Arthroplasty is the reconstruction or reshaping of a damaged or diseased joint. This elective surgery most often involves joint replacement, the implantation of an artificial joint (prosthesis).

Only certain patients are good candidates for the procedure, such as those who are in otherwise good health but experience osteoarthritic pain that has not responded to other treatments and that is interfering with daily activities and decreasing quality of life. The relief of joint pain is often considered a driving factor for many patients who receive arthroplasty.

In addition to osteoarthritis, arthroplasty can be a treatment for conditions including hip fractures, other source of acute trauma and rheumatoid arthritis.

Arthroplasty may be used to:

• Replace all or part of a joint with a prosthesis
• Resurface a joint with the patient’s own tissue
• Reshape the bone and cartilage that make up the joint

When prostheses are used, they may be made of polyethylene, metal, ceramics or silicone. The most common design is metal-on-polyethylene, although metal-on-metal designs have become more popular in recent years.

Arthroplasty is performed under anesthesia and may last several hours. During the procedure, the joint is fully exposed and the damaged bone and cartilage are cut away or reshaped. When prostheses are used, they are inserted after measurements are taken to ensure proper fit. The joint is tested before the incision is closed.

Arthroplasty is typically followed by several days in the hospital. Medications may be given to ease pain and prevent infection and blood clots. Extensive physical therapy is employed to bring the joint to near-normal function while avoiding complications. Occupational therapy may be prescribed to maximize the patient’s independence in daily activities. Patients typically resume normal activities after two to three months.

Arthroplasty is usually employed as a last resort. Alternatives include physical therapy and arthroscopy. Variations of arthroplasty include minimally invasive surgery with smaller incisions, working on multiple joints during a single surgery, and replacing only parts of the affected joints. Arthroplasty may greatly improve a patient’s quality of life but is not without risks.

Arthroplasty is an elective surgery to reshape or reconstruct a damaged or diseased joint. It may entail joint replacement, involving the replacement of part (partial arthroplasty) or the entire joint (total arthroplasty) with a prosthesis (an artificial body part) and the resurfacing or relining of the bones, or more minimal reconstruction of the joint.

Prostheses replace worn-away or destroyed cartilage and bone. They typically last 10 to 13 years. Some new ones have been promoted as being able to last 20 years or longer, but this has not been seen clinically yet.

More than 500,000 joint replacements are performed in the United States each year, according to the Arthritis Foundation. Pain and decreased quality of life are the two main reasons for undergoing arthroplasty.

The success of arthroplasty depends on patient selection, particularly with total arthroplasty. Because of the limited life of prosthetic devices, total arthroplasty is usually not performed in younger patients. However, waiting too long to deal with a joint problem may reduce the likelihood of a good outcome from arthroplasty years later.

Candidates for total arthroplasty are typically over the age of 60 years because physically active young people tend to wear out prostheses quickly. The joint of the candidate must have limited function that interferes with activity, such as chronic stiffness and swelling, difficulty walking (in a joint associated with the legs) or lifting/holding things (in a joint associated with the arms) and moderate to severe pain from osteoarthritis even when at rest. Deformity of the joint increases the likelihood that arthroplasty will be used in treatment.

Arthroplasty is typically not a chosen course of action until other methods (e.g., resting, weight loss, physical therapy, analgesics) have proven unsuccessful. Good candidates for this procedure are generally healthy, without infection or conditions that restrict blood flow, and preferably without diabetes or other endocrine disorders. They generally remain active and maintain a healthy body weight. Candidates for lesser forms of arthroplasty may have fewer and less serious conditions. 

The prostheses that may be used in arthroplasty are finite (limited) in duration. New designs are allowing prostheses to last longer and longer. Regardless of the design, prostheses typically last longer in the older, less active population. Youthful activity levels generally wear out a prosthesis more quickly, requiring that it be replaced more often.

Arthroplasty may be used to treat affected joints in a number of conditions, including:

• Osteoarthritis. A degenerative bone arthritis typically affecting older individuals. Individuals with advanced forms of this condition that do not respond to other treatments are good candidates for arthroplasty. The procedure is often performed primarily to reduce the pain in the joint and improve quality of life. Knee replacements have become a common treatment for severe osteoarthritis in the knees.
  
