Joint alignment is critical to cartilage longevity. A knee that is malaligned will create stress concentration (pressure overload) within the joint. Stress concentration will create cartilage damage and diminish the likelihood that a repair procedure will be successful. An osteotomy is a bone realigning procedure, which shifts the load majority from a damaged part of the knee to an area where there is no cartilage damage.
Realignment procedures have a long and relatively successful history in modern orthopedics. Malalignment can be the result of congenital bowing of the leg. It also occurs as the result of disproportional wear on one side of the knee. The object of the procedure is to cut and realign the bone. Much like realigning the tire of a car, the pressure is redistributed from the area of high wear to an area of the knee with low wear. The concept is sound and has demonstrated reproducibly high levels of success for decades. The procedure is a temporizing one, though one can reasonable expect at least 10 years of improved comfort and function in a moderately degenerative knee.
The classic indication is a malaligned knee with unicompartmental arthritis. The indication for a HTO is a varus knee with medial compartment degeneration. A distal femoral osteotomy is indicated in the valgus knee with lateral compartment degeneration. “Joint space narrowing” is the common radiologic indication. Bone on bone Xray changes are less favorable as an indication. Prior to the advent of reliable knee replacements, osteomies were the procedure of choice in all age groups. It is now used primarily used in patients under 50 years old.
This procedure is performed outside of the joint proper, usually at the distal portion of the femur or the proximal portion of the tibia. It is not an arthroscopic procedure, however, the procedure may be accompanied with an intraarticular cartilage procedure. The procedure is planned preoperatively. An incision is made and the osteotomy is performed with a bone saw. The bone alignment is reset in one of several manners, e.g., opening wedge or closing wedge. Fixation is usually introduced by means of a plate and screw system. Autograft or allograft bone supplementation is often necessary, particularly in the opening wedge HTO, which has become the most common variation of this procedure because of its tissue-sparing nature. The degree of alignment correction is critical to the success of the procedure.
A brace is typically applied. Hospitalization is often necessary for one or more days. Toe touch weight-bearing is usually necessary for up to 6 weeks. Once early healing has occurred, mobilization progresses. Fairly normal gait can be expected at 3 months. Full recovery is expected in 6 to 9 months. This procedure has a long and arduous recovery
Results of realignment osteotomy procedures have been successful. Historically, the average age of patients tends to be older than present day usage of the procedure. Most studies demonstrate 80-90% good results at 5 years from the time of the procedure. These results deteriorate over time to about 50% good results at 10 years. The a large study in 1191, Rudan et al reported on 128 patients, average age 58 years old, showed 70% good results at 10+ years. Results of osteotomies exceed those of cartilage replacement procedures and have longer follow up periods. This operation slows but does not stop the progression of osteoarthritis. We frequently tell patients to expect a revision to a knee replacement at some point in the future, hopefully no less than 15 years from the osteotomy. The longevity of the realignment osteotomy depends on a number of factors, including the severity of the degeneration and BMI.