Biomechanical evaluation of different internal fixation methods for humerus shaft fractures with medial butterfly fragment.

Abstract

The aim of this study was to compare the biomechanical strength of three fixation methods in humerus shaft fractures with medial butterfly fragment. An AO 12B2 fracture with butterfly fragment was created in 21 synthetic cortical shell humeri. Humeri were divided into 3 groups which underwent bridge plating, antegrade intramedullary nailing or retrograde intramedullary nailing. Rotational and four-point bending test displacement curves were obtained. Mean displacement values in the torsion tests were 37.38 (range: 25.75 to 55.69) mm in the bridge plating group, 26.55 (range: 21.25 to 41.81) mm in the antegrade nailing group, and 33.23 (range: 27.50 to 46.45) mm in the retrograde nailing group. Mean displacement values in the four-point bending test were 3.27 (range: 2.54 to 3.73) mm in the bridge plating group, 3.17 (range: 2.69 to 3.55) mm in the antegrade nailing group, and 3.15 (range: 2.10 to 4.03) mm in the retrograde nailing group. No significant difference was found among the groups (p>0.05). The biomechanical stability of bridge plating, antegrade intramedullary nailing and retrograde intramedullary nailing appears to be similar in the fixation of humerus shaft fractures with medial butterfly fragment.