Microstructural classification of resorption lacunae and perforations in human proximal femora

Resorption lacunae and perforation types mirror resorptional activity of osteoclasts and are important for the integrity of bone architecture. In the present study, distinctive microstructural features of cancellous bone dissected from femoral heads of 28 autopsy subjects (14 females and 14 males) were defined and evaluated by light microscopic (LM) histology and scanning electron microscopy (SEM). The work differentiates two types of resorption lacunae in trabecular bone: the longitudinally extended resorption lacunae (LER) and the reticulate patch resorption lacunae (RPR). Further, two types of perforations are distinguished: the lacunar perforation (LP) and the tunneling perforation (TP), which are differentiated from potential blood vessel canals (BC). Evidence is presented that the spatial distribution on rods or plates is highly correlated with the resorption type. The RPR type was more frequently seen and was primarily localized at the nodes of rods, in the middle regions of rods, and in the center region of plates as compared to the LER type. The presented evaluation scheme of resorption and perforation types could prove useful in future studies for systematically investigating potential microstructural changes associated with disturbed bone turnover.