# US 2014/0194895 A1 · Surgical instruments having improved wear resistance, and methods of making the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0194895 A1 - Document ID: US20140194895A1 - Status: Published application - Kind: A1 - Application number: 14/149,535 - Filed: 2014-01-07 - Published: 2014-07-10 - Earliest claimed: 2013-01-08 - Assignees: Intuitive Surgical Operations, Inc. - Applicants: Intuitive Surgical Operations, Inc. - Inventors: Samuel T. CREWS; Andrew CREWS; Edward P. DONLON; Craig GERBI; Kenneth L. GONG; Krish KRISHNANAND; Peling LEE; Theodore W. ROGERS; John Ryan STEGER; Charles E. SWINEHART - Web page: https://patentgrep.com/patent/US20140194895A1 ## CPC - A61B 34/30: Surgical robots - A61B 17/3421: {Cannulas} - A61B 2017/00845: {of moving parts with respect to each other} - A61B 2017/2926: {Details of heads or jaws} - Y10T 29/49826: Assembling or joining - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A surgical apparatus includes a cannula and a surgical instrument. The cannula includes a curved longitudinal axis along at least a portion of its length. The surgical instrument includes an elongated shaft having a distal end and a proximal end, and an end effector coupled to the distal end of the elongated shaft. At least a portion of the end effector is configured to contact an inner surface of the cannula during insertion of the surgical instrument into the curved cannula. A threshold galling stress between the portion of the end effector and an inner surface of the curved cannula is at least 10,000 pounds per square inch. ## Claims ### Claim 1 A surgical apparatus, comprising: a cannula including a curved longitudinal axis along at least a portion of its length; and a surgical instrument having an elongated shaft having a distal end and a proximal end, and an end effector coupled to the distal end of the elongated shaft, wherein at least a portion of the end effector is configured to contact an inner surface of the cannula during insertion of the surgical instrument into the curved cannula; wherein a threshold galling stress between the portion of the end effector and an inner surface of the curved cannula is at least 10,000 pounds per square inch. ### Claim 2 (depends on 1) The surgical apparatus of claim 1, wherein the portion of the end effector comprises an austenitic stainless steel. ### Claim 3 (depends on 1) The surgical apparatus of claim 1, wherein the curved cannula comprises a martensitic stainless steel. ### Claim 4 (depends on 3) The surgical apparatus of claim 3, wherein the martensitic stainless steel is an age-hardenable stainless steel having a composition comprising, in weight percent, about 0.02% max carbon, about 0.25% max silicon, about 10.75% to about 11.25% nickel, about 1.50% to about 1.80% titanium, about 0.25% max manganese, about 11.00% to about 12.50% chromium, about 0.75% to about 1.25% molybdenum, and balance iron. ### Claim 5 (depends on 1) The surgical apparatus of claim 1, wherein the threshold galling stress between the portion of the end effector and the inner surface of the curved cannula is at least 20,000 pounds per square inch. ### Claim 6 (depends on 1) The surgical apparatus of claim 1, wherein the threshold galling stress between the portion of the end effector and the inner surface of the curved cannula is at least 50,000 pounds per square inch. ### Claim 7 (depends on 1) The surgical apparatus of claim 1, wherein the cannula has a proximal end and a distal end, and a rigid curved section between the proximal end and the distal end. ### Claim 8 (depends on 1) The surgical apparatus of claim 1, wherein the end effector is configured to perform at least one surgical procedure chosen from tissue cutting, tissue grasping, tissue sealing, tissue connection, and tissue ablation. ### Claim 9 (depends on 1) The surgical apparatus of claim 1, wherein the surgical instrument is an instrument for a teleoperated surgical system. ### Claim 10 (depends on 1) The surgical apparatus of claim 1, wherein the surgical instrument further comprises a force transmission mechanism configured to be operably coupled to a patient side manipulator of a teleoperated surgical system. ### Claim 11 (depends on 1) The surgical apparatus of claim 1, wherein the curved cannula comprises a tube having the inner surface and an outer surface, wherein the inner surface has a wear resistance and/or galling resistance that is higher than the outer surface. ### Claim 12 (depends on 1) The surgical apparatus of claim 1, wherein the end effector comprises an austenitic stainless steel having a composition comprising, in weight percent, about 0.15% maximum carbon, about 4% to about 8.5% manganese, about 15% to about 21% chromium, about 4% to about 10% nickel, about 2.5% to about 4.5% silicon, about 0.05% to about 0.25% nitrogen, and balance iron. ### Claim 13 A surgical instrument, comprising: an end effector, at least a portion of the end effector being made of an austenitic stainless steel having a composition comprising, in weight percent: about 0.15% maximum carbon, about 4% to about 8.5% manganese, about 15% to about 21% chromium, about 4% to about 10% nickel, about 2.5% to about 4.5% silicon, about 0.05% to about 0.25% nitrogen, and balance iron. ### Claim 14 (depends on 13) The surgical instrument of claim 13, wherein the austenitic stainless steel comprises, in weight percent, about 0.06% to about 0.08% carbon, about 7.50% to about 8.50% manganese, about 16.00% to about 17.00% chromium, about 8.00% to about 8.50% nickel, about 3.7% to about 4.20% silicon, about 0.10% to about 0.18% nitrogen, and balance iron. ### Claim 15 (depends on 13) The surgical instrument of claim 13, wherein the surgical instrument is an instrument for a teleoperated surgical system. ### Claim 16 A method of making a surgical apparatus, comprising: forming a cannula tube including a curved longitudinal axis along at least a portion of its length; burnishing the inner surface of the cannula tube with a material having a hardness greater than the metal of the cannula tube; and providing a surgical instrument configured to be inserted within the curved cannula tube, wherein a threshold galling stress between a portion of the end effector and the inner surface of the curved cannula is at least 10,000 pounds per square inch; wherein, after the burnishing, the inner surface of the curved cannula tube exhibits a galling resistance that is greater than the outer surface of the curved cannula tube. ### Claim 17 (depends on 16) The method of claim 16, wherein the surgical instrument includes an end effector, the end effector comprising an austenitic stainless steel comprising, in weight percent, about 0.15% maximum carbon, about 4% to about 8.5% manganese, about 15% to about 21% chromium, about 4% to about 10% nickel, about 2.5% to about 4.5% silicon, about 0.05% to about 0.25% nitrogen, and balance iron. ### Claim 18 (depends on 16) The method of claim 16, wherein the metal of the curved cannula tube is a martensitic stainless steel. ### Claim 19 (depends on 16) The method of claim 16, wherein the cannula and the end effector are configured to contact one another when the surgical instrument is inserted within the cannula.