Biomechanical Characterization of a New Locking Loop Stitch for Graft Fixation versus Krackow Stitch

Background@#The purpose of this study was to quantify and compare the biomechanical characteristics of a new locking loop stitch (LLS), developed utilizing the concepts of both running locking stitch and needleless stitch, to the traditional Krackow stitch. @*Methods@#The Krackow stitch with No.2 braided suture and the LLS with 1.3-mm augmented polyblend suture tape were compared biomechanically. The LLS was performed with single strand locking loops and wrapping suture around the tendon, resulting in half the needle penetrations through the graft compared to the Krackow stitch. Twenty bovine extensor tendons were divided randomly into two groups. The tendons were prepared to match equal thickness and cross-sectional area. Each suture-tendon was stitched and preloaded to 5 N for 60 seconds, cyclically loaded to 20 N, 40 N, and 60 N for 10 cycles each, and then loaded to failure. The deformation of the suture-tendon construct, stiffness, yield load, and ultimate load were measured. @*Results@#The LLS had significantly less deformation of the suture-tendon construct at 100 N, 200 N, 300 N, and at ultimate load compared to the Krackow stitch (Krackow stitch and LLS at 100 N: 1.3 ± 0.1 mm and 1.0 ± 0.2 mm, p < 0.001; 200 N: 3.0 ± 0.3 mm and 1.9 ± 0.2 mm, p < 0.001; 300 N: 5.1 ± 0.6 mm and 2.9 ± 0.4 mm, p < 0.001; ultimate load: 12.8 ± 2.8 mm and 5.0 ± 1.2 mm, p < 0.001).The LLS had significantly greater stiffness (Krackow stitch and LLS: 97.5 ± 6.9 N/mm and 117.2 ± 13.9 N/mm, p < 0.001) and yield load (Krackow stitch and LLS: 66.2 ± 15.9 N and 237.9 ± 93.6 N, p < 0.001) compared to the Krackow stitch. There was no significant difference in ultimate load (Krackow stitch: 450.2 ± 49.4 N; LLS: 472.6 ± 59.8 N; p = 0.290). @*Conclusions@#The LLS had significantly smaller deformation of the suture-tendon construct compared to the Krackow stitch. The LLS may be a viable surgical alternative to the Krackow stitch for graft fixation when secure fixation is necessary.

Little Leaguer's Shoulder Can Cause Severe Three-Dimensional Humeral Deformity

We analyzed three-dimensional (3D) humeral deformity (valgus–varus, flexion–extension, and rotational deformation) after little leaguer's shoulder using 3D computed tomography in a 15-year-old male baseball player. Humeral retroversion was increased by 27.1° on the dominant side compared with the nondominant side. Compared with the nondominant shaft, the dominant humeral shaft was deformed in the varus direction (9.4°), resulting in a decreased neck–shaft angle (dominant side, 127.5°; nondominant side, 135.1°), and it was also deformed in the extension direction (21.0°). This case demonstrates that little leaguer's shoulder can cause markedly greater humeral retroversion than has been reported previously and can result in varus and extension deformation of the humerus. These findings suggest that humeral deformity in overhead throwing athletes may not always solely reflect adaptation to throwing.