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Stages of knee arthritis

What are the stages of knee joint arthritis?

Knee joint osteoarthritis is the most common disease affecting the musculoskeletal system, seen in about 15% of the world population. Knee osteoarthritis refers to the wear and tear process that leads to thinning or loss of the articular cartilage. The cartilage is the special protective tissue covering the bone surface at the joints, ensuring a smooth and frictionless movement. In osteoarthritis, loss of the cartilage will result in the bones becoming bare (exposed), and may rub against each other. This can result in significant joint pain, swelling and reduced function. In severe cases, there might be crepitus (a grating sensation due to bone on bone rubbing). To find out more, please see our article about knee osteoarthritis.

What are the different parts of the knee joint?

The knee joint has 3 main compartments. The inner compartment (called medial tibiofemoral joint) as it is located between the thigh bone (femur) and the shin bone (tibia). The outer component is called the lateral tibiofemoral joint. The third component is located at the front of the knee, between the knee cap (patella) and the femur. This is referred to as (the patellofemoral joint). Knee osteoarthritis can affect any compartment, including the patellofemoral joint.

How is knee osteoarthritis diagnosed?

Imaging is very useful and usually needed to confirm the diagnosis of knee osteoarthritis. A weight-bearing X-ray (an x-ray performed while you are standing) is usually the first type of scan done to assess the degree of joint space narrowing. Sometimes, more advanced imaging (an MRI scan) is required to provide more information about the state of the articular cartilage. Ultrasound is very useful in assessing for presence of fluid within the knee joint (called knee joint effusion), and guiding intra-articular knee joint injections.

What are the stages of knee joint osteoarthritis?

There are 4 stages of osteoarthritis

Stage 1

In this stage, there is usually very little thinning to the articular cartilage. The symptoms are usually very mild with an occasional “twinge”.

Stage 2 (mild)

In this stage, there is slightly higher degree of thinning to the articular cartilage but the cartilage remains to cover the bone ends within the joint (no exposed bone). The symptoms at this stage usually consists of mild generalised pain and stiffness especially after periods of inactivity of in the morning. The pain can get worse by activities like walking or using the stairs.

Stage 3 (moderate)

The cartilage loss here is more advanced and there is usually a few areas of full thickness chondral fissuring resulting in small areas of exposed bone. The x-ray will start to show obvious findings of arthritis in terms of narrowing of the joint space and formation of small areas of bone overgrowth at the joint (referred to as osteophytes). The symptoms will be more advanced compared to stage 2 and there might be occasional grating sensation (referred to as crepitus). The knee joint may swell due to fluid accumulation within the joint (referred to as joint effusion).

Stage 4 (severe)

This is the most advanced stage of the disease. There will be significant areas of complete loss of the articular cartilage, resulting in complete exposure of the bone surfaces and the bones will start to rub against each other. This usually results in severe pain that could be experienced at rest and can also interfere with sleep. This is stage is usually associated with significant limitation of function.

How to treat knee joint arthritis?

Knee osteoarthritis treatment usually starts with physiotherapy. People with the mild form of osteoarthritis usually respond very well to a combination of physiotherapy and a progressive rehabilitation program. Exercise is usually composed of a mixture of aerobic activities (like walking, cycling) and weight training. Anti-inflammatory are also used in the management of knee osteoarthritis. Other treatment options would be weight loss, modification of activity and education on arthritis.

Will I benefit from a knee joint injection for my arthritis?

if the knee osteoarthritis is severe and not responding to the management above, then an injection may be indicated. This can be very useful in reducing pain, allowing you to undertake an effective physiotherapy program. One injection option is an ultrasound-guided steroid injection. This can provide rapid pain relief and is usually followed by a course of physiotherapy to utilise the window achieved by the injection. Hyaluronic acid and PRP injections can provide an alternative to steroid injections and have been shown an effective treatment option for knee arthritis. They are usually used for mild to moderate knee osteoarthritis in active individuals.

In ultrasound-guided knee joint injections, the ultrasound is used to visualise the needle, guiding it accurately to the target site. There is plenty of evidence showing that ultrasound guided injections are more accurate, less painful and produces better results compared to non-guided injections. Total knee replacements (TKR) is usually the last reserve, and used for those with severe osteoarthritis that are not improving with injections and physiotherapy.

Do I need a knee joint aspiration?

Knee arthritis is often associated with fluid build-up within the joint. This can be diagnosed clinically and confirmed with an ultrasound examination. Aspiration refers to the drainage of excess fluid from the knee joint. This is usually done at the same time of the injection procedure. The removal of knee fluid can help to increase the joint movement and reduce swelling and pain. To find out more, please see our article about knee joint aspiration.

Knee conditions and treatment


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Specialist Consultant Musculoskeletal Radiologist Doctor with extensive experience in image-guided intervention

To book a consultation:

Call us on 020 3442 1259 or Book online

The Musculoskeletal Ultrasound & Injections clinic

Healthshare West London (The Riverside) Clinic
Unit 3, Brentside Executive Park

Brentford, TW8 9DR

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