Knee osteoarthritis is a common joint disease in which cartilage wears over time, causing pain, stiffness and limited movement [1]. The basis of treatment is exercise tailored to you, weight loss where needed and a clear understanding of the condition; medicines and injections support this [3][5]. If quality of life is seriously affected despite non-surgical treatment, knee replacement is considered [3].
What exactly is it?
The protective cartilage that covers the ends of the bones gradually thins and breaks down, leading to pain, swelling and difficulty moving [1]. Despite the name, the problem is not a build-up of lime in the joint; the main change is loss of cartilage with accompanying bone changes. Osteoarthritis is the commonest type of knee arthritis and usually appears after the age of 50; rheumatoid arthritis and post-traumatic arthritis after an old injury can also affect the knee [2].
What symptoms does it cause?
Symptoms vary between people and over time, and pain usually starts slowly [1][2]:
- Knee pain that increases with walking, stairs and long standing
- Stiffness on getting up in the morning or after sitting for a long time
- Swelling and tenderness to touch
- Creaking or grating on movement
- The knee catching, locking or feeling weak
Risk factors
There is no single cause. Older age, excess weight, an earlier knee injury, a family history of arthritis, female sex and another joint disease such as rheumatoid arthritis increase the risk [1].
Diagnosis
Diagnosis is usually made from your history and examination, checking swelling, range of movement and stability of the joint [2]. According to NICE guidance, in people aged 45 or over with activity-related joint pain and no morning stiffness, or stiffness lasting no more than half an hour, the diagnosis can be made clinically without imaging [3].
Imaging is requested if the picture is unusual or another condition is suspected [3]. X-rays can show narrowing of the joint space and bony spurs, and blood tests help separate causes such as rheumatoid arthritis [2]. Treatment decisions are based on symptoms and limitation in daily life rather than on how the film looks [3].
The basis of treatment: exercise, weight, information
Osteoarthritis cannot be reversed, but symptoms can be well controlled in most people [1]. International guidelines recommend exercise tailored to the person, weight loss in those who are overweight, and clear information about the condition as the core of care [3][5].
Muscle strengthening and general fitness exercises are advised, with a physiotherapist where needed. Pain may increase for a while at the start; keeping at it regularly reduces pain and improves function in the long run [3]. A Cochrane review showed that exercise gives short-term improvement in pain and function, and that this can last for months after the programme ends [4]. Even small amounts of weight loss can help [3].
Suitable shoes, walking aids such as a stick and, for some patients, a knee support can also help [2][5].
Medicines and injections
If medicines are needed they are used to support exercise, at the lowest effective dose for the shortest time; for knee osteoarthritis anti-inflammatory painkillers applied to the skin are the first choice [3]. A cortisone injection into the joint can give short-term relief for a few weeks; NICE does not recommend hyaluronic acid injections [3].
Surgery
Arthroscopic washout or tidying of the joint is not recommended on its own for osteoarthritis [3]. If pain, stiffness or deformity clearly harms quality of life and non-surgical treatment is not enough, partial or total knee replacement is considered [3]. For suitable patients an osteotomy that corrects the load axis of the knee is also an option [2].
What does the long term look like?
Knee osteoarthritis is a long-term condition and symptoms can fluctuate between good and bad periods; treatment is therefore an ongoing plan rather than a one-off, and keeping up exercise increases the benefit [3]. Regular review with the doctor and physiotherapist lets the plan be updated as needs change [3].
When not to wait
Seek care without delay if [6]:
- The knee is very painful, cannot be moved or cannot bear weight at all
- There is marked swelling or a change in shape
- The knee locks, gives way or catches painfully
- There is redness and warmth with a high temperature (this can be a sign of joint infection)
Frequently asked questions
- Does knee osteoarthritis go away completely?
- The changes in the cartilage cannot be reversed, but exercise, weight control and supportive treatment can bring symptoms under control in most people [1][3].
- Is exercise harmful for an arthritic knee?
- No; exercise is the core treatment guidelines recommend to all patients. Pain may increase briefly at first, but regular exercise reduces pain and improves function [3][4].
- Do I need an MRI?
- Often not. In people over 45 with typical symptoms the diagnosis can be made by examination [3].
- Should I have hyaluronic acid injections?
- NICE does not recommend hyaluronic acid injections; cortisone can be considered for short-term relief when other treatment is not enough [3].
- When is knee replacement needed?
- When symptoms seriously affect quality of life and exercise, weight loss and painkillers are not enough; the decision rests on clinical assessment, not on the X-ray alone [3].
At our clinic we first ask what limits you: walking, stairs or sleep. We build the plan around that answer more than around the X-ray.
Sources
- Osteoarthritis. NHS (nhs.uk), 2023. nhs.uk
- Arthritis of the Knee. American Academy of Orthopaedic Surgeons (OrthoInfo), n.d.. orthoinfo.org
- Osteoarthritis in over 16s: diagnosis and management (NG226). National Institute for Health and Care Excellence (NICE), 2022. nice.org.uk
- Exercise for osteoarthritis of the knee: a Cochrane systematic review. British Journal of Sports Medicine (Fransen M, et al.), 2015. pubmed.ncbi.nlm.nih.gov
- EULAR recommendations for the non-pharmacological core management of hip and knee osteoarthritis: 2023 update. Annals of the Rheumatic Diseases (Moseng T, et al.), 2024. pubmed.ncbi.nlm.nih.gov
- Knee pain. NHS (nhs.uk), 2023. nhs.uk
This article is general information and does not replace an examination or imaging. If you have symptoms, see a doctor.
More in this area
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- Baker's cyst: what causes a swelling behind the knee and how does it settle?
- Cartilage damage in the knee: does cartilage heal, and how is it treated?
- Knee injections: what do cortisone, hyaluronic acid, PRP and stem cells do?
- Knee pain: what causes it, what helps and who should you see?
- Knee replacement surgery: who is it for and what is recovery like?
- Meniscus tear: exercise or arthroscopy?
- Kneecap pain and chondromalacia patella: what causes it and how does it settle?