The effects of irradiation dose and storage time following treatment on the viscoelastic properties of decellularised porcine super flexor tendon

Decellularised porcine super flexor tendon (pSFT) offers a promising solution to the replacement of damaged anterior cruciate ligament. It is desirable to package and terminally sterilise the acellular grafts to eliminate any possible harmful pathogens. However, irradiation techniques can damage the collagen structure and consequently reduce the mechanical properties. The aims of this study were to investigate the effects of irradiation sterilisation of varying dosages on the viscoelastic properties of the decellularised pSFT. Decellularised pSFT tendons were subjected to irradiation sterilisation using either 30 kGy gamma, 55 kGy gamma, 34 kGy E-beam, 15 kGy gamma, 15 kGy E-beam and (15 + 15) kGy E-beam (fractionated dose). Specimens then underwent stress relaxation testing at 0 and 12 months post sterilisation to determine whether any effect on the viscoelastic properties was progressive. Significant differences were found which demonstrated that all irradiation treatments had an effect on the time-independent and time-dependent viscoelastic properties of irradiated tendons compared to peracetic acid only treated controls. No significant differences were found between the irradiated groups and no significant differences were found between groups at 0 and 12 months. These results indicate the decellularised pSFT graft has a stable shelf-life.