P62 Processing of Whole Femoral Head Allografts: Efficacy and Biological Compatability of a New Procesing Technique

Abstract

Introduction Due to the possibility of disease transmission, removal of marrow components from banked, allograft bone is desirable. The majority of bone supplied by Tissue Banks to surgeons in the UK is whole fresh‐frozen femoral heads, which still contain donor bone marrow. Some surgeons wash the bone in‐theatre whilst others do not and actually incorporate the donor marrow with the graft. Little is known about the efficacy of theatre washing to remove marrow components even though evidence suggests that marrow removal results in improved stability and enhanced incorporation of washed bone. We have recently developed a tissue bank‐based bone washing protocol for whole femoral heads and in this study we compare the efficacy of tissue bank‐washed bone and theatre‐washed bone to remove marrow components and assess the biocompatability of the products.Methods A 12‐step tissue bank protocol has been devised which involves sonication, centrifugation and washes in hydrogen peroxide, ethanol and warm water. Twenty‐four femoral heads were put through this protocol and amounts of soluble protein, DNA and haemoglobin removed at each stage were evaluated. Residual values were obtained by pulverising the final product into a fine powder. Similarly, 24 femoral heads were milled in a bone mill and subjected to four sequential rinses in warm saline, amounts of marrow components removed were evaluated with respect to residual content of pulverised product. Contact and extract cytotoxicity assays were performed on tissue bank‐washed bone, theatre‐washed bone and unwashed bone using a human osteoblastic cell line (MG63) and human skin fibroblasts.Results The tissue bank‐washing protocol removed a minimum of 99% of soluble protein, DNA and haemoglobin from bone, the washed bone product was not cytotoxic. Theatre‐washed bone removed 41% haemoglobin, 72% DNA and 92% soluble protein, the washed bone product was not cytotoxic, however, unwashed bone was found to be cytotoxic against both cell lines.Conclusion Tissue bank‐washed bone and theatre‐washed bone both produce a product which is not cytotoxic and more biocompatible than frozen‐thawed unwashed bone. The tissue bank washing protocol is more efficacious and consistant at removing bone marrow components than currently used techniques of in‐theatre washing after milling. We would suggest that tissue bank‐washed bone would allow for safer and more biocompatible allograft usage.