Which is the best method of sterilization for recycled bone autograft in limb salvage surgery: a radiological, biomechanical and histopathological study in rabbit

Abstract

BackgroundLimb salvage surgery is a treatment of choice for sarcomas of the extremities. One of the options in skeletal reconstruction after tumour resection is by using a recycled bone autograft. The present accepted methods of recycling bone autografts include autoclaving, pasteurization and irradiation. At the moment there is lack of studies that compare the effectiveness of various sterilization methods used for recycling bone autografts and their effects in terms of bone incorporation. This study was performed to determine the effects of different methods of sterilization on bone autografts in rabbit by radiological, biomechanical and histopathological evaluations.MethodsFresh rabbit cortical bone is harvested from the tibial diaphysis and sterilized extracorporeally by pasteurization (n = 6), autoclaving (n = 6), irradiation (n = 6) and normal saline as control group (n = 6). The cortical bones were immediately reimplanted after the sterilization process. The subsequent process of graft incorporation was examined over a period of 12 weeks by serial radiographs, biomechanical and histopathological evaluations. Statistical analysis (ANOVA) was performed on these results. Significance level (α) and power (β) were set to 0.05 and 0.90, respectively.ResultsRadiographic analysis showed that irradiation group has higher score in bony union compared to other sterilization groups (p = 0.041). ANOVA analysis of ‘failure stress’, ‘modulus’ and ‘strain to failure’ demonstrated no significant differences (p = 0.389) between treated and untreated specimens under mechanical loading. In macroscopic histopathological analysis, the irradiated group has the highest percentage of bony union (91.7 percent). However in microscopic analysis of union, the pasteurization group has significantly higher score (p = 0.041) in callus formation, osteocytes percentage and bone marrow cellularity at the end of the study indicating good union potential.ConclusionsThis experimental study shown that both irradiation and pasteurization techniques have more favourable outcome in terms of bony union based on radiographic and histopathological evaluations. Autoclaving has the worst outcome. These results indicate that extracorporeal irradiation or pasteurization of bone autografts, are viable option for recycling bone autografts. However, pasteurization has the best overall outcomes because of its osteocytes preservation and bone marrow cellularity.

Gamma Radiation Sterilization Reduces the High-cycle Fatigue Life of Allograft Bone

“…Methods of sterilization such as heat [31,41,42,45,63], hydrogen peroxide [15,24] and ethylene oxide [47,57,65] can negatively affect allograft mechanical and biological properties. Heat treatment greater than 60°C reduces the strength [41,42,45,71,72] and impairs osteoinductivity [44]. Chemical treatments such as ethylene oxide and hydrogen peroxide also are harmful to osteoinductivity [8,15,24,25,54,56].…”

Biological reconstruction in the treatment of extremity sarcoma in femur, tibia, and humerus

“…Because autoclaving or pasteurization are limited by the thermally-induced weakness of bone and loss of osteoinductive properties, [ 18 ] we mainly used anhydrous alcohol, liquid nitrogen, and radiation due to low tumor recurrence with no difference in these methods. Yet, the nonunion rate was higher in anhydrous alcohol devitalized method (81.82%) than in other methods, partly because of the extended follow-up period and low ability to revascularization and cell repopulation from the surrounding soft tissue.…”

“…Extracorporeal devitalization and re-implantation of the resected bone, which can be achieved by heating, irradiation, or freezing thanks to its biological nature, is an excellent alternative method being much more economical and durable. [ 15 , 18 , 19 ] Biological reconstruction by recycling of resected tumor-bearing bone is prevalent in certain Asian countries for socio-religious reasons.…”

Does Reconstruction with Reimplantation of Sterilized Tumor Bone Provide Survival Benefit in Diaphyseal Osteosarcoma?

“…Extracorporeal radiation and reimplantation was first reported in 1968. e single high dose ensures tumor death avoiding radiation to surrounding normal tissue. Pasteurization (heating at 60-65 degree celsius for 40 min) eradicates tumor cells as shown in both preclinical and clinical studies [3,12,13]. It is reasonable to extend the hypothesis of immunological effects of cryosurgery to extracorporeal radiation and reimplantation as well which allows the immune system to access denatured tumor antigens.…”