AGE-RELATED-CHANGES IN THE COMPRESSIVE STRENGTH OF CANCELLOUS BONE - THE RELATIVE IMPORTANCE OF CHANGES IN DENSITY AND TRABECULAR ARCHITECTURE

Compressive testing to failure in the weight-bearing axis was done on 255 specimens of cancellous bone that had been machined front forty-fo ur femora from human cadavera. The donors had ranged in age from twent y to 102 years at the time of death. After mechanical testing, the app arent density and trabecular architecture were determined. Linear regr ession analysis showed that the compressive strength decreased by 8.5 per cent each decade (p < 0.001). Apparent density and volume fraction also decreased significantly with age (p < 0.001). Histomorphometric analysis demonstrated that the surface-to-volume ratio and the mean se paration of the trabecular plate increased with age, whereas the mean thickness and connectivity of the trabecular plate decreased. Both biv ariate and multivariate analyses demonstrated that age-related changes in apparent density played an important role in the decrease in mecha nical strength, accounting for a 92 per cent reduction. Microstructura l changes were highly correlated with apparent density and therefore h ad little independent effect. Thus, similar to the situation with cort ical bone, the quantitative changes in aging cancellous-bone tissue, r ather than the qualitative changes, influenced the mechanical competen ce of the bone. CLINICAL RELEVANCE: This study provides information co ncerning the difference in the properties of human cancellous bone as a function of age. Because of the importance of changes in apparent de nsity, non-invasive means can be used to estimate the mechanical prope rties of cancellous bone in vivo. Thus, it may be possible to predict the risk of fracture and to explain further some aspects of the mechan ics of fracture in the elderly.