Partial Knee Replacement
What is Partial Knee Replacement?
The knee is made up of the femur (thigh bone) on the tibia (shin bone), with the patella (knee cap) sitting in a groove on the end of the femur. The ends of the bones are covered by articular cartilage (joint surface cartilage) and there are two menisci (cartilage pads) between the bones that act as shock absorbers. Knee arthritis is the caused by the articular cartilage wearing out over time. Knee replacement surgery replaces the worn out areas with metal and plastic prostheses.
If the arthritis only affects one part of the knee and the rest of the knee is normal, you could be suitable for a partial knee replacement (also called unicompartmental knee replacement). This operation has a shorter recovery time and often results in a knee that is more comfortable and moves more naturally than a total knee replacement.
Indications of Partial Knee Replacement
The knee is made up of three "compartments". Between the femur and the tibia, there are the medial and lateral (inner side and outer side) compartments and the third compartment is the patella and the groove it travels in. In a total knee replacement, all three compartments are replaced with metal and plastic prosthetic parts. To gain access to the joint, the anterior cruciate ligament also needs to be excised.
Partial knee replacement only replaces the worn out surfaces in the affected compartment and the rest of the joint surfaces and ligaments are left intact.
Partial knee replacement is a surgical option if your arthritis is confined to a single compartment of your knee and the ligaments, especially the anterior cruciate ligament (ACL) are intact and functioning.
Surgical Procedure of Partial Knee Replacement
Your doctor may recommend surgery if non-surgical treatment options such as medications, injections and physical therapy have failed to relieve the symptoms.
The operation is performed under an anaesthetic, so you don't feel anything. During the surgery, a 10cm incision is made over the front of the knee. The ends of the femur and tibia in the arthritic area are cut and reshaped to fit the prostheses. The femoral and tibial prostheses are then implanted into the bone. A plastic bearing is then inserted. The incision is then closed with an absorbable suture. The whole operation takes about one hour.
Postoperative Care Following Partial Knee Replacement
You may walk with the help of a walker or crutches for the first 1-2 weeks after surgery but it is safe for you to put your whole weight through the leg. A physiotherapist will advise you on an exercise program to follow for 3 to 6 months to help you regain range of motion and restore your strength. You may perform activities such as walking, swimming and biking, but high impact activities and contact sports should be avoided.
Advantages of Partial Knee Replacement
The advantages of Unicompartmental Knee Replacement over Total Knee Replacement include:
- Smaller incision
- Less blood loss
- Quick recovery
- Less post-operative pain
- Better overall range of motion
- Feels more like a natural knee
