title: Biomechanical study comparing a new combined rod-plate system with conventional dual-rod and plate systems.
abstract: Most anterior spinal instrumentation systems are designed as either a plate or dual-rod system and have corresponding limitations. Dual-rod designs may offer greater adjustability; however, this system also maintains a high profile and lacks a locking design. Plate systems are designed to be stiffer, but the fixed configuration is not adaptable to the variety of vertebral body shapes. The authors designed a new combined rod-plate system (D-rod) to overcome these limitations and compared its biomechanical performance with the conventional dual-rod and plate system. Eighteen pig spinal specimens were divided into 3 groups (6 per group). An L1 corpectomy was performed and fixed with the D-rod (group A; n=6), Z-plate (Sofamor Danek, Memphis, Tennessee) (group B; n=6), or Ventrofix (Synthes, Paoli, Pennsylvania) (group C; n=6) system. T13-L2 range of motion was measured with a 6 degrees of freedom (ie, flexion-extension, lateral bending, and axial rotation) spine simulator under pure moments of 6.0 Nm. The D-rod and Ventrofix specimens were significantly stiffer than the Z-plate specimens (P<.05) based on results obtained from lateral bending and flexion-extension tests. The D-rod and Z-plate specimens were significantly stiffer than the Ventrofix specimens (P<.05) in axial rotation. The D-rod combines the advantages of the plate and dual-rod systems, where the anterior rod exhibits the design of a low-profile locking plate, enhanced stability, and decreased interference of the surrounding vasculature. The posterior rods function in compression and distraction, and the dual-rod system offers greater adjustability and control over screw placement. The results indicate that it may provide adequate stability for anterior thoracolumbar reconstruction.
authors: Department of Orthopedics, 175th Hospital of the PLA, Xiamen University Affiliated Hospital, Zhangzhou, Fujian, China.
authors: Mo
authors: M
authors: Sha
authors: Zheng-Qi
authors: ZQ
authors: Ding
authors: Hu S
authors: HS
authors: Ting
authors: Liang-Qi
authors: LQ
authors: Kang
authors: Wen-Liang
authors: WL
authors: Zhai
authors: Hui
authors: H
authors: Liu
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001858:Bone Nails; D001860:Bone Plates; D001863:Bone Screws; D008159:Lumbar Vertebrae; D023421:Models, Animal; D013123:Spinal Fusion / Q000295:instrumentation*; D013131:Spine / Q000503:physiopathology / Q000601:surgery*; D013552:Swine; D013904:Thoracic Vertebrae