Indication for spinal surgery: associated factors and regional differences in Germany. - Tesch, Falko; Lange, Toni; Dröge, Patrik; Günster, Christian; Flechtenmacher, Johannes; Lembeck, Burkhard; Kladny, Bernd; Wirtz, Dieter Christian; Niethard, Fritz-Uwe; Schmitt, Jochen (BMC Health Services Research, 2022)