Knee osteotomy is surgery that removes a part of the bone of the joint of either the bottom of the femur (upper leg bone) or the top of the tibia (lower leg bone) to increase the stability of the knee. Osteotomy redistributes the weight-bearing force on the knee by cutting a wedge of bone away to reposition the knee. The angle of deformity in the knee dictates whether the surgery is to correct a knee that angles inward, known as a varus procedure, or one that angles outward, called a valgus procedure. Varus osteotomy involves the medial (inner) section of the knee at the top of the tibia. Valgus osteotomy involves the lateral (outer) compartment of the knee by shaping the bottom of the femur.
Osteotomy surgery changes the alignment of the knee so that the weight-bearing part of the knee is shifted off diseased or deformed cartilage to healthier tissue in order to relieve pain and increase knee stability. Osteotomy is effective for patients with arthritis in one compartment of the knee. The medial compartment is on the inner side of the knee. The lateral compartment is on the outer side of the knee. The primary uses of osteotomy occur as treatment for:
According to Healthy People 2000, Final Review, published by the Centers for Disease Control and Prevention, the various forms of arthritis "the leading cause of disability in the United States" affect more than 15% of the total U.S. population (43 million persons) and more than 20% of the adult population. Osteoarthritis (OA) is the most common form of knee arthritis and involves a slowly progressive degenerative disease in which the joint cartilage gradually wears away. It most often affects middle-aged and older people. The most common source of ACL injury is skiing. Approximately 250,000 people sustain a torn or ruptured ACL in the United States each year. Research indicates that ACL injuries are on the rise in the United States due to the increase in sport activity.
Osteotomy is performed as open surgery to the knee assisted by pre-operative arthropscopic diagnostic techniques. Surgery takes place on the tibia end or the femoral end at the knee according to whether the malalignment to be corrected is varus, or inward leaning, or valgus, outward leaning. The surgery involves the gaping or wedging of a piece of bone and its removal to change the pressure points of weight-bearing activity. The cut surfaces of the bone are held together with two staples, or a plate and screws. Other devices may be used, especially in tibial osteotomy where a fracture is involved. After surgery, a small plastic suction drain is left in the wound during recovery and early postoperative hospitalization.
Severe or chronic pain and/or knee instability brings the patient to an orthopedic physician. From there, the decision is made for surgery or for rehabilitation. Patients will undergo an examination and history with their physician. Once rehabilitation or other treatments are ruled out and surgery is indicated, the physician must assess for three factors: pain, instability, and knee alignment. Osteotomy is indicated if malalignment is a factor. Debridement , or the shaving of cartilage on the articulate femur or tibia, can usually resolve pain with instability problems. It must be determined whether the instability is related to malalignment and not to other sources such as ACL injury. Since the goal of osteotomy is to shift weight from a symptomatic cartilage to an unsymptomatic area to relieve both an instability and pain due to excessive contact, alignment of the knee is assessed for pressure distribution along the mechanical axis and the loading axis. This requires an analysis of gait pattern, range of motion, localized areas of pain, and neurological factors, as well as other technical tests for anterior instability. A diagnostic arthroscopy—examination of the knee joint with a long tube attached to a video camera—is usually indicated before all knee osteotomies. Cartilage surfaces are examined for degenerative or late-stage arthritis. Magnetic resonance imaging (MRI) is useful in evaluating any intra-articular pathology such as bone chips, padding tears, or injuries to ligaments.
After surgery, patients are placed in a hinged brace. Toe-touching is the only weight-bearing activity allowed for four weeks in order to allow the osteotomy to hold its place. Continuous passive motion is begun immediately after surgery and physical therapy is used to establish full range of motion, muscle strengthening, and gait training. After four weeks, patients can begin weight-bearing movement. The brace is worn for eight weeks or until the surgery site is healed and stable. X rays are performed at intervals of two weeks and eight weeks after surgery.
The usual general surgical risks of thrombosis and heart attack are possible in this open surgery. Osteotomy surgery itself involves some risk of infection or injury during the procedure. Combined surgery for ACL and osteotomy has higher morbidity rates.
Varus malalignment correction with osteotomy through the high tibia (HTO) is a proven and satisfactory operation. Success rates are high when the patient has a small angle deformity (<10°). Knees with more severe deformity have less satisfactory results. Tibial osteotomy for the less common valgus deformity is less satisfactory. Research indicates that only a few individuals are able to return to their previous level of high sports activity after a knee osteotomy, whether done with an ACL repair or not. However, more than half of patients in one study were able to return to leisure sports activities. Reports also indicate that those individuals who had osteotomy without ACL reconstruction had no differences in results with respect to measures of stability. It may take up to a year for the knee to be fully aligned and adapted to its new position after surgery. Most patients, more than 50%, gain stability and are able to walk further than they could walk before osteotomy. However, according to one report, 13% of patients had severe pain or needed a total knee replacement after five years. In one European review, the results were better. Osteoarthritis was arrested in 105 cases (69%), with 47 cases showing deterioration. The main factors associated with further deterioration were insufficient correction and persistence of malalignment.
Morbidity rates include bleeding, inflammation of joint tissues, nerve damage, and infection.
For those individuals suffering from osteoarthritis, muscle-strengthening exercise , weight loss, and rehabilitation can be helpful in relieving pain and gaining stability. Anti-inflammatory medications can also be effective in helping pain and stability. For severe varus or valgus deformities, osteotomy or knee replacement may be indicated. For those with severe ACL injury with secondary trauma to knee cartilage, complete knee replacement may be suggested.
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Shubin Stein, B. E., R. J. William, and T. L. Wickiewicz. "Arthritis and Osteotomies in Anterior Cruciate Ligament Reconstruction." Orthopedic Clinics of North America 34, no. 1 (January 2003).
American Academy of Orthopaedic Surgeons (AAOS). 6300 North River Rd., Suite 200, Rosemont, IL 60018. (847) 823-7186. (800) 346-2267, Fax (847) 823-8125. http://www.aaos.org/ .
Arthritis Foundation. P.O. Box 7669, Atlanta, GA 30357-0669. (800) 283-7800. http://www.arthritis.org .
National Institute of Arthritis and Musculoskeletal and Skin Diseases Information Clearinghouse. 1 AMS Circle, Bethesda, MD 20892-3675. (301) 495-4484, Toll-Free (877) 226-4267. Fax: (301) 718-6366. TTY: (301) 565-2966. http://www.nih.gov/niams .
"Osteotomy for Osteoarthritis." WebMD Health. http://www.webmd.com. .
Nancy McKenzie, PhD
An orthropedic surgeon speciliazing in knee reconstruction surgery performs the operation. Surgery takes place in a general hospital.