What is Total Knee Replacement?
Total knee replacement is a surgical procedure used when non operative treatments no longer provide relief of the symptoms of osteoarthritis. It involves resurfacing the parts of the bones that rub together with metal and plastic implants. The surface of the femur is replaced with a rounded metal component that comes very close to matching the curve of the natural bone. The surface of the tibia is replaced with a smooth plastic component. A flat metal component holds a smooth plastic piece made of ultra-high-molecular-weight polyethylene plastic that serves as the cartilage. The undersurface of the kneecap may also be replaced with an implant made of the same polyethylene plastic.
Minimally Invasive Knee Replacement
A recent advance in the performance of total knee replacement is the use of minimally invasive approaches. This technique is more technically challenging than standard total knee replacement, but has a number of advantages. The incisions are approximately half the size of those used in a standard approach. The smaller incisions and new techniques to expose the joint may result in quicker rehabilitation, less pain and a shorter hospitalization.
In this practice, minimally invasive knee replacement is combined with Computer Aided Surgery to ensure excellent prosthesis component position. The computer helps to “navigate” the position of the bony cuts and any adjustment that may be required.
How can total knee replacement help?
The goal of any form of knee replacement is to decrease pain, and allow routine activities to be performed with less difficulty. More than 90 percent of individuals who undergo knee replacement surgery experience a dramatic reduction of knee pain and a significant improvement in the ability to perform common activities of daily living. But a knee replacement cannot make one a super-athlete or allow one to do more than before the arthritis.
Following surgery, some types of activity will need to be avoided for life, including jogging and high impact sports. With normal use and activity, every knee replacement develops some wear in its plastic cushion. Excessive activity or weight may accelerate this normal wear and cause the knee replacement to loosen and become painful. With appropriate activity modification, knee replacements can last for many years.
What sort of anaesthetic is used?
Most patients need to stay in hospital for a few days.
Knee replacement can be performed under regional, or general anesthesia. Regional anesthesia numbs below your waist, and general anesthesia puts to sleep. The anesthetist will help determine which is the most suitable.
What should I expect after the knee replacement?
Most patients experience mild discomfort when they wake up after a knee replacement. Wounds will be dressed with waterproof dressings under the outer bandage. The outer bandage may be removed 24hrs after surgery. The smaller dressing is to remain intact for 7-10 days.
Walking is encouraged either the day of the operation of early the next morning. Full weight bearing is allowed on the operated leg. The knee should be exercised regularly for several weeks following surgery to strengthen the muscles of the leg and knee. A physiotherapist may help with an exercise program. Exercises will need to continue at home. The physiotherapist will be able to provide instructions about proper home care, and may continue treatment for a period of time.
Will an implant set off a metal detector?
Since knee implants are made of metal, there’s a chance they could set off metal detectors. Patients have reported mixed experiences at airports: some detectors go off and some don’t.
How Long will it take to recover?
Recovery after knee replacement may take up to 18 months. This is the time it takes to regain muscle strength which is required to see the full benefit of the surgery. Patients are usually able to walk without crutches by 2 weeks and are mobilising comfortably by 6 weeks. Sedentary and office workers may return to work approximately 2 weeks following surgery. Driving a car is usually tolerated within four to six weeks after surgery.
Is physiotherapy required after total knee replacement?
Yes. Physiotherapy is commenced immediately post operatively. A physiotherapist will supervise muscle contractions, walking and weight bearing. The physio will help work on knee bend and should continue on a daily basis following surgery until the dressings are removed after 7-10 days.
Ongoing therapy aimed at strengthening the muscles around the knee and increasing knee motion is helpful for the first six months after surgery. Often these exercises can be performed at home after guidance from a therapist.
What are the risks?
Knee replacement is a very safe procedure. The most common side effect is temporary discomfort or bruising. Due to the skin incision patients may notice a numb patch on the outer aspect of their leg past the skin incision. This is of no functional significance and is unavoidable. The numb patch tends to shrink with the passage of time and does not affect the result surgery.
Following surgery there is a less than 1% chance of developing an infection. Most commonly these are superficial wound infections that resolve with a course of antibiotics. More serious infections may require further hospitalization and treatment. Injury to the blood vessels around the knee during surgery is a very rare complication (less than 1%). Other potential problems include post-operative stiffness, pain and wound problems and clots.