Joint Replacement: An Overview
Total hip replacement and knee replacement are considered as the orthopedic success stories. These replacements have provided relief to thousands of people and helped them in active and fuller life.
Joint is a formation of two or more bones combined by tissue known as cartilage. This cartilage helps in low friction and smooth joint movement and also provide protective cushion. When the cartilage gets damaged, the surrounding tissues become inflamed and pain occurs. Wearing of cartilage results in rubbing of bones against each other and increase pain.
If a certain part of joint is damaged, it can be repaired or replaced by surgery. However, if the joint is damaged totally, such damage can be cured only by replacing the joint. In joint replacement, the damaged or diseased part of joint is removed surgically and artificial part (implants or prostheses) is inserted.
Who should Opt for Joint Replacement
People suffering joint abnormalities caused by osteoarthritis are common cases for joint replacement. Osteoarthritis is degenerative in nature and is characterized by breakdown of cartilage of the joint. Though osteoarthritis can affect people of any age, people above the age of 45 years are considered as most common victims of this disease.
Some people have joint abnormalities like defective cartilage or deformed joint since their birth which could lead to development of osteoarthritis. Joint injuries (fractures), damage to cartilage, ligament tears and excess weight are some of the other factors which could cause osteoarthritis.
One may require joint replacement to overcome the complications arisen due to rheumatoid arthritis. In rheumatoid arthritis, swelling, stiffness and pain are caused due to chronic inflammation of joint lining. Such inflamed lining can damage cartilage and bone. People in middle age are considered as most common victims of this disease. However, in some cases it can develop in young adults and children.
People having Bone tumors and people suffering from Van Galen’s disease (bone loss led due to avascular necrosis) are other candidates for joint replacement.
Hip Replacement Surgery
The ball and socket nature of hip joint allows wide range of motion. The joint ball (top of the thighbone) called as femoral head, moves within the acetabulum (a hollow socket) of the pelvis. The smooth gliding of the ball inside socket is ensured by the cartilage layer.
In total hip joint replacement, the joint ball is cut, removed and replaced with another ball attached to a stem. Such attached ball is wedged into a hollowed-out space in the thighbone. The damage bone and cartilage are removed and replaced by inserting a cup-like component into the socket.
Hip replacement can be either cemented or uncemented. In cemented form of hip replacement, bone cement, obtained from a type of polymer, that helps fast curing held the hip parts in place. In uncemented form, specially made components, that are designed to fit tightly into the bone or that permit the growing of new bone into the porous surface of the implant, are used for holding the hip parts in place.
It is an alternative for hip replacement. Instead of using prostheses, this operation is aimed at preserving and reshaping the femoral head using resurfacing prosthesis designs. After resurfacing, such bones are capped with metal prostheses. However, the socket in this procedure is also fitted with prosthesis as is done in the total hip replacement.
Knee is the largest joint in the human body. This joint is formed by combination of lower end of femur (thighbone), upper end of tibia (shinbone) and patella (knee cap). The surface where these three bones meet each other is covered by shock-absorbing cartilage.
In total knee replacement, damaged parts of thighbone, kneecap and shinbone are removed surgically. Such removed parts are then replaced with prostheses. If required, the ends of leftover bones are reshaped and smoothed to accommodate the prostheses. Bone cement is used for holding the replaced pieces of artificial knee in place.
One may have to undertake hospitalization for about three to four days to undergo knee replacement surgery. Factors such as general health and age of the patient, plays greater role is deciding recovery period. Most of the people recover and undertake their routine activities within four to eight weeks after replacement.
Risks and Complications of Joint Replacement
Infection, complications arisen from anesthesia and blood clots are common (but at times life-threatening) risks of joint replacement. Nerve damage, breakage or dislocation after surgery and loosening or wearing out of joint is some other complications. One may have one shorter leg after hip replacement.
Infection can occur in hospital or even after prolonged period if the bacteria travel through replacement area through bloodstream. In certain cases the infection may spread to other joints and one may have to undergo surgery for this. However, such cases are rare.
Wearing out of prostheses is another complication. Prostheses are made from metal (chromium-cobalt mixture or titanium) and plastic (high-density polyethylene) which could wear with the period of time. To overcome this, the manufacturers have started producing prosthesis with new kinds of surfaces, ceramic-on-polyethylene, metal-on-metal and ceramic on ceramic, specifically for hip joint prostheses.
Surgical skills and surgical techniques are very important in joint replacement for achieving desired success. Many surgeons are developing new techniques or refining the existing ones to improve the outcome. They are making all efforts to perform less radical surgeries through smaller incisions. Minimally invasive surgery is other option for joint replacement. Certain orthopedics uses leg positionings, cutting procedures and techniques in which dislocating of knee parts is not involved.