High Tibial Osteotomy for Medial Knee Osteoarthritis

High tibial osteotomy (HTO) has been rapidly adopted as a treatment for medial knee osteoarthritis with varus deformity 1,2) .This lower extremity realignment procedure is used to relieve pain and correct varus deformity of the knee joint.Preoperative planning to determine the correction gap and angle has a significant effect on postoperative results of HTO.However, postoperative correction can be incongruent with the preoperative plan, even with the use of a navigation system and computer imaging.In a clinical situation, postoperative correction may be influenced by several factors, such as muscle action in walking and ligament balance 3) .Still, the main purpose of HTO is relief of pain caused by osteoarthritis, rather than correction of the deformity, and most patients have shown improvement in clinical symptoms.However, good long-term results can be expected if accurate correction can be achieved through careful preoperative planning 4) .Traditionally, the cable method using a radiopaque line or a metal rod has been popular for the determination of correction in HTO as it allows real-time monitoring of the mechanical axis during surgery; however, the results can deviate due to nonweight bearing status and the influence of limb rotation during osteotomy, and it can increase radiation exposure during evaluation of the hip and ankle centers.Accordingly, preoperative planning using full-length weight bearing lower limb radiographs has recently been introduced for calculation of the correction angle and gap in weight bearing status using a picture archiving and communication system (PACS) or special software 5,6) .In this is-