Knee joint is the largest joint in the body. It is made up of the lower end of thigh bone (femur) and upper end of shin bone (tibia). The joint is covered with a small kneecap (patella). The articular structures are enclosed in a capsule and covered with ligaments and muscles. Menisci (C shaped structures) are located between the lower end of thigh bone and upper end of shin bone. Inner aspect of the capsule is lined by synovial lining which produces synovial fluid for joint lubrication. All these structures should work in harmony for perfect functioning of the knee joint. Disease or injury to any of these bony structures, muscles, ligaments or menisci will disrupt normal functioning of the knee joint.
It is a surgical procedure to remove damaged bone and cartilage for the knee joint and replace it with an artificial joint. Knee replacement is one of the most successfully performed orthopaedic surgery.
Your doctor/ orthopedician will perform through evaluation of your signs and symptoms before proceeding with surgery.
After reviewing the results of your diagnostic tests (X-ray/ MRI, etc.), your doctor will have a detailed discussion with you regarding surgery. There are no age or weight restrictions for knee replacement surgery. Most patients are between 50 to 80 years of age. However, surgery has been successful in young and teenage patients as well. Your doctor will brief you about the procedure and its outcome. Never hesitate in asking any kind of questions to your doctor. The more you know, the more prepared you are both physically and mentally.
There are 3 different types of knee replacement surgery, namely-
The surgery usually takes 1 to 2 hours. Your surgeon will start with giving anaesthesia. You may be given either general or spinal anaesthesia depending on your health status. The surgeon will make a cut over the kneecap to expose the joint. He/she will next remove the damaged part of the bone and cartilage and replace it with a prosthetic implant. The bony ends are replaced with metal implants and special plastic is used to replace the backside of the kneecap. Similar plastic material called spacer is placed between the two ends of metal implants to facilitate smooth joint movement. Special surgical cement is used to glue the artificial joint together. Cemented prosthesis are the most common type of artificial prosthetic knee joint. Uncemented prosthesis are not commonly used. However, sometimes a combination of the two is used. A drain may be placed to drain out fluid and prevent postoperative swelling around the joint. The incision site is closed with either stitches or surgical staples and covered with sterile dressing. Most patients stay in the hospital for a day or two after surgery.
After the surgery has been successfully performed, the patient is transferred to the hospital room. On waking up vitals (blood pressure, body temperature, pulse rate and respiratory rate) are taken. Wound is inspected and fresh dressing is applied. Drain is usually removed the next day. Pain medications are often prescribed for a short period of time. Next day the physiotherapist will start with an exercise program. Initially a continuous passive motion machine (CPM) is used to slowly bend the knee joint. The therapist will also assist you in taking a few steps with the help of a walker, crutches or cane. Hospital stay may vary from 2 days to a week.
You will be under close observation of your surgeon and physiotherapist for the next few days. Pain levels will be closely monitored and accordingly doses will be altered. The nursing staff will perform daily wound inspection. Your physiotherapist will encourage you to perform specific strengthening and range of motion exercises for the knee joint. Walking around for short distances is also encouraged. Try to use your knee as much as possible but do not overexert yourself.
Once back home you can resume your normal diet. You should drink plenty of fluids. Certain lifestyle modifications will ease your everyday activities such as, raised toilet seat, handrails in bathroom, hand held jet/shower spray, shower seat and high chair for sitting. It is also important to declutter your house and remove any unnecessary piece of furniture, wires in the walkway, loose rugs and door mats to avoid risk of falls. Always keep the floor of the bathroom dry and keep shampoos and soaps away on a stand. Avoid staircase use until recommended by your surgeon. You can also resume driving after consulting your surgeon.
Continue physiotherapy after discharge from hospital for at least 6 to 8 weeks. You will experience pain and stiffness post surgery but this should not stop you from exercising. Exercises should be performed under supervision and you can contact a physiotherapist for home visits.
The artificial joint will last somewhere between 15 to 20 years depending on the type of artificial joint material used and usage. However, researchers have suggested that with recent advances over 82% of replacements are still functional after 25 years. In case the joint is dislocated or damaged, repeat surgery (knee revision surgery) has to be performed but this one is rather more complicated than the original surgery.
Most patients do not experience any complications after knee replacement surgery. However, few of them may encounter certain complications. Some of them are-
Any unusual signs or symptoms that you notice post surgery are termed as warning signs. These should not be ignored and you should inform your doctor right away. Major warning signs include-
Ignoring these warning signs increases the risk of complications.