“…Stand-alone interbody devices used in the included studies, when specified, included the Brantigan cervical I/F (DePuy Spine, Inc, Raynham, MA), Zero-P (DePuy Synthes Spine, Raynham, MA), Cervios (DePuy Synthes Spine, Raynham, MA), Solis (Stryker Spine, Allendale, NJ), MC+ (Zimmer Biomet, Warsaw, IN), and Shell (Advantage Manufacturing Technologies Company, Nonnweiler, Germany). Only one study 27 measuring NDI scores included both single- and 2-level patients, and was included in this meta-analysis. All other studies were single-level studies.…”