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

Purpose: To compare the biomechanical properties of quadriceps tendon (QT) graft stitch methods using 3 different suture systems for anterior cruciate ligament reconstruction. Methods: A total of 48 QTs were harvested from cadaveric knee specimens (age: 73 ± 7 years; range, 66-86 years). Samples were randomly divided into 3 groups where different suture needle systems were used to create 2 stitch methods: whipstitch (WS) and locking stitch (LS). Surgeons performed each technique to 5 stitches, each 0.5 cm apart. Stitching time was recorded. Samples were preconditioned and 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. Results: WS 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, but 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 groups 1 and 2. Within each stitching method, equivalence was determined for total elongation and ultimate failure load for all 3 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. Conclusions: Both LS and WS provide adequate mechanical properties in each of the 3 suture systems. Differences in performance do exist; however, each method shows equivalent total elongation and ultimate failure load for all 3 suture systems. LS may be preferred over WS due to lower mean elongation and failure displacement. Clinical Relevance: There is an increased use of QT grafts in for anterior cruciate ligament reconstruction. However, there have 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.