The aim of this paper is the investigation of the mechanical properties the Helix Wire, a device that
has been employed for subcapital humerus fracture ostheosynthesis in recent years. There are
several potential clinical advantages associated with its use, but clinical results reported in literature
are controversial.
The Helix Wire has been assimilated to a helical spring, and several analytical solutions for
displacements and stresses have been compared and experimentally validated, showing the
importance of the pitch angle contribution.
Based on the results, the main factor for the clinical indication of this fixation device was found to
be the patient age. In fact, the use of the Helix Wire should be avoided in case of young patients or
of patients with well-developed muscular masses, where the forces may easily lead to critical
stresses in the spring and separation of the fracture surfaces. The clinical results obtained on 30
elderly patients confirmed these findings.
