Medial opening wedge high tibial osteotomy: more than ten years of experience with Puddu plate technique supports its indication.

To describe the short-term and long-term results of patients who underwent a medial opening wedge high tibial osteotomy (MOW-HTO) for unicompartmental medial knee joint osteoarthritis. A retrospective review was conducted of patients with MOW-HTO using a Puddu plate®, with more than ten year follow-up. The degree of correction, initial chondral damage, number of meniscal lesions, preoperative and 1-year postoperative functional scale scores (IKDC and Lysholm), and arthroplasty conversion rates at the ten year follow-up were registered. We assumed early indication when patients underwent the operation before they were 40 years old and delayed ≥ 40. Functional outcomes were analyzed by adjusting for pre-operative values. Fisher's exact test was used to study the association between the arthroplasty conversion rates and the timing of indication. Fifty-five patients were included, 37 of whom were male (67%). Twenty-nine patients had early indications for surgery (53%). All patients completed ten year follow-up. All patients improved IKDC (p < 0.01) and Lysholm (p < 0.01) scores compared to their presurgical scores at the one year post-operative evaluation. We had six minor complications, none requiring revision surgery. We had three conversions to arthroplasty, all in the late indication group, not statistically significant different. Linear regression showed that early indication was associated with a higher IKDC score when adjusting for the Outerbridge chondral damage score, the number of meniscal lesions, and sex (p < 0.01). All patients improved functional scores one year after surgery. Early indication (i.e., younger than 40 years of age) was independently associated with better functional outcomes than late indication at one year follow-up.