Patient-Specific Haptic Boundaries for Precise Knee Bone Resection

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Solution Overview

Problem

Current computer-assisted surgery systems face challenges in customizing haptic boundaries for knee replacement procedures, as they often require surgeons to select undersized prosthetic implants, leading to potential damage to healthy tissue or incomplete resection of diseased tissue, due to the limitations of standard haptic boundaries based on implant geometry rather than patient-specific anatomy.

Innovation Solution

The method involves customizing virtual haptic boundaries by determining the intersection between a reference feature of the virtual implant model and the patient's anatomy, allowing for precise adjustment of the boundary to accommodate the size and shape of the cutting tool and preserve healthy tissue, thereby minimizing the risk of under- or over-resection during knee replacement surgery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a fixed haptic boundary based on implant geometry is used, then the system is simple and easy to operate, but it cannot accommodate patient-specific anatomy variations and may lead to damage to healthy tissue or incomplete resection of diseased tissue

Engineering Contradiction:
Improveadaptability to patient-specific anatomyVSAvoidcomplexity of haptic boundary customization
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system performs preliminary action by pre-calculating and storing multiple haptic boundary definitions corresponding to different implant sizes and configurations before surgery. During surgery, the appropriate pre-defined boundary is selected and applied based on the specific implant choice, eliminating the need for complex real-time boundary generation while achieving patient-specific customization.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The haptic boundary is made dynamic by allowing it to change based on implant selection. The system automatically adjusts the haptic boundary parameters (size, shape, position) to match the selected implant characteristics, enabling the boundary to adapt dynamically during the surgical planning and execution phases without requiring complex manual reconfiguration.

Inventive Principle:
Principle #15Dynamics

2Manufacturing precision

If an undersized prosthetic implant is selected, then the implant fits within the standard haptic boundary, but healthy tissue may be damaged or diseased tissue may not be completely resected

Engineering Contradiction:
Improveprecision of bone resectionVSAvoiddamage to healthy tissue
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The system implements feedback by continuously monitoring the relationship between the selected implant size and the defined haptic boundary. The boundary is automatically adjusted to provide appropriate clearance around the implant while maintaining precise alignment with anatomical landmarks, ensuring that resection boundaries are optimally positioned to remove diseased tissue while preserving healthy tissue based on real-time implant selection feedback.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system applies parameter changes by modifying the haptic boundary parameters (dimensions, position, orientation) based on the selected implant characteristics and patient-specific anatomical measurements. This allows the boundary to be precisely tuned for each case, ensuring optimal resection margins that accommodate the specific implant size while protecting healthy tissue.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3089694B1Systems and methods for generating customized haptic boundaries
Publication Date: 2022.04.13 MAKO SURGICAL CORP
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AI summary

A method for generating a customized haptic boundary based on a patient-specific anatomy includes identifying a standard haptic boundary based on a geometry of a virtual implant model to be implanted on the anatomy. The method also includes identifying a reference feature associated with a virtual implant model and determining an intersection between the identified reference feature and a virtual model associated with an anatomy of the patient. An anatomic perimeter at the intersection between the identified reference feature and the virtual model of the anatomy is identified and an one anatomic feature is determined on the virtual model of the anatomy. The standard haptic boundary is modified based on the anatomic feature to generate a customized haptic boundary.