The interrelation of trabecular microstructural parameters of the greater tubercle measured for different species.

In the present study the trabecular microstructural parameters (bone volume fraction, trabecular thickness, trabecular separation, trabecular number, connectivity density, degree of anisotropy, and structure model index) of the greater tubercle of the humeral head were measured for human healthy, human osteopenic, ovine, bovine, and porcine bones using micro-computed tomography. Except for trabecular thickness and degree of anisotropy the values of the trabecular microstructural parameters generally differed significantly between species. Thus, only the species for which the implant is designed should be used for in vitro mechanical tests on the stability of implants in trabecular bone. Multivariate regression analysis showed that the microstructural parameters have similar principal interrelations in all species. The most significant relations were found between trabecular thickness and bone volume fraction (median (over all species) p < 0.001), trabecular number and bone volume fraction (p = 0.001), the structural change from plates to rods and bone volume fraction (p < 0.001) as well as between connectivity density and trabecular number (p < 0.001). Trabecular thickness, trabecular number, and the structural change from plates to rods each contributed to the bone volume fraction approximately to the same extent. Based on the similar principal interrelations of the trabecular microstructural parameters found in all investigated species the design of trabecular microstructure in the greater tubercle follows similar phenomenological mechanisms in all species. Thus, in vivo experiments on trabecular bone healing and osteoporosis research for application in humans can be conducted in ovine, bovine, or porcine species.