Hip Fractures

Based on a Plenary Symposium

“The Hip Fracture Epidemic”

Chairs: Dennis Black, Bess Dawson-Hughes

Speakers: Mary Bouxsein, Tamara Harris, Steven Cummings

Saturday, October 16, 2010

ASBMR 2010

Toronto, Ontario

Incidence and Cause of Hip Fractures

Due to the aging population, hip fracture incidence is expected to

increase 2- to 3-fold by 2050.

Facts:

• 90% of hip fractures are due to a fall

• 50% of those who sustain a hip fracture do not have osteoporosis (OP) on BMD testing

• A fall to the side is 6x more likely to produce a hip fracture

• In a fall, the femur is 3.5x weaker than in a walking or standing configuration

• Bone loss sustained with age makes people even more vulnerable to a sideway fall

• 1 in 5 people die within the first year after a hip fracture

• 50% of people do not return to their independent living situation if they were independent prior

to the hip fracture

• 50% of people will not walk independently if they were walking independently prior to the hip

fracture

• Psychological outcomes following a hip fracture are poor

In the Western World

• Many countries in the West have seen a fall in the incidence of

aged-standardized hip fracture rates in the last 10 or so years

• Rates in Denmark, Sweden and Norway have fallen by about 20% since

about 1997

• In the US, age-standardized hip fracture rates have fallen by about 25% in

women and 20% in men since 1995

SOF (Study of Osteoporotic Fractures):

Data on 80- to 84-year-olds

• Between 1992 and 2002, hip fracture risk decreased by approximately 23%

• Femoral neck BMD increased substantially in the same age group

• Between 1992 and 2002, weight gain, greater estrogen and bisphosphonate

use, and significantly greater use of vitamin D and calcium may also explain

hip fracture risk decline

 

OP therapies in the US:

• In women, they account for 9% at most of the ~25% decrease in hip fracture rates

• In men, they account for very little of the 19% decrease in hip fracture rates

• In the SOF, increasing use of OP treatments could account for ~25% of the decline in hip

fracture rates

Hip Fractures in the East

In the early 1990s, age-specific hip fractures rates in Beijing, China, were

about one-sixth or less than those in US Caucasians.

Approximately one decade later, age-specific hip fracture rates in women

in Beijing have increased 3- to 4-fold, even though obesity rates are also rising.

Cultural Changes and Hip Fractures

• Use of cars over biking and walking has increased >4-fold since the early 1990s

• Citizens have moved from older residences where there were fewer chairs and no sofas to

more Western-style apartments

• Squatting, which improves leg muscles and balance, was universal whereas now it is less

common

• The incidence of hip fractures appears to rise with urbanization  

Sarcopenia

Sarcopenia is the age-related loss of skeletal muscle mass

• In women, prevalence increases with age; in men, the prevalence increases to about the age of 50, after which it remains

relatively stable

• Women with a history of hip fracture have a high prevalence of sarcopenia

• A reduction/increase in muscle weight = a corresponding loss/increase of bone

• One consequence of muscle loss is the risk of falling and subsequent fracture

OP and Sarcopenia

After adjustment for age and interval between fracture and DXA scan, a significant association between sarcopenia and OP was

observed (P=0.026).

Adapted from Di Monaco et al. Arch Gerontol Geriatr 2010 Mar 4.Epub ahead of print.

Deconditioning and Aging

Deconditioning due to inactivity (bed rest) has a powerful effect on function and physical

activity

Intentional and unintentional weight loss increase bone loss

and hip fracture risk in older women

Exercise in the Elderly

Ten weeks of progressive resistance exercise training and nutritional supplementation in very frail elderly

patients (age =87 years) led to:

• Increased walking speed

• Increased stair-climbing ability

• Increased spontaneous activity

• Decrease in depressive symptoms

Skeletal muscle mass is the strongest independent factor associated with femoral neck BMD in men and women

Future Perspectives

Myostatin and muscle loss:

• As a negative regulator of muscle growth, increasing levels of myostatin cause muscle loss

• Myostatin probably affects bone as well

• Future drugs that neutralize or eliminate myostatin may have appositive effects on muscle and

bone