Vitamin D and Postoperative Recovery in Elderly Ribeirinhos—Riverside Amazon Communities with Femur Fractures

<b>Background/Objectives</b>: Vitamin D deficiency is prevalent in elderly populations and may impact surgical recovery. Despite the equatorial location, vitamin D insufficiency affects many elderly Ribeirinhos in the Brazilian Amazon. This study investigated whether pre-existing vitamin D supplementation influences postoperative outcomes in elderly Ribeirinhos following femur fracture surgery, while examining metabolic parameters and documenting chronic disease prevalence. <b>Methods</b>: This prospective cohort study enrolled 60 elderly Ribeirinhos patients (≥65 years) admitted for femur fracture surgery at the Regional Hospital of Lower Amazon. Twenty-two patients had participated in a vitamin D supplementation program (50,000 IU monthly, 3-6 months) prior to admission; 38 had not. Primary outcomes were hospitalization duration and serum 25-hydroxyvitamin D levels. Secondary outcomes included ionized calcium, blood glucose, and comorbidity documentation. <b>Results</b>: The supplementation group was associated with significantly shorter hospitalization (14.32 ± 0.79 vs. 22.61 ± 0.88 days, <i>p</i> < 0.0001), representing 37% reduction. Vitamin D levels were markedly higher in supplemented patients (50.26 ± 2.55 vs. 21.74 ± 0.84 ng/mL, <i>p</i> < 0.0001). Ionized calcium was elevated in the supplementation group (1.29 ± 0.01 vs. 1.08 ± 0.02 mmol/L, <i>p</i> < 0.001) without hypercalcemia. Blood glucose was lower in supplemented patients (83.8 ± 1.4 vs. 152.2 ± 9.6 mg/dL, <i>p</i> < 0.001). Medical records revealed that 73.3% had hypertension and 31.7% had diabetes, with 25% having both conditions. <b>Conclusions</b>: Pre-existing vitamin D supplementation was associated with reduced hospitalization duration following femur fracture surgery, though causality cannot be inferred due to observational design. Community-based vitamin D programs may warrant further investigation in vulnerable populations, with randomized trials needed.