Anatomy of the Knee
The knee is made up of the femur (thighbone), the tibia (shinbone), and patella (kneecap). The meniscus, the soft cartilage between the femur and tibia, serves as a cushion and helps absorb shock during motion. The knee can be divided into three compartments:
- Patellofemoral: Compartment behind the kneecap
- Medial: Compartment on the inside of the knee
- Lateral: Compartment on the outside of the knee joint
What is Arthritis?
Arthritis (inflammation of the joints), injury, or other diseases of the joint can damage the protective layer of cartilage, causing extreme pain and difficulty in performing daily activities. Osteoarthritis is the most common form of knee arthritis in which the joint cartilage gradually wears away. It often affects the elderly.
In a normal joint, articular cartilage allows for smooth movement within the joint, whereas in an arthritic knee, the cartilage itself becomes thinner or completely absent. In addition, the bones become thicker around the edges of the joint and may form bony “spurs”. These factors can cause pain and restricted range of motion in the joint.
What is Tricompartmental Knee Replacement?
Tricompartmental knee replacement, also called total knee arthroplasty, is a surgical procedure in which the worn-out or damaged surfaces of the knee joint are removed and replaced with artificial parts.
Indications of Tricompartmental Knee Replacement
Tricompartmental knee replacement surgery is commonly indicated for severe osteoarthritis of the knee.
Your doctor may advise this procedure if you have:
- Severe knee pain that limits your daily activities (such as walking, getting up from a chair or climbing stairs)
- Moderate-to-severe pain that occurs during rest or awakens you at night
- Chronic knee inflammation and swelling that is not relieved with rest or medications
- Failure to obtain pain relief from medications, injections, physical therapy or other conservative treatments
- A bow-legged knee deformity
Tricompartmental Knee Replacement Procedure
The goal of tricompartmental knee replacement surgery is to relieve pain and restore the alignment and function of your knee. Your doctor may recommend surgery if non-surgical treatment options have failed to relieve the symptoms.
The surgery is performed under spinal or general anesthesia. Your surgeon will make an incision on the skin over the affected knee, to expose the knee joint.
Then, the damaged portions of the femur bone are cut at appropriate angles using specialized jigs. The femoral component is attached to the end of the femur with or without bone cement. Your surgeon then cuts or shaves the damaged area of the tibia (shinbone) and cartilage. This removes the deformed part of the bone and any bony growths, as well as creates a smooth surface on which the implants can be attached.
Next, the tibial component is secured to the end of the bone with bone cement or screws. Your surgeon will place a plastic piece called an articular surface between the implants to provide a smooth gliding surface for movement. This plastic insert will support the body’s weight and allow the femur to move over the tibia, like the original meniscus cartilage.
The femur and tibia with the new components are then put together to form the new knee joint. To make sure the patella (kneecap) glides smoothly over the new artificial knee, its rear surface is also prepared to receive a plastic component.
With all the new components in place, the knee joint is tested through its range of motion. The entire joint is then irrigated and cleaned with a sterile solution. The incision is carefully closed, drains are inserted and a sterile dressing is placed over the incision.
Postoperative Care following Tricompartmental Knee Replacement
Rehabilitation begins immediately following the surgery. A physical therapist will teach you specific exercises to strengthen your leg and restore knee movement. Knee immobilizers are used to stabilize the knee. You will be able to walk with crutches or a walker. A continuous passive motion (CPM) machine can be attached to the treated leg. This constantly moves the joint through a controlled range of motion, while you relax. Your physical therapist will also provide you with a home exercise program to strengthen your thigh and calf muscles.
Risks and Complications of Tricompartmental Knee Replacement
As with any major surgery, the possible risks and complications associated with tricompartmental knee replacement surgery include:
- Knee stiffness
- Blood clots (deep vein thrombosis)
- Nerve and blood vessel damage
- Ligament injuries
- Patella (kneecap) dislocation
- Wearing out of the plastic liner
- Loosening of the implant