Summary

This poster describes the biocompatibility and in vivo performance of a decellularised porcine tendon graft for ACL reconstruction.

Abstract

Background

Current treatment options for primary ACL reconstruction include several choices. Autografts are attractive in most cases, but do have limitations, including patient age, concomitant ligament injuries or previous surgeries. Allografts have varied availability according to region, and can be inconsistent: quality, size specifications, donor age and sterilisation methods. Synthetic grafts have limited regulatory availability, and have been linked to higher failure rates. The ideal graft for ACL reconstruction would have the following characteristics: biocompatibility, biomechanical strength, consistent specifications, room temperature storage, and the capability of integration and remodelling. A decellularised xenogeneic biological graft, such as the OrthoPure™ XT device, could provide these advantages, and deliver a suitable regenerative solution. The objective of this study was to demonstrate the biocompatibility and in vivo performance of the OrthoPure™ XT device material.

Methods

The OrthoPure™ XT device material was subjected to biocompatibility testing (cytotoxicity, acute systemic toxicity, sensitisation, intracutaneous reactivity, bacterial mutagenicity). The local tissue effects and in vivo performance of the device material were assessed against controls (contralateral ACL and autograft) following implantation in an ovine model for 12 and 26 weeks. Fixation was achieved by resorbable interference screws. At 0, 12 and 26 weeks, the performance of the test and control articles were evaluated by biomechanical testing. At 12 and 26 weeks, the quality of the ACL-bone graft junction and tissue effects on the knee joint and distant organs were macroscopically and histopathologically evaluated.

Results

Following testing, the OrthoPure™ XT device material was deemed biocompatible. For the ovine model, the surgeries were successful. Fixation of the graft immediately after surgery was not significantly different between the test and control groups. At 12 weeks post-implantation, the biomechanical performance of the test group was reduced compared to the control. The inflammatory reaction observed in the test group was slightly higher than that of the control group. All other assessments were similar for test and control, including multifocal calcification/ossification, Sharpey’s fibre formation and screw osteointegration at the bone contact sites. The inflammatory reaction observed in the test group at 12 weeks decreased and was similar to the control group by 26 weeks. Ossification, Sharpey’s fibre formation and osteointigration scores were lower in the test group than the control group at 26 weeks. By 26 weeks, the biomechanical performance of the test and control groups were not statistically different.

Discussion

The biocompatibility and functionality of the OrthoPure™ XT device material has been demonstrated by in vitro and in vivo testing. The results obtained from the ovine model reflect the typical course of graft healing, with a reduction then increase in mechanical performance. The increase then decrease in inflammatory response also correlates with graft remodelling. Ossification and Sharpey’s fibre formation at the bone contact sites are important for graft anchorage. These results indicate that the OrthoPure™ XT device material could provide a suitable alternative treatment option to autograft, allograft or synthetic grafts for ACL reconstruction.

Conclusion

Based on these results, the OrthoPure™ XT device is currently undergoing a clinical investigation in the EU.