Q2. What is the significance of the FCR locus?
It would also be beneficial to explore the effects of spinal geometry and muscle contraction on FCR location, to add coronal plane validation and to confirm whether the FCR locus might be used to assess relationships between structural change and the in vivo biomechanical performance characteristics of discs under load.
Q3. What was the motor used to drive the 73 vertebrae?
It was driven 77 by an actuator motor and controller (Arduino Software Ltd. UK – resolution 0.01mm) 78 providing anterior to posterior translation across the lower vertebral end-plate during the 79 rotation.
Q4. What was the position of the central ray of a digital 82 fluoroscope?
The central ray of a C-arm digital 82 fluoroscope (Siemens Arcadis Avantic – Siemens GMBH, Germany) was positioned so as to 83 pass through the centre of the disc space.
Q5. How many millimetres were converted for the in vivo studies?
For the in vivo studies VBUs were converted to millimetres based on a standard vertebral depth of 35mm and for the specimens by their actual measurement.
Q6. What was the average RMS in the fixed centre of rotation specimen?
For the fixed centre of rotation specimen, the average discrepancy (RMS) in translation range between reference and image data was 0.004 VBU (0.10mm) (LoA 0.01mm).
Q7. What was the axis of rotation of the vertebra in a pair?
The axis of rotation was then displayed relative to the inferior vertebra in a pair as a function of the four- corner template on the inferior vertebra.
Q8. What was the method used to obtain automated frame to frame image tracking of the vertebral bodies?
Bespoke software written in Matlab (V R2007b, The Mathworks Inc.) used a cross-correlation method to obtain automated frame to frame image tracking of the vertebral bodies in subsequent images [20].
Q9. What was the reliability for the sagittal plane translation and FCR?
The best reliability was within observers at L2-3 in flexion ((ICC=0.998 (0.958-0.997)) and the worst within observers at L3-4 in flexion ((ICC=0.533 (0.406-0.849)).
Q10. What is the optimum method for measuring lumbar spine kinematics?
The method also suffers from the inability to detect 37 the true end-range during motion and lack of standardised measurement methods [6].38 Studies of quantitative fluoroscopy (QF) for measuring lumbar spine intervertebral 39 kinematics using continuous motion tracking began in the 1980s [7].
Q11. What was the proportion of vertebral body depth that was translated in the moveable centre specimen?
The proportion of vertebral body depth that was translated in the moveable centre specimen as measured by the actuator motor was 0.52 VBU (17.95mm).