Surgical neck fractures of the proximal humerus : A laboratory evaluation of ten fixation techniques

Objective : A biomechanical cadaver study was performed to compare the stability and ultimate strength of ten standard fixation techniques used for the treatment of surgical neck fractures of the proximal humerus. Design : One hundred twenty (60 fresh frozen, 60 embalmed) proximal humerus specimens were selected and divided into two groups : fresh frozen specimens represented a nonosteopenic group and embalmed specimens an osteopenic group. Simulated fractures were created at the level of the surgical neck, reduced, and randomly assigned to one of ten methods of fixation (six fresh frozen and six embalmed specimens per fixation group). These constructs were then mechanically tested with the humeri oriented to create primarily shear loading of the fixation. Results and Conclusions : The T-plate and screws provided significantly stronger fixation (p < 0.005) in the fresh frozen specimens than all other methods. The Ender nails/tension band construct was the second strongest fixation technique, providing significantly stronger fixation (p < 0.01) than all the remaining techniques. Four Schanz pins with one pin placed through the greater tuberosity followed by the T-plate and screws provided the strongest fixation in embalmed specimens. Tension band fixation in both humeral groups was shown to provide the least effective fixation.