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Knee replacement

Replacing a worn-out knee with a plastic and metal one

Knees are the largest joints in our body. The normal knee is made up of the following parts: the lower end of the thighbone (femur), the upper end of the shinbone (tibia), the kneecap (patella), cartilage that covers the ends of the bones, C-shaped wedges called menisci that cushion the joint, and large ligaments that hold the femur and tibia together. The thin, synovial membrane covering the surfaces of the knee releases lubricating fluid to reduce friction of the bones.

As with hip pain, the most common cause of chronic knee pain are three forms of arthritis:

  • osteoarthritis that results from age-related wear-and-tear, 
  • rheumatoid arthritis in which the cushioning, or synovial, membrane in the joint becomes inflamed and thickened, or 
  • post-injury arthritis that sets in after an injury or fracture. 

Depending on the injury or damage, your doctor may recommend either total knee replacement or partial knee replacement. It is possible to have both knees replaced at the same time, if your physician determines that is the best treatment plan for you.

With a total knee replacement, the worn-out surfaces of the knee are resurfaced with metal and plastic components. During total knee replacement surgery, your surgeon will:

  • Prepare the bone by removing damaged cartilage surfaces of the femur and tibia and small amounts of the underlying bone
  • Replace the removed cartilage and bone with metal components.
  • Resurface the patella, if necessary
  • Insert a medical-grade plastic spacer between the metal components. This creates a smooth, gliding surface to allow for movement.

Partial knee replacement is a minimally invasive surgical procedure in which the worn, damaged surfaces of the knee joint are resurfaced with metal and plastic components. This can be an option for those whose injury or pain is limited to one area of the knee.