Is suture comparable to wire for cerclage fixation? A biomechanical analysis

Cerclage wire is the current standard for circumferential bone fixation. Advances in technology have improved modern sutures, allowing for expanded utility and broader application. The present study compared the strength and durability of cerclage fixation between modern suture materials and monofilament wire.

The Surgeon's Knot, the Nice Knot and the Modified Nice Knot, were each tied using three separate suture materials: no. 2 FiberWire (Arthrex, Naples, FL, USA), no. 2 Ultrabraid (Smith & Nephew, Andover, MA, USA) and no. 5 Ethibond (Johnson & Johnson, Somerville, NJ, USA). These sutures were compared with monofilament wire. Sutures were secured around a fixed diameter using three additional half hitches, whereas a 1.2-mm (18 gauge) stainless steel monofilament wire was used for comparison. One fellow and one orthopaedic surgery resident each tied five trials with every knot/material combination. Samples were subjected to cyclic loading and quasi-static load testing. Respectively, cyclic displacement over time and load to failure were analyzed. Clinical failure (3 mm of cyclic displacement) and absolute failure (opening of the knot or material failure) were the outcomes of interest.

During cyclic loading, Ethibond displaced significantly less over time compared to monofilament wire (p < 0.003), whereas FiberWire showed no significant difference. Ultrabraid also behaved similar to wire, except displacing significantly more than wire only with the Surgeon's Knot (p = 0.02). During load to failure, Ethibond and FiberWire failed at significantly greater loads than monofilament wire (p < 0.001), whereas Ultrabraid performed similar to wire. Knot types did not appear to impact the results.

High-performance sutures achieve superior results in biomechanical testing under cyclic and quasi-static load compared to monofilament wire, suggesting that they provide an alternative to wire for cerclage fixation with select clinical application. Biomechanical security of suture cerclage is dependent on suture material, although it is not altered significantly by choice of knot. An ex-vivo study with clinical application would further reinforce whether suture cerclage offers a valid alternative to wire cerclage.