Later is better for knee replacement

More than 500,000 people have knee replacements each year, according to the National Center for Health Statistics. Dr. Daniel Tang, an orthopedic surgeon at Howard County General Hospital, discusses the purpose of and the procedures involved in the surgery.

•The purpose of a knee replacement is to relieve a person's pain, restore movement, restore alignment and remove the impairments to activities of daily living.

The ideal candidate for a knee replacement is a generally healthy individual who has failed conservative management of arthritis and who is past the age of 60.

Persons with issues of diabetes, peripheral vascular disease and obesity have increased risk factors for the replacement of a joint.

•A knee replacement consists of metal pieces constructed to replace the surfaces on the end of the femur and the top of the tibia.

Plastic is then used as a bearing surface attached to the tibial piece and the surface of the patella or knee cap. This then eliminates the contact of surfaces of bone on which cartilage has worn away.

The knee replacement has evolved so that only a part of the knee, such as the inner half, can be replaced. Studies continue on replacing the surfaces of the kneecap and the femur.

•Patients with arthritis suffer from pain with activity and even at rest, prolonged stiffness, loss of motion, swelling that can limit a person's abilities of daily activity such as walking and stair climbing. This can ultimately affect a person's health and well being.

Before surgical treatments, nonsteroidal anti-inflammatories, viscosupplement injections, exercise therapy, braces, activity modification and weight loss should be tried.

A goal is to live with the arthritis until an age can be reached to minimize the necessity to have to do the replacement again.

•Complications following total knee replacement can include poor wound healing, stiffness, persistence of pain, weakness, neurological and vascular injury, blood clots, and infection.

Over time the plastic pieces can wear out and the metal pieces can loosen, requiring revision.