Commentary & Perspective

Commentary & Perspective on
"Foot and Ankle Fractures in Elderly White Women. Incidence and Risk Factors"
by Carl T. Hasselman, MD, et al.

Commentary & Perspective by
Charles L. Saltzman, MD, and Kevin B. Jones, MD*,
Department of Orthopaedic Surgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa

Are there Modifiable Risk Factors for Foot and Ankle Fractures in Elderly White Women?

The substantial morbidity and mortality associated with hip fractures in elderly women have rightly been the focus of much research and literature. Relatively little is known about the outcomes of fractures of the foot and ankle in this population. Multiple trauma patients often find that their foot and ankle injuries cause the longest-term difficulties^1,2. Thus, we welcome this report by Hasselman et al. that appropriately focuses new attention on the prevention of foot and ankle fractures in the elderly population.

The Study of Osteoporotic Fractures has already provided a wealth of information on the incidence of and risk factors associated with various types of fractures in elderly white women. Since subject recruitment began in 1986, this study group has collected prospective data on patients at four centers and has almost a decade of follow-up data on nearly 10,000 patients. It must be noted that the requirement of a three-hour interview before subjects could be enrolled in the study created a bias toward subjects who were generally healthy at baseline, but this bias hampers only its extrinsic, not its intrinsic, validity. Also, the generalizability of this study in terms of race/ethnicity and gender is limited, but analyses of its database nonetheless continue to provide valuable information to the medical community.

This analysis by Hasselman and colleagues follows a fairly exhaustive analysis of the risk factors associated with foot and ankle fractures, which was conducted by Seeley et al.³ at an earlier stage of follow-up in the Study of Osteoporotic Fractures. This new analysis incorporates data from another five years of follow-up and includes new information about an additional 103 foot fractures and 100 ankle fractures. The clinical perspective supplied by two of the authors who are orthopaedic surgeons strengthens this analysis, whereas the analysis by Seeley et al. was primarily an epidemiological study. This added perspective is reflected in the reporting of specific fracture types and their classifications according to a modification of the system adopted by the Orthopaedic Trauma Association Committee for Coding and Classification. Unlike Seeley et al. in their initial study, Hasselman et al. provided no information about the etiology of the fracture or the patients' baseline characteristics at enrollment.

This report on the Study of Osteoporotic Fractures answers two important questions: 1) How frequently do foot and ankle fractures occur in elderly females? and 2) Are there risk factors that we can identify to reduce such fractures? This prospective cohort study is, to date, the largest study of the incidence of foot and ankle fractures in elderly women. The large sample size, rigorous methodology, and high rate of follow-up combine to yield trustworthy results that provide a benchmark for comparison with clinical studies of other types of fractures in this population and an incidence rate that can be used as the baseline for measuring the effects of preventive interventions. The findings of three new foot and three new ankle fractures confirms an earlier analysis by the Study of Osteoporotic Fractures Study Group. While the true prevalence of these fractures in the population at large may differ somewhat due to the inclusion criteria of the study, the findings reported by Hasselman et al. and their implications are striking. A typical primary-care provider treating 1000 elderly women over a ten-year period can expect to diagnose sixty new foot and ankle fractures! Clearly information that can help to reduce the number of these fractures is vital.

Applying a case-control study design to their data analysis, the authors attempted to identify potentially modifiable risk factors for foot and ankle fractures in the subject population. Because the data were gathered prospectively, the typical recall bias of a case-control study design was minimized. Numerous demographic and medical variables in women who had a new fracture during the course of the study were compared with those in women who did not. After adjusting for potentially confounding variables, an increased body-mass index and the incidence of recurrent falls (defined as two or more falls in the year before study enrollment) were baseline characteristics that were associated with an increased risk of ankle fractures. Of interest, factors associated with foot fractures differed from those associated with ankle fractures. Factors related to foot fractures included decreased bone mineral density in the distal part of the radius, a history of fracture at another site that occurred after the age of fifty years but before study enrollment, and use of benzodiazepines at the time of study enrollment.

Given the small overall number of total fractures in this study, subgroup analyses of risk factors in elderly women for fracture subtypes as classified by the Orthopaedic Trauma Association cannot be done. However, the existing information on risk factors for foot and ankle fractures may be used to perform power analyses for future studies involving this patient population to better understand outcomes. Beyond the satisfaction of mere academic interest, identification of the risk factors associated with foot and ankle fractures can guide preventive efforts. The true modifiability of risk factors can only be accurately measured in prospective, randomized, controlled trials, but common sense can be used to distinguish the identified risk factors that are modifiable from those that are not. To modify the risk of foot fractures, improving bone mineral density and decreasing the use of benzodiazepines should be the targets of future preventive measures in this population. Future studies should address the role of dietary mineral supplementation and medicines that prevent bone resorption in patients with foot fractures. Weight-loss programs and patient education about the hazards of falling might modify the risk for ankle fracture and the effects of these preventive measures should be studied.

In our experience, foot and ankle fractures in elderly women often cause major adverse changes in their quality of life because of compromised mobility. These fractures are frequently associated with prolonged periods of convalescence, loss of independence, and the need for greater assistance with activities of daily living. The impetus to reduce the associated morbidity by preventing fractures is evident, and the data from the Study of Osteoporotic Fractures sheds needed light on which factors provide a starting point for a concerted effort toward prevention.

*The authors did not receive grants or outside funding in support of the research or preparation of this manuscript. They did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the authors are affiliated or associated.

References

1. Turchin DC, Schemitsch EH, McKee MD, Waddell JP. Do foot injuries significantly affect the functional outcome of multiply injured patients? J Orthop Trauma. 1999;13:1-4.
2. Tran T, Thordarson D. Functional outcome of multiply injured patients with associated foot injury. Foot Ankle Int. 2002;23:340-3.
3. Seeley DG, Kelsey J, Jergas M, Nevitt MC. Predictors of ankle and foot fractures in older women. The Study of Osteoporotic Fractures Research Group. J Bone Miner Res. 1996;11:1347-55.