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German Congress of Orthopaedics and Traumatology (DKOU 2022)

25. - 28.10.2022, Berlin

Helical Plating Of Proximal Third Humeral Shaft Fractures. A Biomechanical Comparative Study

Meeting Abstract

  • presenting/speaker Ivan Zderic - AO Research Institute Davos, Davos, Switzerland
  • Torsten Pastor - AO Research Institute Davos, Davos, Switzerland; Lucerne Cantonal Hospital, Lucerne, Switzerland
  • Kenneth P. van Knegsel - AO Research Institute Davos, Davos, Switzerland; Lucerne Cantonal Hospital, Lucerne, Switzerland
  • R. Geoff Richards - AO Research Institute Davos, Davos, Switzerland
  • Boyko Gueorguiev - AO Research Institute Davos, Davos, Switzerland
  • Matthias Knobe - Lucerne Cantonal Hospital, Lucerne, Switzerland

Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2022). Berlin, 25.-28.10.2022. Düsseldorf: German Medical Science GMS Publishing House; 2022. DocAB76-341

doi: 10.3205/22dkou609, urn:nbn:de:0183-22dkou6094

Published: October 25, 2022

© 2022 Zderic et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 License. See license information at http://creativecommons.org/licenses/by/4.0/.


Outline

Text

Objectives: Proximal humeral shaft fractures are commonly treated with long straight plates or intramedullary nails. Helical plates might overcome the downsides of these techniques as they are able to avoid the radial nerve distally. The aim of this study was to investigate in an artificial bone model: (1) the biomechanical competence in terms of stiffness and fracture gap movements of different plate designs (straight vs. 45° helix vs. 90° helix) and (2) to compare them against the alternative treatment option of intramedullary nails.

Methods: Twenty-four artificial humeri were assigned in 4 groups and instrumented as follows: group 1 - straight 10-hole PHILOS; group 2 - MULTILOCK nail; group 3 - 45° helical PHILOS; group 4 - 90° helical PHILOS. An unstable proximal humeral shaft fracture was simulated. Specimens were tested under quasi-static loading in axial compression, internal/external rotation and bending in 4 directions monitored by optical motion tracking.

Figure 1 [Fig. 1]

Results and conclusion: Axial stiffness (N/mm) was significantly higher in group 2 (364±133) compared to all other groups (1: 66±223; 3: 75±27; 4: 56±19), p≤0.010. Axial displacement (mm) was significantly lower in group 2 (0.1±0.1) compared to all other groups (1: 3.7±0.6; 3: 3.8±0.8; 4: 3.5±0.4), p<0.001. Varus stiffness in group 2 (0.8±0.1) was significantly higher compared to groups 1 and 3, p≤0.013 (1: 0.7±0.1; 3: 0.7±0.1; 4: 0.8±0.1). Varus bending (°) was significantly lower in group 2 compared to all other groups (p<0.001) and group 4 to group 1, p=0.022. Flexion stiffness in group 1 was significantly higher compared to groups 2 and 4 (p≤0.03) and group 4 to group 1, p≤0.029 (1: 0.8±0.1; 2: 0.7±0.1; 3: 0.7±0.1; 4: 0.6±0.1). Flexion bending (°) in group4 was higher compared to all other groups (p≤0.024) and lower in group 2 compared to groups 1 and 4, p≤0.024. Torsional stiffness remained non significantly different, p≥0.086. Torsional deformation in group 2 was significantly higher compared to all other groups, p≤0.017. Shear displacement remained non significantly different, p≥0.112.

From a biomechanical perspective, helical plating with 45° and 90° may be considered as a valid alternative fixation technique to standard straight plating of proximal third humeral fractures. Intramedullary nails demonstrated higher axial and bending stiffness as well as lower fracture gap movements during axial loading compared to all plate designs. However, despite similar torsional stiffness they were associated with higher torsional movements during internal/external rotation as compared to all investigated plate designs.