Biomechanical testing of a modified knotless transscleral suture fixation technique: an ex vivo study

BACKGROUND: To investigate the safety and effectiveness of a modified transscleral suture through ex vivo tests. METHODS: Ex vivo tests were performed in full-thickness porcine scleral pieces using modified knotless transscleral zigzag-shaped suture (Z-suture) fixation technology. The minimum traction force required to loosen or rupture the suture was assessed. The effects of different polypropylene sutures (10-0, 8-0), different suture spans (2.0, 3.0, 4.0 mm), different passes (3, 4, 5 passes), and scleral grooves were investigated. RESULTS: The average minimum traction forces required to loosen 10-0 polypropylene sutured for 3.0 mm with a suture span of 3, 4, and 5 passes, were 0.18 (0.15–0.18), 0.22 (0.21–0.22), and 0.37 (0.37–0.37) N, respectively. The maximum traction force to prevent the suture from rupturing for the 10-0 polypropylene suture was 0.37–0.41 N in the sclera. The average of the minimum traction forces required to loosen the 8-0 polypropylene sutured with 5 passes and spanning 2.0, 3.0, and 4.0 mm were 0.37 (0.3 –0.39), 0.42 (0.42–0.45), and 0.50 (0.50–0.51) N, respectively, which were 14–28% higher than that of the 10-0 polypropylene suture under same conditions (all P values <0.01). In addition, there was no statistical difference (P=0.3258) for the 8-0 polypropylene suture used with a 3.0-mm suture span and 5 passes between conditions with or without scleral grooves. CONCLUSIONS: The minimum traction force required to loosen or rupture the suture in the sclera was associated with suture specification, suture span, and the number of passes, but was uncorrelated with double scleral grooves. The 8-0 polypropylene suture with double scleral grooves may be a more favorable choice for knotless transscleral fixation.