Objective: The aim of this study was to evaluate the long-term results of cases applied with femoral varus derotation osteotomy (FVDO) in our clinic because of Legg-Calve-Perthes disease (LCPD), and to determine the factors affecting the results.

Methods: This retrospective, single centre study included 22 patients (19 males, 3 females) who had undergone FVDO for a diagnosis of LCPD, had regular clinical and radiological follow-up, and could be contacted by telephone. The patients were evaluated with the Waldenström and Lateral Pillar classifications, the Harris Hip score, the Stulberg Hip score, and the short-form-36, and the results were compared.

Results: Evaluation was made of 22 patients, comprising 19 males and 3 females with a mean age of 31.5±6.9 years, operated on because of LCPD. The mean follow-up time was 23±6.2 years and the mean age at first presentation was 6.5±2.6 years. Lateral pillar class C was determined as an indicator of a poor outcome in patients in the Waldenström fragmentation stage. The outcomes were better in patients who were diagnosed at the age of <8 years and operated on <10 yearsin the early stages of the disease.

Conclusion: Although FVDO is an effective surgical method in LPCD cases, the chance of success is higher when diagnosis is made before 8 years old, and surgery is applied before the age of 10 years in the initial stage according to the Waldenström classification. Therefore, the importance of early and diagnosis and treatment in LCPD must be emphasised.