Strength of stainless steel surgical wire in various fixation modes

Although wire is a commonly used fixation device in orthopedics, little is known about the effects of fastening methods and configurations on the strength of wiring systems. Three sizes of stainless steel surgical wire were tested in noncyclic tensile loading. Load failure levels increased with enlarging wire diameter. Fastening twists were stronger than knots or the ASIF bend technique. The failure mode for twists was untwisting. More than two twists gave no additional strength to the system. Two commercial wire tightening devices gave stronger and more reproducible twists than did ordinary pliers. The addition of a tension equalizing loop opposite the fastening loop weakened the wire system by 10%-15%. The combination of two single wire loops was stronger than a continuous double loop of wire. The results from this study are intended to help the orthopedic surgeon optimize the use of wire.