European Radiology Experimental | 2019
Quantitative CT-based bone strength parameters for the prediction of novel spinal implant stability using resonance frequency analysis: a cadaveric study involving experimental micro-CT and clinical multislice CT
Abstract
BackgroundTo predict conventional test forces (peak torque and pull-out force) and a new test force (implant stability quotient [ISQ] value of a spinal pedicle screw) from computed tomography (CT) parameters, including micro-architectural parameters, using high-resolution micro-CT and clinical multislice CT (MSCT) in human cadaveric vertebrae.MethodsMicro-CT scans before/after screw insertion (n\u2009=\u200968) and MSCT scans before screw insertion (n\u2009=\u200958) of human cadaveric vertebrae were assessed for conventional test forces and ISQ value. Three-dimensional volume position adjustment between pre-insertion micro-CT and MSCT scans and post-insertion scans (micro-CT) was performed to extract the volume of the cancellous bone surrounding the pedicle screw. The following volume bone mineral density and micro-architectural parameters were calculated: bone volume fraction, bone surface density (bone surface/total volume (BS/TV)), trabecular thickness, trabecular separation, trabecular number, structure model index, and number of nodes (branch points) of the cancellous bone network/total volume (NNd/TV) using Spearman’s rank correlation coefficient with Bonferroni correction.ResultsConventional test forces showed the strongest correlation with BS/TV: peak torque, ρ\u2009=\u20090.811, p\u2009=\u20094.96\u2009×\u200910−17(micro-CT) and ρ\u2009=\u20090.730, p\u2009=\u20097.87\u2009×\u200910−11 (MSCT); pull-out force, ρ\u2009=\u20090.730, p\u2009=\u20091.64\u2009×\u200910−12 (micro-CT) and ρ\u2009=\u20090.693, p\u2009=\u20091.64\u2009×\u200910−9 (MSCT). ISQ value showed the strongest correlation with NNd/TV: ρ\u2009=\u20090.607, p\u2009=\u20094.01\u2009×\u200910−8 (micro-CT) and ρ\u2009=\u20090.515, p\u2009=\u20093.52\u2009×\u200910−5 (MSCT).ConclusionsTest forces, including the ISQ value, can be predicted using micro-CT and MSCT parameters. This is useful for establishing a preoperative fixation strength evaluation system.