Parabolic Haptic Volume for Single-Stage Acetabular Reaming

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Solution Overview

Problem

Current haptic robotic systems for surgical bone reaming in total hip arthroplasty surgeries are limited by straight-line haptic paths, which restrict single-stage reaming and increase the complexity and time required for procedures, especially when dealing with multiple surgical tools and precise angular orientations, leading to potential misalignment and complications.

Innovation Solution

A haptic robotic surgical system that generates a parabolic haptic volume, allowing movement within the volume and providing feedback to constrain the cutting tool, enabling single-stage reaming and accommodating various tool sizes and orientations through Equations (1) and (2) for optimal acetabular cup positioning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a straight-line haptic path is used to constrain the cutting tool, then manufacturing precision of the reamed indentation is improved, but the ease of operation is worsened due to inability to accommodate single-stage reaming and multiple tool configurations

Engineering Contradiction:
Improveprecision of reamed indentationVSAvoidflexibility in reaming procedure
Core Design Contradiction:
Manufacturing precisionVSEase of operation

Solution Approach 1:

The patent transitions from a one-dimensional straight-line haptic path constraint to a three-dimensional haptic volume constraint. The haptic volume is defined by a paraboloid surface with the intended indentation center as vertex and the planned cup radius as parameter, allowing the cutting tool to move freely within this volumetric boundary while maintaining precision at the target location.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent changes the constraint parameter from a fixed straight-line path to a volumetric region defined by paraboloid geometry. The haptic volume parameters (vertex position, radius) are dynamically adjusted based on the intended indentation location and the specific cutting tool being used, allowing adaptation to different tool sizes and reaming strategies including single-stage reaming.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If multiple surgical tools with different configurations are used, then adaptability of the surgical procedure is improved, but the device complexity is worsened due to need for removing and attaching different tools

Engineering Contradiction:
Improveaccommodation of multiple tool typesVSAvoidcomplexity of haptic control system
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The haptic volume constraint system serves as a universal control mechanism that works with multiple types of cutting tools (different sizes, configurations, and functions). The same volumetric boundary defined by the paraboloid geometry accommodates various reamers and surgical instruments, eliminating the need for tool-specific haptic paths and simplifying the overall control architecture.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Measurement precision

If a straight-line haptic path is enforced, then measurement precision of tool position is improved, but the productivity is worsened due to increased operating time from multi-stage procedures

Engineering Contradiction:
Improveaccuracy of tool position trackingVSAvoidsurgical procedure efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The haptic constraint transitions from a static straight-line path to a dynamic volumetric region. The paraboloid-shaped haptic volume allows the cutting tool to dynamically adjust its position within the volume boundaries during single-stage reaming, enabling faster completion of the procedure while maintaining precision through real-time haptic feedback within the defined geometric constraints.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP4302722B1Haptic volumes for reaming during arthroplasty
Publication Date: 2024.09.25 MAKO SURGICAL CORP
  • EP4302722B1 patent drawingFigure 1~3
  • EP4302722B1 patent drawingFigure 4~5
  • EP4302722B1 patent drawingFigure 6~7

AI summary

A haptic robotic system for reaming an acetabulum prior to inserting an acetabular cup is more accurate than conventional instruments and may reduce the risk of dislocation and improve durability of a hip implant. Disclosed is a three-dimensional tool path, referred to as a haptic volume. Once the haptic volume is implemented into the software of a haptically constrained surgical robotic system, the cutting tool or reamer can only be utilized within the haptic volume. The haptic volume guides the surgeon in preparing the final reamed bone surface with a greatly reduced chance of the reaming unintended bone and greatly increases the chance that the reaming procedure may be carried out using one reaming tool, or using a single-stage reaming process.