An osteotomy is an elective surgical procedure, performed under general anesthesia, in which a bone is cut or a portion is taken out in order to fix a bad bone alignment, to shorten or lengthen the bone, or to correct damage due to osteoarthritis. An osteotomy is needed when a bone has healed badly or crooked, or when a deformity is caused by disease or disorder.

There are several deformities that can be corrected by an osteotomy: among them hallux velux, a deformity of the big toe; coxa vera, a deformity of the hip; genu valgum, commonly known as "knock knees"; and genus varus, in which the legs are severely bowlegged. Osteotomies are commonly performed on patients who have experienced a break that has healed crookedly, or has grown slower than the bones around it. Trauma to a growth plate can affect how a bone grows, and the results of uneven growth may require an osteotomy.

Patients suffering from osteoarthritis may find that an osteotomy is a good alternative to a total hip or knee replacement. This procedure is an option when only one side of the joint is affected or worn. With a knee osteotomy, the bone is cut in order to shift the weight to the good side of the joint. This stabilizes the knee and reduces the pain of putting weight on worn cartilage. This type of procedure is good for young, active patients who will likely outlive the lifespan of a knee replacement.

As with any surgical procedure, there are risks and drawbacks. The recovery can be long and very painful, and requires extensive physical therapy and rehabilitation. A cast or splint will be worn for approximately four to eight weeks. Risks include improperly healed bones, blood clots, bleeding in the joint, inflammation of joint tissues, infection, and nerve damage.