  
• Rheumatoid arthritis (RA). A chronic inflammatory form of arthritis that may affect individuals of any age. Adult and juvenile rheumatoid arthritis may lead to the need for arthroplasty. Individuals with RA often require knuckle arthroplasty.
  
  
• Fractures. Falls and osteoporosis often cause hip fractures in elders that may require a partial or total hip replacement.

• Osteonecrosis. Death of bone tissue caused by obstructed blood flow. Arthroplasty may be useful in the treatment of this condition, particularly when it occurs in parts of the bones close to the joint, such as the head of the femur in the hip.
  
  
• Post-traumatic arthritis. Arthritis caused by injury. Arthritis that follows a dislocation or fracture may call for the use of arthroplasty.
  
  
• Hip dysplasia. Abnormal growth of the hip. When the acetabulum (the cavity in the pelvic bone into which the head of the femur fits) is shallow and the femoral head is exposed, early osteoarthritis often results. In these cases, a total hip arthroplasty may be required.
  
  
• Primary bone cancer or metastasis (spread of cancer cells from other tumors to bone tissue). When this occurs at a joint, arthroplasty may be needed to restore the joint.
  
  
• Joint deformity. Some joints, such as the knees, bow in or out, causing pain and limiting range of motion. Other deformities that may in severe causes require arthroplasty include hammer toes and mallet toes, common sources of foot pain.
  
  
• TMJ disorder. Used to repair, reposition, replace or remove the articular disc that cushions the temporomandibular joint in the jaw.
  
  
• Psoriatic arthritis. A form of arthritis that occasionally affects patients with psoriasis and can cause painful inflammation in the joints of the hands.
  
  
• Sports injuries. Acute or cumulative trauma sustained during athletics can often be treated with noninvasive methods or arthroscopy, but sometimes arthroplasty is needed.

Some sources of back pain and neck pain can be treated with vertebral arthroplasty, but spine surgery is often considered separately.

There are many types of arthroplasty. Some require prostheses (artificial body parts), and others do not. When prostheses are required, there are many options available.

Joint replacements are the most common kind of arthroplasty and are among the most common procedures performed by orthopedic surgeons. Many joints may be totally or partially replaced, including the knees, hips, ankles, shoulders, elbows, wrists, fingers and toes.

Total joint arthroplasty may be used to repair acute conditions, such as a hip fracture, or to treat chronic conditions if the patient is experiencing disabling daytime and nighttime pain that prevents everyday activities. There also needs to be x-ray evidence of joint damage, including:

• Obvious narrowing of the joint space
• Osteophytes (bone spurs)
• Subchondral (below the cartilage) cysts
• Subchondral sclerosis (thickening or hardening of the bone)

With chronic disorders, joint replacement is typically used only when conservative therapies such as bedrest or physical therapyphysical therapy have failed. Total joint arthroplasty is typically reserved for patients over age 60, sometimes 55. Sometimes younger patients  are candidates if they are experiencing moderate arthritis and increasing deformities that seem likely to jeopardize future results from an arthroplasty.

Variations on joint replacements include:

• Single-stage bilateral total joint arthroplasty. Both corresponding joints (e.g., both hips) are replaced at the same time. This is most common with the knees.
  
  
• Unilateral total joint arthroplasty. One joint is replaced. An option recently approved by the U.S. Food and Drug Administration for less-invasive hip replacement is hip resurfacing, in which a small amount of bone is removed from the ball-like head of the femur (thighbone) and metallic parts are implanted into the femur and the socket-like acetabulum of the pelvis.
  
  
• Hemiarthroplasty. Only one side of the joint is replaced. For example, only the head of the femur in the hip joint may be replaced, leaving the natural acetabulum as is.
  
  
• Unicompartmental joint arthroplasty. Only a single piece of the joint is replaced. This is an even more limited replacement than hemiarthroplasty.
  
  
• Minimally invasive surgery. Works with smaller incisions. This may be employed in total joint arthroplasty. Some centers can even perform this variation as an outpatient procedure. The soft tissues around the joint suffer less trauma, and the patient recovers much more quickly. However, this technique has only recently been developed, and long-term results are not yet available.
  
  
• Replacement arthroplasty. When a joint prosthesis wears out or becomes infected, another arthroplasty is required to replace it. This is most common in patients younger than 60 because of their more active lifestyles.

