Do Needleless Knots have Similar Strength as the Krackow Suture? An In Vitro Porcine Tendon Study

Abstract

Background: Numerous needleless techniques for tendon graft fixation that feature several advantages have been reported. However, there are few studies that have compared the holding strength between the needleless techniques (rolling hitch and modified rolling hitch) and traditional suture methods. Questions/purposes: To compare the tendon graft-holding strength of the rolling hitch and modified rolling hitch with the Krackow stitch in an in vitro porcine biomechanical model. Methods: Thirty fresh-frozen porcine flexor profundus tendons were randomly divided into three groups of 10 specimens. The experimental procedure was designed to assess elongation of the suture-tendon construct across the needleless tendon-grasping techniques and the Krackow stitch. All suture configurations were completed with a braided nonabsorbable suture. Each tendon was pretensioned to 100 N for three cycles, cyclically loaded from 50 to 200 N for 200 cycles, and then finally loaded to failure. Elongation, load to failure, and mode of failure were recorded for each specimen. Results: Five of the 10 rolling hitch specimens failed during cyclic loading. With the numbers available, elongation after cyclic loading was not different among the successful rolling hitch specimens (19% [1.19 cm/6.17 cm] ± 6%), modified rolling hitch fixations (19% [1.11 cm/ 5.93 cm] ± 6%), and Krackow stitch fixations (26% [1.41 cm/5.43 cm] ± 6%); ultimate failure loads also were not different among the rolling hitch fixations (316 ± 35 N), modified rolling hitch fixations (342 ± 14 N), and Krackow stitches (327 ± 33 N) with the numbers available. Conclusions: With the numbers available, the rolling hitch, modified rolling hitch, and Krackow stitch techniques were not different in terms of elongation after cyclic loading and to failure in this in vitro biomechanical evaluation. Clinical Relevance: Based on the biomechanical properties from this in vitro animal study, the modified rolling hitch may be an attractive alternative for tendon graft fixation in ligament-reconstruction surgery. Future studies might consider further evaluating these needleless techniques in a cadaver model, in an in vivo animal model, and in an intraarticular model in which the testing is performed in the presence of synovial fluid.