Introduction Medial compartment osteoarthritis (MCOA) of the knee is a common musculoskeletal condition that can result from undue force on the medial compartment of the knee, lead- ing to the development of secondary arthritis and medial knee pain. Operative measures include arthroscopic de- bridement, high tibial osteotomy (HTO), unicompartmen- tal knee arthroplasty, and total knee arthroplasty [9, 16, 17, 18, 19, 26, 32, 39]. The type of procedure generally depends on the surgeon’s preference and skills, as well as patient factors of age, weight, specific knee mechanics, etiology of malalignment, course and progression of symp- toms, and lifestyle. When MCOA of the knee is related to malalignment, a redirectional valgus high tibial osteo- tomy is a widely accepted treatment option. HTO can be effective in reducing pain and delaying the need for knee arthroplasty [26, 27, 32, 39]. The biome- chanical principle of HTO is to reduce knee pain by more evenly distributing the forces acting across the knee. When HTO is performed for genu varum of the knee, the mechanical axis is shifted laterally, unloading the medial compartment of the knee. Most techniques for performing HTO involve an osteotomy above the tibial tubercle [8, 11, 22, 23, 26, 30, 32]. The lateral closing wedge osteo- tomy above the tibial tubercle is the technique initially de- scribed by Coventry and is one of the more popular meth- ods of treating MCOA of the knee [11]. The use of an Ilizarov apparatus in the treatment of MCOA of the knee remains controversial. Catagni et al. described a method employing an Ilizarov apparatus for the treatment of genu varum in MCOA (Fig. 1) [8]. The tibial osteotomy site is located below the tibial tubercle. Several long-term studies have evaluated the efficacy of HTO for MCOA of the knee [7, 12, 13, 20, 25, 35, 36, 41]. Insall noted that the initial good results of HTO dete- riorated over time [20, 21]. Factors associated with good Abstract A matched-pair compara- tive analysis was done comparing outcomes between a Coventry-type closing wedge valgus high tibial os- teotomy (HTO) and an HTO using an Ilizarov apparatus. Thirty patients were treated with a mean follow-up interval of 28.1 months. Functional outcomes were evaluated using the Western Ontario and McMaster Uni- versity (WOMAC) osteoarthritis in- dex. Clinical and radiographic as- sessment of the index knee, compli- cations, and over-all satisfaction of the patients were assessed. The pro- cedures were performed between 1994 and 1997. The two groups were equal with respect to baseline demo- graphics – age, sex, body mass in- dex, smoking status. The patients un- dergoing an Ilizarov HTO had a sig- nificantly greater decrease in pain and increase in function at final fol- low-up assessment. Eleven of the 15 patients in the Ilizarov group were satisfied with the procedure compared to five in the closing wedge HTO group. The treatment of medial compartment osteoarthritis in genu varum of the knee with an Ilizarov apparatus produces outcomes that are comparable to the standard lateral closing wedge osteotomy. Keywords Ilizarov · External circular fixator · High tibial osteotomy · Mechanical axis · Osteoarthritis KNEE Knee Surg, Sports Traumatol, Arthrosc (2002) 10 : 169–176 DOI 10.1007/s00167-001-0250-2 Anthony Adili Mohit Bhandari Robert Giffin Chris Whately Desmond C. Kwok Valgus high tibial osteotomy Comparison between an Ilizarov and a Coventry wedge technique for the treatment of medial compartment osteoarthritis of the knee Received: 31 January 2001 Accepted: 15 August 2001 Published online: 4 December 2001 © Springer-Verlag 2001 A. Adili · M. Bhandari · C. Whately · D.C. Kwok Department of Orthopaedic Surgery, McMaster University, Hamilton, Ontario, Canada R. Giffin University of Pittsburgh, Pittsburgh, PA, USA M. Bhandari (✉) Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, L8N 3Z5, Canada e-mail: Bhandari@sympatico.ca, Tel.: +1-905-5259140 ext. 22825, Fax: +1-905-5770017