Total knee replacement

Total knee replacement is surgery that resurfaces a knee damaged by arthritis. The surgeon removes worn cartilage and a thin layer of bone from the ends of the thighbone and shinbone and caps them with metal implants, with a plastic spacer in between. The underside of the kneecap may also be resurfaced. The aim is less pain and easier movement in daily life.

Knee replacement is considered for the symptoms of a badly damaged knee. It may be worth discussing when you have:

• Knee pain that limits walking, stairs, or getting up from a chair
• Pain at rest or pain that disturbs sleep
• Ongoing swelling and stiffness
• A knee that is bowing inward or outward
• Too little relief from medication, injections, physical therapy, or other non-surgical care

Most knee replacements are done for osteoarthritis. Others include rheumatoid and other inflammatory arthritis and arthritis that develops after a knee injury, such as a fracture or ligament tear. Age by itself is not the deciding factor; the level of pain and disability is.

The evaluation includes a review of your health history and symptoms, an examination of knee motion, stability, strength, and alignment, and X-rays taken while standing. Other imaging or blood tests are occasionally needed.

Preparing for surgery usually includes a medical checkup, routine tests, a review of your medications, and attention to anything that could raise the risk of infection, such as dental problems, skin sores, or a urinary infection. Arranging help at home, setting up a safe living space, and practicing with a walker or crutches beforehand makes the first weeks easier.

Knee replacement is generally recommended after non-surgical care — exercise and physical therapy, weight management when appropriate, medications, bracing or a walking aid, and injections — no longer controls symptoms. When arthritis is limited to one part of the knee, a partial knee replacement may be an alternative.

The operation is done under general anesthesia or spinal or regional anesthesia. The damaged surfaces are shaped to fit the implants, which are held with bone cement or press-fit into the bone, and a plastic spacer is placed to create a smooth gliding surface. The surgeon balances the ligaments so the knee is stable as it bends and straightens.

Risks include infection, blood clots, stiffness from scar tissue, ongoing pain, injury to nerves or blood vessels, and, over many years, wear or loosening of the implant that may need further surgery.

Many people go home the same day or after a short hospital stay. Physical therapy starts right away, because regaining knee motion early matters. Blood clot prevention, pain control that combines several types of medication, and ice and elevation for swelling are part of the early plan.

Recovery generally involves several weeks of walking with an aid and doing daily exercises, followed by a gradual return to everyday activities, and to driving when your surgeon says it is safe. Swelling and stiffness can take months to settle, and strength keeps improving long after surgery.

Over the long term, walking, swimming, cycling, golf, and similar low-impact activities are generally encouraged; running and jumping are usually discouraged. Periodic follow-up visits help track the implant.

Steps that help protect a new knee:

• Do your exercises as prescribed, especially those that restore bending and straightening
• Use your walking aid until your care team says it is safe to stop, and clear tripping hazards at home
• Take blood clot prevention medication as prescribed
• Keep the incision clean and dry until it has healed
• Tell your dentist and other clinicians that you have a joint replacement, and ask your surgeon whether you need antibiotics before dental work
• Keep a healthy weight and stay active with low-impact exercise