In this article Mr Luke Jones discusses osteoarthritis of the knee and one of the treatment options: partial knee replacement.
The knee is one of the largest joints in the body that functions as a complex hinge between the upper and lower parts of your leg. Your knee is comprised of four bones: the femur (thigh bone), tibia (shin bone), patella (knee cap) and the fibula (a smaller bone in your lower leg). The surfaces of the four bones in contact with one another are covered by articular cartilage. The cartilage is designed to allow the bone surfaces to move over each other smoothly. The knee should normally have a painless range of movement.
Knee Osteoarthritis and Symptoms
In the X-ray images here, the cartilage occupies the dark space between the ends of the femur and the tibia. In the left image, the cartilage is in normal condition but in the right image, it has worn away and thinned on one side. When the smooth articular surface of the tibia or the femur becomes worn through injury or overuse, the knee joint becomes painful to move. This condition is known as osteoarthritis. The knee may become stiff and some patients report that the knee becomes noisy, or “cracks” when it is used. Other symptoms may also include pain at night, stiffness first thing in the morning, and pain that is aggravated by increased use of the knee.
Treatment Options for Knee Osteoarthritis
For some patients with knee osteoarthritis, particularly in the early stages, several strategies exist to reduce symptoms and minimise the disruption to daily activities. These include weight loss, physiotherapy, injections, bracing and painkillers. However, if these methods do not help to relieve the symptoms, then knee replacement surgery is an option. The aim of knee replacement surgery is to relieve your pain and therefore improve the function of your knee. This means that you should be able to walk further, return to your normal activities and regain your quality of life.
What is a Unicompartmental Knee Replacement?
Osteoarthritis frequently affects only the medial half of the knee. In such cases, surgeons may be able to perform a partial knee replacement on only the affected side of the knee (known as a Unicompartmental Knee Replacement – UKR) as opposed to a Total Knee Replacement (TKR) in which both sides of the knee are replaced.
A Unicompartmental Knee Replacement can be thought of as a reconstruction of the worn side of the knee. As shown on the X ray here, the tibial surface is resurfaced with a thin flat metal plate, and the femoral surface is replaced by a rounded metal surface. A plastic insert, known as a bearing, is placed between the two metal surfaces to allow them to move against each other.
The supporting ligaments that hold the joint together are not cut, and as much of your normal knee is preserved as possible.
In cases where Unicompartmental Knee Replacement is not an option, an alternative procedure known as a Total Knee Replacement can be carried out. In a Total Knee Replacement three compartments of the knee are replaced, rather than just one. In most cases, the clinical team can establish whether a Unicompartmental Knee Replacement is the right option before your surgery, but the final decision on whether to perform a Unicompartmental Knee Replacement or Total Knee Replacement is made at the time of the surgery, when the surgeon is able to inspect the joint surfaces and the ligaments inside the knee.
Benefits of Unicompartmental Knee Replacement
In those patients who are suitable for the procedure, Unicompartmental Knee Replacement has several potential benefits over Total Knee Replacement. These include:
- Smaller incision and less soft tissue damage
- Less blood loss during surgery and therefore less need for blood transfusion
- Quicker recovery
- Fewer medical complications
- Better post-operative range of movement in the knee
- A more “normal” feeling knee
- Generally higher levels of satisfaction
How successful is Unicompartmental Knee Replacement surgery?
Research shows that 85% of patients who have a Unicompartmental Knee Replacement surgery consider the operation to be very successful with a significant improvement in their quality of life. Of the remainder, 10% reported an improvement but not as much as they had hoped, and 5% consider themselves to have had a poor outcome. At 20 years post-surgery, more than 80% of Unicompartmental Knee Replacement patients reported that their knees were still functioning well.
Research shows that when performed by experienced surgeons, Unicompartmental Knee Replacement lasts as long as, or longer than, Total Knee Replacement. It is unlikely that you would need to have your Unicompartmental Knee Replacement converted to Total Knee Replacement in the future, although this is relatively straightforward to do if necessary
| Mr Luke Jones DPhil(Oxon), FRCS(Tr&Orth), MB BS, BSc(hons) Consultant Orthopaedic Knee Surgeon SECRETARY DETAILS Shona Brogan Email: jonespa@gop.health Practice Direct Dial: 020 3824 2290 |
References
