Three-dimensional characterization of resorption cavity size and location in human vertebral trabecular bone

The number and size of resorption cavities in cancellous bone are believed to influence rates of bone loss, local tissue stress and strain and potentially whole bone strength. Traditional two-dimensional approaches to measuring resorption cavities in cancellous bone report the percent of the bone surface covered by cavities or osteoclasts, but cannot measure cavity number or size. Here we use three-dimensional imaging (voxel size 0.7 × 0.7 × 5.0 μm) to characterize resorption cavity location, number and size in human vertebral cancellous bone from nine elderly donors (7 male, 2 female, ages 47-80 years). Cavities were 30.10 ± 8.56 μm in maximum depth, 80.60 ± 22.23 ∗ 103 μm2 in surface area and 614.16 ± 311.93 ∗ 103 μm3 in volume (mean ± SD). The average number of cavities per unit tissue volume (N.Cv/TV) was 1.25 ± 0.77 mm− 3. The ratio of maximum cavity depth to local trabecular thickness was 30.46 ± 7.03% and maximum cavity depth was greater on thicker trabeculae (p < 0.05, r2 = 0.14). Half of the resorption cavities were located entirely on nodes (the intersection of two or more trabeculae) within the trabecular structure. Cavities that were not entirely on nodes were predominately on plate-like trabeculae oriented in the cranial-caudal (longitudinal) direction. Cavities on plate-like trabeculae were larger in maximum cavity depth, cavity surface area and cavity volume than cavities on rod-like trabeculae (p < 0.05). We conclude from these findings that cavity size and location are related to local trabecular microarchitecture.

► The first 3D measures of resorption cavities in human cancellous bone are presented. ► Resorption cavities have an average maximum depth of 30 μm. ► Resorption cavities are located primarily at intersections of trabeculae (nodes). ► Resorption cavities are larger on plate-like trabeculae than rod-like trabeculae. ► Resorption cavity size is related to location in the trabecular microstructure.