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German Congress of Orthopaedics and Traumatology (DKOU 2022)

25. - 28.10.2022, Berlin

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Biomechanical Analysis Of Helical Versus Straight Plating Of Proximal Third Humeral Shaft Fractures

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  • 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
  • Björn-Christian Link - Lucerne Cantonal Hospital, Lucerne, Switzerland
  • Frank Beeres - Lucerne Cantonal Hospital, Lucerne, Switzerland
  • Reto Babst - Lucerne Cantonal Hospital, Lucerne, Switzerland; University of Lucerne, Lucerne, Switzerland
  • Boyko Gueorguiev-Rüegg - 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. DocAB79-332

doi: 10.3205/22dkou640, urn:nbn:de:0183-22dkou6409

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

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Objectives: Proximal humeral shaft fractures are commonly treated with long straight locking plates endangering the radial nerve distally. The aim of this study was to investigate the biomechanical competence in a human cadaveric bone model of 90°-helical PHILOS plates versus conventional straight PHILOS plates in proximal third comminuted humeral shaft fractures.

Methods: Eight pairs of humeral cadaveric humeri were instrumented using either a long 90°-helical plate (group1) or a straight long PHILOS plate (group2). An unstable proximal humeral shaft fracture was simulated by means of an osteotomy maintaining a gap of 5cm. All specimens were tested under quasi-static loading in axial compression, internal and external rotation as well as bending in 4 directions (Figure 1 [Fig. 1]). Subsequently, progressively increasing internal rotational loading until failure was applied and interfragmentary movements were monitored by means of optical motion tracking.

Results and conclusion: Flexion/extension deformation (°) in group1 was (2.00±1.77) and (0.88±1.12) in group2, p=0.003. Varus/valgus deformation (°) was (6.14±1.58) in group1 and (6.16±0.73) in group2, p=0.976. Shear (mm) and displacement (°) under torsional load were (1.40±0.63 and 8.96±0.46) in group1 and (1.12±0.61 and 9.02±0.48) in group2, p≥0.390. However, during cyclic testing shear and torsional displacements and torsion were both significantly higher in group 1, p≤0.038. Cycles to catastrophic failure were (9960±1967) in group1 and (9234±1566) in group2, p=0.24.

In conclusion, although 90°-helical plating was associated with improved resistance against varus/valgus deformation, it demonstrated lower resistance to flexion/extension and internal rotation as well as higher flexion/extension, torsional and shear movements compared to straight plates. From a biomechanical perspective, 90°-helical plates performed inferior compared to straight plates and alternative helical plate designs with lower twist should be investigated in future paired cadaveric studies.