Low-energy lower extremity long bone fractures are associated with lower vitamin D levels than high-energy fractures.

Studies suggest that vitamin D may be protective against upper extremity low-energy (LEn) fractures. We hypothesized that there may be a similar effect in lower extremity long bone (LLB) fractures. We prospectively enrolled pediatric patients (ages 3 to 18) with LLB fractures. Exclusion criteria were pathologic, vertebral or pelvic fracture, or patients with metabolic and neuromuscular disorders. The 25-hydroxyvitamin D (25OH vit D) in the LEn group (18.3 ± 6.6 ng/ml, n  = 48) was significantly lower than that in the high-energy group (HEn) (23.5 ± 7.4 ng/ml, n = 22) ( P = 0.0086). As ankle fractures were predominantly in the higher 25OH vit D range, a subgroup analysis of 25OH vit D in LEn above ankle fracture group (LEnAA) (16.8 ± 5.5 ng/ml) was significantly lower than that in the HEn above ankle fracture group (HEnAA) (22.6 ± 6.3 ng/ml) ( P = 0.011). Defining vitamin D deficiency, insufficiency, and sufficiency as 25OH vit D < 20, 20-29, and ≥ 30 ng/ml respectively, the percentage of patients with vitamin D sufficiency in LEnAA (0%) was significantly less than that in HEnAA (19%); vitamin D deficiency in LEnAA (68%) was significantly greater than that in HEnAA (38%). A greater percentage of patients with vitamin D deficiency were treated operatively compared to those with vitamin D insufficiency and sufficiency ( P = 0.02). Our study found that LEn and LEnAA had significantly lower 25OH vit D compared to HEn and HEnAA and supported the hypothesis that vitamin D may be protective against LLB LEn fractures. Our recommendation is to obtain 25OH vit D in LLB LEn.