Osteoarthritis of the knee is a common condition that can cause pain, stiffness and difficulty moving the joint. For some people, symptoms are occasional and manageable. For others, knee pain can become persistent and start to affect walking, work, exercise, sleep and everyday activities.
Understanding knee osteoarthritis symptoms, how the condition can progress and what treatments are available can help you make informed decisions about your care.
There is no single treatment that is right for everyone. Management depends on your symptoms, how they affect your daily life, your general health and how you respond to non-surgical treatments.
This guide explains what knee osteoarthritis is, the commonly described stages of knee arthritis, what people mean by a “bone-on-bone knee”, and the treatment options available in the UK.
What is knee osteoarthritis?
Osteoarthritis is a condition that affects the joints. It commonly affects the knees, hips, hands and feet.
The knee contains several structures that work together to allow smooth movement. Articular cartilage covers the ends of the bones within the joint and helps them move against each other. Other structures, including the menisci, ligaments and muscles around the knee, also contribute to its stability and movement.
With osteoarthritis, changes occur within the joint. These can include deterioration of cartilage, changes to the underlying bone and inflammation within or around the joint.
Osteoarthritis is a long-term condition, but it does not necessarily become progressively worse in every person. Symptoms can fluctuate, with periods when they are more noticeable followed by periods when they settle.
What are the symptoms of knee osteoarthritis?
The most common knee osteoarthritis symptoms are pain and stiffness.
You may notice:
- Pain during or after activity
- Stiffness after periods of inactivity
- Difficulty bending or straightening the knee
- Swelling or tenderness around the joint
- A grating, clicking or crackling sensation
- Reduced range of movement
- Weakness in the muscles around the knee
- Difficulty walking, climbing stairs or standing for prolonged periods
- Symptoms that become more noticeable during periods of increased activity
Knee osteoarthritis symptoms can vary considerably between people. Some people experience relatively mild symptoms despite changes visible on an X-ray, while others can have significant pain and difficulty with everyday activities.
Pain can also come and go rather than being constant. NHS guidance notes that symptoms may occur in episodes and can sometimes flare before settling again.
When should you see a healthcare professional?
Persistent or worsening knee pain is worth discussing with a healthcare professional, particularly if it is affecting your mobility or everyday activities.
You should also seek medical advice if your knee becomes very swollen, hot or suddenly much more painful, particularly if this occurs with other symptoms. These features can have causes other than osteoarthritis and may require prompt assessment.
Knee pain can have many causes, including injuries affecting ligaments or cartilage, inflammatory conditions and other joint problems. Our knee pain guide highlights persistent pain, swelling, restricted movement, difficulty bearing weight and instability as reasons to consider seeking professional assessment.
What causes knee osteoarthritis?
There is not always one identifiable cause.
Osteoarthritis becomes more common with age, but it is not simply an inevitable consequence of getting older. Previous injuries, joint problems, genetics, body weight and other factors can contribute to the development of osteoarthritis.
A previous knee injury can sometimes increase the likelihood of developing osteoarthritis in the affected joint. Repeated stress on the knee may also contribute to joint problems.
Osteoarthritis is more common in people aged 45 and over and in people living with obesity, although it can affect people with a wide range of characteristics and circumstances.
How is knee osteoarthritis diagnosed?
Knee osteoarthritis is often diagnosed through your symptoms and a physical examination.
NICE recommends that osteoarthritis can usually be diagnosed clinically in people aged 45 or over who have activity-related joint pain and either no morning joint stiffness or stiffness lasting no longer than 30 minutes. Routine imaging is not normally required to make the diagnosis when the symptoms and examination are typical.
However, imaging may sometimes be appropriate when symptoms are unusual, another condition needs to be considered, or further information is needed as part of a person’s assessment.
An X-ray can show changes within the bones and joint space associated with osteoarthritis. Our private X-ray service provides bone and joint X-rays to help investigate conditions such as arthritis and other joint problems.
It is important to remember that an X-ray is only one part of an assessment. The amount of change visible on an X-ray does not always correspond directly to the amount of pain someone experiences.
