It is projected that the number of primary total knee replacements will increase from 450,400 to 3.48 million by 2030, compared with a growth in the number of primary total hip replacements from 208,600 to 572,100 during the same interval (www.organizedwisdom.com )

So how often do complications occur after joint replacement surgery? While joint replacement surgery is considered "routine", complications are a consideration. In one study involving patients with osteoarthritis, 17 percent undergoing replacement surgery had postoperative complications and 38 percent had pain lasting more than four weeks following surgery. (Hamel MB, Toth M, Legedza A, Rosen MP. Archives Int Med. 2008;168(13):1430-1440.) These figures are in line with other studies.

Two percent of patients undergoing joint replacement surgery will have a serious complication resulting in long term consequences or death.

Potential complications a patient should know about...

Dislocation is among the most common complication of joint replacement surgery. This is more of an issue with hip replacement surgery than knee replacement. When a hip replacement dislocation occurs, the hip must be put back in place, necessitating another surgical procedure with its attendant risk.

Infection after a total joint replacement surgery is a serious complication that can have devastating consequences. While antibiotics and proper sterile technique can lower the risk, infections can still occur requiring removal of the prosthesis and prolonged intravenous antibiotic treatment.

Loosening of the replaced joint may develop over time... and sometimes not that long after the initial replacement procedure. This process is called osteolysis. When this happens, replacement revision surgery may be necessary.

Blood clots (called deep venous thrombosis) in the legs are extremely common following joint replacement surgery. The danger is they may break off and go to the lungs. This is called pulmonary embolism and is often fatal.

Wear of the plastic polyethylene socket (hip replacement). The plastic socket is the weakest part of a hip joint implant. The rate of plastic wear against a metal ball is about 0.1 millimeters per year, but is more rapid in active patients.

Revision. Unfortunately, joint replacements wear out over time. Revision joint replacement, or repeat joint replacement surgery may need to be performed. Revision joint replacement surgery is a much more complex procedure than the initial procedure.

Wound healing can occasionally be a problem after joint replacement. Parts of the skin and underlying tissue can die after the surgery. When this develops, it may require extensive skin grafting and hospitalization.

Nerve damage can occur with joint replacement. If it does occur, the affected nerve usually recovers after 6 to 12 months. However, damage can be permanent.

Patella (Knee cap) complications (knee replacement) can occur. Occasionally the knee cap does not track properly causing it to jump out of place as the knee bends. Also, the plastic part of the knee cap can wear through. These problems may need a repeat surgery to correct the problem.

Injuries to the arteries of the leg are a serious complication. The major arteries of the leg lie near joints. While injuries to arteries can usually be repaired by a vascular surgeon, loss of the leg is a possibility

Loss of joint motion. Some patients form excessive scar tissue in the joint after surgery. This limits the ability of the joint to move. Pain may also be present.

Fracture of the bones rarely occurs during joint replacement. It is more common during revision surgery.

Bleeding complications. Sometimes the wound may bleed several days after surgery as a result of the use of blood thinners. If it is excessive, it may require re-opening the wound to evacuate the blood.

Anesthesia complications can occur and death has been reported.
Allergy to the metal parts of the implant has occasionally been noted. While uncommon, it may have serious consequences.

Complications from blood transfusions. AIDS transmission from screened, banked blood happens in the range of 1 in 250,000 units transfused. The risk of Hepatitis B transmission is estimated to be approximately 1 in 550 units, and that for Hepatitis C is 1 in 100. The risk of an allergic reaction to blood transfusion is 1 in 500. The risk of death from blood transfusion is 1 in 100,000.

Fat embolism. Fat from the bone marrow can get into the circulation and cause pulmonary embolism or stroke. While rare, it can be fatal.

Numbness around the surgical site is common and may be permanent.

Chronic pain. Some patients who have had a joint replacement suffer chronic pain after the surgery. The causes are variable. Pain in the outside of the knee can occur because of irritation of the peroneal nerve from the knee replacement appliance.

Death. This is the ultimate complication.

So... while the chances for a serious complication are relatively low, the chances for a complication are relatively high. That is why the thrust of arthritis research now is to develop alternatives to joint replacement surgery. One such option is the use of autologous stem cells.