Biomechanical study on different high-strength sutures and suture site for repairing posterior root tear of the medial meniscus

Abstract

To compare biomechanical characteristic of different high-strength sutures and suture sites for repairing posterior root tear of the medial meniscus with modified Mason-Allen technique. Forty-eight specimen of medial meniscus of knee joint from fresh porcine (female, aged from 5 to 9 months with an average of 7 months) were chosen and established experimental model. The samples were divided into red zone fixation group and red-white zone fixation group according to suture sites, 24 in each group; and then were randomly divided into 3 subgroups which 8 in each group, and fixed with Ethibond suture, Ultrabraid suture and FiberWire suture, respectively. Biomechanical tests were performedon universal electromagnetic and mechanical testing machine. Each specimen was underwent 1 000 cyclic tests on the first time, then pull out test until failure. The maximum failure load, yield load, stiffness and displacement were analyzed. All specimen were successfully completed biomechanical tests. The failure mode of Ethibond group was caused by suture fracture; 6 cases of Ultrabraid suture group was caused by suture fracture which belong to red zone fixation group, 10 cases were caused by suture pull out, which 2 cases belong to red zone fixation group, 8 cases belong to red-white zone fixation group;8 cases of FiberWire group was caused by suture pull-out. Biomechanical test showed that:(1)In terms of suture strength, comparison of the maximum failure load, yield load and stiffness showed that Ethibond suture group <Ultrabraid suture group <FiberWire suture group, and had statistical differences among groups (P<0.05);comparison of cyclic displacement at 100, 500 and 1 000 cycles showed that Ethibond suturegroup>Ultrabraid suture group >FiberWire suture group, and had statistical differences among groups (P<0.05);the results showed the suture strength in Ethibond was the best, Ultrabraid suture took the second place, and FiberWire suture was the worst. (2)As for different suture sites, comparison of the maximum failure load, yield load and stiffness showed that red zone fixation group >red-white region fixation group, and had statistical difference between two groups(P< 0.05);comparison of cyclic displacement at 100, 500 and 1 000 cycles showed that red zone fixation group <red-white zone fixation group, and had statistical difference between two groups (P<0.05);the results showed that suture strength in red zone fixation group was better than that of red white zone fixation group. Mason-Allen suture could effectively fix posterior root tear of the medial meniscus and meet needs of early partial weight bearing after surgery. Suturing with Fiberwire in red zone is stronger and better for the meniscus healing and rehabilitation.