The goal of any knee replacement surgery is to relieve pain and improve function. For some patients, this may be achieved without replacing the entire knee. For some patients, in which the arthritis is confined only to one or two of the three knee compartments, replacing only the damaged compartments may be an option.
Partial or unicompartmental knee replacement is a minimally invasive surgery in which only the damaged compartment of the knee is replaced with an implant. The knee can be divided into three compartments: patellofemoral, the compartment in front of the knee between the knee cap and thigh bone, medial compartment, on the inside portion of the knee, and lateral compartment which is the area on the outside portion of the knee joint.
Traditionally, total knee replacement was commonly indicated for severe osteoarthritis of the knee. In total knee replacement, all worn out or damaged surfaces of the knee joint are removed and replaced with new artificial parts. Partial knee replacement may be a surgical option if your arthritis is confined to a portion of your knee.
Advantages and Disadvantages
There are some advantages of partial Knee Replacement over Total Knee Replacement. Typically, partial knee replacement can be performed through a smaller incision. Because the entire knee is not being replaced, patients usually experience less blood loss and pain resulting in a faster recover. Additionally, since all of the knee ligaments remain after a partial replacement, patients will usually report the knee feels more natural and will have improved range of motion compared to total replacement.
Partial knee replacement can have some disadvantages, however, and it is important for the patient to understand these. Since a portion of the knee joint remains, there is a risk of developing arthritis in these portions of the knee. This is the most common reason for a partial knee replacement to be converted later to a total knee replacement. Additionally, the components can loosen over time, ligament injury in the future can lead to knee instability and knee deformity often cannot be fully corrected. If knee replacement surgery is appropriate, Dr. Melvin will have a thorough discussion of pros and cons of partial versus total knee replacement as it relates to your specific situation.
During the surgery, a small incision is made over the knee to expose the knee joint. Only the damaged portion of your knee will be removed. It will be replaced with metal and plastic. These will be secured to the bone with bone cement. Once the components are fixed in proper place, the knee is taken through a range of movements. The incision is then closed and a sterile bandage is placed.
There are several aspects to a healthy, safe and rapid recovery following partial knee replacement
- Minimize narcotic pain medication to limit side-effects
- Maintain a healthy diet and adequate nutrition.
- Incision care - Dr. Melvin will educate you on proper incision care for the best possible recovery. Typically, a water-proof bandage will be placed over the incision and may stay in place until follow-up if it remains well sealed to the skin.
- Physical activity is important. You should perform home exercises and walk daily. Your body will need to adapt to your new prosthetic over time, so continued motion is an important factor. Physical therapy will also be prescribed.
- Follow-up appointments will be scheduled with Dr. Melvin. This will allow him to monitor the new knee and ensure that your recovery is proceeding well.
As with any major surgery, there are associated risks and complications may occur. Complications of partial knee replacement are similar to total knee replacement and can include:
- Knee stiffness
- Blood clots (deep vein thrombosis)
- Nerve and blood vessel damage
- Ligament injuries
- Patella (kneecap) dislocation or avascular necrosis
- Plastic liner wears out
- Loosening of the implant
- Progression of arthritis in the remaining joint
- Heart attack, stroke, death