Eur J Orthop Surg Traumatol(1999) 9:103-105 European Journal of Orthopaedic Surgery & Traumatology © Springer-Verlag 1999 AIIogenicbone and HA-coatings. Histological evaluation in humans P. Frayssinet L4, J.P. Vidalain 2, A. Machenaud 2, J.C. Cartillier 3 and N. Rouquet ~ 1DePuy-Bioland,132 Rte d'Espagne,F-3noo Toulouse, France, e-mail: patrickf@worldnet.fr Clinique d'Argonnay,Argonnay, France 3 Clinique Mutualiste, Rue Tardieux, Lyon, France 4 Laboratoiredu Tissu Osseuxet des Pathologies Ostéoarticulaires,Université Paul Sabatier, Toulouse, Summary: Bone reconstruction by allo- geneic bone is offen used in conjunction with the implantation of an HA-coated device in order to obtain the osteointe- gration of this latter. We studied the his- tological behavior of 9 allogeneic implantations in contact either with the HA-coating of acetabular component or around the femoral stem. Normal can- cellous bone could be evidenced in the implantation zone around the femoral stem, whereas abnormal tissue consis- ting either of dead cancellous bone or a connective tissue patchwork was found in the retroacetabular region. Immune cells and macrophages with phagocyto- sed metal or polymer particles occurred in these latter sections. This study sug- gests that integration of the HA-coating within the allogeneic bone graft is directly linked to the integration ability of the allogeneic material. Key words: Hydroxyapatite -- Alloge- neic bone Allogeneic bone integration is conside- red to depend on bone volume and architecture [1]. Large fragments of cor- tical bone, except for the thin outermost layer are not generally integrated. Can- cellous bone seems to be more easily integrated by a process of creeping sub- stitution that evolves in several stages and leads to replacement of the alloge- neic material by mature bone [1, 2, 3]. Matching of the donor and receiver MHC is not checked before implanta- tion of allogeneic bone. It has thns been suggested that an immunitary reaction against the allogeneic implant might occur which impair subsequent integra- tion [4, 5]- The osteolysis of massive implants has in fact been attributed to such a reaction. The use of cancellous allogeneic bone to reconstruct the receiver bone around HA-coated devices would seem of interest, the aim being to obtain osseointegration of the coating after that of the graft. We had the opportu- nity either during autopsies or surgical intervention of making histological sections of allogeneic graft biopsies that had been in contact with an HA- coated device. Materials and methods Code Méary: O871.1 Correspondence to: P. Frayssinet One femur and 8 acetabularreconstructions were analyzed. According to the radiographs, none of the gratis could be considered as failures and all seemed to be integrated and living. The gratis had not been recognized as necrotic by the surgeon during the biopsy.The graft materialsconsisted of France crushed cancellousbone or canceUous bone frag- ments for acetabular reconstruction and cancel- lous bone parallelepipedsfor femoralreconstruc- tion. The mean implantation period was 2.3 years in a x8month-5year range. The biopsy of acetabular region were perfor- med after the acetabularcomponentwas removed or not using a trocard z mm in diameter. The femur sectionswereperformed afterthe femurwas in block retrieved during an autopsy procedure. The biopsywere ffxedin a 4% formaldehyde solution, dehydrated in increasing ethanol solu- tion and embeddedin PMMA. 5 gm undecalcified thick sections were performedand giemsaor fuc- sin toluidine stained. Results Femoral sections: after a two years implantation period, the allogeneic bone could not be discerned from the newly formed bone bridging the endosteum to the prosthesis surface. This bone was layered and all the lacunae in the trabe- culae were filled with living osteocytes. The stromal tissue and bone marrow in the bone pores showed a normal cytolo- gy suggesting that the allogeneic bone was totally replaced. Acetabular biopsies: Different kind of tissues were found at the interface with HA-coatings: • Cancellous bone with their pores occupied by a loose connective tissue containing macrophages, adipose tis- sue remnants, plasmocytes and masto- cytes islets (Figs. 1, 2, 3). Most of the