Suture Slippage After Arthroscopic Cuff Repair: Medial Displacement of Suture Knots on Follow-up Ultrasonography

Background: Compared with the single-row technique, the double-row rotator cuff repair technique is known to have a higher load to failure and a lower frequency of gap formation, leading to a lower retear rate. There are some patients with poor clinical outcomes or poor muscle strength without radiologic retear. Purpose/Hypothesis: To assess the postoperative position of suture knots via serial ultrasonography in patients who had undergone arthroscopic rotator cuff repair with the suture-bridge technique. Our hypothesis was that the suture would pull out of the lateral anchor (suture slippage), changing the positions of the medial suture knots during healing. Study Design: Case series; Level of evidence, 4. Methods: This study included 53 patients (55 shoulders) who underwent arthroscopic suture-bridge repair and were evaluated for a minimum of 24 months. On serial ultrasonography, a straight line was drawn between the top of the greater tuberosity and the medial cortex of the anchor hole. The distances between the knots of the medial rows and the perpendicular line through the center of the anchor hole were measured in longitudinal plane images of the supraspinatus. Follow-up ultrasonography was performed at 2, 3, and 6 months postoperatively as well as at the final visit. The visual analog scale, the American Shoulder and Elbow Surgeons score, the Constant score, and the University of California, Los Angeles shoulder score were recorded preoperatively and on the final follow-up. Results: Of the 55 shoulders, 6 developed retears at repaired sites. The mean follow-up duration was 37.5 months (range, 24-65 months). Slippage distance increased significantly over time ( P < .001). The slippage at the final visit did not differ between patients with retear and no retear (13.4 mm for retear group; 10.6 mm for no retear group [ P = .096]). Conclusion: Suture knots of the medial row migrated medially via a suture pullout from the lateral row anchor of suture-bridge technique. Suture slippage distance did not differ significantly between retear and no retear groups.

Analysis of Synthetic Fiber Pull-Out from a Cement Matrix

ABSTRACTExperiments were conducted on specimens containing nylon or polypropylene monofilaments embedded in a precracked matrix. During pull-out tests, it was generally observed that the pulling force continued to increase after one or both sides of the filament had begun to slip out, even though one or both of the embedded filament lengths were decreasing. This indicated that the fiber/matrix shear stress increased with the fiber slippage distance. Examination of the extracted filaments under a scanning electron microscope (SEM) revealed the increased shear resistance to be the result of fiber surface abrasion. The severity of abrasion was observed to increase with the fiber slippage distance before complete pull-out. A theoretical model has been developed to predict the pull-out force versus displacement relationship based on given fiber/matrix shear strength as an increasing function of the slippage distance. The model gives good prediction in comparison with experimental results.