Knee osteoarthritis is the name given to age-related arthritis which causes the knee joint to become painful and stiff.
The process of osteoarthritis involves wearing or thinning of the smooth cartilage joint surfaces as well as stiffening to the soft tissue surrounding the joint. These aspects combine to produce swelling, inflammation and pain.
Several factors normally combine to cause symptoms of osteoarthritis:
- Previous joint damage
- Increased bodyweight
- Age (risk increases with age)
- Family history (genetics)
- Poor lower limb alignment (termed biomechanics)
General exercise such as walking, cycling and playing sport does not increase the risk of developing or increase the rate of deterioration of knee osteoarthritis.
Pain will normally be felt adjacent to the affected compartment/s of the knee. Knee osteoarthritis can involve the outer part of the knee (lateral compartment), the inner part of the knee (medial compartment), under the knee cap (patellofemoral joint) or a combination of these. The pain may be felt as a referred pain radiating into the shin or calf muscle.
Pain on walking is often the main aggravating activity. If knee osteoarthritis becomes more severe the movements of the knee may become increasingly stiff and there may be associated instability and giving way of the knee joint.
The presence of knee osteoarthritis does not always cause pain so it is quite possible to be pain-free despite reasonably advanced arthritis. In addition, the knee undergoes a ‘wear and repair cycle’ so pain can improve with time and appropriate management.
Knee osteoarthritis can be reliably diagnosed by your doctor or physiotherapist by taking a history of your condition. A physical examination may help to assess the severity.
The main feature on examination is often a painful reduction in the range of movement. There is often weakness of the thigh muscles. may be deviation of the normal alignment of the knee and associated grinding (crepitus).
There may be swelling of the joint as a result of the inflammatory change ( ‘synovitis’) within the joint . This will often settle but if it gives symptoms may need aspiration . On occasions the fluid will cause swelling at the back of the knee which is known as a ‘Bakers cyst’. This is not serious and will often resolve as the joint swelling settles. It can however become painful and inflamed in which case it should be brought to medical attention , but rarely require surgery.
X-rays are not routinely required but may be requested if symptoms are severe enough that total knee replacement surgery is being considered.
In the majority of cases, the symptoms of knee osteoarthritis can be managed effectively by non-invasive measures as described below. The most effective are exercises and weight loss for those who are overweight.
You can use a BMI calculator which will tell you if it might be advisable for you to try to lose some weight.
Losing weight reduces the load which weighs down on your joints as you move about. Evidence shows that weight loss can result in significantly better mobility; there is also some evidence to suggest that weight loss alone may actually help to reduce pain. However, in combination with exercise, the results can be staggering.
There is lots of support and advice available. For example, you can find some excellent ideas, including recipes and advice on making healthy food choices, on the NHS Change 4 Life website, where there is also information about healthy activities near you.
Regular exercises to maintain flexibility and strength to the affected knee joint:
5×30 second holds, 2x per day
3-4 sets of 10 reps, 3-4x per week
3-4 sets of 10 reps, 3-4x per week
Using painkillers when needed
Over-the-counter analgesia is available through pharmacies when needed. Paracetamol is most commonly prescribed. Anti-inflammatories, such as Ibuprofen, are also used, but as there is little or no inflammation involved in osteoarthritis these are best avoided without discussing with your GP. Side effects are even more common than with paracetamol so please ensure to take appropriate medical advice. There is a good booklet on the Arthritis Research UK website with information about the various drug options.
Using a walking stick if needed:
APOS Therapy trial
For patients with advanced osteoarthritis who want to avoid surgery, APOS Therapy may provide a treatment option. It is based around a shoe-like biomechanical device which can help to distribute the forces more evenly through the joint and aid in strengthening the joint.
If your are suitable for this therapy your clinician will discuss a referral when you are seen in the MSK service. Please note this service is only currently available for Bedfordshire patients.
Corticosteroid injection therapy
For individuals with mild to moderate knee OA who continue to suffer disabling symptoms in spite a course of non-surgical management (outlined above) or for patients who are unable to commence a supervised exercise program due to pain levels, a corticosteroid injection may be offered.
Total knee replacement (TKR) surgery is an effective option for patients with advanced stage knee osteoarthritis who:
- Have trialled a course of non-surgical management without success
- Have consistent, disabling pain significantly limiting mobility or affecting sleep pattern
- Have a satisfactory Body Mass Index (BMI) or if BMI >35 have made lifestyle changes to lose excess bodyweight
You may be asked to complete a questionnaire called an Oxford Knee score. This can help the clinician assess the impact of your symptoms which can be useful in assessing suitability for surgery.
Further information about osteoarthritis – Arthritis Research UK