All surgeries have a risk of complications. Understanding these risks and how they apply to you should be part of deciding whether or not to have surgery.

Proper care and planning before surgery may prevent these risks or make them less likely to occur.

Choose a doctor and hospital that provide high-quality care. Then talk with your doctor long before your surgery about what you can do to prevent problems during and after surgery.

• Breathing problems after surgery. These are more common if you have had general anesthesia and a breathing tube.
• Heart attack or stroke during or after surgery
• Infection in the knee, lungs (pneumonia), or urinary tract
• Poor wound healing. This is more likely for people who are not healthy before surgery, people who smoke or have diabetes, or people who take medicines that weaken the immune system.
• An allergic reaction to any of the medicines you receive is rare, but one may occur. Some of these reactions may be life threatening.
• Falls in hospitals can be a major problem. The cause may be loose gowns, slippery floors, medicines that make you sleepy, pain, unfamiliar surroundings, feeling weak after surgery, or moving around with a lot of tubes attached to your body

It is normal to lose blood during hip- or knee-replacement surgery. Some people need a blood transfusion during surgery or their recovery in the hospital. You are less likely to need a transfusion if you are not anemic (have a low blood count) before surgery.

Much of the bleeding during surgery comes from the bone that has been cut. A hematoma (bruise) may occur if blood collects around the new knee joint or under the skin after surgery.

You are more likely to form a blood clot during and soon after hip- or knee-replacement surgery. Sitting or lying down for long periods of time during and after surgery will make your blood move more slowly through your body. This increases your risk of a blood clot.

Two types of blood clots are:

• Deep vein thrombosis (DVT) -- these are blood clots that may form in your leg veins after surgery.
• Pulmonary embolism -- these are blood clots that may travel up to your lungs and cause serious breathing problems.

To lower your risk of blood clots, you:

• May receive blood thinners before and after surgery
• May wear compression stocking on your legs after surgery to improve blood flow
• Will be encouraged to get out of bed and walk in the halls to improve blood flow

Some problems that may occur after your hip- or knee-replacement surgery include:

• Infection in your new joint. If this occurs, your new joint may need to be removed to clear the infection. This problem is more likely in people who have diabetes or a weakened immune system. After surgery, and often before surgery, you will learn what you can do to prevent infections in your new joint.
• Loosening of your new joint over time. This can cause pain, and sometimes another surgery is needed to fix the problem.
• Wear and tear of the moving parts of your new joint over time. Small pieces may break off and damage the bone. This may require another operation to replace the moving parts and repair the bone.
• An allergic reaction to the metal parts in some artificial joints. This is very rare.

Other problems from hip- or knee replacement surgery can also occur, but these are rare, including:

• Not enough pain relief. Joint-replacement surgery relieves the pain and stiffness of arthritis for most patients. Some patients may still have some symptoms of arthritis, though. Surgery usually provides enough relief of symptoms for most people.
• A longer or shorter leg. Because bone is cut away and a new knee implant is inserted, your leg with the new joint may be longer or shorter than your other leg. This difference is usually about 1/4 of an inch. It rarely causes any problems or symptoms.

Lachiewicz PF. Comparison of ACCP and AAOS guidelines for VTE prophylaxis after total hip and total knee arthroplasty. Orthopedics. 2009;32:74-78.

Harkess JW. Arthroplasty of the hip. In: Canale ST, Beatty JH, eds. Campbell's Operative Orthopaedics. 11th ed. Philadelphia, Pa: Mosby Elsevier; 2007:chap 7.