Bone repair in the otic capsule of the rabbit

The repair of 1 mm drill hole lesions in rabbit long bones and otic capsules was studied in undecalcified sections. Following surgery, bone formation was monitored during 12 weeks by intravital sequential time labeling with bone-seeking fluorochromes. In diaphyseal bone, initial repair by trabecular woven bone was accompanied by a transient remodeling response in primary repair bone and the surrounding compacta. In comparison, capsular defects showed a slightly deficient initial repair by woven bone which, once formed, persisted unchanged with no subsequent osteonal remodeling. In the surrounding capsule, the remodeling response was subtle and its duration much shorter. Moreover, the centrifugal distribution of bone remodeling units around inner ear spaces was preserved, suggesting that capsular repair is affected by the same morphogenetic field that controls perilabyrinthine growth, modeling and remodeling. The significance of these findings is briefly discussed in relation to otosclerosis and cochlear implant strategies.