Sterilization of Allograft Bone: is 25 kGy the Gold Standard for Gamma Irradiation?

Cell Tissue Banking (2007) 8:8191

DOI 10.1007/s10561-006-9019-7

REVIEW PAPER

Sterilization of allograft bone: is 25 kGy the gold standard for gamma irradiation?

Huynh Nguyen David A. F. Morgan Mark R. Forwood

Received: 1 December 2005 / Accepted: 10 May 2006 / Published online: 5 July 2006 Springer Science+Business Media B.V. 2006

Abstract For several decades, a dose of 25 kGy of gamma irradiation has been recommended for terminal sterilization of medical products, including bone allografts. Practically, the application of a given gamma dose varies from tissue bank to tissue bank. While many banks use 25 kGy, some have adopted a higher dose, while some choose lower doses, and others do not use irradiation for terminal sterilization. A revolution in quality control in the tissue banking industry has occurred in line with development of quality assurance standards. These have resulted in signicant reductions in the risk of contamination by microorganisms of nal graft products. In light of these developments, there is sufcient rationale to re-establish a new standard dose, sufcient enough to sterilize allograft bone, while minimizing the adverse effects of gamma radiation on tissue properties. Using valid modications,

several authors have applied ISO standards to establish a radiation dose for bone allografts that is specic to systems employed in bone banking. These standards, and their verication, suggest that the actual dose could be signicantly reduced from 25 kGy, while maintaining a valid sterility assurance level (SAL) of 106. The current paper reviews the methods that have been used to develop radiation doses for terminal sterilization of medical products, and the current trend for selection of a specic dose for tissue banks.

Keywords Bacterial contamination Bioburden level Bone allografts Gamma radiation dose IAEA code of practice Inoculation method ISO standards Standard dose Terminal sterilization Tissue banking

Introduction

Since the rst full-service tissue bank was established in 1949 in the USA (Strong 2000), an international network of tissue banks has been developed widely to meet rapidly growing demands in tissue transplantation (Eastlund and Strong 2003). These banks supply a wide range of allograft bones, including massive bone allografts, cortical bone allografts, and milled bone. These tissues play an important role in lling bone defects, and recovering the mobility of patients

H. Nguyen M. R. Forwood (&)

Department...