Tectoplasty was performed 10 times on adult dysplasic hips with advanced secondary OA for which femoral osteotomy could be considered. The 5 hips with pre-operative osteoarthritis staged IV according to De Mourgues scale and 3 of the 5 hips pre-operatively staged III displayed at maximal follow-up (on an average of 9.6 years), improvement of the radiographic articular space. The other 2 hips showed a stabilization of the x-ray osteoarthritis. Clinical improvement with an average gain of 2.5 points according to Merle d'Aubigné scale was always noted along with these improvements or these x-ray stabilizations.