Introduction: Concave ribs are in a position to act as a butttress preventing the reduction of the spine towards the midline. Segmental concave ribs osteotomy decrease the buttress effect increases the flexibility of the curve and allow the spine to approach a more mideline position.

Purpose: To analyze radiographic and perioperative data in patients undergoing posterior thoracic instrumented fusion and concave ribs osteotomies.

Methods: 34 patients with rigid thoracic curves treated with hybrid constructs (hooks, wires and pedicle screw) and concave rib osteomies( averaged 5) between 2000 and 2003 are included. All patients obtained pre-operative upright and bending films and postoperative upright films. Cobb angle was collected and three parameters were assessed: percent flexibility, percent scoliosis correction and the percent bend corecction. Main age was 14 years with 20 females and minimun follow up 1 year.

Results: There were 13 A.I.S., 8 neuromuscular cases and the rest associate to different pathologies (syringomyelia, cardiopathy ect.). Preoperative thoracic curve averaged 78(60–112); percent bend correction veraged 25% and postoperative correction averaged 58%. There were no neurological complications, 4 patients developed pulmonary complications ( pleural effusion) who required suction drenage.

Conclusions. Rigid curves undergoing concave rib osteotomies achieved a postoperative curve that was 58% of the preoperative bend curve. Concave rib osteomomies increase flexibility of severe rigid curves avoiding anterior realese in the great majority of large curves with minimmal pulmorary complication. Overlapping the osteotomized ribs on the concave rod the chest asymmetry improves and the cosmetical result of the operation is improved.