Corrosion and Tissue Reaction to MP35N, L605 & 316L Guide Wires in Combination with a Conventional 316L Cannulated Stainless Steel Screw

INTRODUCTION: Cannulated screws, along with guide wires, are commonly used for a variety of orthopedic indications. Typically they are used for fractures in cancellous regions. Breakage or bending deformation of the guide wire is a clinical concern. Therefore it would be advantageous to use Co-Cr alloys such as MP35N and L605 in these applications as the occurrence of breakages and bendings would be reduced. If Co-Cr alloy guidewires are to be used with 316L stainless steel cannulated screws, it is important to rule out galvanic or crevice corrosion. Therefore, we designed an experiment to determine if galvanic or crevice corrosion occurred in the in vivo environment. Implant devices were designed to replicate a clinical situation where dissimilar metals could potentially form a galvanic couple. METHODS: Custom-made implants were developed (Fig 1). In all cases the screw was 316L stainless steel while the guide wire (centre component in fig 1) was interchanged between 316L (control), MP35N and L605. The cannulated part of the screw had a conical shape. This construct was considered to mimic a cannulated screw with a broken guide wire remaining in situ.