The Effect of Grip Location on Kirschner Wire Bend Characteristics; an In Vitro Study

Introduction: Kirschner Wires (K-wires) are commonly used in orthopaedic procedures. Bending of K-wires is employed to prevent local irritation or persistent lameness. The objective of this study was to determine the optimal K-wire grip, when performing a Z-bend, such that bend angle, radius, and torque were minimized. We hypothesized that there would be a grip location that optimized bend angle and radius for each K-wire diameter. Additionally, we hypothesized that K-wire-bending torque decreased as grip location, away from the fulcrum, increased.

Materials and Methods: Kirschner wires of three diameters (0.035, 0.045, and 0.062-inch) were drilled into the PVC pipe, and a Jacob's chuck was used to bend the wires at five periodic grip points. Torque, bend angle, and bend radius were measured for each sample. Treatment group data were reviewed to identify relationships and check for spurious observations.

Results: Bend angles for 0.035, 0.045, and 0.062-inch K-wires ranged from 75.92 to 89.31 degrees, 72.88 to 92.62 degrees, and 74.38 to 113.29 degrees, respectively. Bend radius for 0.035, 0.045, and 0.062-inch K-wires ranged from 2.80 to 4.49 degrees, 2.22 to 4.55 degrees, and 2.11 to 6.31 degrees, respectively. Bending torque for 0.035, 0.045, and 0.062-inch K-wires ranged from 0.62 to 0.87 N-m, 0.52 to 1.47 N-m, and 1.15 to 2.15 N-m, respectively.

Discussion/Conclusion: We accepted our hypothesis that an optimal grip length point for each K-wire diameter exists. We also accepted our hypothesis that as grip distance from the fulcrum increases, maximum torque decreases. Kirschner wires should be gripped at measured distances from the bending fulcrum: 0.035 inch, 2.0 cm; 0.045 inch and 0.062 inch, 3.0 cm.

Acknowledgement: IMEX Veterinary Inc. provided K-wires, Essential Medical Devices provided the apparatus, and Richard Evans, PhD, PSTAT performed statistical analysis.

Publication History

Article published online:
26 October 2022