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Do K-wires made from shape memory alloys increase pull-out forces? A preliminary experimental cadaver study in bovine
U Wiebking1, T Gösling, W Monschizada
1Department of Traumatology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany, Ulrich.Wiebking@t-online.de
Medical & Biological Engineering & Computing
|June 2, 2007
Summary
Shape memory alloy Nitinol (NiTi) K-wires showed poorer bone fixation than steel K-wires in pull-out tests. Further research is needed to optimize NiTi wire design for improved stability in proximal humerus osteosynthesis.
Area of Science:
- Orthopedic surgery
- Biomaterials science
- Materials engineering
Background:
- Osteosynthesis of the proximal humerus using Kirschner wires (K-wires) can lead to loosening and secondary displacement.
- Conventional steel K-wires are commonly used, but their limitations necessitate the exploration of alternative materials.
Purpose of the Study:
- To compare the primary fixation strength of Nitinol (NiTi) shape memory alloy (SMA) K-wires against conventional steel K-wires.
- To evaluate the stability provided by NiTi-K-wires with split apex geometry versus threaded and non-threaded steel K-wires in cancellous bone.
Main Methods:
- Pull-out tests were conducted on cancellous bone blocks to assess wire fixation.
- Three types of wires were tested: NiTi-K-wire with split apex, conventional steel K-wire, and threaded steel K-wire.
Main Results:
- Nitinol (NiTi) K-wires demonstrated significantly easier pull-out from bone compared to steel K-wires (P=0.05).
- Despite having rougher surfaces, NiTi-wires did not provide superior stability due to premature triggering of the shape memory effect.
- The stability offered by NiTi-wires was comparable to conventional steel K-wires.
Conclusions:
- Nitinol (NiTi) K-wires, in their current design, do not offer improved stability over conventional steel K-wires for proximal humerus osteosynthesis.
- Further investigations into alternative NiTi wire designs, surface modifications, and placement strategies are required to ascertain their potential superiority.
