In which cases do surgeons specializing in total disc replacement perform fusion in patients with symptomatic lumbar disc degeneration? - Zigler JE; Guyer RD; Blumenthal SL; Satin AM; Shellock JL; Ohnmeiss DD (European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society, 2022)