Fatigue Microdamage in Perilabyrinthine Bone

Fatigue microdamage may develop in compact bone in response to mechanical loading. The accumulation in vivo of crack lesions is normally balanced by bone remodeling, but osteonal remodeling is inhibited in perilabyrinthine bone. In each of 20 undecalcified adult human temporal bones studied by combined microradiography, UV-microscopy and osteoid staining, abundant intra vital crack lesions containing connective tissue were found in the perilabyrinthine area. This proves that the otic capsule is subjected to bone strains and related fatigue, which would normally trigger a modeling/remodeling response in extracapsu-lar bone; it also suggests that fatigue microdamage may be of significance in otic capsular pathology. Key words: bone remodeling, bone modeling, fatigue microdamage, strain, temporal bone, otic capsule, otosclerosis.