Background Age is the most important risk factor for osteoarthritis (OA). However, the pathogenesis of OA is not fully understood, but the subchondral bone plate may be thickened in osteoarthritis. How aging of the joint corresponds to OA changes is poorly elucidated, but preliminary OA alterations may occur in healthy old individuals and progress into symptomatic OA.
Objectives The objective was to investigate the age-related changes in different tissue compartments of the femoral head hypothesizing that a positive correlation with age would be found for 1) volume of the femoral head; 2) volume and thickness of the subchondral bone plate and calcified cartilage.
Methods Sixty-one femoral heads from 29 females (median, range) (49, 20–74 years) and 32 males (47, 23–78 years), who had accidently died, were obtained by autopsy from the Institute of Forensic Medicine. Individuals were excluded in case of known bone or joint diseases, or macroscopic cartilage erosions.
Design-based stereological methods using systematic uniform random sampling were applied to estimate absolute volume. The femoral heads were randomly rotated around a vertical axis and sawn in 5–8 slabs with a thickness of 7 mm. The slabs were halved and alternating right or left half were embedded in methylmethacrylate from where 7-μm thick sections were cut. The sections were stained with Masson-Goldner trichrome or May-Grünwald toluidine blue. The total absolute volume of the femoral head, calcified cartilage, and the subchondral bone plate were estimated using the Cavalieri estimator. Orthogonal thicknesses of the calcified cartilage and the subchondral bone were measured in uniform randomly selected sampling points and related to the overlying articular cartilage alterations using the OARSI score of histological osteoarthritis. Linear regression was used to test the effect of age on the parameters and t-tests were applied for comparing men and women.
Results The volume and thickness of the subchondral bone did not correlate with age (Table 1). Calcified cartilage volume and thickness correlated positively with age only in women. The volume of the femoral head correlated positively with age only in men. Women and men did not differ in OARSI-stage or grade.
Conclusions In complete human femoral heads obtained from a cross-sectional population without macroscopic OA changes, we found no correlation with age for the volume or thickness of the subchondral bone plate. Surprisingly, the two genders differed in the effect of age on volume of the femoral head and volume and thickness of the calcified cartilage even though they had corresponding damage of the articular cartilage.
Disclosure of Interest None declared