title: Kinematics and load-sharing of an anterior thoracolumbar spinal reconstruction construct with PEEK rods: An in vitro biomechanical study.
abstract: BACKGROUND
  Polyetheretherketone rod constructs provide adequate spinal stability. Kinematics and load sharing of anterior thoracolumbar reconstruction with polyetheretherketone rods under preload remains unknown.
  
  
  METHODS
  Eight human cadaveric specimens (T11-L3) were subjected to a pure moment of 5.0Nm in flexion-extension, lateral bending and axial rotation, and flexion-extension with a compressive preload of 300N. An anterior reconstruction of L1 corpectomy was conducted with a surrogate bone graft and anterior rod constructs (polyetheretherketone or titanium rods). An axial load-cell was built in the surrogate bone graft to measure the compressive force in the graft. Range of motion, neutral zone and compressive force in the graft were compared between constructs.
  
  
  RESULTS
  The polyetheretherketone rod construct resulted in more motion than the titanium rod construct, particularly in extension (P=0.011) and axial rotation (P=0.001), but less motion than the intact in all directions except in axial rotation. There was no difference in range of motion or neutral zone between constructs in flexion-extension under preload. The polyetheretherketone rod construct kept the graft compressed 52N which was similar to the titanium rod construct (63N), but allowed the graft compressed more under the preload (203N vs. 123N, P=0.003). The compressive forces fluctuated in flexion-extension without preload, but increased in flexion and decreased in extension under preload.
  
  
  CONCLUSIONS
  The polyetheretherketone rod construct allowed more motion compared to the titanium rod construct, but provided stability in flexion and lateral bending without preload, and flexion and extension under preload. The anterior graft shared higher load under preload, particularly for the polyetheretherketone rod construct. The results of this study suggest that rigidity of rods in the anterior reconstruction affects kinematic behavior and load sharing.
authors.affiliation: Department of Spine Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, People's Republic of China; Department of Spine Surgery, the First People's Hospital of Chenzhou, Chenzhou, Hunan, People's Republic of China.
authors.forename: Ruozhou
authors.initials: R
authors.lastname: Zhou
authors.affiliation: Department of Spine Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, People's Republic of China.
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Huang
authors.affiliation: Department of Spine Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, People's Republic of China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Spine Surgery, the First People's Hospital of Chenzhou, Chenzhou, Hunan, People's Republic of China.
authors.forename: Jie
authors.initials: J
authors.lastname: Tong
authors.affiliation: Department of Spine Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Ji
authors.affiliation: Department of Spine Surgery, the First People's Hospital of Chenzhou, Chenzhou, Hunan, People's Republic of China.
authors.forename: Sheting
authors.initials: S
authors.lastname: Liu
authors.affiliation: Department of Spine Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, People's Republic of China. Electronic address: qinganzhu@gmail.com.
authors.forename: Qingan
authors.initials: Q
authors.lastname: Zhu
mesh_terms: D000328:Adult; D000368:Aged; D001577:Benzophenones; D001696:Biomechanical Phenomena; D016025:Bone Transplantation / Q000379:methods*; D001864:Bone Wires; D002102:Cadaver; D019245:Compressive Strength / Q000502:physiology; D006801:Humans; D007659:Ketones; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009984:Orthopedic Fixation Devices; D011092:Polyethylene Glycols; D011108:Polymers; D016059:Range of Motion, Articular / Q000502:physiology; D012399:Rotation; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods; D013904:Thoracic Vertebrae / Q000503:physiopathology / Q000601:surgery*; D016474:Weight-Bearing / Q000502:physiology*
chemical_list: D001577:Benzophenones; D007659:Ketones; D011108:Polymers; C063834:polyetheretherketone; D011092:Polyethylene Glycols
keywords: Anterior reconstruction; Corpectomy; Kinematics; Load sharing; Polyetheretherketone rod