A biomechanical comparison of crossed and parallel rod configurations in atlantoaxial internal fixation.

Background: Posterior atlantoaxial fixation with screw rod forms an approximate "II" shape or "H" increasing transverse link for better stability. In order to improve stability and in consideration of difficult placement of transverse connecting rod, possibility of inadequate bone graft, some scholars have preliminarily researched biomechanics of a novel crossed rod as an approximate "X" configuration of screw rod.

Purpose: The aim of this study was to evaluate and compare the biomechanics of the crossed and parallel rod configurations in the screw rod system for posterior atlantoaxial fixation on a cadaveric model.

Relationship between the laminectomy extension and spinal cord injury caused by acute spinal shortening: goat in vivo experiment.

Objective: To investigate the relationship between different types of laminectomy extension and spinal cord injury subsequent to acute spinal shorting after 3-column osteotomy in living goat model.

Methods: A total of 18 healthy goats were selected, and a procedure of bivertebral column resections and total laminectomy of T13 and L1 was completed followed by different laminectomy extensions under the somatosensory evoked potential (SSEP) monitoring. The samples were divided into three groups according to types of subsequent laminectomy extension.