BackgroundDisplaced olecranon fractures after a simple fall are common in elderly patients. This patient group often has multiple medical co-morbidities and low functional demands. Standard treatment for these fractures has been operative fixation, using either wires or a plate. Recent case series suggest that such injuries can be managed without surgery with good functional outcomes. There has been no published trial comparing operative to non-operative treatment for displaced olecranon fractures.This project aims to test for superiority of operative treatment versus non-operative treatment for displaced olecranon fractures in the elderly, by comparing pain and function in the affected limb up to one year after the injury.Methods/DesignSOFIE is an international study with a multicentre pragmatic randomised controlled trial design. The primary objective of the study is to compare a patient related outcome, the Disability of the Arm Shoulder and Hand (DASH) Score, between patients treated operatively and non-operatively at twelve months.Patients will be considered for the study if they are 75 years of age or older, medically fit for surgery, have an isolated displaced olecranon fracture, and present within 14 days of injury. Eligible patients willing to participate will be randomised either to operative fixation, with surgery using the preferred technique of the treating orthopaedic surgeon (tension band wiring or plate fixation), or to non-operative treatment involving early range of motion as tolerated.Secondary outcome measures will include pain, active range of motion, elbow extension strength, and any adverse events (infection, secondary interventions) at 3 and 12 months.DiscussionThe study will answer an important clinical question about the effectiveness of a commonly performed orthopaedic procedure, and will guide future treatment for displaced olecranon fractures in the elderly.Trial registration numberWorld Health Organisation Universal Trial Number (WHO UTN) - U111111574090.Australian and New Zealand Clinical Trials Registry (ANZCTR) - ACTRN12614000588695.Electronic supplementary materialThe online version of this article (doi:10.1186/s12891-015-0789-6) contains supplementary material, which is available to authorized users.