title: In vitro investigation of a new dynamic cervical implant: comparison to spinal fusion and total disc replacement.
abstract: For the treatment of degenerative disc diseases of the cervical spine, anterior cervical discectomy and fusion (ACDF) still represents the standard procedure. However, long term clinical studies have shown a higher incidence of pathologies in the adjacent segments. As an alternative to spinal fusion, cervical total disc replacement (cTDR) or dynamically implants were increasingly used. This in vitro study analyzed the kinematics and intradiscal pressures in seven multi-segmental human cervical spine using hybrid multidirectional test method. The aim of our study was to compare the intact condition with a single-level dynamic stabilization with DCI(®), with cTDR (activC(®)) and with simulated ACDF (CeSPACE(®) cage and CASPAR plate).
  
  
  
  No significant changes in the kinematics and pressures were observed in all segments after arthroplasty. The DCI(®) significantly decreased the motion of the treated segment in flexion/extension and lateral bending with some remaining residual mobility. Thereby the motion of the upper segment was increased significantly in flexion/extension. No significant changes of the intradiscal pressures were observed. With simulated fusion the motion of the indexed level was significantly decreased in flexion/extension and axial rotation with the greatest changes in the adjacent levels and the highest pressures.
  
  
  
  Based on our biomechanical study the DCI(®) can pose an alternative to fusion, which has a lesser effect on adjacent levels. This might reduce the risk of long-term degeneration in those levels. In particular, the facet joint arthritis and kyphotic deformity, as a contraindication to the arthroplasty, could be a clinical application of the dynamic implant.
authors.affiliation: Laboratory for Biomechanics and Biomaterials, Department of Orthopaedic Surgery, Hannover Medical School, Anna-von-Borries-Str. 1-7, 30625, Hannover, Germany. welke.bastian@mh-hannover.de.
authors.forename: Bastian
authors.initials: B
authors.lastname: Welke
authors.affiliation: Laboratory for Biomechanics and Biomaterials, Department of Orthopaedic Surgery, Hannover Medical School, Anna-von-Borries-Str. 1-7, 30625, Hannover, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Schwarze
authors.affiliation: Laboratory for Biomechanics and Biomaterials, Department of Orthopaedic Surgery, Hannover Medical School, Anna-von-Borries-Str. 1-7, 30625, Hannover, Germany.
authors.forename: Christof
authors.initials: C
authors.lastname: Hurschler
authors.affiliation: Department of Orthopaedic Surgery, Hannover Medical School, Anna-von-Borries-Str. 1-7, 30625, Hannover, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Book
authors.affiliation: Department of Orthopaedic Surgery, Hannover Medical School, Anna-von-Borries-Str. 1-7, 30625, Hannover, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Magdu
authors.affiliation: Department of Orthopaedic Surgery, Hannover Medical School, Anna-von-Borries-Str. 1-7, 30625, Hannover, Germany.
authors.forename: Dorothea
authors.initials: D
authors.lastname: Daentzer
mesh_terms: D000328:Adult; D000368:Aged; D001178:Arthroplasty / Q000379:methods; D001696:Biomechanical Phenomena; D001860:Bone Plates; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D017586:Diskectomy / Q000379:methods; D005260:Female; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011312:Pressure; D019736:Prostheses and Implants; D011859:Radiography; D016059:Range of Motion, Articular; D012399:Rotation; D013123:Spinal Fusion / Q000379:methods*; D059145:Total Disc Replacement / Q000379:methods*
keywords: Cervical disc replacement; Cervical fusion; Cervical spine; Dynamic cervical implant; In vitro biomechanics