Knee Replacement Surgery
Osteoarthritis often develops in just one compartment of the knee, usually the inner (medial) compartment. A uni-compartmental knee replacement (UKR) is designed to replace the worn joint surfaces on one side of the joint, thereby relieving pain and improving function. The operation can be performed through a smaller incision (12cm) which allows quicker healing and recovery. It also maintains normal function of the ligaments including the ACL and has been shown to provide better functional outcomes.
If the arthritis involves more of the knee then a total knee replacement (TKR) may be recommended. This decision may sometimes be made at the time of surgery when the surgeon can directly inspect the joint surfaces.
A TKR replaces the surfaces of the knee with plastic and metal. The femoral replacement is a smooth metal component, which fits snugly over the end of the bone. The tibial replacement is in two parts: a metal base sitting on the bone and a plastic insert, which sits between the metal base on the tibial and femoral component. If necessary the patellar surface (under the knee cap) is replaced with a plastic button, which glides over the metal surface of the femoral replacement, however the patella is often satisfactory, and may not require surgery. To be able to replace the surface of the knee joint a 20cm incision is made down the front of the knee and the joint opened. The arthritic joint surfaces and anterior cruciate ligament are removed and the bone is shaped so that the joint replacement components sit firmly on the bone. The replacement parts are positioned and held in place with bone cement.
A knee arthroscopy is a key hole operation using 2 or more small cuts (each about 1cm) from which a camera and instruments can be used inside the knee. It is most commonly used to treat symptomatic tears to the menisci (sports cartilages). The menisci are a commonly injured structure within the knee. Injuries can occur in any age group. In younger patients the meniscus is tough and rubbery, but can be torn in fairly forceable twisting injuries (traumatic tear). The meniscus grows weaker and less elastic with age, and can be torn with fairly minor injuries, even sometimes a simple squat (degenerative tear).
Anterior Cruciate Ligament Reconstruction
Anterior Cruciate Ligament reconstruction involves placing a graft inside the knee by arthroscopic surgery (keyhole).
In the surgery a graft will be harvested to use to reconstruct the torn ligament. Usually 2 of the hamstring tendons are taken, but sometimes other suitable graft choices are used (e.g. patella tendon). This will be discussed with you prior to the operation. The remnants of the torn ACL are removed with keyhole surgery and tunnels are made in the tibia (shin bone) and femur (thigh bone) to allow the graft to be positioned across the knee. The graft is pulled through these tunnels, it is then fixed at both ends to secure it in place.
For younger patients who are developing symptomatic knee arthritis this treatment allows the potential for both reduction in symptoms but also aims to delay any progression of the arthritis, delaying the requirement for knee replacements. For some patients with instability of the knee an osteotomy may be recommended to help stabilise the knee.
Cartilage Repair Techniques
If localised areas of cartilage have been lost techniques can be employed to try and allow healing of repair cartilage over the exposed bone. Microfracture techniques involving penetrating the bone at the base of a defect, this allows a clot to form in the defect with cells that can change into cartilage forming cells allowing a repair to the area. Sometimes more specialized techniques are needed (ACI/MACI) where cartilage cells are harvested from areas of the knee not involved in normal function. These cells are then grown in laboratories to produce a large number of new cartilage cells. In a second procedure they can be implanted into the defect with the aim of creating a