Wire gauge is not a reliable indicator of the diameter, tensile strength, or handling properties of orthopedic wire: an experimental study.

Abstract

Objective: To experimentally compare the diameter, maximal tension, number of twists, and slope of tension prior to failure for 18-gauge orthopedic wire from 3 vendors.

Methods: On November 22, 2024, 25 samples of 18-gauge orthopedic wire were each cut from spools of 3 different commercially available orthopedic wire brands (group A, IMEX; group B, VOI; group C, JORVET). Each sample's diameter was measured with a digital micrometer. Wires were secured with a twist knot around a simulated bone model attached to a digital load cell. Tension was recorded with each full twist until the wire broke. Maximum tension and number of twists prior to failure were recorded. Analysis of variance and Kruskal-Wallis tests were used for comparative analyses.

Results: Wire diameter (SD [mm]) was statistically smaller in group A (0.99 [0.01]) than in groups B (1.19 [0.01]) and C (1.2 [0.01]), and group C was statistically larger than B. Mean (SD) maximum tension was lower in group A (191.6 N [37.3]) than groups B (271.9 N [41.3]) or C (288.4 N [42.2]) but not statistically different between groups B and C.

Conclusions: Metrics of orthopedic wire gauge were not standardized across all suppliers. Smaller-diameter wire had a lower maximum tension but greater ductility and withstood more twists prior to wire breakage than larger-diameter wire.

Clinical relevance: Wire gauge is a flawed metric when specifying or describing wire size and subsequent mechanical behavior. Future clinical and research publications should specify wire gauge and wire diameter to promote accuracy due to the lack of standardization.