Biomechanical efficacy of wire fixation methods for oblique metacarpal shaft fractures
Yung-Cheng Chiu, Tsung-Yu Ho, Chen-Wei Yeh, Ming-Tzu Tsai, Cheng-En Hsu, Jui-Ting HsuBackground:
Fractures of the metacarpal shaft are common. In treating stable metacarpal fractures, conservative treatment with splint immobilization yields favorable outcomes. Complex and unstable fractures typically require surgical intervention. The objective of this study was to determine the fixation capabilities of multiple combinations of K-wires and cerclage wiring in treating oblique metacarpal shaft fractures.
Methods:
Vertical oblique metacarpal fractures at the midshaft of 28 artificial metacarpal bones (Sawbones, Vashon) were induced by using an electric saw. The fractured metacarpal bones were divided into 4 fixation treatment groups: Group 1 used 2 K-wires (2K), group 2 used 1 K-wire and a cerclage wire (1K&CW), group 3 used a vertical bone wire and a cerclage wire (VBW&CW), and group 4 used a lateral bone wire and a cerclage wire (LBW&CW). To measure maximum fracture force and bone stiffness, cantilever bending tests were conducted. The fixation capabilities of the 4 groups were compared using analysis of variance and Tukey test.
Results:
Maximum fracture force in the LBW&CW group (mean ± standard deviation, 113.60 ± 8.66 N) considerably exceeded that in the VBW&CW group (66.51 ± 17.27 N) and that in the 1K&CW group (65.44 ± 16.59 N). The 2K group (36.10 ± 8.32 N) exhibited the weakest maximum fracture force. The ranking of the groups from highest to lowest by average stiffness was as follows: LBW&CW group (32.34 ± 4.62 N/mm), VBW&CW group (25.47 ± 5.96 N/mm), 1K&CW group (17.70 ± 6.27 N/mm), and 2K group (15.51 ± 2.48 N/mm).
Conclusion:
The LBW&CW method provides superior fixation strength to that of the other 3 methods in the fixation of midshaft vertical oblique metacarpal fractures.