Biomechanical Comparison of Different Volar Screw Placements for Horizontal Oblique Scaphoid Fractures

Ting-Sheng Lin,Yuan-Kun Tu,I-Ming Jou,Chin-Hsien Wu,Cheng-Yo Yen,Ching-Hou Ma

doi:10.3390/app10238592

Abstract

Recently, some surgeons reported that most scaphoid waist fractures were horizontal oblique and not transverse in orientation. Therefore, this cadaveric study aimed to biomechanically compare fixation strength between central and eccentric screw placements for the volar fixation of this most common scaphoid waist fracture. Eight matched pairs of fresh-frozen forearm cadaver specimens were prepared for testing and randomly assigned to two groups: group I specimens were fixed by screws in a central placement, and group II specimens were fixed by screws in an eccentric placement. Horizontal oblique osteotomy was performed along the scaphoid waist. Then, each specimen was placed under the increasing load of a pneumatically driven plunger. We recorded stiffness, load to failure, and failure mechanisms between the central and eccentric screw placement groups. Stiffness was higher in central screw placement (74.1 N/mm) than in eccentric screw placement (29.39 N/mm). The median loads to failure in groups I and II were 54.14 and 26.22 N, respectively. In this biomechanical model, we demonstrated that central screw placement is superior to eccentric placement in terms of fixation strength. However, further clinical investigation is warranted to evaluate whether the different screw placements for volar approach of horizontal oblique scaphoid fractures affect the clinical outcomes.

Highlights

In the last few decades, screw fixation of acute scaphoid fractures has become a favorable alternative after the development of headless cannulated screws [1,2,3]
The results showed that central screw placement for volar fixation of horizontal oblique scaphoid fractures provided relatively better strength than eccentric placement in terms of biomechanical stability
We adopted a cadaveric study to evaluate the biomechanical stability of different screw placement techniques in the same fracture pattern

Summary

Introduction

In the last few decades, screw fixation of acute scaphoid fractures has become a favorable alternative after the development of headless cannulated screws [1,2,3]. Screw fixation of scaphoid fractures may be performed through a dorsal or volar approach [1,4,5]. Meermans and Verstreken [7] conducted a study using three-dimensional (3D) computer modelling with computed tomography (CT) scans of the scaphoid bone to compare two approaches and showed that a volar approach could allow the surgeon to use longer screws.

Objectives

Methods

Results

Conclusion