Age and Female Sex Are Important Risk Factors for Stress Fractures: A Nationwide Database Analysis.

BACKGROUND: Stress fractures are caused by micro-trauma due to repetitive stress on bone, common in active individuals and athletes. Previous studies demonstrate that the weightbearing bones of the lower extremities incur stress fractures most often, especially in women and older adults.

HYPOTHESIS: Prior literature does not quantify the difference in frequency of stress fractures among different genders, age groups, or body mass indices (BMIs). We hypothesized that older female patients would have higher rates of lower extremity stress fractures than male patients.

STUDY DESIGN: Epidemiological research.

LEVEL OF EVIDENCE: Level 3.

METHODS: Records of female and male patients with lower extremity stress fractures from 2010 to 2018 were identified from the PearlDiver administrative claims database using the International Classification of Diseases (ICD)-9/ICD-10 codes. Stress fractures were classified by ICD-10 diagnosis codes to the tibial bone, proximal femur, phalanges, and other foot bones. Comorbidities were incorporated into a regression analysis.

RESULTS: Of 41,257 stress fractures identified, 30,555 (70.1%) were in women and 10,702 (25.9%) were in men. Our sample was older (>60 years old) (37.3%) and not obese (BMI <30 kg/m2 , 37.1%). A greater proportion of female patients with stress fracture were older ( P < 0.001) and had foot stress fractures ( P < 0.001), while a greater proportion of male patients with stress fracture were younger than 19 years ( P < 0.001) and had metatarsal ( P < 0.001), hip ( P = 0.002), and tibia stress fractures ( P < 0.001).

CONCLUSION: Stress fractures commonly occur in women and older adults with low BMIs. Metatarsal and tibia stress fractures were the most common, and a greater proportion of women had foot stress fractures.

CLINICAL RELEVANCE: Our study examined the large-scale prevalence of different lower extremity stress fractures among a wide patient population sample of varying ages and BMIs. These findings can help clinicians identify active populations at greater risk for stress fracture injuries.