Fifteen percent of all scolioses are idiopathic thoracolumbar and are characterized by significant imbalance in the frontal plane. A large curve of more than 40 degrees creates a trunk shift and under these circumstances an active correction is necessary. It is this imbalance that is the cause of increasing muscular fatigue. Arthritic changes may appear later which also are responsible for pain. The aim of a surgical procedure is to stop the progression of scoliosis, to obtain the reequilibrium of the spine in a frontal and a sagittal plane, and to correct the deformity. During the 1960s Dwyer6 developed his anterior instrumentation mainly for thoracolumbar and lumbar curves. In 1980 Hall developed the concept of a short anterior fusion with overcorrection for patients with thoracolumbar curves. In the present study 10 patients are presented who were operated on for thoracolumbar adolescent idiopathic scoliosis using short posterior fusion instrumented by segmental convex transpedicle screw fixation and concave hook stabilization. With a mean followup of 49 months, the results show that frontal and sagittal balances are restored. In the present study all patients achieved frontal and sagittal balances at the last followup. The angular correction achieved by surgery always is more effective than what is visualized in radiographs of the patient in the bending position obtained before surgery. The correction of the major curve in the frontal plane improved from a mean angle of 47 degrees preoperatively to 14 degrees postoperatively and to 17 degrees at the last followup. In all cases, mobile discs in the lower lumbar area are open. The posterior short fusion has the same power of correction as the anterior fusion with the advantage of an easier surgical approach and a better control of the lordosis. This paper will describe the operative indications, the choices of instrumented levels, and the medium term followup results.