Mechanical Testing of Two Different Variable Angle Locking Systems for Treatment of Distal Radius Fractures

Tom Adler, Thomas Schaefer and Piers Yates

Department of Orthopaedic Surgery, Fremantle Hospital and Health Service, Australia

^*Correspondance to: Tom Adler 

 PDF  Full Text DOI: 10.25107/2474-1647.1313

Abstract

Background: In recent years, the volar locking plating of distal radius fractures has become popular. Locking mechanisms have improved with the variable angle locking mechanism. The aim of the study was to evaluate the different behavior of different screw plate locking mechanisms and, furthermore, the influence on the stability in the fracture setting.Methods: Distal radius plates Synthes VA-LCP Two-Column and Stryker VariAx were compared. The locking mechanisms were tested as cantilever bending tests ascyclic staircase loading tests in 0° and 15° screw angulation as well as relocking in 0° angulation after locking in 15° using the Zwick/Roell Z010 material testing machine. The stability in an extraarticular, dorsally comminuted fracture (AO 23.A3) with Sawbones was also compared.Findings: The Synthes plate showed a load to failure of 834.1 N for 0°, 500.2 N for 15°. The Stryker plate showed a load to failure of 492.2 N for 0°, 202.9 N for 15°. In the relocking test a load to failure of 372.2 N was found for the Synthes plates and 155.3 N for the Stryker plates with high significance to 0° for both plates, no significance to 15°. In all three locking mechanism tests the difference between the two plates was significant. The fracture setting showed no significant difference, but different failure mechanisms.Interpretation: Higher screw plate angulation led to less stability. Relocking does not decrease the stability compared to 15°. Although Synthes plates were superior in the locking tests, a difference in the fracture fixation could not be found.

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Cite the article

Adler T, Schaefer T, Yates P. Mechanical Testing of Two Different Variable Angle Locking Systems for Treatment of Distal Radius Fractures. Clin Surg. 2017; 2: 1313.