What are the stages of knee arthritis?
People often search for the stages of knee arthritis to understand how advanced their osteoarthritis may be.
There is no single universally used system that describes exactly how every person’s osteoarthritis progresses. However, doctors and researchers commonly use radiographic grading systems to describe changes seen on X-rays.
One commonly recognised system is the Kellgren-Lawrence classification, which broadly grades osteoarthritis from 0 to 4.
Grade 0: No radiographic osteoarthritis
There are no obvious X-ray features of osteoarthritis.
A person can still experience knee pain for other reasons, so a normal X-ray does not automatically mean that pain has no physical cause.
Grade 1: Possible early changes
There may be very minor or questionable changes, such as possible narrowing of the joint space or small bone changes.
These findings may not necessarily explain someone’s symptoms.
Grade 2: Mild osteoarthritis
More definite signs of osteoarthritis may be visible, including possible joint-space narrowing and small osteophytes, which are bony growths that can develop around the joint.
Symptoms may include activity-related pain and stiffness, although their severity varies between individuals.
Grade 3: Moderate osteoarthritis
X-rays may show more obvious joint-space narrowing, multiple osteophytes and changes to the underlying bone.
Pain and stiffness may become more persistent, and activities such as walking, climbing stairs or exercising may become increasingly difficult.
Grade 4: Severe osteoarthritis
There may be marked joint-space narrowing, larger osteophytes and changes to the underlying bone.
This is the stage often associated with what people describe as a bone-on-bone knee.
However, the phrase “bone on bone” is not itself a diagnosis or a guarantee that knee replacement is necessary. Treatment decisions should be based on the whole clinical picture, including pain, function and quality of life.
NICE specifically recommends using clinical assessment rather than a numerical disease-severity score alone when considering referral for joint replacement.
What does “bone on bone” knee mean?
“Bone on bone” is a term commonly used to describe severe loss of cartilage within a joint.
Healthy cartilage helps provide a smooth surface between the bones. When cartilage becomes severely damaged or the joint space becomes substantially narrowed, the bones may appear much closer together on an X-ray.
This is what people commonly mean when they say they have a bone-on-bone knee.
However, there is an important distinction between an X-ray finding and a person’s symptoms.
Someone with significant changes on an X-ray may have relatively manageable pain, while another person with less extensive visible changes may experience considerable symptoms.
For this reason, the decision about treatment should not be based on an X-ray alone.
What is the treatment for knee osteoarthritis?
There are several approaches to knee arthritis treatment UK patients may be offered.
Treatment generally begins with non-surgical management. Surgery may be considered when symptoms have a substantial effect on quality of life and non-surgical approaches have not provided sufficient benefit or are unsuitable.
Exercise and physiotherapy
Therapeutic exercise is one of the core treatments recommended by NICE for osteoarthritis.
A suitable programme may include exercises designed to strengthen muscles around the affected joint as well as activities that support general fitness.
Exercise can sometimes cause a temporary increase in discomfort when you first begin or change a programme. NICE recommends explaining this to patients while emphasising the benefits of consistent, long-term participation.
A physiotherapist can help tailor exercises to your symptoms, abilities and goals.
Weight management
If you are living with overweight or obesity, weight management can form part of osteoarthritis treatment.
NICE recommends offering support with weight loss to people with osteoarthritis who are living with overweight or obesity. It states that any amount of weight loss can be beneficial, while greater weight loss may provide greater benefits for pain, physical function and quality of life.
This should be approached as part of overall health management rather than as a requirement for everyone with knee osteoarthritis.
Pain relief and medicines
Medicines may be used alongside exercise and other non-surgical approaches to help manage symptoms.
NICE recommends offering a topical non-steroidal anti-inflammatory drug (NSAID) for people with knee osteoarthritis. Oral NSAIDs may also be considered where appropriate, taking individual risk factors and potential side effects into account.
A healthcare professional can advise which medication, if any, is appropriate for you.
Steroid injections
In some circumstances, a corticosteroid injection into the knee may be considered.
