Kinematics and load-sharing of an anterior thoracolumbar spinal reconstruction construct with PEEK rods: An in vitro biomechanical study. (December 2016)

• Record Type: Journal Article
• Authors: Zhou, Ruozhou; Huang, Zhiping; Liu, Xiang; Tong, Jie; Ji, Wei; Liu, Sheting; Zhu, Qingan
• Is Part Of: Clinical biomechanics. Volume 40(2016)
• Page Start: 1
• Page End: 7
• Publication Date: 2016-12
• Subjects: Polyetheretherketone rod -- Kinematics -- Load sharing -- Corpectomy -- Anterior reconstruction; Biomechanics -- Periodicals; Osteopathic medicine -- Periodicals; Biomechanics -- Periodicals; Osteopathic Medicine -- Periodicals; 612.76
• DOI: 10.1016/j.clinbiomech.2016.10.001
• Languages: English
• ISSNs: 0268-0033

Abstract

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 5.0 Nm in flexion-extension, lateral bending and axial rotation, and flexion-extension with a compressive preload of 300 N. 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. Findings: 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 52 N which was similar to the titanium rod construct (63 N), but allowed the graft compressed more under the preload (203 N vs. 123 N, P = 0.003). The compressive forces fluctuated in flexion-extension without preload, but increased in flexion and decreased in extension under preload. Interpretation: 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. Highlights: The PEEK rod allowed more motion compared to the titanium rod, but constrained motions in flexion and lateral bending. The compressive preload resulted in higher compressive force in the anterior graft, particularly with the PEEK rod construct. The compressive force in the graft increased in flexion and decreased in extension under compressive preload.