Why Norwegian women are twice as likely to fracture a hip as Spanish women

The result was presented today in Prague by Daysi Duarte Sosa, of Oslo University Hospital, speaking at the 41st European Calcified Tissue Society Congress, held May 17-20, 2014. Dr Duarte Sosa described how earlier studies had been unable to demonstrate significant differences in bone mass or calcium metabolism between the women of Norway and the women of Spain, and was proposing that the answer might instead lie in the strength of their bone material.

To investigate this, teams from Oslo University Hospital and Hospital del Mar-IMIM of Autonomous University, Barcelona, examined 41 Norwegian and 46 Spanish women, all of whom had normal bone mineral density (BMD) values, no clinical or morphometric vertebral fractures, no detectable signs of secondary osteoporosis and no use of drugs with known influence on bone metabolism. An Osteoprobe® device was used to measure microindentation of the thick cortex of the mid tibia (following local anesthesia), with results expressed as BMS (Bone Material Strength) units.

The investigation showed that the BMS value of Norwegian women was indeed significantly lower than that of Spanish women, by an average of 3.7%. It also showed that Norwegian women had a significantly higher total BMD but analysis showed the indentation values did not vary with BMD or age.

Dr Duarte Sosa said of the findings: "It's clear that the quality of bone material in Norwegian women is impaired, in comparison to Spanish women, and this could partly explain why Norwegian women are more likely to have hip fractures than Spanish women."

She added: "This is the first demonstration of ethnical differences in bone material properties."