Knee Replacement

Knee Replacement Patients with severe destruction of the knee joint associated with progressive pain and impaired function may be candidates for total knee replacement. Total knee replacement surgery is considered for patients whose knee joints have been damaged by either progressive arthritis, trauma, or other rare destructive diseases of the joint. Osteoarthritis is the most common reason for knee replacement operations in the world. A total knee replacement is a surgical procedure whereby the diseased knee joint is replaced with artificial material. 

During a total knee replacement, the end of the femur bone is removed and replaced with a metal shell. The end of the lower leg bone (tibia) is also removed and replaced with a channelled plastic piece with a metal stem. Depending on the condition of the kneecap portion of the knee joint, a plastic "button" may also be added under the kneecap surface. The artificial components of a total knee replacement are referred to as the prosthesis.

Types of knee replacement surgery 

Total knee replacement (TKR) 

Surgery involves the replacement of both sides of the knee joint. It is the most common procedure. Surgery lasts between 1 and 3 hours. The individual will have less pain and better mobility, but there will be scar tissue, which can make it difficult to move and bend the knees. 

Partial knee replacement (PKR)

Partial replacement replaces only one side of the knee joint. Less bone is removed, so the incision is smaller, but does not have the longevity as a total knee replacement replacement. PKR is suitable for people with damage to only one part of the knee. Post-operative rehabilitation is faster, there is less blood loss and a lower risk of infection and blood clots. The hospital stay and recovery period are normally shorter, and there is a higher chance of more natural movement. 

What are the risks of undergoing a total knee replacement? 

There is a very low rate of complication which is associated with knee replacement such as infection and pulmonary embolism. 

What happens in the postoperative period? What is involved in the recovery from surgery? 

A total knee replacement generally requires between one and a half to three hours of operative time. Post-surgery, patients are taken to a recovery room, where vitality is frequently monitored. When stabilized, patients are returned to their hospital room. Physical therapy is an extremely important part of rehabilitation and requires full participation by the patient for an optimal outcome. Patients can begin physical therapy 48 hours after surgery. Some degree of pain, discomfort, and stiffness can be expected during the early days of physical therapy but progressively these symptoms improve over a period of time. 

A unique device that can help speed recovery is the continuous passive motion (CPM) machine. The CPM machine is first attached to the operated leg. The machine then constantly moves the knee through various degrees of range of motion for hours while the patient relaxes. Patients will start walking using a walker and crutches from day one. Eventually, patients will learn to walk up and downstairs. A number of home exercises are given to strengthen thigh and calf muscles. 

Before the procedure 

Knee replacement surgery requires anesthesia. Your input and preference help the team decide whether to use general anesthesia, which makes you unconscious or spinal anesthesia, which leaves you awake but unable to feel pain from your waist down. You'll be given an intravenous antibiotic before, during and after the procedure to help prevent post-surgical infection. You might also be given a nerve block around your knee to numb it. The numbness wears off gradually after the procedure. 

During the procedure

Your knee will be in a bent position to expose all surfaces of the joint. After making an incision about 6 to 10 inches (15 to 25 centimetres) long, your surgeon moves aside your kneecap and cuts away the damaged joint surfaces. After preparing the joint surfaces, the surgeon attaches the pieces of the artificial joint. Before closing the incision, he or she bends and rotates your knee, testing it to ensure proper function. The surgery lasts about two hours. 

After the procedure

You'll be taken to a recovery room for one to two hours. You'll then be moved to your hospital room, where you'll likely stay for a couple of days. Medications are prescribed to help control pain. During the hospital stay, you'll be encouraged to move your foot and ankle, which increases blood flow to your leg muscles and helps prevent swelling and blood clots. You'll likely receive blood thinners and wear support hose or compression boots to further protect against swelling and clotting. You'll be asked to do frequent breathing exercises and gradually increase your activity level. 

The day after surgery, a physical therapist will show you how to exercise your new knee. After you leave the hospital, you'll continue physical therapy at home or at a center. Do your exercises regularly, as instructed. For the best recovery, follow all of your care team's instructions concerning wound care, diet and exercise. 

Results

Knee replacement provides pain relief, improved mobility and a better quality of life. And most knee replacements can be expected to last more than 15 years. Three to six weeks after surgery, you generally can resume most daily activities, such as shopping and light housekeeping. Driving is also possible at around 4 weeks if you can bend your knee far enough to sit in a car, if you have enough muscle control to operate the brakes and accelerator, and if you're not still taking narcotic pain medications. 

After recovery, you can engage in various low-impact activities, such as walking, swimming, golfing or biking. But you should avoid higher impact activities — such as jogging, skiing, tennis and sports that involve contact or jumping. Talk to your doctor about your limitations.