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This short review focuses on hip fracture and its assessment (se diagram
below), since for the patient it carries the most serious clinical
consequences of all fractures and is associated with the major economic
burden on the health care system.
- Hip fracture is related to a high degree of both morbidity and mortality,
particularly for the elderly patient.
- Complications may arise from the
fracture itself and the resulting surgical management and comorbidity.
Only a small proportion of patients retain their previous mobility, while
about 20% will require nursing home care.
- Mortality is also significant,
estimates of 12 to 40% at one year having been reported from different
populations and countries.
- Hip fracture however is also related to both
bone strength and mechanical stress placed on the bone.
- In the majority
of cases hip fracture typically results from a fall. Since most elderly
subjects are osteopenic, the likelihood of falling with age becomes an
important risk factor.
- It has been proposed that the incidence of hip
fracture is 85% explained by underlying bone mass and 15% by age.
Since Laboratory measurement of BMD provides the most accurate assessment
of actual bone mass, this value may be used to provide a prediction of
future hip fracture, exactly as plasma cholesterol concentration is now
used to indicate a risk of future cardiovascular disease.
- Studies have
established that bone density at the actual femoral neck is the best
predictor of hip fracture, in comparison to measurements at either the
wrist, spine or calcaneus.
- It has been estimated that for each standard
deviation (SD) decrease in BMD at the femoral neck there is a 2.6-fold
increase in risk of hip fracture.
- This means that a woman classified as
osteoporotic (greater than 2.5 SD below her mean for age) is 28.3 times
more likely to have a hip fracture than a woman whose density is 1 SD
above the mean.
Efforts to lower the incidence of dilapidating hip fractures should
therefore concentrate on those women who have been shown to have low hip
BMD as measured by bone densitometry.
Assessment of Hip Fracture Risk
The diagram below shows the 10 year % risk of cervical hip fracture
based on bone mineral density (BMD) measured at the proximal femur
for women over 50 years. The risk is shown to increase for each
age decade (plotted as the separate lines). If the woman
already has had any fracture then the risk is increased equivalent
to one extra decade of age - that is with a fracture at 55 years, the %
risk would be similar to that at age 65 years.
(see Aloia JF, Flaster ER.
Estimating the risk of fracture in osteopenic patients.
The Endocrinologist 1995; vol 5: pp 397-402)
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