643 - Static versus Dynamic Bending Flexion Extension Radiographs: The Influ...

#643 Static versus Dynamic Bending Flexion Extension Radiographs: The Influence on Reduction in Patient Reported Pain Post Lumbar Fusion

Value and Outcomes in Spine Surgery

Poster Presented by: C. Wade


A. Lewis (1)
J. Lynch (2)
C. Wade (3)

(1) Jackson Neurological Institute, Jackson, MS, United States
(2) Spine Nevada, Reno, NV, United States
(3) Auburn University, Industrial and Systems Engineering, Auburn, AL, United States


Segmental instability of the lumbar spine plays a significant role within the US health care system, is considered a primary cause of low back pain, and is recognized as qualifying measure for identifying radiographic instability. Moreover, given that there is no accepted radiologic criteria by which the change in alignment on flexion-extension views can be considered instability, there tends to be significant variation in the diagnosis and treatment of the spine pathologies. More importantly given these variations in diagnostic criteria, there is potential to have significant variations in postoperative outcomes. While there is a wide range of proposed quantified definitions of radiographic instability, the diagnostic modalities of X-ray, CT, and MRI are widely accepted. Dynamic bending FE and computer- assisted manual measurements have been shown to significantly improve the diagnostic accuracy in deriving measurements of ROM compared to the standard FE. It has been proposed that FE methods that involve controlled patient bending via the use of a handling device that assists patients through a standard arc of lumbar bending have the potential to reduce variability in patient bending during FE [1]. Technology advancements have shown to reduce the level of measurement variability in FE and improve diagnostic accuracy [2]. The purpose of this paper is to retrospectively evaluate static FE and dynamic bending FE in identifying radiographic instability (based on a common radiographic threshold criteria) on changes in patient reported pain outcomes.

Methods: 99 patients (33 per 3 groups) who received a single level lumbar fusion were retrospectively evaluated. Static FE and dynamic bending FE were evaluated via a vertebral motion analysis system (VMA) (Orthokinematics, Austin, TX). The analysis was compared to known thresholds of 15% intervertebral translation (IVT, equivalent to 5.3mm assuming a 35mm vertebral body depth). 3 delineations were made for the identification of radiographic instability based on the threshold criteria: Group1-the bending FE was positive while the static FE were negative, Group 2- the bending FE was positive and the static FE were positive, Group 3-the bending FE was negative while the static FE were positive. Patient reported outcomes were measured via a Visual Analog Scale (VAS) and Oswestry Disability Index (ODI) pre and post 12-months.

Results: There was a statistically significant reduction in both the ODI and VAS reported outcomes post-surgery for Group 1 and Group 2. Results show a 52% improvement in the VAS and a 43% improvement in the ODI for Group 1, and a 35% improvement in the VAS and a 34% improvement in the ODI for Group 2. Group 3 showed insignificant improvements of 29% and 28% in VAS and ODI scores, respectively.

Conclusion: The utilization of dynamic bending FE with computer assisted measurements showed greater reduction in post-operative pain scores than that of static FE using the same computer assisted measurement capabilities.

References: [1] Davis, R., Lee, D., Wade, C., Cheng, B. (2014). Measurement Performance of a Computer Assisted Vertebral Motion Analysis System. Volume 9 Article 36 - Biomechanics Special Issue [2] Breen A, Muggleton J, Mellor F. An objective spinal motion imaging assessment (OSMIA): Reliability, accuracy and exposure data. BMC Musculoskeletal Disorders 2006; 7: 1-10.