Abstract
Introduction Over recent years the techniques of femoral and acetabular impaction allografting with fresh frozen morsellised bone have become incressingly popular for revision total hip arthoplasty with osseous defects. In many centres lack of availability or legislation has required surgeons to explore alternatives to fresh frozen bone that may have different structural and biological properties. In this study we compare in vitro the load carrying capacity of irradiated morsellised bone against a control non-irradiated sample.
Methods Fresh frozen heads were divided in halves with one half irradiated at 25 kGy and the control half left non-irradiated. A custom-built pneumatic loading apparatus applied a force of 1200N at a cycle rate of 1Hz for a total of 1500 cylcles. This loading cycle was chosen to simulate the loads normally experienced by the human femur during walking gait. The reduction in height (subsidence) of each test specimen was measured and statistical analysis performed.
Results Results from each treatment group displayed similar patterns of subsidence, with an initial rapid rate of subsidence occurring up to 50 to 100 load cycles, followed by a more gradual, slower rate as the tests progressed. The results for each treatment (mean ± standard deviation) were −3.59 ± 0.91 mm and −2.98 ± 0.812 mm for the irradiated and non-irradiated groups, respectively (P+0.049). The irradiated specimens demonstrated an increased amount of subsidence compared to the non-irradiated specimens.
Conclusions This study has shown that gamma irradiation of morsellised bone allograft material decreases its load-carrying capacity, as expressed by an increase in subsidence due to an applied cyclic load. The ability for morsellised bone allograft material to bear applied loads in vivo is an important biomechanical parameter and one indicator of a successful clinical outcome. The clinical implications of this result are important when considering the most appropriate methods of treating human bone allograft material.
In relation to the conduct of this study, one or more of the authors is in receipt of a research grant from a commercial source.
The abstracts were prepared by Mr Jerzy Sikorski. Correspondence should be addressed to him at the Australian Orthopaedic Association, Ground Floor, William Bland Centre, 229 Macquarie Street, Sydney NSW 2000, Australia.
