Trabecular bone resorption depth decreases with age: differences between normal males and females.

The resorption depth below osteoclasts, mononuclear cells, and preosteoblast-like cells can be estimated by counting the number of lamellae of known thickness eroded below the three cell types. In a previous study on bone resorption in young normal individuals, we demonstrated that the mean depth below osteoclasts was smaller than the mean depth below mononuclear cells, which again was smaller than the mean depth below preosteoblast-like cells, the last taken as the final depth reached. In order to investigate the variation in resorption depth with age in both sexes, we examined bone biopsy specimens from 42 normal females and 34 normal males aged 17-90 years. For each patient the mean osteoclastic, mononuclear, and preosteoblast-like cell resorption depths were calculated, and the surface extensions of the three types of resorption lacunae were determined. The surface extent of preosteoblast-like cell lacunae increased with age in females (p less than 0.05). Osteoclastic resorption depth was constant throughout the ages in females as well as in males. Mononuclear and preosteoblast-like cell resorption depths decreased significantly with age in females (p less than 0.01 and p less than 0.05, respectively) as well as in males (p less than 0.05 and p less than 0.01, respectively). The mean depth of lacunae where resorption had terminated (i.e., preosteoblast-like cell resorption depth) was larger in females aged 30-60 years than in men of the same age (p less than 0.05). The reduction in final resorption depth with age is parallel to the decrease in mean thickness of completed walls previously described.(ABSTRACT TRUNCATED AT 250 WORDS)