Femoral derotational osteotomy is the gold standard to correct symptomatic patients with increased femoral AV. There is no clear evidence in the literature supporting which surgical technique or implant that should be used. Traditionally these patients are treated with an open osteotomy and plate and screw fixation. In recent years intramedullary nailing with adolescent interlocking nail has been described and has shown to be a safe method. Percutaneous osteotomy and intramedullary nailing is considered a less invasive technique compared with open osteotomy and plate and screw fixation. The primary objective of this project, is to investigate if derotational osteotomy by means of percutaneous osteotomy and nailing is a safe and accurate method compared to an open approach and plating.