The effect of knot location, suture material, and suture size on the gliding resistance of flexor tendons.

The effect of knot location, suture material, and suture size on gliding resistance between the pulley and flexor tendon was investigated in a canine model. Different suture materials [monofilament nylon (Ethilon), braided polyester suture coated with silicone (Ticron) and uncoated braided polyester suture (Mersilene)] and suture sizes (4-0, 5-0) were tested. A knot was made on either the volar surface, on one lateral side, or on both lateral sides of canine hind-paw tendons, and gliding resistance was measured. In addition, the frictional coefficient between three suture materials (4-0 nylon, 4-0 Ticron, 4-0 Mersilene) and a nylon rod were measured. The gliding resistance of the tendon with knots on both sides was highest, while tendons with one lateral knot had the lowest resistance (p < 0.01). The gliding resistance of 4-0 suture size was higher than that of 5-0 size (p < 0.0001). The coefficient of friction of nylon was lower than that of braided polyester suture (Ticron or Mersilene) (p < 0.001). The placement of knots and choice of suture material affect gliding resistance after tendon repair, and may, therefore, have an effect on the result of tendon repair.