Other types of arthroplasty include:

• Interposition arthroplasty. The affected joint is resurfaced with a piece of the patient’s own body tissue. Either a piece of the patient’s skin (usually from the abdomen) or tendon (usually from the Achilles tendon) is stitched in place between the bones of the joint. This keeps the bones from rubbing together and reduces pain. This option is generally best for patients under age 60.
  
  
• Osteocapsular arthroplasty. This involves the removal of osteophytes, loose bone, loose cartilage and bits of inflamed synovium (fluid sac that lubricates between joints) and the reshaping of deformed or deteriorated bones. Osteocapsular arthroplasty can be very successful, but it is not widely performed. It is a relatively new surgery that employs a very difficult technique and requires substantial expertise.

With joint replacements, there is a wide range of options available for prostheses. The many materials that may be used include:

• Polyethylene. This has been the most common material used in prostheses. However, it has been heavily scrutinized because of its high production of wear debris, which leads to osteolysis (enzymes break down and reabsorb the bone tissue in an attempt to get rid or foreign particles).

In the past, this wear rate has been very high, but because of improvements in sterilization and development, new polyethylene designs have become much more resistant to wear. Still newer developmental designs demonstrate even less wear but require further long–term study. Polyethylene is the least expensive material for prostheses.

• Metal alloys. Chromium cobalt is often used, but stainless steel or titanium may also be employed. These metals produce very small amounts of wear debris and the wear rate actually improves once the prosthesis has been broken in. Metal alloys may still cause osteolysis, but to a smaller degree than polyethylene. Any metal surface, including the metal alloys used in prostheses, may generate corrosion, but this is typically reduced, especially in newer designs.

There is some concern over the absorption of metal ions in the body. These ions may be deposited throughout the body and metallic levels in the blood and urine may be many times higher than normal. No adverse effects have been reported over 20 years of use in any individual, but this issue requires further study.

• Ceramics. Alumina is typically used. Ceramics are more brittle than other materials used for prostheses but have lower wear rates than metal. However, though they do generate less debris, they may still cause osteolysis. Little is known about the response of the body to ceramic wear particles.
  
  
• Carbon. Pyrolytic carbon and graphite have been used successfully in small joint implants and can be incorporated into composites of larger implants.

A prosthesis may incorporate any of a number of designs, including:

• Metal-on-polyethylene. This is the most commonly used prosthesic design. It has a low coefficient of friction close to that of normal joints and typically lasts for about 20 years.
  
  
• Metal-on-metal. The earliest prosthesis designs were metal-on-metal. These early designs showed many failures, generally due to design flaws and the misunderstanding of how specific joints work. The designs were nearly replaced by metal-on-polyethylene designs as a result. However, metal-on-metal regained popularity when polyethylene particles were linked to osteolysis. These designs typically last for about 20 years.
  
  
• Ceramic-on-ceramic. These designs were initially investigated for high scratch resistance and wearability. Early designs had many problems with cracking, but this fracture problem has been nearly eliminated in current designs. Ceramic-on-ceramic prostheses typically last for about 15 years but have not yet been approved for widespread use in the United States.
  
  
• Silicone spacers. These are typically reserved for very small joints, such as the knuckles. This is a one-piece design rather than a hinge. Small silicone discs are placed between the bones of the joint to cushion them and keep them from rubbing together. Over time, the soft tissues and ligaments around the joint heal and strengthen and joint movement and function is partially regained. Silicone spacers typically last about 10 years.

A final option in the choice of prosthesis lies in the method used to adhere the prosthesis to the bone. These options include:

• Bone cement. Polymethylmethacrylate (PMMA) is used to secure the prostheses to the bone. It may wear and cause osteolysis and has higher rates of loosening than with press fit. The decision on whether to use bone cement is often dependent on the clinical situation and the surgeon’s preference. Though cemented components are currently the most popular method of fixation, cementless components are becoming increasingly popular.
  
  
• Press fit. This cementless approach encourages bone to grow directly into the prosthesis. The prosthetic surface is rough, to increase surface area, and coated in an osteoconductive substance, such as hydroxyapatite, that encourages the bone to grow and adhere to the surface.
  
  
• Hybrid approach. Bone cement is used on part of the joint and press fit on the other.

Patients may be prescribed exercise therapy in advance of their surgery to promote recovery afterward.

