MICRODENSITY OF GLENOID

Abstract

Objectives: The aim of this study was to quantify bone microarchitecture within the glenoid fossa of the scapula.

High-resolution micro-computed tomography ([mu]CT) imaging have been instrumental in providing true quantitative and qualitative three-dimensional data on baseline bone morphology

Materials and Methods: 25 fresh-frozen human cadaveric shoulders were analysed. The mean age of the specimens was 66 years. All scapulae were inspected for normal anatomic landmarks.

The glenoids were cut at the glenoid neck and at the base of the coracoid process.

The total, trabecular, and cortical BMDs of the 5 regions of the glenoids were determined by use of peripheral quantitative computed tomography (pQCT) (Xtrem Ct;Scanco, Zurich, Ch) Each glenoid was fixed horizontally in a custom-made jig, and axial pQCT scans (pixel size,1536/1536; slice thickness 80 microns), perpendicular to the articular surface, were obtained at the level of each area. From the resulting binarized three-dimensional reconstruction, Scanco software was used to calculate the bone volume per tissue volume; mean trabecular separation; mean trabecular number, connectivity density.

Results: The total BMD of the posterior and superior glenoid were significantly higher than those of the anterior and inferior glenoid. Trabecular BMD of the posterior glenoid was significantly higher than that of the anterior glenoid, and cortical BMD of the superior glenoid was significantly higher than that of the inferior glenoid.

The mean total BMD in different regions of 20 glenoid specimens ranged from 0,243 to 0,489 g/cm2. The center of the glenoid was surprisingly poor in trabecular structures as we found a bony gap at 8 mm of distance from the articular surface.

Conclusions and clinical relevance: Although the specimen age was quite high in our material, we believe aging does not affect our study as shoulders prosthesis are generally performed on old patients.

In the future, component design should use areas of stronger subchondral bone. Posterior and superior bone area could be another alternative for fixation in decreasing glenoid-loosening rates. As the inferior center of the glenoid is an area devoided of trabecular bone, center-keel design component doesn’t seem to be the best choice.