Open reduction and internal fixation of proximal humerus fractures with angular stable plates is, beside antegrade nailing of the humerus, a standard procedure. A retrograde nail has been developed to avoid penetrating the rotator cuff and to avoid opening the fracture side during osteosynthesis.

The aim of our biomechanical study was to evaluate if retrograde nailing of proximal humerus fractures is as stable as locking plate osteosynthesis.

The biomechanical properties of 2 implants were tested in 11 human fresh frozen cadaveric humeri pairs. The Retron Nail® and the Philos® plate were implanted after osteotomy. All specimens were suspected to axial and torque load for 1000 cycles in a servo pneumatic testing apparatus.

The Philos® plate had greater torsion stiffness than the Retron® nail, but we found no significance. The Retron® nail had greater axial stiffness but our findings were not statistically significant.

Our study showed, that there are no significant differences between a retrograde nail and locking plate osteosynthesis for proximal humerus fractures concerning axial and torsion deformities. Therefore the retrograde nail is a suitable alternative for fixation of proximal humerus fracture.