed by orthopaedics and traumatology. The diagnosis can usually be made by examination alone ^[1]: this checks whether movements such as squatting bring on the pain, and looks at the alignment of the leg, the movement of the kneecap, the strength of the hip and thigh muscles, and the way you walk ^[1][3].

An X-ray is also requested in most cases to make sure there is no damage to the bones; an MRI may be requested if, after a period of time, the symptoms have not improved with physiotherapy and home exercises ^[1].

Not every pain at the front of the knee is patellofemoral pain. Tendon problems, meniscus and ligament injuries, osteoarthritis, Osgood-Schlatter disease in the growing years, and a kneecap that dislocates or slips out of place (instability) are separate conditions and are assessed separately ^[3].

The main treatment: exercise for the hip and thigh muscles

The American Physical Therapy Association (APTA) guideline recommends, on strong evidence, combining hip-targeted and knee-targeted exercises to reduce pain and improve function ^[3]. The hip exercises work the muscles at the back and side of the hip, and the knee exercises work the muscle at the front of the thigh ^[1][3].

A Cochrane review of 31 trials found very low quality but consistent evidence that exercise may bring a clinically important reduction in pain and improve function; there is not enough evidence to determine the best form of exercise ^[4].

What helps kneecap pain at home?

Anti-inflammatory painkillers (NSAIDs) can reduce the pain ^[1]; ask your pharmacist or doctor which one is suitable for you. Painkillers are the only medicines that appear in the sources this article is based on; they do not mention any medicine or food supplement that renews cartilage ^[1][2]. The main measures that can be taken at home are ^[1][7]:

• Stopping the activities that make the pain worse until the pain has gone
• Switching to activities that put less stress on the knee, such as a stationary bike and swimming
• An ice pack wrapped in a towel for up to 20 minutes every 2 to 3 hours
• Losing weight if you are overweight
• Increasing the intensity and duration of training gradually

The place of taping, knee braces, insoles and injections

Taping: according to the guideline, taping of the kneecap tailored to the individual, used together with exercise, may help reduce pain immediately and improve the results of exercise in the short term (4 weeks) ^[3].

Knee braces: a Cochrane review found very low quality evidence that, in adults who were also exercising, a knee brace did not reduce pain or improve function in the short term (under three months) ^[5]; the guideline likewise does not recommend prescribing a knee brace ^[3].

Insoles: the guideline recommends ready-made insoles, for a short period (up to 6 weeks) and together with exercise, for people whose feet roll inwards more than normal ^[3].

Injections: according to the source reviewed, PRP is sometimes advocated but is not standard care and has not been shown to improve outcomes consistently; high-dose or frequent cortisone injections into the joint, meanwhile, can soften the cartilage ^[2]. The types of injection, and the debate about the effect of cortisone on cartilage, are described in the article on knee injections in this guide.

When is surgery considered and how long does recovery take?

Surgery is very rarely needed; it is performed only in severe cases that have not responded to non-surgical treatment ^[1]. One source recommends at least one year of non-surgical treatment first ^[2]. The options include removing damaged cartilage by arthroscopy (keyhole surgery) and procedures that correct the alignment of the kneecap ^[1][2]. Cartilage damage and cartilage repair operations are described in a separate article in this guide.

Recovery can take as little as a month or it can take years ^[2]. According to the AAOS, the pain is usually fully relieved with simple measures or physiotherapy; it may come back if the training routine is not adjusted ^[1]. The physiotherapy guideline, however, states that this is not a condition that goes away by itself and that it can last for years; more than half of the people who took part in clinical trials reported an unfavourable outcome 5 to 8 years later ^[3].

When not to wait

See a doctor if the pain does not improve within a few weeks or if it becomes more difficult to move your knee ^[1][7]. In the following situations seek care without waiting ^[7]:

• The knee is very painful, cannot be moved, or you cannot put any weight on it
• The knee is badly swollen or has changed shape
• The knee locks, gives way or clicks painfully
• A high temperature and shivering together with redness or heat around the knee (this can be a sign of infection)
• The kneecap has changed shape after a collision or a sudden change of direction (this may be a dislocated kneecap)

Sources

1. Patellofemoral Pain Syndrome. American Academy of Orthopaedic Surgeons (OrthoInfo), n.d.. orthoinfo.org
2. Chondromalacia Patella. StatPearls, NCBI Bookshelf (Habusta SF, et al.), 2023. ncbi.nlm.nih.gov
3. Patellofemoral Pain: Clinical Practice Guidelines. Journal of Orthopaedic & Sports Physical Therapy (Willy RW, et al.), 2019. pubmed.ncbi.nlm.nih.gov
4. Exercise for treating patellofemoral pain syndrome. Cochrane Database of Systematic Reviews (van der Heijden RA, et al.), 2015. pubmed.ncbi.nlm.nih.gov
5. Knee orthoses for treating patellofemoral pain syndrome. Cochrane Database of Systematic Reviews (Smith TO, et al.), 2015. pubmed.ncbi.nlm.nih.gov
6. Structural Abnormalities on Magnetic Resonance Imaging in Patients With Patellofemoral Pain: A Cross-sectional Case-Control Study. The American Journal of Sports Medicine (van der Heijden RA, et al.), 2016. pubmed.ncbi.nlm.nih.gov
7. Knee pain. NHS (nhs.uk), 2023. nhs.uk