The objective measurement of continuous cervical inter-vertebral motion in living subjects
Conference: World Federation of Chiropractic 12th Biennial Congress
Dates: 8-13 April 2013
Journal: Journal of Chiropractic Medicine
Most neck pain is believed to be mechanical in origin (Binder 2008) and spinal manipulation is predicated on the idea that inter-vertebral motion can be changed. Attempts to accurately measure inter-vertebral motion have previously been prevented by the lack of an objective reproducible method. Quantitative fluoroscopy (QF), the measurement of inter-vertebral motion from digital fluoroscopic sequences, has solved this problem for the lumbar spine (Breen et al 2006; Breen et al 2012) but not yet for the cervical spine. This paper reports on adaptations to the QF method as well as accuracy and reproducibility for the measurement of inter-vertebral range-of-motion (IV-ROM) and the location of instantaneous axes of rotation (IAR) for cervical inter-vertebral motion in the sagittal plane.
A patient stabilisation and motion-control frame was adapted from the standard lumbar spine apparatus2 for interfacing with a Siemens Arcadis Avantic C-arm fluoroscope. Sequential images were captured in DICOM format at 15 frames per second for export and image processing using bespoke tracking codes written in Matlab (Mathworks, R2007b). IV-ROMs and IAR locations from C1-6 were extracted from the resulting continuous inter-vertebral motion pattern data.
1. Accuracy: A model was constructed from two dry human cervical vertebrae (C4-5) with a digital inclinometer (Penny & Giles STT 280; resolution ± 0.07°) fixed to the superior segment. The model was rotated through 20° flexion then 20° extension while simultaneously being imaged. This was repeated with the model 10° out-of-plane to the x-ray beam.
2. Reproducibility (agreement and reliability): Flexion and extension fluoroscopic sequences were obtained from a sample of ten (5 males, 5 females) adult participants aged 23 – 50 years using a standardised image acquisition protocol. Sequences were analysed twice six weeks apart by one observer and once by a second observer. Results
IV-ROMs and IAR locations were comparable to previously published plain x-ray and cineradiography studies (Amevo et al 1991; Deitz et al 2011; van Mameren et al 1990; van Mameren et al 1992).
1. The root-mean-square (RMS) error for IV-ROM against the reference standard was 0.21° and 0.34° in-plane and 0.50° and 0.40° for out-of-plane flexion and extension. For IAR location (x, y co-ordinates) RMS error was (x 1.06mm, y 0.79mm) for flexion and (x 0.73mm, y 0.98mm) for extension. IAR location was only marginally affected by out-of-plane imaging. 2. Maximum intra-observer standard error of measurement (SEM) for IV-ROM was 1.14° (C5/6 in extension) and the lowest intra-class correlation coefficient (ICC) (95% confidence interval) was 0.895 (0.635 to 0.973) (C1/2 in extension). For IAR location the maximum SEM was 3.56mm and the lowest ICC was 0.040 (-0.726 to 0.937). Maximum inter-observer SEM for IV-ROM was 0.80° (C3/4 in extension) with the lowest ICC 0.921 (0.711 to 0.981) (C3/4 in extension). The maximum SEM for IAR location was 7.66mm with the lowest ICC -0.080 (-0.866 to 0.937).
Cervical spine QF demonstrated good agreement for IV-ROM and IAR locations so can be used to identify changes in these parameters in patients before and after an intervention, or to determine normal variation in controls when measured at two or more time points. However IAR differences between individuals cannot be confidently identified in the current population due to poor reliability. References Binder A. Neck Pain - Clinical Evidence Review. Musculoskeletal Disorders. 2008:1103.
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Preferred by: Jonny Branney