Fragility Fractures are not always Osteoporotic Fractures
Jarvinen et al are to be commended for their comprehensive analysis of fragility fracture evaluation in hip fracture prevention(1). It is to be welcomed. It is vitally important that we consistently question apparently accepted medical orthodoxy. However, there is a significant gravamen against fragility fracture treatment algorithms, not highlighted in the article. Bisphosphonates have been proven to be efficacious at preventing fragility fracture in those with osteoporosis or severe osteopenia (BMD <-2.0SD)(2). Their effectiveness in those who do not fall within this category remains to be definitively determined. The authors correctly identify that most fragility fractures occur in those who are not osteoporotic. They also note that the UK’s National Osteoporosis Guideline Group (NOGG) would advocate treatment, for example, in a 55 year-old UK woman if her 10-year fracture risk exceeds 1.5%, as determined by FRAX. However, FRAX is not dependent on bone mineral density in its evaluation of fracture risk. Bone mineral density is only a facultative variable for this calculator. Hence some of those for whom treatment is recommended may not be osteoporotic. This is problematic as it is not clear that bisphosphonates or anti-resorptives are effective at preventing fragility fracture in this context.
Fragility fracture is a much more sophisticated phenomenon than originally thought. Bone mineral density and bone mineral content may not be the sole or even the most important determinative factors. Even after correction for BMD, weight and other covariates, Barret-Connor et al found that Asian American and Black post-menopausal women had 0.3 and 0.5 the risk of fragility fractures respectively of white post-menopausal women. Similarly Uitterlinden et al observed that even following adjustment for BMD and a number of other potential confounders, post-menopausal women who were heterozygotes of a collagen 1 gene polymorphism have a significantly higher risk of fracture(3). Consider an analogy in cardiology. One might determine the 10-year risk of myocardial infarction in a patient and find this to be high. If the patient were normotensive, his blood pressure would not be targeted for intervention, however high the risk of ischaemic heart disease. However, some of the fragility fracture recommendations seem to suggest a similar logic with regard to bisphosphonates and modifying fragility hip fracture risk.
The authors do identify a real problem, however; this is that osteoporotic fractures are often thought to be synonymous with fragility (low energy) fractures. Hence there is the temptation to treat all fragility fractures with agents that improve bone mineral density. However, the root cause may not lie here. This may explain the limited efficacy observed by the authors of bisphosphonates. Abraham Maslow, psychologist, famously stated
“it is tempting, if the only tool you have is a hammer, to treat everything as if it were a nail”.(4)
My emendation would be
“it is tempting, if the only tool you have is a bisphosphonate, to treat every fracture as if it were osteoporosis”
1.Järvinen TL, Michaëlsson K, Jokihaara J, Collins GS, Perry TL, Mintzes B, Musini V, Erviti J, Gorricho J, Wright JM, Sievänen H.Overdiagnosis of bone fragility in the quest to prevent hip fracture. BMJ. 2015 May 26;350:h2088
2.Barrett‐Connor E, Siris ES, Wehren LE, Miller PD, Abbott TA, Berger ML, Santora AC, Sherwood LM. Osteoporosis and fracture risk in women of different ethnic groups. J Bone Miner Res. 2005;20:185–194.
3.Uitterlinden AG, Burger H, Huang Q, Yue F, McGuigan FE, Grant SF, Hofman A, van Leeuwen JP, Pols HA, Ralston SH.Relation of alleles of the collagen type Ialpha1 gene to bone density and the risk of osteoporotic fractures in postmenopausal women. N Engl J Med. 1998 Apr 9;338(15):1016-21
4.Abraham H. Maslow (1962), Toward a Psychology of Being:
Competing interests: No competing interests