Abstract
INTRODUCTION AND IMPORTANCE: A re-nonunion after failed intramedullary nailing for a nonunion of the humeral shaft and a peri-implant distal humeral fracture with an ununited humeral shaft are rare cases. Therefore, no consensus has been established regarding the treatment strategies. CASE PRESENTATION: Case 1: An 84-year-old woman presented with humeral shaft re-nonunion after intramedullary nailing. The images revealed callus formation and loosening of the implant, suggesting a lack of mechanical stability. Nail removal and helical plating were performed. One year postoperatively, bony union was achieved. Case 2: A 59-year-old woman presented with a peri-implant distal humeral fracture with an ununited humeral shaft after nailing. Nail removal and helical plating were performed using a minimally invasive plate osteosynthesis (MIPO) technique. The distal humeral fracture was fixed with plates. One year postoperatively, bony union was achieved. CLINICAL DISCUSSION: Imaging findings in Case 1 indicated that nonunion was caused by a lack of mechanical stability. In Case 2, stabilization of the ununited humeral shaft was also needed. Helical plating provides a mechanically strong fixation and prevents damage to the radial nerve and soft tissues. CONCLUSION: Evaluating the causative factors of nonunions is important. Helical plating provides mechanical stability and is associated with bony union without autologous bone grafting for a re-nonunion of humeral shaft lacking mechanical instability. For a peri-implant distal humeral fracture with an ununited humeral shaft, helical plating with the MIPO technique provides diaphyseal fracture union and enables the minimal length of distal humeral plate fixation.