Identifying and Managing Ankle Fractures in Older Patients

ABSTRACT: The incidence of ankle fractures in the older patient population is rising. These fractures are characterized as fragility fractures associated with osteoporosis, but propensity for falls, increased weight, and polypharmacy may be bigger risk factors than poor bone quality. Operative fixation is widely accepted as the proper treatment for younger patients, but the optimal treatment for older patients is less clear. The literature supports operative intervention for displaced ankle fractures in older patients. However, the presence of osteoporosis may increase the complexity of these cases, potentially requiring alteration of standard operative techniques. Orthopedic surgeons and primary care physicians need understanding of the risk factors associated with ankle fractures in older patients as well as appropriate evaluation and management strategies. (J Musculoskel Med. 2011;28:137-147)

Management of ankle fractures in older patients is a growing problem that affects the practices of both orthopedic surgeons and primary care physicians. Ankle fractures are common in older patients, and both their incidence and severity have increased significantly in this patient population during the past 30 years. In the United States, ankle fractures have been reported to occur in as many as 8.3 persons per 1000 Medicare recipients.¹ Kannus and associates² reported that the number of ankle fractures in Finnish patients older than 70 years increased 3-fold between 1970 and 2000. They also showed an increase in the more severe Lauge-Hansen supination-eversion stage 4 ankle fracture, compared with more stable ankle fracture patterns.

To achieve successful treatment outcomes, physicians need a clear understanding of the risk factors associated with ankle fractures in older patients as well as appropriate evaluation and management strategies. Ankle fractures in older patients typically result from low-energy injuries that involve a twisting mechanism, possibly reflecting the relative strength of the ankle ligaments and osteopenic bone. Recent studies have shown that propensity for falls, increased weight, and polypharmacy may play a larger role than osteoporosis does in the occurrence of ankle fractures in older patients; these findings challenge the categorization of ankle injuries in older persons as fragility fractures.

There is no consensus about what constitutes optimal management of ankle fractures in this potentially complex patient population. Most orthopedic surgeons agree that operative intervention is appropriate for younger patients with ankle fracture. However, treatment of injured older patients is controversial.³ Conservative treatment has been recommended for older patients because of poor outcomes after surgery in patients with osteoporosis and medical comorbidities, such as diabetes mellitus (DM) and peripheral vascular disease.^4-7

In this article, we review the risk factors for ankle fracture in older patients, appropriate patient evaluation, and initial management strategies. We also describe data supporting operative or nonoperative management to help primary care physicians determine whether to treat or refer the older patient with ankle fracture.

DIAGNOSIS
Risk factors
Most clinical studies that evaluate ankle fractures in older patients have identified female sex, DM, and obesity as the main predictors of injury.⁸ Some investigators have categorized ankle fractures as osteoporotic fragility fractures on the basis of the high incidence of ankle fractures in postmenopausal women.^9,10 However, observational studies have shown that the incidence of ankle fracture in older women increases until age 65 and then either plateaus or declines; this finding contradicts the notion that bone quality and fracture risk are associated.^8,11-15 The increase in the number of ankle fractures seen in the older patient population may be a function of active older adults increasing in number rather than the presence of osteoporosis.

Clinical studies have examined the relationship of bone mineral density (BMD) to ankle fracture incidence in older patients and identified risk factors for these injuries (Table 1). In an evaluation of 9704 women older than 65 years, Seeley and colleagues¹⁵ found that after adjusting for age, the risk of ankle fracture was increased in women who had a history of falls in the previous year, were heavier, used their arms to rise from a chair, and either engaged in strenuous physical activity or rarely left their homes. The authors found no significant relationship between peripheral BMD and the incidence of ankle fracture in this patient cohort. They concluded that the risk factors for ankle fracture in older women are different from those associated with typical osteoporotic fragility fractures of the hip, distal radius, or proximal humerus.

In the Kuopio Osteoporosis Risk Factor and Prevention (OSTPRE) study of 11,798 older Finnish women, Valtola and coworkers¹⁶ found 4 independent predictors for ankle fracture in this patient population: overweight status, previous fracture history, polypharmacy, and cigarette smoking. The investigators identified a dose-response relationship between smoking and ankle fracture risk: the hazard ratio increased from 1.73 for study participants who smoked less than 1 pack of cigarettes per day to 2.94 for those who smoked more than 1 pack. In the OSTPRE study, patients who were taking 3 or more prescription drugs were twice as likely to sustain an ankle fracture as those who were not taking any prescribed medication.

Greenfield and Eastell⁹ used dual-energy x-ray absorptiometry scanning and quantitative ultrasonography to compare 103 women aged 50 to 80 years who had ankle fractures with 375 controls of similar age. They found no significant difference in BMD in the patient cohorts, except for in the trochanteric region, where patients with ankle fracture had a higher BMD than the population-based group. However, the authors did find that the ankle fracture population had a significantly higher body mass index than the controls. They concluded that increased body weight may contribute to a fracture about the ankle by increasing the forces applied to the ankle during a fall.