Our study aimed to investigate the clinical and radiological results of humerus proximal or distal shaft fractures treated with minimally invasive plate osteosynthesis (MIPO) using a 3.5/5.0 metaphyseal locking plate.

We reviewed the clinical and radiographic records of 17 patients with humeral proximal or distal shaft fractures who had undergone 3.5/5.0 metaphyseal locking plate osteosynthesis with a minimally invasive technique. We evaluated the results with respect to the anatomical reduction and union of the humerus shaft fracture through radiologic studies. We also evaluated the clinical results using the motion of shoulder and elbow functional outcome, American Shoulder and Elbow Surgeons (ASES) score, Mayo elbow performance score (MEPS), and postoperative complications.

Complete union was achieved in all cases. The mean union time was 14.2 weeks. According to the functional outcome rated by the ASES score and MEPS, 15 cases were considered excellent and 2 cases were good. There were no cases of surgically-related complications like metal failure, loss of anatomical reduction, or postoperative nerve injuries.

Using a 5.0 metaphyseal locking plate for humerus shaft fracture has the limitation that difficulties can arise in achieving sufficient screw fixation for small bony fragments. The 3.5/5.0 metaphyseal locking plate used in MIPO for humerus 1/3 proximal or distal shaft fractures was concluded to give good clinical and radiologic results.