The establishment of ideal management for unstable distal clavicular fractures remains a subject of active discussion, and the topic of distal clavicular fragment management is rarely discussed. This study aimed to biomechanically investigate the effectiveness of adding sutures to plate fixation for Craig type V unstable distal clavicular fractures. Two types of clavicular models made of polyurethane foam conforming to ASTM F-1839-08 were prepared to replicate bone fragments of Craig type V fracture. A series of loading tests were conducted on models fixed with locking plates (LP Group), those fixed with double arm Scorpion NEO plates (SN Group), and those fixed with double arm plates and additional sutures (SF Group). SF Group exhibited significantly higher flexural rigidity in normal and poor bone qualities compared with LP Group, while no significant difference in torque rigidity was observed among the three groups in both bone qualities. The effect of additional sutures was not clear, although it would be beneficial if the double arm plate and bone fragments can be restored together. The double arms support the distal clavicle fragment to reintegrate fragments by pressing them from above and fixing them. In conclusion, the double arm plate was mechanically effective in fixing type V fractures in which distal bone fragments would separate in the vertical direction.