Introduction: Fractures of the humeral shaft are relatively common, accounting for approximately 1% to 5% of all fractures. The purpose of this work is to show the results obtained in fractures of the humeral shaft, through minimally invasive fixation, with a fine intramedullary nail (Steimann) and a monopolar external fixator.

Method: Prospective descriptive study with patients with humerus fracture in the period from January 2018 to August 2023, treated by osteosynthesis with a fine intramedullary nail (Steimann) and a monopolar external fixator, who underwent a six-month post-surgical follow-up. .

Results: 103 humeral shaft fractures were treated, classified according to AO/OTA as: 47 - A (21 - 12A1, 15 - 12A2 and 11 - 12A3); 31 – B (19 – 12B2 and 12 – 12B3) and the remaining 25 were type C fractures (14 – 12C2 and 11 – 12C3). In some cases, basically in groups 12B and 12C, it was required to increase interfragmentary compression after 6 - 8 weeks due to little bone callus visible on radiographs, consolidation was achieved in 98% of the patients between 12 and 16 weeks, without presence of neurological injury (radial nerve) and functional recovery of the scapulohumeral joint was complete in all cases.

Conclusion: Minimum invasive osteosynthesis of humerus shaft fractures with closed fine intramedullary nail and monopolar external fixator produces good results related to bone consolidation and scapulo-humeral functional recovery, in a relatively short time.

Keywords: Humerus shaft fracture, fine intramedullary nail, minimally invasive osteosynthesis, monopolar external fixator.