Treatment of proximal humerus fractures. Relative position of different locking plates to the axillary nerve

Objectives. Placement of a proximal humerus locking plate through a percutaneous transdeltoid approach bears the advantages of a minimally invasive approach but may compromise the anterior branches of the axillary nerve. This anatomic study aimed to develop a risk profile for 6 types of modern proximal humerus locking plates as to their interference with the axillary nerve. Materials and methods. In this study six different implants (Arthrex (R), DePuy (R), K"nigsee (R), Smith & Nephew (R), Stryker (R) and Synthes (R)) were placed on the intact proximal humerus of 33 embalmed cadaveric upper extremities and the relative positioning between the axillary nerve and the screw holes was determined. Results. All locking plates displayed an area of risk which concerned 3 out of 7 (Arthrex (R)), 4 out of 10 (DePuy (R)), 2 out of 9 (Konigsee (R)), 3 out of 11 (Smith & Nephew (R)), 3 out of 11 (Stryker (R)) and 6 out of 12 (Synthes (R)) screw holes of the plate. Conclusions. Using the anterolateral percutaneous deltoid splitting approach the relative position of the axillary nerve to the holes of a specific implant is of relevance for avoidance of iatrogenic lesions to the nerve.