Joints and pain
Knee Osteoarthritis (Knee Arthritis)
In short
Knee osteoarthritis is a common joint condition in which the cartilage of the knee gradually wears down, causing pain, stiffness and reduced movement. The core of treatment is regular exercise, weight loss where needed and good information about the condition; medicines and injections support this programme. If quality of life remains seriously affected despite non-surgical care, knee replacement may be considered.
What is knee osteoarthritis?
Knee osteoarthritis develops when the protective cartilage covering the ends of the bones in the joint thins and breaks down over time. This leads to pain, swelling and difficulty moving the knee. The knee, together with the hip and the small joints of the hand, is among the joints most often affected [1].
Osteoarthritis is the most common type of knee arthritis and usually appears after the age of 50. Other forms that can affect the knee include rheumatoid arthritis and post-traumatic arthritis, which develops after an earlier knee injury [2].
Symptoms
Symptoms vary from person to person and can change over time. Pain usually builds up gradually, although it can sometimes start suddenly. Common symptoms include [1][2]:
- Knee pain that worsens with walking, stairs or standing for long periods
- Stiffness on getting up in the morning or after sitting for a while
- Swelling and tenderness around the knee
- A crackling or grating feeling when the knee moves
- The knee catching, locking or feeling weak
Causes and risk factors
There is no single cause of cartilage breakdown. The following factors increase the risk of knee osteoarthritis [1]:
- Older age
- Being overweight
- A previous knee injury
- A family history of osteoarthritis
- Female sex
- Another joint condition, such as rheumatoid arthritis
Diagnosis
The diagnosis is usually made from the history and a physical examination, which checks swelling, range of motion and the stability of the joint [2]. According to the NICE guideline, osteoarthritis can be diagnosed clinically, without imaging, in people aged 45 or over who have activity-related joint pain and either no morning stiffness or stiffness lasting no more than 30 minutes [3].
Imaging is considered when the picture is unusual or another condition is suspected [3]. X-rays can show narrowing of the joint space and bone spurs, while blood tests help rule out conditions such as rheumatoid arthritis [2]. Treatment decisions are guided mainly by symptoms and day-to-day function rather than by how the X-ray looks [3].
Treatment
Non-surgical treatment: Osteoarthritis cannot be reversed, but for most people the symptoms can be managed well [1]. International guidelines place tailored exercise, weight loss for those who are overweight, and clear information about the condition at the centre of care [3][5].
Muscle-strengthening and general fitness exercises are recommended, and supervised sessions with a physiotherapist can help. Pain may increase for a while when starting exercise, but keeping it up regularly reduces pain and improves function in the long run [3]. A Cochrane review found that exercise improves pain and function in the short term, with benefits lasting for months after a programme ends [4]. Even modest weight loss is likely to help [3].
Suitable footwear, walking aids such as a cane and, for some people, a knee brace may also help [2][5]. If medicines are needed, they are used to support exercise, at the lowest effective dose for the shortest time; for knee osteoarthritis, an anti-inflammatory gel applied to the skin is usually tried first [3]. A steroid injection into the joint can give short-term relief lasting a few weeks, whereas NICE does not recommend hyaluronic acid injections [3].
Surgery: Arthroscopic washout or debridement is not recommended for osteoarthritis [3]. When pain, stiffness or deformity substantially affects quality of life and non-surgical treatment has not worked, partial or total knee replacement may be considered [3]. In selected patients, an osteotomy that realigns the weight-bearing axis of the knee is another option [2].
Recovery
Knee osteoarthritis is a long-term condition, and symptoms may come and go in flares. Treatment is therefore an ongoing plan rather than a one-off fix, and sticking with exercise increases its benefit [3].
Support to build exercise into daily life, advice on managing work, and assistive devices can all be part of the plan [5]. Regular reviews with a doctor and physiotherapist allow treatment to be adjusted as needs change [3].
When to see a doctor urgently
Seek medical help promptly if [6]:
- The knee is very painful, cannot be moved or cannot take any weight
- There is marked swelling or a change in the shape of the knee
- The knee locks, gives way or catches painfully
- There is a high temperature together with redness and warmth around the knee, which can signal a joint infection
Frequently asked questions
+Can knee osteoarthritis be cured?
Changes in the cartilage cannot be reversed. However, with exercise, weight management and suitable supportive treatments, most people can keep their symptoms under control [1][3].
+Is exercise harmful for an arthritic knee?
No. Exercise is the core treatment that guidelines recommend for everyone with osteoarthritis. Pain may rise temporarily at first, but regular exercise reduces pain and improves function [3][4].
+Do I need an MRI scan?
Usually not. In people over 45 with typical symptoms, the diagnosis can be made on examination; imaging is reserved for unusual cases [3].
+Should I have hyaluronic acid injections?
The NICE guideline advises against hyaluronic acid injections. A steroid injection may be considered for short-term relief when other treatments are not enough or to support exercise [3].
+When is a knee replacement needed?
Replacement is considered when symptoms seriously affect quality of life and measures such as exercise, weight loss and pain relief have not helped. The decision rests on clinical assessment, not on an X-ray score alone [3].
Sources
- [1]Osteoarthritis — NHS (nhs.uk), 2023.
- [2]Arthritis of the Knee — American Academy of Orthopaedic Surgeons (OrthoInfo).
- [3]Osteoarthritis in over 16s: diagnosis and management (NG226) — National Institute for Health and Care Excellence (NICE), 2022.
- [4]Exercise for osteoarthritis of the knee: a Cochrane systematic review — British Journal of Sports Medicine (Fransen M, et al.), 2015.
- [5]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.
- [6]Knee pain — NHS (nhs.uk), 2023.
This article is general information and does not replace an examination or personal medical advice. In an emergency, go to the nearest emergency department.