A prospective, feasibility, randomised study was performed to compare intramedullary versus extramedullary fixation of unstable pertrochanteric fractures and to assess the feasibility of including patients with dementia. From July 2016 to November 2017, 60 consecutive patients with an unstable pertrochanteric (OTA/AO 31-A2) fracture were randomized to either receive a short cephalomedullary nail (Endovis EBA2, Citieffe) or a dynamic hip screw (DHS, Zimmer Biomet). Primary feasibility measures included randomisation, recruitment, and retention rates. Secondary outcomes included peri-operative parameters, patient-reported outcomes and radiographic outcomes. Patients were followed-up at two, four, and twelve weeks. There was no difference in the randomisation rate between patients with and without cognitive impairment. Significantly more patients without cognitive impairment attended the 12-week follow-up. The overall recruitment rate was 0.9 patients per week. Patients treated with the nail had less pain at 2 weeks and less neck collapse, medialisation, and leg shortening at all time points. The rest of secondary outcomes were similar. Patients with dementia can successfully be enrolled in a randomised trial on hip fractures. Patients treated with the Endovis nail had lower levels of pain at two weeks and better radiographic outcomes.