The Biomechanical Study Of The Stable Suture For The Achilles Tendon Rupture

Background:Surgeons has paid more attention to early rehabilitation in recent years.The knot security is crucial to the biomechanical stability of early rehabilitation,especially in the stable suture,such as tendon-tendon suture and tendon-bone suture.Objective:To explore the knot security of PRBT(Panda Rope Bridge Technique),and whether PRBT composed of the optimal knots can pass the cyclic loading test which simulate the early rehabilitation of Achilles tendon rupture.Methods:Experiment 1: seeking the optimal knots of No.5 Ethibond suture and No.2 Ultrabraid suture,according to the throws of knot,each kind of sutures was divided into four groups,including 2A+B,3A+B,4A+B and 5A+B.The combination of 2 A throw represented a square knot,and the combination of A throw and B throw represented a surgeon's knot.Each group had six samples.Each knot was loaded at 0.5 Hz for 4 different cyclic loading levels: 20-100 N,20-200 N,20-300 N,20-400 N,and 250 cycles were performed at each level.Experiment 2: the optimal knots of two kind of sutures was used in simulated PRBT biomechanical test with fresh frozen bull Achilles tendon.According to the different number of Krackow stitch,experiment 2 was divided into two parts,and with the same measurement as Experiment 1.Results:In Ethibond suture groups of experiment 1,there was no significant difference of peak load between group(3A+B),group(4A+B)and group(5A+B)(P > 0.05),there was no significant difference of peak load between group(3A+B)and group(2A+B)(P > 0.05),but group(4A+B)and group(5A+B)was greater than group(2A+B)(P =0.005,P = 0.007).There was no significant difference in number of cycles to failure among the four groups in Ethibond suture groups(P > 0.05).The group(2A+B)in Ethibond suture had one knot slipped.In Ultrabraid suture groups of experiment 1,the peak load to failure of group(5A+B)was greater than other groups(P<0.001),the number of cycles to failure of group(5A+B)was greater than other groups(P=0.001,P=0.001,P=0.005).In addition to group(5A+B),all failure modes of other groups in Ultrabraid suture were knot slipped.In part 1,four samples in Ethibond suture and one sample in Ultrabraid suture had suture breakage before 1000 cycles finished.In part 2,one sample in Ethibond suture had suture breakage before 1000 cycles finished,and there was no failure happened in Ultrabraid suture.Conclusion:The combination of 3 throws and 1 double throw half knot is the optimal knot of No.5 Ethibond suture,and the combination of 5 throws and 1 double throw half knot is the optimal knot of No.2 Ultrabraid suture.The PRBT with No.2 Ultrabraid suture may be suitable for early rehabilitation after Achilles tendon repaire,but PRBT with No.5 Ethibond suture may not be suitable for early functional exercise or need to be rehabilitated under limited protection.