High tibial osteotomy (HTO) is an operation to realign the lower leg. This procedure is generally performed in patients with medial compartment arthritis on the inside of the knee. HTO is also performed in patients with instability and lateral ligament laxity with varus alignment (bowed leg).
There are several techniques that can be used for HTO. The most common technique involves correcting alignment of the knee and holding the corrected position using a plate and screws. Either closing-wedge or opening-wedge technique can be used. There are pros and cons to both methods, but the opening-wedge technique is generally preferred due to the ease of the procedure and a lower complication rate. In opening-wedge HTO, the tibia is partially divided and then opened through the osteotomy site. The tibia is subsequently fixed in that position with a plate and screws.
Bone graft may be placed in the osteotomy site to facilitate healing. The bone graft may be an allograft (a donor’s bone) or an autograft (the patient’s own bone). Allograft is generally preferred to reduce the amount of surgery performed. This donor bone is not structural, so it can be highly irradiated and therefore has no risk of disease transmission.
After HTO, partial weight-bearing can begin immediately and full weight-bearing can usually begin six weeks after surgery, when the osteotomy has provisionally healed. Patients are typically walking normally by 10 weeks after surgery and have fully recovered by four months after the operation. HTO is a good option for young patients who have knee arthritis requiring surgery, but who would prefer to avoid knee replacement. When HTO is performed for arthritis of the medial compartment, approximately 80 to 90% of patients have not had a knee replacement by five years after surgery, and 60 to 70% of patients have not had a knee replacement after 10 years.