Hip Protectors? --- HealthandAge

September 5, 2008


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Falls and Injuries Center


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Hip Protectors?

Summarized by Robert W. Griffith, MD
January 22, 2001 (Reviewed: February 18, 2002)

Introduction

Fractures of the hip in the elderly are becoming more common. This can be due to a number of causes: an increased number and average age of older people, an increased risk of falls because of increased activity by elders, and lessened bone mineral density with age. Specific steps to reduce the likelihood of falls in the elderly are carried out in many homes and institutions, and there are widespread efforts to improve bone strength - medications, exercise, calcium and vitamin D supplements, etc. In spite of these attempts, falls will continue to occur, and impact on the greater trochanter will result in a fractured hip. Researchers at Tampere, Finland, have just reported the benefits offered by simple protective, padded shields worn bilaterally over the greater trochanter.

Method

1,750 adults over 70 were selected who had at least one risk factor for hip fracture (a previous fall or fracture, impaired balance or mobility, impaired vision, poor nutrition, or a disease or medication putting them at risk). They were located in 22 community-based healthcare centers. Once the eligible candidates from a center were identified, the center was randomly assigned to be a hip-protector unit or a control unit; there were 2 control units for each hip-protector unit.

It was found that 31% of subjects in units assigned to hip-protectors and 9% of subjects in the control units declined to participate in the study. This left 446 subjects in the hip-protector group and 981 control subjects at baseline. There was a fairly high drop-out rate after baseline, due to deaths, inability to walk refusal to continue, and other causes. To compensate for this, new eligible subjects were enrolled from the waiting list for each unit. However, all subjects who dropped out were included in the analysis for the period they participated in the study.

The hip protector used was shaped to fit anatomically over the greater trochanter and the proximal femur; it measured 19 cm long, 9 cm wide, and 4.5 cm deep. The design was intended to shunt the energy of an impact from a lateral fall away from the greater trochanter to the soft tissues anterior, posterior and superior to the femur. Two padded protectors were worn using special stretch undergarments with a pocket on each side for placement. They did not interfere with any normal movements.

The primary outcome variable was fracture of the hip or the proximal femur. Secondary variables were the number and rate of falls and the number of days the hip protectors were worn; in addition, a record was kept of whether the subject was wearing the protector at the time of a fall.

Results

The analysis included 653 subjects in the hip-protector group and 1,148 controls. With a few irrelevant exceptions, the two groups were similar with respect to baseline characteristics. In the hip-protector group, there was 48% mean use compliance - i.e. the protector was worn 48 + 29% of the available follow-up days. There were over 2 falls per subject in this group, of which 74% occurred when the hip protector was being worn. There were no relevant side effects associated with wearing the protector.

During the study period (just over 18 months), 13 subjects in the hip-protector group and 67 control subjects had a hip fracture, giving rates of hip fracture per 1,000 person-years of 21.3 and 46.0, respectively. This represents a relative hazard of fracture in the hip-protector group of 0.4 (95% confidence interval, 0.2 to 0.8; p=0.008).

Two subjects in the hip-protector group had pelvic fractures, compared with 12 controls, giving rates of 3.3 and 8.2 per 1,00 person-hours, respectively - this difference was not statistically significant. The risk of other fractures was similar in both groups, and the results were unchanged after adjustment for potentially confounding variables.

Importantly, 4 subjects in the hip-protector group had hip fractures (among 1,034 falls) while wearing the protector, while 9 subjects in the same group had fractures among 370 falls) when they were not wearing the protector. In this group, the relative hazard of hip fracture while wearing the protector was 0.2 (95% CI, 0.05 to 0.5; p=0.002).

Comment

These results show that subjects at increased risk of hip fracture can reduce their fracture risk by 60% by using hip-protector shields. "Users" may not always wear the protector all the time. If the subject is wearing the protector at the time of a fall, the risk is reduced by 80%.

The authors of the study point out that 41 people would need to use a hip protector for one year, or 8 people use one for 5 years, to prevent one hip fracture. The study showed that not all the subjects were willing to wear the jip protector regularly. Over 30% of eligible subjects refused to wear the protector; on the other hand, nearly 10% of control unit subjects also refused to participate, so that at least some members of this population may be generally unwilling to try new preventative approaches.

Compliance among those who agreed to use the hip protector device was not high - it was actually worn on less than 50% of the days of the study. Obviously, if we are to benefit from the results of this study, subjects at risk need to be better educated about the value of hip protectors, and the devices themselves must be optimized to provide maximum protection together with maximum comfort and appearance. Moreover, other risk-reducing steps - diet, exercise, etc. - must be continued, and even intensified; falls will still occur, and other bones are easily broken.

Source

Prevention of hip fracture in elderly people with use of a hip protector. P. Kannus, J. Parkkari, S. Niemi, N Engl J Med, 2000, vol. 343, pp. 1506--1513