Post-Operative Adding-On in Adolescent Idiopathic Scoliosis, A Particular Etiology: Conflict Between the Upper Articular Process and the Instrumentation Material : A Case Report

The aim of surgical treatment of adolescent idiopathic scoliosis (AIS) is to achieve a balanced spine. Distal addingon is a postoperative phenomenon in AIS, which is characterized by a progressive correction loss. A 13-Year-old girl with AIS who underwent posterior arthrodesis showed aggravation of the disequilibrium under the last instrumented vertebra (LIV) 30 months post operatively and an increase of the lumbar curvature with no evident cause. Extension surgery was made and per operatively we noticed that the distal end of the arthrodesis was disengaged and that the left rod was conflicting with the upper left articular process of L2. Among the causes of adding-on we report in this article a particular etiology that consists in a conflict with the instrumentation material. This conflict has to be looked for postoperatively if an adding-on phenomenon is suspected in addition to a distally protruding rod, and could motivate a CT scan imaging for diagnosis.