121 patients (83 children and 38 adults) with a proximal interphalangeal joint hyperextension injury without fracture were randomized to treatment through either buddy strapping with the neighbour finger or an aluminum orthosis which immobilized the joint at 15 degrees flexion, with each applied for one week. The purpose was to determine whether there was a difference in range of motion, edema, pain, or strength between the two treatment options. The results indicated that motion restoration and resolution of edema was significantly better with buddy strapping within the first 2 weeks, and more patients were pain-free at the 2-week follow-up. From the third week of follow-up and thereafter (up to 1 year after injury), no significant differences were observed between groups. Both treatments were associated with similarly good outcome at 1 year. Better results were observed in children, and in those with less severe injuries, regardless of the treatment allocation.