Whipstitch and Locking Stitch Show Equivalent Elongation and Load to Failure Across 3 Suture Systems in a Biomechanical Model of Quadriceps Tendon Grafts for Anterior Cruciate Ligament Reconstruction

Abstract

PurposeThe purpose of this study was to compare the biomechanical properties of quadriceps tendon (QT) graft stitch methods using three different suture systems for anterior cruciate ligament (ACL) reconstruction. MethodsA total of 48 QTs were harvested from cadaveric knee specimens (age: 73 ± 7 years; range 66-86 years). Samples were randomly divided into three groups where different suture needle systems were used to create two stitch methods: whip stitch (WS) and locking stitch (LS). Surgeons performed each technique to five stitches, each 0.5cm apart. Stitching time was recorded. Samples were pre-conditioned then underwent cyclic loading, followed by load-to-failure. Stiffness (N/mm), ultimate failure load (N), peak-to-peak displacement (mm), elongation (mm), and failure displacement (mm) were recorded. ResultsWS and LS were equivalent across stiffness, ultimate load and peak to peak displacement within Groups 2 and 3. In Group 1, the LS was stiffer than the WS, however the WS achieved a higher ultimate load. For all Groups, the LS achieved lower elongation and failure displacement than the WS, with significant differences in Group 1 and 2. Within each stitching method, equivalence was determined for total elongation and ultimate failure load for all three suture system groups. For WS samples, Group 1 all failed from suture breakage, and both Groups 2 and 3 had instances of failure from suture pull through. All LS samples failed from suture breakage. ConclusionBoth LS and WS provide adequate mechanical properties in each of the three suture systems. Differences in performance do exist; however, each method shows equivalent total elongation and ultimate failure load for all three suture systems. LS may be preferred versus WS due to lower mean elongation and failure displacement. Clinical RelevanceThere is an increased use of a quadriceps tendon (QT) grafts in ACL reconstruction. However, there has been a limited number of studies comparing various stitching methods and optimizing techniques for QT graft fixation. This study may provide important information to surgeons about which suture techniques have better biomechanical profiles.