Oral Posters: Values and Outcomes in Spine Surgery

Presented by: C. Wade( - View Audio/Video Presentation (Members Only)

Author(s):

S. Chang(1), B. Kelly(1), B. Santoni(2), P. Simon(2), C. Wade(3)

(1) Barrow Neurological Institute, Phoenix, AZ, United States
(2) Foundation for Orthopedic Research and Education (FORE) , Tampa, FL, United States
(3) Auburn University, Industrial and Systems Engineering, Auburn, AL, United States

Abstract

Background: While segmental instability of the cervical spine contributes significantly to the overall cost of spine care in the US; the orthopedic and neurosurgical literature is not consistent in defining the radiographic measurements of an unstable cervical spine. As such, indications for treatments and the treatments themselves often vary. It is widely agreed the diagnostic imaging modalities of standard roentgenograms (X-rays), computed tomography (CT), and magnetic resonance imaging (MRI) are accepted as the modalities for successfully evaluating spinal pathologies; however current thresholds for indication of radiographic instability are not well defined. There have been improvements to the measurement evaluation techniques used for interpreting the flexion/extension radiographs (FE) from the traditional static bending films and manual measurements; to the dynamic bending films and identifying landmarks in digital radiographs using computer software to derive measurements of ROM.

Purpose: To determine the performance measurements (specificity, sensitivity, and prevalence) of sagittal cervical intervertebral measurements using a computer-assisted measurements of the cervical spine using motion sequences from a video-fluoroscopic technique.

Patient Sample: A total of 3474 intervertebral levels from 579 symptomatic patients, and 582 intervertebral levels from 97 asymptomatic participants were retrospectively evaluated.

Methods: Asymptomatic individuals and symptomatic patients were all evaluated using both the Vertebral Motion Analysis (VMA) system and fluoroscopic flexion extension static radiographs (FE). The standardized imaging protocol consist of a standard FE radiographs of uncontrolled bending under fluoroscopy and VMA radiographs captured during controlled bending with the patient positioned in the seated patient handling device. The seated motion platform “guided” active cervical bending, under normal physiologic weight-bearing conditions, while constricting flexion extension to the sagittal plane and bolstering the shoulder complex to minimize shoulder, scapula, and upper torso motion and maximize cervical bending. The analysis was compared to known thresholds of 22% intervertebral translation (IVT), equivalent to 3.5mm (assuming a 35mm vertebral body depth) and 11° intervertebral rotation (IVR).

Results: The VMA measurements demonstrated greater specificity, % change in sensitivity, and prevalence compared with FE for radiographic evidence of instability. Specificity was 98.9% and 98.6% in the VMA compared to 98.2% and 98.1% in the FE for IVR and IVT, respectively. Sensitivity in this study was 38.7% and 39.1% greater in the VMA compared to the FE for IVR and IVT, respectively. Prevalence was 10.2% and 9.6% for the VMA compared to 6.8% and 6.1% for the FE in IVR and IVT, respectively.

Conclusions: The VMA system showed greater measurement performance in the detection of radiographic instability compared with FE radiographs.