Measurement of intervertebral motion using quantitative fluoroscopy: report of an international forum and proposal for use in the assessment of degenerative disc disease in the lumbar spine

Abstract

Quantitative fluoroscopy (QF) is an emerging technology for measuring intervertebral motion patterns to investigate problem back pain and degenerative disc disease. This International Forum was a networking event of three research groups (UK, US, Hong Kong), over three days in San Francisco in August 2009. Its aim was to reach a consensus on how best to record, analyse, and communicate QF information for research and clinical purposes. The Forum recommended that images should be acquired during regular trunk motion that is controlled for velocity and range, in order to minimise externally imposed variability as well as to correlate intervertebral motion with trunk motion. This should be done in both the recumbent passive and weight bearing active patient configurations. The main recommended outputs from QF were the true ranges of intervertebral rotation and translation, neutral zone laxity and the consistency of shape of the motion patterns. The main clinical research priority should initially be to investigate the possibility of mechanical subgroups of patients with chronic, nonspecific low back pain by comparing their intervertebral motion patterns with those of matched healthy controls.

Figure 1

(a) Passive recumbent supine right lateral flexion acquisition. (b) Passive recumbent flexion acquisition.

Figure 2

(a) Weight-bearing flexion-extension image acquisition following an upright motion frame. (b) Weight-bearing side-bending acquisition: position of motion frame.

Figure 3

Frobin et al.'s [36] method for registering the positions of vertebrae.

Figure 4

(a) Lateral view of lumbar spine image with enhancement. (b) User interface output showing lateral view of lumbar spine image with tracking and reference templates.

Figure 5

(a) Continuous intervertebral angles for 5 levels (left y-axis) and global (trunk) motion (right y-axis) in a patient with unstable L5-S1 spondylolytic spondylolisthesis. (Passive recumbent extension motion, note excessive motion at L5-S1, with irregular motion at L3-4 and L4-5. Maximum L4-5 range attained before maximum global motion range). (b) Translational motion path at L5-S1 extension in the same image sequence as in 5(a). (Solid line is mean translation and shaded area is all data). Note translational range of 8 mm.

Figure 6

Example of use of intervertebral versus trunk motion graphs for the calculation of laxity by ratio of their slopes in the first 10 degrees of global motion (slope of global motion = −0.536).

Figure 7

Illustration of geometric determination of IAR: (a) on a simple block diagram, (b) on vertebral body images. The IAR is located in the posterior half of the disc space.

Figure 8

User interface image showing graphical and numerical output of overall IAR position and as the location of this position on the image.