Background: Although supramalleolar osteotomy with an opening medial wedge or a dosing lateral wedge have been described for yarns ankle deformity, these may be associated with failure due to persistence of the medial intra-articular defect, resulting in recurrent varus deformity. We report the results of a retrospective study assessing the outcome of an intra-articular opening wedge osteotomy of the distal medial tibia (plafond-plasty) for intra-articular yarns ankle deformity associated with osteoarthritis and ankle instability. Method: The results of 19 plafond-plasties in 19 patients for correction of intra-articular yarns osteoarthritis of the ankle associated with ankle instability were reviewed. Fourteen men and five women of a mean age of 47 (range, 32 to 63) years were treated. Followup ranged from 14 to 98 (mean, 59) months. Results: Lateral ligament reconstruction was done at the time of the surgery in 18 out of 19 patients. The radiographic parameters including the TAS and TAL showed no statistical significant improvement when compared pre and post operatively. The yarns ankle tilt deformity improved from 18 degrees preoperatively to 10 degrees postoperatively (p < 0.05). The pre- and postoperative AOFAS score improved significantly from 46 to 78, respectively (p < 0.05). Two patients underwent ankle arthrodesis at 7 and 36 months, and two patients underwent ankle replacement at 30 and 48 months following the index procedure. Of the remaining :15 patients, :14 reported stable or very stable ankles, and 15 of the 19 were either satisfied or very satisfied with the outcome of treatment. Conclusions: These results demonstrate that plafond-plasty osteotomy associated with lateral ligament reconstruction may be a suitable for patients presenting with intra-articular yarns ankle osteoarthritis associated with ankle instability, providing pain relief and better function and stability in most patients.