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Published on: June 6, 2025
Retrograde nailing versus locking plate osteosynthesis of proximal humeral fractures: a biomechanical study
Sven-Oliver Dietz1, Frank Hartmann, Thomas Schwarz
1Center for Musculoskeletal Surgery, Department of Trauma Surgery, University Medical Center, Johannes Gutenberg University, Mainz, Germany. sven-oliver.dietz@unimedizin-mainz.de
Background:
In locking plate osteosynthesis of proximal humeral fractures, secondary varus malalignment is a specific complication. Retron nails (Tantum AG, Neumunster, Germany), among others, have been designed to improve medial support of the calcar humeri. The aim of our biomechanical study was to examine whether Retron nails provide increased stiffness for axial loads and adequate stiffness for torsional loads when compared with Philos plates (Synthes AG, Umkirch, Germany).
Materials And Methods:
Twenty-two fresh-frozen paired humeri were collected. After potting the specimens, intact bones were exposed to sinusoidal axial (10-120 N) and torsional (±2.5 Nm) loading for 8 cycles to calculate the initial stiffness and exclude pairs with differences. Afterward, an unstable proximal humeral fracture (AO 11-A3) was created by means of an oscillating saw, and the respective osteosynthesis devices were implanted. After another 4 cycles, initial changes in stiffness were measured. Subsequently, all specimens were tested for 1,000 cycles of loading before final stiffness was assessed.
Results:
We found no statistically significant differences between Retron and Philos specimens after 4 or 1,000 cycles of loading.
Conclusion:
Our study suggests that retrograde nailing provides sufficient stability for axial and torsional loading in 2-part fractures of proximal humeri.
