Total knee arthroplasty

The knee is the joint where the lower end of the thighbone (femur), the upper end of the shinbone (tibia), and the patella at the front meet. The ends of the bones are covered with smooth cartilage, and the meniscus between them absorbs shock. When cartilage wears down after prolonged loading, the bones come into contact, causing pain, swelling, and stiffness when walking or standing up. This change is characteristic of knee osteoarthritis, the most common form of knee arthritis. Surgery may also be considered for inflammatory arthritis, such as rheumatoid arthritis, or after a major injury.

During replacement surgery, a thin layer of the worn surfaces is removed, and the following components are fitted.

• Metal covering on the femoral side — A metal cap that fits over the lower end of the femur.
• Metal plate on the tibial side — A flat metal base that covers the top of the tibia.
• Plastic insert — A piece of specialized plastic that helps the two metal components glide against each other.
• Patellar button — A small plastic piece attached to the back of the kneecap. It may or may not be used.

Total replacement replaces the entire knee joint, while partial replacement replaces only one compartment when damage is limited to that area. The orthopedic team determines which approach is appropriate based on imaging and the person's condition. Modern artificial joints are known to last 15–20 years or longer in many cases, although this varies with body weight, activity level, and bone condition.

Exercises to bend and straighten the knee and practice standing with a walker usually begin on the day of surgery or the following day. The hospital stay is generally a few days, but returning to everyday life takes several weeks to several months.

• Swelling and warmth can last a long time. It is common for the knee to remain warm and swollen for several months. Elevating the leg and applying cold packs can help.
• The bending angle increases gradually. Being able to bend the knee about 90–110 degrees usually makes using stairs or getting up from a chair more comfortable. Rehabilitation exercises gradually increase this range.
• Straightening the knee is important, too. Not being able to straighten the knee fully can make walking awkward, so practice fully straightening it as well.
• Kneeling and squatting are uncomfortable. These positions are often not recommended, so check with your healthcare team.

Pain in the operated knee can lead you to favor the leg, which quickly weakens the thigh muscles. Walking patterns often change, and the opposite knee and lower back may compensate. Rehabilitation therefore aims to restore the linked movements from the hip to the ankle, rather than focusing on the knee alone.

The lower-extremity textbook for Integrative Manual Therapy (IMT), Volume 2, includes a separate sequence for assessment and treatment after total knee arthroplasty. Its framework is almost the same as that for hip surgery (total hip arthroplasty). This approach examines connections throughout the body rather than looking only at the operated knee.

• Assessment — Neurological status and gait are checked, along with range of motion from the lower back through the hips, knees, and ankles. The assessment also examines muscles at the front, back, inside, and outside of the thigh and in the calf that have tightened while protecting the surgical area; the condition of the fascia in the pelvic floor, thigh, knee, and ankle; and foot posture.
• Acute phase (before approximately 10 days after surgery) — Rather than working directly on the operated knee during this period, the approach describes gently releasing transverse diaphragms across the body (the diaphragm, pelvic diaphragm, and others) and releasing fascia around the hip and ankle. The aim is to ease tension around the joints above and below the knee first, without placing strain on the surgical area.

This is the IMT account of the approach. Which manual techniques can be used, and at what stage after surgery, depends on the surgical procedure and the individual's condition. These decisions need to be coordinated with the rehabilitation guidelines of the hospital where the surgery was performed.

• Keep doing the exercises your hospital has taught you. Daily knee-bending, knee-straightening, and front-of-thigh muscle exercises are important.
• Increase walking gradually. Start with short walks indoors, then gradually walk longer distances on level ground. See Walking for details.
• Use stairs safely. Common guidance is to lead with the stronger leg when going up and the operated leg when coming down. Hold the handrail securely, and follow your hospital's instructions for the specific technique. The Stair ascent and descent article may also be helpful.
• Tell the practitioner about your surgery beforehand. When receiving massage or manual therapy, tell the practitioner the date of your surgery and any precautions provided by your hospital.

If the surgical area becomes red and hot, you develop a fever, and fluid drains from the wound, notify the hospital where you had surgery immediately. Swelling and pain in only one calf, or shortness of breath and chest pain, require emergency medical care. These may be signs of a blood clot. Also have the knee checked at the hospital if it suddenly becomes unstable or the pain becomes much worse.