Fig. 1

Study Intervention Protocol. a The preparation and storage of 40 mL study solutions, either 2 mg/mL gentamicin (intervention) or normal saline (placebo control). b The process of intraoperative randomization. Following fracture debridement and bony stabilization with planned fixation, the surgeon confirms that the wound amenable to primary closure. If the wound is primarily closable, participants are randomized to receive intraoperative local injection of either intervention or placebo control, labeled either ‘Solution A’ or ‘Solution B’. Research coordinators retrieve the allocated syringe of study solution from the dedicated study refrigerator. c The process of solution administration. Following wound closure, the surgeon draws the study solution from a sterile basin into a sterile syringe and injects the study solution by inserting the needle down to bone through an anteromedial approach at the level of the fracture site. A minimum of 5 mL of study solution may be injected, and the injection is continued until either extravasation is seen through the traumatic wound or a maximum of 40 mL has been administered, whichever occurs first. d The process of solution administration. A full-video demonstration of injection procedure can be found in Additional file 1