NICE recommends considering corticosteroid injections when other pharmacological treatments are ineffective or unsuitable, or to support therapeutic exercise. The guidance states that the benefit is short term, generally lasting around two to 10 weeks.
Injections are not suitable for everyone, so this should be discussed with an appropriate healthcare professional.
Walking aids and supportive devices
Some people may benefit from a walking aid, such as a stick, to help with mobility.
NICE does not recommend routinely offering insoles, braces, tape, splints or supports to everyone with osteoarthritis. They may be considered in particular circumstances, such as joint instability or abnormal biomechanical loading, when exercise alone is ineffective or unsuitable.
When is knee replacement considered?
Knee replacement is one of the surgical options for severe knee osteoarthritis.
It may be considered when symptoms such as pain, stiffness, reduced function or progressive joint deformity are substantially affecting quality of life and non-surgical management has been ineffective or unsuitable.
Importantly, having severe osteoarthritis on an X-ray does not automatically mean that you need a knee replacement.
Similarly, age alone should not determine whether someone is considered for joint replacement. NICE advises against excluding people from referral because of age, sex or gender, smoking, comorbidities, overweight or obesity.
A consultant will consider your symptoms, functional limitations, medical history, examination findings and treatment history when discussing whether surgery may be appropriate.
What happens during knee replacement surgery?
During knee replacement surgery, damaged areas of the knee are removed and replaced with artificial components.
At Transform Medical, we perform knee replacement surgery by removing damaged bone and cartilage and replacing them with prosthetic components. The procedure typically takes around 1.5 to two hours, and you will generally stay in hospital for one night, although this can vary depending on your individual circumstances.
Knee replacement is a significant operation and, like all surgery, carries potential risks. These should be discussed with your consultant before deciding whether to proceed.
Recovery varies between individuals. At Transform Medical, we currently advise that light activities may typically be possible within six to 12 weeks, although your recovery time will depend on your individual circumstances.
Can knee osteoarthritis be cured?
There is currently no cure for osteoarthritis itself.
However, symptoms can often be managed using a combination of approaches. NHS guidance states that osteoarthritis does not necessarily become progressively worse and that treatment can help relieve symptoms and maintain function.
For some people, exercise, weight management where appropriate, medication and other supportive measures are sufficient to manage their symptoms.
For others, particularly when pain and reduced function continue despite non-surgical treatment, joint replacement may eventually be considered.
What should you do if knee pain is affecting your life?
Persistent knee pain should not simply be attributed to getting older.
If pain, stiffness or reduced mobility is affecting your ability to walk, work, exercise or carry out everyday activities, speak to a healthcare professional.
An assessment can help determine whether your symptoms are consistent with osteoarthritis or another knee condition and whether further investigation is appropriate.
If you need imaging, you can use our Private X-ray Service for bone and joint X-ray imaging.
You can also learn more about common causes and warning signs in our Knee Pain Explained guide.
Exploring treatment options for knee osteoarthritis
Knee osteoarthritis can affect people differently, so treatment needs to reflect the individual rather than simply the appearance of an X-ray.
Exercise, physiotherapy, weight management where appropriate, medication and other non-surgical treatments can all have a role. Knee replacement may be considered when symptoms significantly affect quality of life and non-surgical treatment is no longer effective or suitable.
If you have been diagnosed with osteoarthritis and are considering whether knee replacement could be appropriate, a consultation can help you understand your options.
At Transform Medical, we provide consultant-led assessment and private knee replacement for patients who are clinically suitable. Our current all-inclusive fixed price is from £10,995. Prices and treatment details may change, so we recommend confirming the latest information with us when considering treatment.
Book a free consultation
If persistent knee pain is affecting your everyday life and you would like to discuss your symptoms and treatment options with a consultant, you can book a free consultation with us.
A consultation does not mean that you have to proceed with surgery. Your suitability for treatment will be assessed individually, and your consultant can discuss the potential benefits, risks and alternatives available to you.
Individual results vary. Knee replacement is not suitable for everyone, and all surgery carries risks. Treatment recommendations are based on individual clinical assessment.