# US 2023/0056596 A1 · System and method for implant surface matching for joint revision surgery > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2023/0056596 A1 - Document ID: US20230056596A1 - Status: Published application - Kind: A1 - Application number: 17/883,024 - Filed: 2022-08-08 - Published: 2023-02-23 - Earliest claimed: 2021-08-12 - Assignees: Smith & Nephew, Inc.; Smith & Nephew Orthopaedics AG; Smith & Nephew Asia Pacific Pte. Limited - Applicants: Smith & Nephew, Inc.; Smith & Nephew Orthopaedics AG; Smith & Nephew Asia Pacific Pte. Limited - Inventors: Daniel Farley; Nathaniel M. Lenz - Web page: https://patentgrep.com/patent/US20230056596A1 ## CPC - A61B 34/20: Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis - A61B 34/10: Computer-aided planning, simulation or modelling of surgical operations - A61B 34/25: {User interfaces for surgical systems} - A61B 90/361: {Image-producing devices, e.g. surgical cameras} - G16H 20/40: relating to mechanical, radiation or invasive therapies, e.g. surgery, laser therapy, dialysis or acupuncture - G16H 50/50: for simulation or modelling of medical disorders - A61B 34/30: Surgical robots - A61B 2034/102: {Modelling of surgical devices, implants or prosthesis} - A61B 2034/105: {Modelling of the patient, e.g. for ligaments or bones} - A61B 2034/108: {Computer aided selection or customisation of medical implants or cutting guides} - A61B 2034/2051: {Electromagnetic tracking systems} - A61B 2034/2055: {Optical tracking systems} - A61B 2034/2057: {Details of tracking cameras} - A61B 2034/2063: {Acoustic tracking systems, e.g. using ultrasound} - A61B 2034/2065: {Tracking using image or pattern recognition} - A61B 2034/252: {indicating steps of a surgical procedure} - A61B 2090/365: {augmented reality, i.e. correlating a live optical image with another image} - A61B 2090/372: {Details of monitor hardware} - A61B 2090/502: {Headgear, e.g. helmet, spectacles} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - G16H: HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA ## Abstract Disclosed herein is a system and a method for registering a surgical site to a surgical navigation system when the surgical site contains an implant for revision joint replacement surgery. The method creates a depth map of the surgical site and provides a possible identification of the existing implant using surface matching algorithms. The model of the implant is iteratively oriented with respect to the to the depth map until an optimal fit is achieved. Once the implant has been identified and localized, the registered landmarks are used in robotic-assisted surgery. ## Claims ### Claim 1 A method for registering a surgical site containing an implant comprising: positioning arrays of reflective markers on the patient; creating a depth map of the surgical site; localizing surfaces of the implant; providing a possible identification of the implant; calculating an error between the depth map and the identification of the implant; and iteratively reorienting the identification of the implant with respect to the depth map to minimize the error. ### Claim 2 (depends on 1) The method of claim 1 wherein creating a depth map of the surgical site comprises: imaging the surgical suite using a camera in a structured light modality. ### Claim 3 (depends on 1) The method of claim 1 wherein creating a depth map of the surgical site comprises: using a depth sensor selected from a group comprising a time of flight sensors, a LIDAR, a laser scanner and an epipolar scanner. ### Claim 4 (depends on 1) The method of claim 1 wherein the identification of the implant is an implant model selected from a library of implant models using a surface matching technique. ### Claim 5 (depends on 4) The method of claim 4 wherein, during creation of the depth map, a confidence metric is provided that characterizes a likelihood of a match between the depth map and an implant model in the library. ### Claim 6 (depends on 1) The method of claim 1 further comprising: orienting the implant relative to the depth map using an iterative-closest-point (ICP) algorithm. ### Claim 7 (depends on 1) The method of claim 1 wherein the error between the orientation of the implant and the depth map is calculated using a Hausdorff distance. ### Claim 8 (depends on 1) The method of claim 1 wherein the error between the orientation of the implant and the depth map is calculated using a dice coefficient. ### Claim 9 (depends on 1) The method of claim 1 further comprising: identifying critical regions of the implant; wherein the critical regions are given greater importance when calculating the error between the depth map and the identification of the implant. ### Claim 10 (depends on 1) The method of claim 1 wherein the identification of the implant is considered a positive match to the actual implant if the minimized error falls below a predetermined threshold. ### Claim 11 (depends on 1) The method of claim 1 wherein the identification of the implant is considered a negative match to the actual implant if the minimize error is above the predetermined threshold. ### Claim 12 (depends on 1) The method of claim 1 further comprising: providing a new identification of the implant if the minimized error falls above the predetermined threshold. ### Claim 13 (depends on 4) The method of claim 4 wherein the library contains various models and sizes of implants from various manufacturers. ### Claim 14 (depends on 1) The method of claim 1 wherein the implant is identified using a visual marker disposed on the implant. ### Claim 15 (depends on 2) The method of claim 2 wherein the camera is a stereoscopic camera. ### Claim 16 (depends on 2) The method of claim 2 wherein the surfaces of the implant are localized using a machine learning model. ### Claim 17 (depends on 2) The method of claim 2, wherein the surfaces of the implant are localized using a navigated probe. ### Claim 18 A system for registering a surgical site containing an implant comprises: a surgical computer; a library of surgical implants; and software, executing on the surgical computer and causing the surgical computer to perform the functions of: registering arrays of reflective markers on the patient; creating a depth map of the surgical site; localizing surfaces of the implant; providing a possible identification of the implant; calculating an error between the depth map and the identification of the implant; and iteratively reorienting the identification of the implant model with respect to the depth map to minimize the error. ### Claim 19 (depends on 18) The system of claim 18 further comprising: a stereoscopic camera in a structured light modality; wherein the surgical computer performs the further function of: imaging the surgical suite using the stereoscopic camera to create the depth map. ### Claim 20 (depends on 18) The system of claim 18 wherein the surgical computer performs the further function of: providing a new identification of the implant if the minimized error falls above the predetermined threshold.