title: Assessing validation of dual fluoroscopic image matching method for measurement of in vivo spine kinematics.
abstract: BACKGROUND
  Accurate knowledge of the spinal structural functions is critical to understand the biomechanical factors that affect spinal pathology. Many studies have investigated the human vertebral motion both in vitro and in vivo. However, determination of in vivo motion of the vertebrae under physiologic loading conditions remains a challenge in biomedical engineering because of the limitations of current technology and the complicated anatomy of the spine.
  
  
  METHODS
  For in vitro validation, a human lumbar specimen was imbedded with steel beads and moved to a known distance by an universal testing machine (UTM). The dual fluoroscopic system was used to capture the spine motion and reproduce the moving distance. For in vivo validation, a living subject moved the spine in various positions while bearing weight. The fluoroscopes were used to reproduce the in vivo spine positions 5 times. The standard deviations in translation and orientation of the five measurements were used to evaluate the repeatability of technique. The accuracy of vertebral outline matching with metallic marks matching technology was compared.
  
  
  RESULTS
  The translation positions of the human lumbar specimen could be determined with a mean accuracy less than 0.35 mm and a mean repeatability 0.36 mm for the image matching technique. The repeatability of the method in reproducing in vivo human spine six degrees of freedom (6DOF) kinematics was less than 0.43 mm in translation and less than 0.65° in rotation. The accuracy of metallic marks and vertebral outline matching did not show significant difference.
  
  
  CONCLUSIONS
  Combining a dual fluoroscopic and computerized tomography imaging technique was accurate and reproduceable for noninvasive measurement of spine vertebral motion. The vertebral outline matching technique could be a useful technique for matching of vertebral positions and orientations which can evaluate and improve the efficacy of the various surgical treatments.
authors: Department of Orthopaedics, Peking University Third Hospital, Beijing 100191, China.
authors: Jian-Qiang
authors: JQ
authors: Bai
authors: Yong-Cheng
authors: YC
authors: Hu
authors: Li-Qing
authors: LQ
authors: DU
authors: Jing-Liang
authors: JL
authors: He
authors: Kai
authors: K
authors: Liu
authors: Zhong-Jun
authors: ZJ
authors: Liu
authors: Qun
authors: Q
authors: Xia
mesh_terms: D001696:Biomechanical Phenomena; D005471:Fluoroscopy / Q000379:methods*; D006801:Humans; D066298:In Vitro Techniques; D008159:Lumbar Vertebrae / Q000033:anatomy & histology / Q000502:physiology; D008875:Middle Aged; D013131:Spine / Q000033:anatomy & histology* / Q000502:physiology*