Spinal Cord DiseasesIntervertebral Disc DegenerationIntervertebral DiscIntervertebral Disc DisplacementLumbar VertebraeSpinal CordSpinal FusionMuscular Atrophy, SpinalDiskectomySpinal DiseasesSMN Complex ProteinsSpinal Cord InjuriesTotal Disc ReplacementFibrocartilageProsthesis ImplantationProstheses and ImplantsInternal FixatorsSurvival of Motor Neuron 1 ProteinCervical VertebraeIridoid GlycosidesSpondylolisthesisLow Back PainSpondylosisArthroplastySacrumRibonucleoproteins, Small NuclearSpinal StenosisBack PainMotor NeuronsAggrecansBone ScrewsMagnetic Resonance Imaging