Background: The initial strength of the repair depends on the material properties and knot security of the sutures as well as on the holding capacity of the suture grip of the tendon.
Objective: Detecting the effect of cyclic loading on the strength of flexor tendon repair using 6 strand Tang suture experimentally.
Materials and Methods: In the present ex vivo study of 50 sheep flexor tendons, six strand Tang suture technique was used: Twenty five repairs were subjected to cyclic tensile testing, and twenty five repairs were subjected to static tensile testing using 4/0 polypropylene simple suture material + epitendinous continuous running sutures using 5/0 polypropylene suture material.
Results: The results of the study showed that 44 % survival at 41.7 N cyclic testing, without evidence of significant gap formation or rupture and the breaking force on continuous loading mean 55.95 N. The Tang suture method provided much more sufficient gap resistance and tensile strength able to withstand early active mobilization after primary flexor tendon repair.
Conclusion: The Tang suture method provided sufficient gap resistance and tensile strength able to withstand early active mobilization after primary flexor tendon repair. There were some disadvantages regarding to time consuming during surgery and  difficult to use in pediatrics and small tendons.