[Age- and gender-related distribution of bone mineral density and mechanical properties of the proximal humerus].

PURPOSE To evaluate age- and gender-related mechanical properties and bone mineral density (BMD) of the proximal humerus at different levels and regions. MATERIALS AND METHODS Mechanical indentation testing, DXA, QCT, pQCT and the radiogrammetry (Cortical Index, CI) were carried out in 70 freshly harvested humeri from 46 human cadavers (23 females, 23-males; median age 70.5 years). RESULTS In the female group, a high correlation between age and BMD was found (rho = 0.62 to -0.70, p < 0.01) with statistically significant differences between specimens of patients 69 years or younger, and 70 years or older (p < 0.05). In the group of female specimens of age 70 years or older, BMD values were found to be significantly lower compared to their male counterparts (p < 0.05). Regardless of the specimen's age, the highest BMD and bone strength were found in the proximal aspect and in the medial and dorsal regions of the proximal humerus. CONCLUSION These findings provide an insight into the fracture mechanism of the proximal humerus and should be the basis for designing structure-oriented implants with improved implant-bone stability in osteoporotic patients.