3D Analysis of Lumbar Spine Facet Joint Cartilage Thickness Distribution

Quantitative knowledge of lumbar facet joint morphology is crucial in understanding the relationship between the geometry and kinematics of the facet joint as well as better understanding degenerative changes. Accurate prediction of lumbar facet joint contact area and stresses requires 3D representation of the thickness distribution of the articular cartilage of the facet joint. Several groups have reported on cervical facet joint cartilage thickness measurements using different approaches [2,3]. To the best of our knowledge, three-dimensional (3D) distribution of lumbar facet joint cartilage thickness has not been reported. Current methods of measuring various geometrical parameters of facet joint cartilage usually utilize high resolution magnetic resonance (MR) imaging techniques. Although these techniques represent the most up-to-date advanced methods in the soft tissue imaging field, facet joint cartilage reconstruction cannot be accomplished with reasonable fidelity using this approach. A study by Koo et al. [1] on knee joint cartilage showed that the accuracy of cartilage thickness measurement in the cartilage models derived from MRI (1.5T) varies with cartilage thickness. This study reported accurate measurements only for cartilage whose thickness ranged from 2.5 mm to 3.3 mm, which is in the range larger than the average lumbar facet joint cartilage assumed to be around 0.8 mm. Therefore, the objective of this study was to 1) analyze 3D lumbar facet joint cartilage thickness distributions based on laser scanner data, 2) compare this method using μCT and 3T MRI.