Estimating Posterior Lumbar Fusion Integrity Using Conductivity Analysis

PLF are used to therapeutically fuse vertebrae (Example 1). This project used non-dimensional conductivity analysis to estimate the structural integrity of PLF surgically introduced to rabbit vertebrae.  Images were converted to grams of hydroxyapatite per cc using standards. Load bearing regions of cortical bone within the PLF were identified using flow analysis (Figure 1).

Example 1

PLF between sequential rabbit vertebrae

Figure 1

Flow analysis identified regions of the PLF that can be reached from both vertebrae without traversing in a direction more than 45 degrees from the direction of the spine.

The conductivity at each point, at each slice along the PLF and of the entire PLF were calculated.  For the conductivity numbers to be more meaningful, and for these numbers to be comparable across species of different scale, conductivity metrics were normalized to typical voxel-wise, slice by slice, and net PLF conductivity derived from the spine. Color coded images of each PLF were presented to the sponsor, along with group level and statistical analysis as seen below (Figure 2).

Figure 2

Color coded images showing projections of the PLF (left), the regions of analysis (center) and slices of min and max conductivity (right)