All surgeries have risks for complications. Knowing what these risks are and how they apply to you is part of deciding whether or not to have surgery.

You can help lower your chances of risks from surgery by planning ahead.

• Choose a surgeon and a hospital that provide high-quality care.
• Talk with your health care provider long before your surgery.
• Find out what you can do to help prevent problems during and after surgery.

All types of surgery involve risks. Some of these include:

• Breathing problems after surgery. These are more common if you've had general anesthesia and a breathing tube.
• Heart attack or stroke during or after surgery.
• Infection in the joint, lungs (pneumonia), or urinary tract.
• Poor wound healing. This is more likely for people who are not healthy before surgery, who smoke or have diabetes, or who take medicines that weaken their immune systems.
• An allergic reaction to a medicine that you received. This is rare, but some of these reactions may be life threatening.
• Falls in the hospital. Falls can be a major problem. Many things can lead to a fall, including loose gowns, slippery floors, medicines that make you sleepy, pain, unfamiliar surroundings, weakness after surgery, or moving around with a lot of tubes attached to your body.

It is normal to lose blood during and after hip or knee replacement surgery. Some people need a blood transfusion during surgery or during their recovery period in the hospital. You are less likely to need a transfusion if your red blood count is high enough before surgery. Some surgeries require you to donate blood before surgery. You should ask your surgeon about whether there is a need for that.

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

Your chances of having a blood clot form are higher 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 and health problems.

To lower your risk of blood clots:

• You may receive blood thinners before and after surgery.
• You might wear compression stockings on your legs to improve blood flow after surgery.
• You will be encouraged to do exercises while in bed and get out of bed and walk in the halls to improve blood flow.

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

• Infection in your new joint. If this occurs, your new joint may need to be exchanged or 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.
• Dislocation of your new joint. This is rare. It most often occurs if you return to activities before you are ready. This can cause sudden pain and inability to walk. You should call your provider if this happens. It is likely that you will need to go to the emergency room or return to the hospital. You may need a revision surgery if this happens repeatedly.
• 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.
• Fractures around the replacement can occur after falls or other injuries. Most of these injuries will require periods of rest or another operation to repair the fracture.
• An allergic reaction to the metal parts in some artificial joints. This is very rare.

Other problems from hip or knee replacement surgery can occur. Although they are rare, such problems include:

• Not enough pain relief. Joint replacement surgery relieves the pain and stiffness of arthritis for most people. Some people may still have some symptoms of arthritis. For most people, surgery usually provides a significant relief of symptoms.
• 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 (0.5 centimeters). It rarely causes any problems or symptoms.

Edwards PK, Mears SC, Lowry Barnes C. Preoperative education for hip and knee replacement: never stop learning. Curr Rev Musculoskelet Med. 2017;10(3):356-364. PMID: 28647838 pubmed.ncbi.nlm.nih.gov/28647838/.

Ferguson RJ, Palmer AJ, Taylor A, Porter ML, Malchau H, Glyn-Jones S. Hip replacement. Lancet. 2018;392(10158):1662-1671. PMID: 30496081 pubmed.ncbi.nlm.nih.gov/30496081/.

Harkess JW, Crockarell JR. Arthroplasty of the hip. In: Azar FM, Beaty JH, eds. Campbell's Operative Orthopaedics. 14th ed. Philadelphia, PA: Elsevier; 2021:chap 3.

Mihalko WM. Arthroplasty of the knee. In: Azar FM, Beaty JH, eds. Campbell's Operative Orthopaedics. 14th ed. Philadelphia, PA: Elsevier; 2021:chap 7.