LUBRICATING TENDONS IN A TENDON-ACTUATED SURGICAL INSTRUMENT
A flexible surgical instrument employs sheaths around tendons that actuate an end effector or other mechanisms in the instrument. A liquid lubricant can be introduced in the sheaths to reduce friction. Disclosed combinations of tendon, sheath, and lubricant compositions reduce friction to suitable levels for operation of a minimally invasive instrument and are not harmful or toxic to a patient.
1 . A surgical system comprising:
a sheath;
a tendon extending through the sheath; and
a liquid lubricant between the tendon and the sheath.
2 . The system of claim 1 , wherein each of the tendons comprises a synthetic fiber.
3 . The system of claim 2 , wherein each of the tendons comprises braided strands of ultra high molecular weight polyethylene.
4 . The system of claim 2 , wherein the braided strands of ultra high molecular weight polyethylene are partially fused to provide a smooth outer surface.
5 . The system of claim 2 , wherein each of the tendons comprises a tubular braid of ultra high molecular weight polyethylene fibers surrounding an inner core of poly(p-phenylene-2,6-benzobisoxazole) fibers.
6 . The system of claim 1 , wherein the sheath is made of a material selected from the group consisting of stainless steel, nickel-titanium alloy, polyetheretherketone, polyether block amide, Nylon, and polyimide.
7 . The system of claim 1 , wherein the sheaths comprise a composite construction of helically wound stainless steel embedded in a synthetic matrix.
8 . The system of claim 1 , wherein the lubricant comprises an aqueous solution containing an additive selected from the group consisting of mineral oil, a fatty acid, and a surfactant.
9 . The system of claim 1 , wherein the liquid lubricant comprises polyethylene glycol.
10 . The system of claim 9 , wherein the liquid lubricant further comprises an additive selected from the group consisting of a fatty acid and a surfactant.
11 . The system of claim 1 , wherein the liquid lubricant comprises mineral oil.
12 . The system of claim 11 , wherein the liquid lubricant further comprises a surfactant.
13 . The system of claim 1 , wherein:
the sheaths are made of a metal; and
the tendons are made of a synthetic material.
14 . The system of claim 13 , wherein the metal is stainless steel.
15 . The system of claim 14 , wherein the synthetic material is selected from the group consisting of Ultra High Molecular Weight Polyethylene (UHMWPE), a Liquid Crystal Polymer (LCP), an aramid polymer, and poly(p-phenylene-2,6-benzobisoxazole) (PBO).
16 . The system of claim 15 , wherein the lubricant comprises an aqueous solution containing an additive selected from the group consisting of mineral oil, a fatty acid, and a surfactant.
17 . The system of claim 15 , wherein the liquid lubricant comprises polyethylene glycol.
18 . The system of claim 17 , wherein the liquid lubricant further comprises an additive selected from the group consisting of a fatty acid and a surfactant.
19 . The system of claim 15 , wherein the liquid lubricant comprises mineral oil.
20 . The system of claim 19 , wherein the liquid lubricant further comprises a surfactant.
21 . A method for lubricating a tendon in a surgical instrument, comprising:
applying a liquid lubricant to a tendon; and
connecting the tendon to a distal tip of the surgical instrument, wherein the tendon slides against a surface of a mechanical component of the distal tip during actuation of the distal tip, and the liquid lubricant reduces friction when the tendon slides on the surface.
22 . The method of claim 21 , wherein the liquid lubricant comprises an aqueous solution.
23 . The method of claim 22 , where in the aqueous solution comprises saline.
24 . The method of claim 22 , wherein the aqueous solution comprises an additive selected from a group consisting of a fatty acid, mineral oil, and a surfactant.
25 . The method of claim 21 , wherein the liquid lubricant comprises polyethylene glycol.
26 . The method of claim 25 , wherein the liquid lubricant further comprises an additive selected from a group consisting of a fatty acid and a surfactant.
27 . The method of claim 21 , wherein the liquid lubricant comprises mineral oil.
28 . The method of claim 27 , wherein the liquid lubricant further comprises a surfactant.
29 . The method of claim 21 , wherein the surface of the mechanical component comprises a material selected from the group consisting of stainless steel, a nickel-tin alloy, Polyamide-imide, mica-reinforced poly(tetrafluoroethylene), polybenzamidazole, polyparaphenyl copolymer, and polyetheretherketone.