A retrospective study on annual evaluation of radiation processing for frozen bone allografts complying to quality system requirements

Abstract

Bone allografts have been used widely to fill up essential void in orthopaedic surgeries. The benefit of using allografts to replace and reconstruct musculoskeletal injuries, fractures or disease has obtained overwhelming acceptance from orthopaedic surgeons worldwide. However, bacterial infection and disease transmission through bone allograft transplantation have always been a significant issue. Sterilization by radiation is an effective method to eliminate unwanted microorganisms thus assist in preventing life threatening allograft associated infections. Femoral heads procured from living donors and long bones (femur and tibia) procured from cadaveric donors were sterilized at 25 kGy in compliance with international standard ISO 11137. According to quality requirements, all records of bone banking were evaluated annually. This retrospective study was carried out on annual evaluation of radiation records from 1998 until 2012. The minimum doses absorbed by the bones were ranging from 25.3 to 38.2 kGy while the absorbed maximum doses were from 25.4 to 42.3 kGy. All the bones supplied by our UMMC Bone Bank were sterile at the required minimum dose of 25 kGy. Our analysis on dose variation showed that the dose uniformity ratios in 37 irradiated boxes of 31 radiation batches were in the range of 1.003-1.251, which indicated the doses were well distributed.

Performance of cooling materials and their composites in maintaining freezing temperature during irradiation and transportation of bone allografts

“…Based on our radiation service records from 2013 to 2015, time taken for radiation sterilization process was around 24 h including 4 h for packaging and transporting the bones to the irradiator and another 2 h to bring back to the Bone Bank for storage. 24 In the seven batches of 2015, the bones packed in 20 kg DI were still frozen at À64.33 + 6.90 C after completing the radiation process confirming that the bones were irradiated in deep freezing state. The temperature profiles of varying composites developed in the study are useful in predicting the temperature during irradiation process and at any time during transportation.…”

“…23 Terminal sterilization of frozen bone allografts by gamma irradiation as practiced by the UMMC Bone Bank since its establishment in 1998 is effective and there were no complaints from the surgeons on the bone sterility based on the retrospective study conducted from 1998 to 2012. 24 The initial minimum temperature must be deep freezing which reflects the ability of the cooling material to maintain deep freezing condition below À40 C during the longdistance transportation and irradiation process. The ability of the cooling material to maintain the freezing temperature below À20 C is required for short-distance transportation of bone allografts that will be immediately used for transplantation upon reaching the hospitals.…”

“…Terminal sterilization of frozen bone allografts by gamma irradiation as practiced by the UMMC Bone Bank since its establishment in 1998 is effective and there were no complaints from the surgeons on the bone sterility based on the retrospective study conducted from 1998 to 2012. 24…”