EFFECT OF DECALCIFICATION ON BONE-MINERAL CONTENT AND BENDING STRENGTH OF FELINE FEMUR

The relationships between bone mineral content (BMC), bone calcium, an d bone strength were studied in fractionally demineralized feline femu rs. In 44 pairs of cat femurs, the right bones were decalcified in eth ylene diaminetetra acetic acid (EDTA) to 20%, 40%, 60%, 80%, and 100% of the mineral content of the intact left bone (= control). The bones were then loaded to failure, and maximum strength values were recorded . The data were then used to calculate the percentage strength of the right relative to the left femurs. A correlation coefficient (r) of 0. 970 was found between the percentage decalcification and percentage be nding strength. A direct relationship (r = 0.876) was also observed be tween the total calcium extracted and total loss in BMC. The EDTA solu tions were spot checked for protein content to determine if the organi c matrices had been altered by demineralization. Protein was never det ected. Nor did the demineralized tissues display histologic evidence o f gross microscopic damage. This study has shown that in cat femurs, 2 0% decalcification led to about 35% loss in bending strength, and 60% decalcification caused 75% loss in strength. These values are signific ant as they highlight the importance of calcium to the strength of ost eopenic bone.