Ankle fractures are a common orthopedic injury. Certain ankle injuries have been associated with patient demographics such as obesity and smoking. Obese patients are more prone to severe ankle injuries. Naturally, these injuries affect the lower extremity mobility significantly, which itself is a risk factor for obesity. Although obese patients have increased complications across the board, there are specific techniques that can be used to assure the best possible outcome. The perioperative, surgical, and postoperative considerations as well as the outcomes are discussed in this article.
Ankle fractures are a common orthopedic injury, occurring at an annual incidence of 187 fractures per 100,000 people. Certain ankle injuries have been associated with patient demographics such as obesity and smoking. Unlike fractures of the distal radius, hip, and spine, osteoporosis does not seem to be a major risk factor for ankle fractures. A study of more than 3500 patients with ankle fracture revealed their average body mass index (BMI), calculated as the weight in kilograms divided by height in meters squared, to be higher than the general population across all age and gender categories. Naturally, these injuries affect the lower extremity mobility significantly, which itself is a risk factor for obesity. Although overweight adults with disabilities are generally as likely to attempt weight loss as those without disabilities, overweight adults having difficulty walking or using a mobility aid are the exception. In part, this stems from physicians not counseling this population on the importance of physical exercise. Physicians may focus more on diet than exercise in light of limited mobility; however, recent studies suggest that reduced energy expenditure is more causative than increased food intake in the development of obesity.
The implications to one’s health of being overweight are numerous. More than 80% of type 2 diabetes can be attributed to obesity, which may also account for many diabetes-related deaths. The association between diabetes and complications of ankle injuries has been well documented. In addition, obesity has been associated with an increased risk of deep vein thrombosis (DVT) and pulmonary embolus (PE), which are concerns with any lower extremity injury. Finally, obesity syndrome predisposes patients to osteoarthritis by altering cartilage and bone metabolism independent of weight bearing, as evidenced by the involvement of non-weight-bearing joints. The tibiotalar joint is subject to joint reaction forces of 4.5 times the body weight during walking and 10 times the body weight with running. Posttraumatic arthritis in the setting of a biologic predilection for osteoarthritis can be devastating to mobility. Although there may be some protective effect of obesity on bones, with recent evidence showing that leptin resistance in obese individuals may have a favorable effect on bone mass, ankle injuries in the setting of obesity are fraught with complications.
Data on ankle injuries in the obese population require well-defined parameters of obesity. Technically, overweight refers solely to excess body weight, whereas obesity is excess fat. The 2 commonly used definitions are ideal body weight, based on one’s height and gender, and BMI, which correlates with body fat and relatively unaffected by height. A study of 314 ankle fractures over a 3-year period revealed 39% of cases to have resulted from slips and falls in obese individuals, defined as greater than 120% ideal body weight, compared with a general prevalence of obesity less than 20% at the time of study. The study also demonstrated almost double the prevalence of diabetes in the cohort with ankle injuries than would be expected in the general population. The latest data compiled in 2008 detailed an obesity rate (BMI>30) of 33.8% in the United States among those aged 18 years and older, with 68% being overweight (BMI>25). Another retrospective review of 279 ankle fractures reported a similar increased incidence of concomitant obesity, with 35.5% incidence in patients with BMI greater than 30.
Fracture pattern also seems to be affected by obesity. Although sustaining an open versus closed injury for distal tibial fractures does not seem to be a consequence of body mass, obese individuals were more likely to sustain Orthopaedic Trauma Association type B and C fractures, and less likely to have type A fractures than nonobese patients, at rates of 1% and 11%, respectively. Furthermore, the mean BMI of patients with displaced fractures is significantly higher than those with nondisplaced fractures, with one study demonstrating 83% of displaced fractures in overweight patients. Almost one-third of patients with displacement had a BMI more than 30, whereas only 1 of 24 significantly obese patients had a nondisplaced fracture.