REPRODUCIBILITY OF TECHNIQUES USING ARCHIMEDES PRINCIPLE IN MEASURINGCANCELLOUS BONE VOLUME

Researchers have been interested in developing techniques to accuratel y and reproducibly measure the volume fraction of cancellous bone. His torically bone researchers have used Archimedes' principle with water to measure the volume fraction of cancellous bone. Preliminary results in our lab suggested that the calibrated water technique did not prov ide reproducible results. Because of this difficulty, it was decided t o compare the conventional water method to a water with surfactant and a helium method using a micropycnometer. The water/surfactant and the helium methods were attempts to improve the fluid penetration into th e small voids present in the cancellous bone structure. In order to co mpare the reproducibility of the new methods with the conventional wat er method 16 cancellous bone specimens were obtained from femoral cond yles of human and greyhound dog femora. The volume fraction measuremen ts on each specimen were repeated three times with all three technique s. The results showed that the helium displacement method was more tha n an order of magnitudes more reproducible than the two other water me thods (p < 0.05). Statistical analysis also showed that the convention al water method produced the lowest reproducibility (p < 0.05). The da ta from this study indicate that the helium displacement technique is a very useful, rapid and reproducible tool for quantitatively characte rizing anisotropic porous tissue structures such as cancellous bone. P ublished by Elsevier Science Ltd for IPEMB.