Impact of Aging on Distal Tibia Metaphysis Diameter

One of the many bone changes that occur with aging is “cortical drift”, the absorption and deposition of bone on the endosteal and periosteal side, respectively, which results in bone enlargement in some but not all metaphyses. The distal tibia is one of the most fractured sites in the body and where anatomically shaped implants are mostly used. The economic viability of these implants depends on the maintenance of bone contour throughout life. MRI sagittal ankle images from 422 patients aged 18 to 100 years were analyzed and total distal tibia diameter measured. No correlation was observed between the parameters age and distal tibia diameter (Pearson-0.099), or when individuals were separated by sex (Pearson-0.021 for men and 0.049 for women). When separated by age, patients younger and older than 60 years old had a similar average height (1.65 and 1.62 m, respectively, student’s t- test = 0). This is the first study to evaluate possible age-related distal tibia enlargement. Bone changes with age do not result in distal tibia enlargement and possibly the majority of anatomically shaped bone implants are suitable irrespective of age.

Tomographical description of tennis-loaded radius: reciprocal relation between bone size and volumetric BMD

Effects of long-term tennis loading on volumetric bone mineral density (vBMD) and geometric properties of playing-arm radius were examined. Paired forearms of 16 tennis players (10 women) and 12 healthy controls (7 women), aged 18–24 yr, were scanned at mid and distal site by using peripheral quantitative computerized tomography. Tomographic data at midradius showed that tennis playing led to a slight decrease in cortical vBMD (−0.8% vs. nonplaying arm, P< 0.05) and increase both in periosteal and endocoritcal bone area (+15.2% for periosteal bone, P < 0.001; and +18.8% for endocortical bone, P < 0.001). These data suggest that, together with an increase in cortical thickness (+6.4%, P < 0.01), cortical drift toward periosteal direction resulted in improvement of mechanical characteristics of the playing-arm midradius. Enlargement of periosteal bone area was also observed at distal radius (+6.8%, P < 0.01), and the relative side-to-side difference in periosteal bone area was inversely related to that in trabecular vBMD ( r = −0.53, P < 0.05). We conclude that an improvement of mechanical properties of young adult bone in response to long-term exercise is related to geometric adaptation but less to changes in vBMD.