title: Evidence for interrupted bone resorption in human iliac cancellous bone.
abstract: Bone resorption and formation are coupled both in time and space and may occur simultaneously in the same remodeling unit. A number of studies have shown that the formative phase of the remodeling sequence may undergo temporary interruptions prior to completion and it is possible that bone resorption may be subject to similar interruptions. We have investigated this hypothesis by studying the distribution of eroded depth in resorption cavities in human cancellous bone. Eroded depth was assessed in iliac crest cancellous bone from 41 normal healthy subjects using a cubic spline curve fitting technique. The distribution of mean eroded depths was skewed to the right. Comparison of the observed distribution with an expected distribution, which was calculated from previously published data and assumes resorption begins rapidly and slows as it approaches completion, showed a significantly greater proportion of shallower cavities than expected (p<0001). Similarly, comparison of observed and uniform distributions, which assumes a constant rate of resorption throughout the erosion period, also showed a significantly greater proportion of smaller cavities (p<0.01). In subjects aged less than 39 years, there were fewer small cavities than in those aged 40-59 years. In addition, there was some evidence that females of 40-59 years had a proportionately greater number of smaller cavities than males; however, there were no differences in other age groups. Our results demonstrate a significantly greater proportion of smaller resorption cavities than would be expected from current models of bone remodeling and are consistent with the hypothesis that resorption undergoes temporary interruptions and/or permanent arrest during the process of bone remodeling.
authors.affiliation: Department of Medicine, University of Cambridge Clinical School, UK.
authors.forename: P I
authors.initials: PI
authors.lastname: Croucher
authors.forename: W R
authors.initials: WR
authors.lastname: Gilks
authors.forename: J E
authors.initials: JE
authors.lastname: Compston
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001846:Bone Development; D016723:Bone Remodeling / Q000502:physiology; D001862:Bone Resorption / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007085:Ilium / Q000502:physiology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011336:Probability