Ageing joints and osteoarthritis

Osteoarthritis is a condition characterised by a loss of articular cartilage in a joint and deterioration of the supporting structures that results in symptoms, for the patients, of pain and disability, and loss of ability to do normal daily functions. The most commonly affected joints in osteoarthritis are the weight bearing joints of the hip and the knee, followed by the hand. The older a patient gets, the more likely they are to develop osteoarthritis. For example, in patients over 70 years of age, the incidence of symptomatic knee osteoarthritis is around 40% to 45%, whereas the incidence of symptomatic osteoarthritis in younger patients is very much lower.

Obesity has been found, in many studies, to be directly related to both susceptibility to osteoarthritis and the rapidity of its progression. There is modest data on occupational risks for osteoarthritis. Patients who have a very heavy manual labour job are at an increased risk of knee osteoarthritis, although this risk association is much less than the associations with age and obesity. There is also a subgroup of patients who may get osteoarthritis as a secondary event, following, for example, a previous fracture. If a patient has a fracture at a joint site that heals sub-optimally, then that places them at a significantly increased risk of osteoarthritis in the future.

Similarly, patients who have major ligament damage at a joint, for example cruciate ligament damage that is incompletely repaired, then they are also at increased risk of osteoarthritis in later life. Osteoarthritis may also occur secondarily to previous infection. And also, in situations where there’s been some childhood developmental abnormality, we may also see the development of osteoarthritis later in life. 50% of an individual’s susceptibility to osteoarthritis is due to heritable factors, that is genetic factors that are inherited from your parents. This illustration here shows the difference between an osteoarthritic joint and a normal joint. On this split half of the image, we can see an essentially normal joint with the normal cartilage and underlying bone and ligaments.

However, on the right-hand side of the image we can see features of osteoarthritis. So we have cartilage loss as exampled here, damage to the other cartilages within the joint. This is the meniscus here with damage to it. We can see that it also affects the underlying bone. We see thickening of the underlying bone, and it has cysts within it. The other feature we can see is these outgrowths of bone from the side of the joint, which are a feature of arthritis. And the other key features to note are the inflammation of the lining of the joint, that’s the synovial lining.

And also the capsule of the joint, which you can see here in green, is very much thickened, contributing to the overall stiffness of the joint when compared with the thinner capsular lining of the joint on the normal side. The treatment of osteoarthritis predominantly centres around managing symptoms and lifestyle modification. The best ways to seek to minimise the effects of osteoarthritis are to maintain a healthy lifestyle, for example, having a body mass index that is within the normal range, doing regular exercise. Surgery is considered in patients when conservative measures such as lifestyle modification, painkillers, and weight loss are no longer effective in controlling the symptoms of the disease, which are pain, and stiffness, and loss of function.

And at that point, then referral for a surgical opinion is made. The surgical options in osteoarthritis are largely limited to replacement of all or part of the affected joint. For example, at the knee the damaged joint can be replaced with a prosthesis. This prosthesis goes on the end of the thigh bone, and this part of the prosthesis goes at the top of the shin bone, for example, as shown here. And these articulate against each other to replace the damaged arthritic bone.