Allografts promote skeletal regeneration of periprosthetic femoral bone loss

Background

Periprosthetic bone loss is a common clinical problem in hip arthroplasty that must be addressed during revision surgery to achieve adequate implant stability. Although bone allografts represent the clinical standard among substitute materials used, evidence of their regenerative potential at the microstructural, cellular, and compositional level is lacking.

Methods

A multiscale imaging approach comprising contact radiography, undecalcified histology, scanning electron microscopy, and nanoindentation was employed on human femoral explants obtained postmortem many years after allograft use during revision surgery.

Results

The degree of skeletal regeneration through allograft incorporation between host bone and allograft bone was highly dependent on the defect depth (R² = 0.94, p < 0.001), while no association between the allograft time in situ and incorporation (R² = 0.06, p = 0.61) was apparent. The host bone-allograft interface showed a high overlap of 4.0 ± 2.9 mm and was characterized by active bone remodelling, as indicated by osteoid accumulation, high abundance of bone cells and vasculature. While bone cement generally limited the incorporation process, the osteocytic canalicular system of the host bone reached the allograft interface to guide bone remodelling.

Conclusion

This is the first multiscale, histomorphometry-based evaluation of bone allografts used in revision hip arthroplasty for femoral bone loss in humans, demonstrating that they adequately facilitate skeletal regeneration through osteoconduction and subsequent remodelling.

The translational potential of this article

This study identified the mechanisms and determinants of femoral defect regeneration through allografts on the basis of a unique sample collection. While our results support their favourable clinical outcomes, the scientific basis for incomplete incorporation is also demonstrated.