Osteoarthritis is the disease process by which joints wear out. As the joint surface wears away it sheds wear particles which stimulate the joint lining to produce fluid causing the knee to swell. When the articular cartilage wears through the underlying bone becomes exposed. When walking the exposed bone rubs against exposed bone and this causes pain. The arthritic ache is often described like a toothache type pain.
In the early stages of arthritis most people can be well managed without operations. By a plan involving optimising pain killing medication, some simple exercises and keeping weight down the knee symptoms can often improve. With time as the joint becomes more worn out we may recommend joint replacement surgery. For more information about what treatments are available for managing your knee symptoms and to help you decide which treatment seems best suited to your individual situation you may find the NHS Direct Decision Making Aid useful.
Factors contributing to the development of osteoarthritis include:
- Genetic factors
- The alignment of the limb and distribution of load (In the early stages an Osteotomy operation may be discussed with you, this aims to correct any malalignment of your legs reducing the rate of progression of your arthritis)
- Body weight and activity level
- Injuries including fractures and ligament tears
- Removal of the meniscal cartilages.
Often one side of the knee joint wears out first. If the remaining cartilage and ligaments of the knee are in a good condition then this part of the knee can be replaced, a unicompartmental (partial) knee replacement. This preserves bone for any future surgery. The operation is less traumatic and allows a speedier recovery and better function in the knee. In Oxford we have a particular interest and expertise in Partial Knee replacements. We believe about 40% of patients with arthritis who are considering knee replacement would be suitable for partial knee replacements.
If the pattern of wear involves more than one area, or the ligaments are not functioning normally then a Total knee replacement can be performed. This can replace all the bearing surfaces of the knee with metal and plastic (high density polyethylene) components. New technology is constantly being developed and in Oxford we are involved in several areas of on going development. Patient Specific Total Knee replacements are currently being evaluated which involve custom jigs being made for your knee to allow the new knee to be implanted more precisely.