Introduction Subtrochanteric fractures are more difficult to treat than other proximal femoral fractures. The aim of this study was to report the outcomes for patients with subtrochanteric fractures treated using a cephalomedullary nail following open reduction and cerclage wiring versus closed reduction alone, regarding health-related quality of life (HRQoL) and social function. Materials and methods We performed a prospective cohort study including patients aged 60 years or older suffering fragility subtrochanteric fractures of the femur treated with cephalomedullary nails, with a minimum 2-year follow-up. We defined two treatment groups: one treated with closed reduction manoeuvres (60 patients), and another treated with open reduction and cerclage wiring (30 patients). The outcomes were mortality, orthopaedic complications (reoperation and no-union), social function (Jensen Index), and HRQoL (EQ-5D index score). Results There were no differences regarding sex, age, side affected, type of implant, anaesthetic risk, 1-year mortality, and orthopaedic complications. Surgical time was longer in the cerclage wire group, but length of stay was 2 days shorter for the cerclage group and reduction was better. Patients treated with cerclage wiring had significantly better EQ-ED at 12 months (0.66 +/- 0.22 points vs. 0.78 +/- 0.15 points); and social status at 12 and 18 months (2.77 +/- 1.00 points vs. 2.10 +/- 1.22 points). Conclusion Better reduction is achieved when using cerclage wires for fragility subtrochanteric fractures. These fractures had a negative effect on quality of life and social function, but better outcomes were observed in the cerclage group.