PROGRESSIVE DEFORMATION DURING ADULTHOOD: Though not commonly recognized, lumbar and thoracoscoliosis can progress during adulthood. This slow, insidious evolution concerns not only the anatomic configuration of the spinal curatures (three dimensional angular deformation) but also spinal function (development or aggravation of spinal or radicular pain and/or impaired equilibrium). This fact emphasizes the importance of regular prolonged surveillance of all patients with spinal deformations.Three anatomic elements affecting function are evidenced on serial x-rays: development of rotational dislocation, stiffening of the main curvature, especially in the lumbosacral spine, and progressive instaliation, thoracolumbar kyphosis.Three types of treatment can be proposed: physical therapy, orthopedic treatment, surgery. Physical therapy and orthopedic treatment can relieve pain and improve equilibrium but cannot change the progressive pattern of the spinal deviation. Surgery also provides effective symptom relief and has the advantage of definitively stopping the progression of the deformation.Indications are much more complex than simply determining an angle of deformation beyond which surgery is needed. For each case, indications are established on knowledge of the type of deformation, its extent, potential or ongoing modifications in the main curvature and compensatory curvatures, the patient's age, as well as the functional impairment and the patient's general status.