Comparison of the fixation ability between lag screw and bone plate for oblique metacarpal shaft fracture

Yung-Cheng Chiu,Tsung-Yu Ho,Ming-Tzu Tsai,Cheng-En Hsu,Jui-Ting Hsu,Yen-Nien Ting

doi:10.1186/s13018-022-02963-3

Abstract

BackgroundFor oblique metacarpal shaft fracture, if anatomical reduction is achieved through conservative cast immobilization rather than stable fixation, bone malrotation can easily occur, resulting in severe loss in hand prehensile function. However, whether bone plate fixation or only lag screw fixation is more preferable remains unclear. Few studies have evaluated whether screw fixation can provide biomechanical fixation strength similar to bone plate fixation.ObjectiveWe assessed the difference in fixation strength between fixtation with two lag screws and bone plate for oblique metacarpal shaft fractures.Materials and methodsWe created oblique metacarpal shaft fractures on 21 artificial bones and fixated them using (1) double lag screw (2LS group), (2) regular plate (RP group), or (3) locked plate (LP group). To obtain the force–displacement data, a cantilever bending test was conducted for each specimen through a material testing machine. One-way analysis of variance and a Tukey test were conducted to compare the maximum fracture force and stiffness of the three fixation methods.ResultsThe maximum fracture force of the 2LS group (mean + SD: 153.6 ± 26.5 N) was significantly lower than that of the RP (211.6 ± 18.5 N) and LP (227.5 ± 10.0 N) groups (p < 0.001). However, no significant differences were discovered between the RP and LP groups. The coefficient of variation for the maximum fracture force of the 2LS group (17.3%) was more than twice as high as that of the RP (8.7%) and LP (4.4%) groups. In addition, the stiffness of the three fixation methods was similar.ConclusionCompared with bone plate fixation, double lag screw fixation yielded slightly lower maximum bearable fracture force but similar stiffness. Therefore, this technique could be used for treating oblique metacarpal shaft fractures. However, using double lag screw fixation alone is technically demanding and requires considerable surgical experiences to produce consistent results.

Highlights

Metacarpal fractures are common, accounting for approximately 36%–42% of hand trauma cases [1]
Compared with bone plate fixation, double lag screw fixation yielded slightly lower maximum bear‐ able fracture force but similar stiffness. This technique could be used for treating oblique metacarpal shaft fractures
Unlike metacarpal neck, which is mostly composed of cancellous bone, the

Summary

Introduction

Metacarpal fractures are common, accounting for approximately 36%–42% of hand trauma cases [1]. Stable, nondisplaced metacarpal shaft fractures can be treated conservatively through cast immobilization. If conservative treatment is adopted in such cases, satisfactory anatomic reduction is difficult to achieve, the probability of nonunion becomes high, and bone malrotation can occur. This leads to scissoring deformity of the fingers during hand grasping and severe loss of hand prehensile function [5]. For oblique metacarpal shaft fracture, if anatomical reduction is achieved through conservative cast immobilization rather than stable fixation, bone malrotation can occur, resulting in severe loss in hand pre‐ hensile function. Few studies have evaluated whether screw fixation can provide biomechanical fixation strength similar to bone plate fixation

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