THE HISTOLOGIC FEATURES OF THE INTERFACIAL MEMBRANE OF INTRAMEDULLARYNAILS

Thirty-six interfacial membranes collected at the time of removal of i ntramedullary L316 stainless steel nails were studied histologically. The membranes consisted of bland fibrous tissue in a minority of cases . Most often, the nails were enclosed within a synovial-like membrane. Palisading macrophages and fibroblasts abutted on the metallic surfac e of the nails. Foreign body giant-celled granulomas were scattered in the midzone of the membranes, mono- and polykaryonic macrophages havi ng phagocytozed small metallic particles, necrotic bony debris, and, s ometimes, lipidic compounds. Aggregates of hemosiderin-containing macr ophages occasionally marked the sites of previous hemorrhages. When pr esent in the retrieved specimen, the bone underlying the membrane was undergoing remodeling. Interfacial motion, consequent on dissimilar st iffness of the bone and nail, as well as deposition of metallic and bo ny debris, are likely responsible for the formation of the synovial-li ke interfacial membrane.