In this multicenter randomized clinical trial of 254 patients aged 18–64 years with severe open tibial shaft fractures (Gustilo-Anderson Type-IIIB and severe-Type IIIA), patients were randomized to either internal fixation (IF) (n=132) or modern external ring fixation (EF) (n=122). The primary outcome was patient-reported physical function measured by the Short Musculoskeletal Function Assessment (SMFA) Dysfunction and Bother scores and the Veterans RAND 12-Item Health Survey (VR-12) Physical Component Score (PCS). Secondary outcomes included ambulatory status and assistive device use, assessed up to 12 months post-randomization. Overall, the results of the study revealed no clinically important differences in SMFA scores between IF and EF groups at 6 and 12 months. VR-12 PCS was slightly higher for IF at 3 months, but no difference was seen at 12 months. EF was associated with higher assistive device use at 6 months. These findings suggest that functional outcomes at 1 year are similar between treatments, but EF patients had more device use early on.