Of all the joints in the body, the knee arguably has the heaviest burden. It is the largest joint in the body and allows the leg to bend.
It is a complicated joint made up of the shinbone, the thighbone and the patella, or knee cap which is a shield-shaped bone that actually protects the joint proper. The patella in turn is only protected by skin and ligaments.
Injury to the knee is common, as is osteoarthritis. This is the type of arthritis that develops over time as the cartilage that cushions the bones in the knee start to wear down, and the bones start to grind against each other.
Sometimes, injury or arthritis is so extensive that doctors must recommend that the knee or at least a compartment of the knee be replaced. The former is called a total knee replacement, while the latter is called a partial knee replacement.
Partial Knee Replacement:
This operation is done to replace a compartment of the knee that’s been damaged by arthritis. It is mostly used to repair medial arthritis in the knee. Medial arthritis is found on the inside of the knee and is the most common type of arthritis to affect this joint.
Patients appreciate the partial knee replacement because it preserves more of the natural components of the knee and allows it to keep more of its range of motion.
The operation requires a smaller incision than a total replacement, results in less blood loss, less pain and has a shorter recovery period.
During the surgery, the damaged compartment is replaced by a plastic and metal prosthesis. Before the surgery, the doctor and patient have a consultation where the doctor takes the patient’s medical history. The knee is then X-rayed or examined through an MRI or other imaging test.
In the first phase of the surgery, the incision is made in the knee, and the doctor checks to see how much damage there is. If the damage is extensive, they may opt for a total knee replacement.
During the partial knee replacement:
• The doctor uses special saws to prepare the bone and remove the cartilage
• Positions the metal implant
• Inserts the plastic spacer
The patient is urged to walk the day after surgery, and soon after they go home they start physical therapy. There’s usually full recovery after about six to eight weeks.
Total Knee Replacement:
Total knee replacement surgery requires four steps:
• The bone is prepared by removing the cartilage and shaping the ends of the shinbone and the thighbone
• The metal implants are press-fitted or cemented in
• A plastic button is placed beneath the patella
• The plastic spacer is inserted beneath the metal in the shinbone and the thigh bone
There are two types of total knee replacement surgery. One type removes the posterior cruciate ligament, which is a large ligament in the back of the knee. A cam and post device is inserted to do the work of this ligament.
The other type preserves the posterior cruciate ligament. The surgeon determines that the ligament is still healthy and inserts an artificial joint with a groove to support it.
Knee replacement surgery can be done with the traditional 12 inch long incision or the minimally invasive three to four inch long incision. The smaller incision causes less trauma to the thigh muscles, and the kneecap is pushed aside during the surgery instead of being turned over.
Whether they have a partial or total knee replacement, most patients make a full recovery and eventually enjoy being able to use their knee without pain.