Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

Featured on Channel NewsAsia

Your Total Knee Surgery

There are several ways to treat the pain caused by arthritis. One way is total knee replacement surgery. The decision to have total knee replacement surgery should be made very carefully after consulting your doctor and learning as much as you can about the knee joint, arthritis, and the surgery.

In total knee replacement surgery, the bone surfaces and cartilage that have been damaged by arthritis are removed and replaced with artificial surfaces made of metal and a plastic material. We call these artificial surfaces “implants,” or “prostheses.”

During Surgery

The patient is first taken into the operating room and given anesthesia. After the anesthesia has taken effect, the skin around the knee is thoroughly scrubbed with an antiseptic liquid. The knee is flexed about 90 degrees and the lower portion of the leg, including the foot, is placed in a special device to securely hold it in place during the surgery. Usually a tourniquet is then applied to the upper portion of the leg to help slow the flow of blood during the surgery. An incision of appropriate size is then made.

knee replacement 3

knee replacement 3

Removing the Damaged Bone Surfaces

The damaged bone surfaces and cartilage are then removed by the surgeon. Precision instruments and guides are used to help make sure the cuts are made at the correct angles so the bones will align properly after the new surfaces (implants) are attached.

Small amounts of the bone surface are removed from the front, end, and back of the femur. This shapes the bone so the implants will fit properly.The amount of bone that is removed depends on the amount of bone that has been damaged by the arthritis.

A small portion of the top surface of the tibia is also removed, making the end of the bone flat.

The back surface of the patella (kneecap) is also removed.

damaged tibial bone surface

damaged tibial bone surface

Attaching the Implants

An implant is attached to each of the three bones. These implants are designed so that the knee joint will move in a way that is very similar to the way the joint moved when it was healthy. The implants are attached using a special kind of cement for bones.

The implant that fits over the end of the femur is made of metal. Its surface is rounded and very smooth, covering the front and back of the bone as well as the end.

knee replacement

knee replacement

The implant that fits over the top of the tibia usually consists of two parts. A metal baseplate fits over the part of the bone that was cut flat. A durable plastic articular surface is then attached to the baseplate to serve as a spacer between the baseplate and the metal implant that covers the end of the femur.

knee replacement

knee replacement

The implant that covers the back of the patella is also made of a durable plastic.

knee replacement

knee replacement

Artificial knee implants come in many designs. Some designs may have pegs, requiring small holes to be drilled into the bone after the damaged surfaces have been removed. Others may have central stems. In addition, some designs may allow screws to be used on the lower implant to provide added attachment security. The surgeon will choose the implant design that best meets the patient’s needs.

knee replacement

knee replacement

Closing the Wound

If necessary, the surgeon may adjust the ligaments that surround the knee to achieve the best possible knee function.

When all of the implants are in place and the ligaments are properly adjusted, the surgeon sews the layers of tissue back into their proper position. A plastic tube may be inserted into the wound to allow liquids to drain from the site during the first few hours after surgery. The edges of the skin are then sewn together, and the knee is wrapped in a sterile bandage. The patient is then taken to the recovery room.

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