Krackow Locking Stitch Versus Locking Premanufactured Loop Stitch for Soft-Tissue Fixation: A Biomechanical Study

PurposeTo biomechanically compare construct elongation under loading conditions and to compare load to failure for the locking premanufactured loop stitch versus the Krackow stitch.MethodsTwenty porcine Achilles tendons were randomly assigned to receive the locking Krackow stitch with No. 2 FiberWire (Arthrex, Naples, FL) or the locking premanufactured loop stitch with No. 2 FiberLoop (SpeedWhip; Arthrex). Each tendon was pre-tensioned 3 times at 100 mm/min to 100 N for removal of slack, preloaded to 50 N to simulate tension applied clinically, and cyclically loaded at 200 mm/min to 200 N for 200 cycles. Total elongation of both suture strands was measured at each stage. Each tendon was loaded to failure.ResultsElongation (mean ± standard deviation) in the Krackow group and the SpeedWhip group did not differ with initial loading at 50 N (4.5 ± 1.0 mm and 5.0 ± 1.7 mm, respectively; P = .4) or with cyclic loading (15.6 ± 5.7 mm and 17.0 ± 2.6 mm, respectively; P = .5). Load to failure was significantly higher in the SpeedWhip group as compared with the Krackow group (344.0 ± 23.1 N and 301.3 ± 24.4 N, respectively; P = .001).ConclusionsIn a porcine tendon model, the locking loop stitch group was not significantly different regarding construct elongation with initial or cyclic loading compared with the Krackow stitch group. These findings suggest that the locking loop stitch has adequate strength to serve as an alternative to the Krackow stitch in procedures where the Krackow stitch is used. The elongation data suggest that augmentation or protection with early stress postoperatively would be needed with the locking loop stitch as with the Krackow stitch clinically.Clinical RelevanceSimilar elongation in the 2 constructs suggests that this locking loop stitch has adequate strength to serve as an alternative to the Krackow stitch in procedures where the Krackow stitch is used.