People with a condition that can complicate arthroplasty or recovery from the surgery may be put on a program to improve management of that condition weeks or even months in advance. For example, people with unstable diabetes will typically undergo more intensive measures to control and monitor their glucose (blood sugar).

The physician may recommend an autologous blood donation, in which the patient’s own blood is collected before surgery in case a transfusion is necessary. Generally, one unit of blood is obtained per week for several weeks prior to the procedure.

The patient’s medical history is evaluated, with emphasis on symptoms, level of pain, interference with daily activities due to pain, other medical problems, medications and allergies. The physician performs a physical examination, including observation of the joint, palpation (feeling and moving the joint) and other tests to assess range of motion, stability and strength. The patient may be asked to complete a pain assessment form before the surgery and after recovery.

The physician may also order imaging tests and laboratory tests, such as:

• X-rays. Painless tests in which an image is created of part of the body by using low doses of electromagnetic radiation that are reflected on film or fluorescent screens. X-rays are typically taken from multiple angles to determine the extent of the damage.
  
  
• Arthrography. An x-ray test that uses a contrast medium to highlight a joint.
  
  
• Magnetic resonance imaging (MRI). A safe and noninvasive or minimally invasive test that produces cross-sectional or three-dimensional images of the body’s tissues, even through bone and other obstructions.
  
  
• Bone scan.  A nuclear imaging test that identifies areas of breakdown or new growth in the bone. Bone scans are performed by injecting small amounts of a radioactive substance called a tracer into the body through a vein in the arm. The tracer travels through the bloodstream and to the bones. A special device called a gamma camera detects radioactivity and is used to produce images of the bones.
  
  
• Electrocardiogram (EKG). A recording of the heart’s electrical activity as a graph or series of wave lines on a moving strip of paper. EKGs are noninvasive, quick, safe and painless.
  

• Complete blood count (CBC). A routine blood test that measures the composition of blood cells within the body.
  
  
• Urine tests. Tests that detect abnormally high or low levels of substances in the urine.

The physician typically reviews the risks and benefits of the procedure and treatment alternatives with the patient before prosthetic components (if any) are selected.

Medications (e.g., corticosteroids, nonsteroidal anti-inflammatory drugs) may be adjusted or halted before the procedure. The patient will typically be instructed not to eat or drink after midnight before the procedure. The patient should plan to be hospitalized for several days after the procedure and make appropriate arrangements (e.g., schedule time off from work, cancel newspaper delivery).

Arthroplasty is typically performed in a hospital. Anesthesia is administered prior to the procedure. It may be general, regional (e.g., epidural) or local, depending upon the joint being worked with, the extent of the surgery and the wishes and needs of the patient and surgeon. Antibiotics are typically administered to help prevent infection.

The procedure itself may last from one to four hours, depending upon the joint being worked on and the type of arthroplasty employed. Vital signs (e.g., heart rate, blood pressure, blood oxygen levels) are monitored throughout the procedure.

The joint will be angled or manipulated to expose all surfaces. This may mean dislocation. An incision is made over the joint, and the muscles and connective tissues around the joint are moved aside. The size of the incision used depends on the joint being worked on and the type of arthroplasty used but is typically several inches in length.

Many forms of arthroplasty involve removal of osteophytes (bone spurs) or pieces of inflamed synovium (fluid sac lubricating the joint). Damaged bone and cartilage are cut away or reshaped. If a prosthesis (artificial part) is to be used, it will be inserted after measurements have been made to ensure a proper fit. The joint is then manipulated, tested and balanced to ensure proper function, and the incision is closed.

Arthroplasty may be a crucial step to alleviate pain, restore function or correct a developmental or hereditary joint defect. Patient satisfaction and the increase in quality of life are dramatic in the vast majority of cases. However, the procedure is not without its risks.

In many cases, certain factors may rule arthroplasty out as an option. Young age and high activity levels may cause extra stress on a joint or cause a prosthesis (artificial part) to wear out faster, making prosthetic options limited for younger individuals. A nonfunctioning extensor mechanism (which extends the joint) or poor circulation or vascularity may rule out the option of arthroplasty. Prior surgeries in the affected area may also complicate the procedure.

Many conditions can complicate recovery and in some cases may rule out arthroplasty as an option. These conditions include:

• Circulatory and respiratory disorders, such as cardiovascular disease.
  
