- Osteoarthritis (OA) is the most common type of joint disorder.
- It is a chronic condition of the synovial joint causing pain and stiffness and sometimes inflammation and swelling.
- It involves all of the structures of the joint.
- It has a large individual impact due to effects on the quality of life as well as large socioeconomic consequences due to it being so common and costly.
- It is important to understand as much as possible about the condition as this will help in future management of the OA.
What is Osteoarthritis?
It is a chronic condition of the synovial joint that develops over time and is the result of damaging processes overwhelming the joint’s ability to repair itself.
It can affect all of the joint tissues (including bone, ligaments, muscle, and synovium), not just cartilage. Many define OA as a condition that primarily affects hyaline articular cartilage. This cartilage is a troublesome thing that once destroyed, is not able to repair.
The Joints Affected by Osteoarthritis
The joints that are most prone to osteoarthritis include the hands and wrists as well as the weight-bearing joints of the body: the knee, hip and back. Other joints such as ankle, shoulder, and elbow are less likely to develop osteoarthritis unless there has been previous trauma to that joint.
What are the Signs and Symptoms of Osteoarthritis?
OA tends to come on slowly, over months or even years. The symptoms for those who have osteoarthritis consist of pain and stiffness (the latter is often relieved in a few minutes by movement) in the affected joints although they vary between individuals. Early in the disease course the pain is experienced with activity, although in later stages of disease it can occur at rest. In come cases the pain can lead to reduced movement, which in turn limits the function of the joint. In severe cases inflammation can develop, causing the joint to become swollen and warm. The signs that clinicians identify as part of the osteoarthritis condition include swelling, reduced range of motion, joint tenderness and bony enlargement around the joint, and crepitus (creaking of the joint when moved).
The Joint with Osteoarthritis
The synovial joint is made up of two bone ends, a layer of cartilage lining the end of each bone, a capsule lined by synovium which produces synovial fluid, ligaments, tendons and muscles.
The role of cartilage, which healthy is usually smooth, firm, white and rubbery in nature, is to help the bone ends move smoothly and painlessly against each other when the joint is moved.
Synovial fluid is a viscous fluid of a similar consistency to car engine oil and also helps the joint ends move easily by acting as a lubricant. A s a result we move joints naturally, often without noticing the action.
The tendons attach the muscles to bone and are involved in moving and stabilising the joints. The ligaments attach the two bones together and help to stabilise the joint at rest and during the movement.
The bone tissue and cartilage are always undergoing regeneration and as long as this continues the joints are work smoothly together. In osteoarthritis the damaging forces overcome the joint’s reparative ability.
The Joint with Mild Osteoarthritis
The above figure shows a joint with mild osteoarthritis changes. As you will see, the cartilage over time has become thinner, scantier, and less smooth in appearance such that the two bones do not move as smoothly during joint movement. The space between the bone ends has also become narrower due to the thinning of the cartilage, and as a result more pressure is put on the tendons and ligaments to maintain joint stability. In response to the depleted cartilage and imbalance the bone starts to grow little bony spurs called ‘osteophytes’.
The Joint with Severe Osteoarthritis
You an see in below figure that there is now much greater cartilage loss, including areas where the cartilage has disappeared, exposing the underlying bones. The osteophytes are now bigger and the bone ends start to thicken in response to the increased stresses that they encounter due to the loss of the shock-absorbing effect of the overlying cartilage. As the cartilage breaks down, debris can be found in the synovial fluid, which is struggling to produce enough lubricant for the bone ends and remaining cartilage.
This advanced stage of osteoarthritis results in pain, stiffness, and inflammation as the joint struggles to maintain its smooth function.
Osteoarthritis is a chronic or long-term disease of the synovial joints associated with pain and stiffness. The impact and experience of osteoarthritis vary between individuals.