Visit 2 after 3 months Clinical examination: functional assessment of the back, muscle strength of the back extensors, hand grip strength with JAMAR, pain drawing, manual balance test, back pain measured by VAS scale and Borg CR-10, EQ-5D, SF-36, Qualeffo-41. Adjustment of spinal orthotic. Spirometry. Weight and height. Report of falls since visit 1. Use of drugs and analgesics.