Incorporation of morselized bone grafts: a study of 24 acetabular biopsy specimens

Animal studies have shown almost complete incorporation of impacted morselized bone grafts. To determine whether this also is true in humans, 24 acetabular bone biopsy specimens from 21 hips of 20 patients were examined. Biopsy specimens were obtained 3 months to 15 years after acetabular reconstruction in primary and revision total hip arthroplasties in combination with a cemented cup. Histologic examination showed rapid revascularization of the graft, directly followed by osteoclastic resorption and woven bone formation on the graft remnants. New bone also was formed on fibrin accumulations or without any scaffold in the fibrous stroma tissue that had invaded the graft. Thereafter the mixture of graft, new bone, and fibrin was remodeled completely into a new trabecular structure, with normal lamellar bone and only scarce remnants of graft material. Localized areas of nonincorporated bone graft surrounded by fibrous tissue remained, irrespective of the followup period. Large nonincorporated fragments of cartilage also were found, particularly in cases in which femoral head bone chips were produced by a bone mill. In general, impacted trabecular bone chips incorporate by a mechanism that is similar to that previously observed in animal studies. In some patients, however, areas of nonincorporated bone graft remained and long-term alterations were found, probably related to the loosening process.