Indications and results of high tibial osteotomy
The leading intent of high tibial osteotomy (HTO) is to shift the mechanical axis of a varus malaligned knee to a slightly valgus axis in order to reduce pain, slow down the degenerative process and avoid or delay the joint replacement. The effectiveness of the procedure is strongly related to the correct patient selection; an ideal patient for HTO is a moderately active, high-demand patient, between 40–60 years old, with isolated joint line tenderness, body mass index <30, malalignment <15°, metaphyseal varus, full range of motion, near-normal lateral and patellofemoral compartments, non-smoker, and with some level of pain tolerance. Although instability has been traditionally considered a contraindication for osteotomy, a growing indication of the procedure is the correction of load imbalance in ligamentous insufficiency. Using total knee replacement as the end point, HTO 10-year survival rate reported by the literature ranges from 51% to 93%. More than 80% of patients return to work and sport, mainly by 1 year postoperatively, two-thirds of them at a level of physical demand equal to or greater than their preoperative level. Due to the technical advances, the surgical procedure has a low specific complication rate nowadays; the incidence of nonunion has been reported between 0–4.4%. HTO is currently considered as a preferred alternative to a knee arthroplasty in young patients with medial degenerative changes in a malaligned knee, particularly in active population or physically demanding workers.