  
• Blood disorders, such as anemia.
  
  
• Endocrine disorders, such as uncontrolled diabetes and hyperthyroidism.
  
  
• Lipid disorders. Disorders in fat production and metabolism.
  
  
• Urologic disorders, such as benign prostatic hypertrophy (enlargement of the prostate), prostate cancer or urinary tract infection.
  
  
• Infectious diseases.

Arthroplasty carries some risks, though complications are uncommon. They include:

• Thromboembolism. A blood vessel may be blocked by a blood clot dislodged from its site of origin. In particular, deep vein thrombosis is one of the more common serious complications after arthroplasty. Prevention of thromboembolism occurs during and after surgery. Anticoagulants may be used to prevent the formation of blood clots and compression devices and early movement may help to increase circulation.
  
  
• Infection. When infection occurs, the prosthetic devices are removed and the patient is put on several weeks of antibiotics. This is typically unavoidable unless infection occurs in the early postoperative period and is treated aggressively. Infection complications may occur even years after the procedure.
  
  
• Osteolysis. Prosthetic components wear over time, and small particles of debris collect within the joint and surrounding tissues. This causes an inflammatory response that includes enzymes that break down the bone. The frequency of this has decreased with more durable materials and implant designs for prostheses but still represents the largest threat to long-term prosthetic survival. Osteolysis is typically treated surgically.
  
  
• Ossification. Soft tissues around the joint harden. This may be a response to surgical trauma. It is most common in the knee and is usually not painful.
  
  
• Periprosthetic fracture. Fracture that occurs in proximity to a prosthetic implant. Minor fractures may be left alone, whereas surgery may be required to treat larger fractures.

• Prosthetic break. The prosthesis itself may break. Surgery is required to repair it.
  
  
• Aseptic loosening. The prosthesis may become loose. This is more common when bone cement is used to secure it to the bone. Surgery may be required.
  
  
• Dislocation. A prosthetic joint may become dislocated, particularly immediately following surgery when the soft tissues surrounding the joint are weak and still healing. Surgery is usually not required to relocate the joint.
  
  
• Allergic reaction. Many people have allergies to metals but in some cases are unaware of this. This can be a concern with certain prosthetics. Skin patch testing before surgery can avert implantation of a problematic prosthetic.
  
  
• Nerve damage. A number of causes may lead to this, including the compression of a nerve by a prosthesis. Treatment depends upon the cause and may require surgery.
  
  
• Vascular injury. A blood vessel may be injured during surgery. Bleeding must be controlled during the surgery itself.
  
  
• Leg-length discrepancy. Occasionally, one leg may be shorter or longer than the other after a total hip arthroplasty. Surgeons typically take action to avoid this cause of gait disturbance before and during the surgery.

Patients need to follow precautions issued by their physician. Some patients, particularly those who have undergone a hip replacement, may need adaptations at home, such as addition of a railing or shower bench. If necessary, the physician may order physical therapy, occupational therapy or both to perform a home safety evaluation, recommend equipment or provide home health services.

A prosthetic (artificial) joint is not as effective as a normal, natural bone joint. Function is typically limited depending on which joint is affected.  Range of motion and strength may be reduced. Patients are usually encouraged to exercise but may be advised to avoid high-impact activities such as running and tennis.

Furthermore, prostheses do not last forever. Though they may last the entirety of an older patient’s lifetime, young patients generally have to have them replaced several times throughout their lives.

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about arthroplasty:

1. Do I have any alternatives to arthroplasty?
   
   
2. Which type of arthroplasty is recommended for me?
   
   
3. If I will receive a prosthesis, what kind do you recommend for me? What is it made of?
   
   
4. What can I expect this surgery to accomplish?
   
   
5. How extensive will my operation be?
   
   
6. What sort of anesthesia and other medications will I receive?
   
   
7. How long will I be in the hospital?
   
   
8. How might my medical conditions affect the outcome of this surgery?
   
   
9. Do I need to do anything in preparation?
   
   
10. What precautions do I need to follow afterward?
    
    
11. Will I need physical therapy after the procedure?
    
    
12. Will I benefit from occupational therapy?
    
    
13. How active should I be? Are there any activities I need to avoid?
    
    
14. How long will my prosthesis last?