Two studies of pediatric patients with fractures, which were presented at the 2012 AAOS Annual Meeting, found that obese children are more likely to incur fractures that involve the growth plate, or physis, than nonobese children.

In a study examining lower-extremity long-bone fractures in obese and nonobese pediatric trauma patients, Shawn R. Gilbert, MD, and colleagues found that obese patients were more likely to have fractures involving the physis as a result of blunt trauma compared to nonobese patients. A second study on the effect of obesity on both low- and high-intensity pediatric fractures, conducted by Rushyuan J. Lee, MD, and colleagues, also found that obese and overweight children had a greater number of growth plate injuries than children of normal weight. In light of epidemic obesity among children, the topic has implications for a growing number of surgeons.

Altered patterns, different treatment
Dr. Gilbert and colleagues sought to evaluate the possibility of an association between trauma-caused lower-extremity fractures and obesity with respect to fracture patterns, treatment, and complications. The retrospective review used the trauma registries of two freestanding Level I pediatric trauma centers. Researchers identified 356 patients aged 2 to 14 years with femur or tibia fracture who met the inclusion criteria.

Patients were classified as obese based on weight-for-age (WFA) percentile; patients in the 95th percentile or higher were considered obese. In this study, 78 patients (22 percent) were obese, while 278 (78 percent) were classified as nonobese. Mean age of the obese children was 9.9 years; for nonobese children, it was 8.8 years (P = 0.018). No statistically significant differences were found in racial composition or sex.

A total of 266 femur fractures had radiographs available for fracture classification; 82.7 percent were diaphyseal fractures, 5.6 percent were proximal fractures, and 11.7 percent were distal fractures. Of the 146 tibia fractures with radiographs, 52 percent were diaphyseal, 10 percent were proximal, and 38 percent were distal.

When segments were further classified as epiphyseal or metaphyseal, obese patients were more likely to fracture the epiphysis compared to nonobese patients. For example, among patients with femur fractures, 91.7 percent of obese children fractured the epiphysis, compared to 44.1 percent of nonobese children (P < 0.01). Among patients with tibial fractures, 81.8 percent of obese children fractured the epiphysis, compared to 36 percent of nonobese children (P < 0.01). Obese patients had more epiphyseal fractures at all locations, and the differences reached statistical significance for the proximal femur and distal tibia.

Significant differences in treatment were also found. Nearly three out of four fractures (74.7 percent) were treated surgically with internal or external fixation in obese patients, compared to 6 out of 10 fractures treated surgically in nonobese children (age-adjusted P value = 0.022). When femur and tibia fractures were analyzed separately, tibial fractures were treated similarly in both groups. A higher proportion of femur fractures, however, were treated surgically in the obese group than in the nonobese group (89.9 percent vs. 79.1 percent, P = 0.0484). This higher rate of surgical intervention is likely due to the difficulty of managing femur fractures in spica casts in obese children.

Musculoskeletal complications reported during the inpatient stay were not statistically different between the two groups.

Different fractures, same conclusion
Dr. Lee’s study involved 224 consecutive pediatric fractures in patients between ages 2 and 16 years, enrolled in an Institutional Review Board–approved registry. This study used a broader definition of overweight/obesity (85th percentile), and children who met this definition accounted for more than 40 percent of the study group.

Mean ages of the normal weight group and the overweight/obese group were similar (9.2 years vs. 8.7 years). The percentage of females in the overweight/obese group was higher than in the normal weight group, but this was not statistically significant. The distribution of upper and lower extremity fractures was also comparable between groups. However, the overweight/obese group had a significantly higher rate of growth plate injuries (36 percent compared to 20 percent among normal weight children, P = 0.004).

“The growth plate is the weakest part of the bone,” noted the authors, “so the finding that obese/overweight children had a greater number of growth-plate injuries is not surprising. The finding that obese children had more low-energy injuries supports the idea that obese children are more sedentary.”

Coauthors of “Lower-Extremity Long Bone Fractures in Obese vs. Non-obese Pediatric Trauma Patients” are Dr. Gilbert (no conflicts); Jeffrey R. Sawyer, MD (Synthes, Medtronic); Ian Backstrom, BS (no conflicts); Aaron Creek (no conflicts), and Paul McLennan, PhD (no conflicts).

Coauthors of “The Effect of Obesity on Pediatric Fractures” are Dr. Lee (Synthes, Medtronic), Arabella I. Leet, MD (no conflicts); Colleen Cullen, NP (no conflicts); Fina Baca-Ascher, PA (no conflicts); Meredith A. Lazar-Antman, MD (Contract Pharmacal Corp.); Sara Polk, MD (no information); and Jacky M. Jennings, PhD (no information).

Terry Stanton is the senior science writer for AAOS Now; he can be reached at tstanton@aaos.org

Bottom Line

• A study examining lower-extremity long-bone fractures in obese and nonobese pediatric trauma patients found that obese patients were more likely than nonobese patients to have fractures involving the metaphysis as a result of blunt trauma.
• The study also found that more obese children with femur fractures were treated surgically than nonobese children; tibial fractures, however, were treated similarly in both groups.
• A second study on the effect of obesity on both low- and high-intensity pediatric fractures also found that obese and overweight children had a greater number of growth plate injuries than children of normal weight.
• Obese children also had more low-energy fractures than children of normal weight.

Additional Resources
Lower Extremity Long Bone Fractures in Obese vs. Non-obese Pediatric Trauma Patients

The Effect of Obesity on Pediatric Fractures