Stemless Shoulder Implant Placement Using Bone-Density Robotic Guidance
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Solution Overview
Problem
Existing robotic systems lack precision and accuracy in preparing bones for shoulder arthroplasty, particularly when using stemless implants, which require less bony material removal and enhanced stability.
Innovation Solution
A robotic surgery system with a robotic manipulator, cutting tool, and localizer that tracks bone movement, controlled by a controller to remove material based on a virtual object defined by bone density data, ensuring the eccentric distal projection of the implant is seated in a region of higher density for stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stemmed implant is used, then implant stability is improved, but bony material removal increases
Solution Approach 1:
The patent extracts the stem component from the traditional stemmed implant design, creating a stemless implant that eliminates the need for a humeral canal preparation. This allows the implant to be secured directly to the humeral head through cortical bone engagement, thereby reducing bony material removal while maintaining stability through alternative fixation mechanisms.
Solution Approach 2:
The stemless implant design engages specifically with the cortical bone of the humeral head rather than requiring preparation of the entire humeral canal. This localized engagement strategy preserves the medullary canal and surrounding bone structures, reducing overall bony material removal while concentrating stability mechanisms at the critical implant-bone interface.
2Loss of substance
If bony material removal is reduced for stemless implants, then bone sparing is improved, but implant stability deteriorates
Solution Approach 1:
The system performs preliminary planning and preparation by registering a coordinate system to the bone and using density data to identify optimal implant locations before actual implantation. This advance planning ensures that the implant is positioned in regions that maximize stability while minimizing bone removal, as the virtual object is defined based on pre-analyzed bone density characteristics.
Solution Approach 2:
The robotic system uses real-time tracking of bone movement and density data feedback to adjust and refine implant positioning. The system continuously monitors the relationship between the cutting tool and bone, and between the implant and prepared site, allowing for precise adjustments that ensure optimal stability while maintaining bone conservation goals.
3Manufacturing precision
If robotic precision is increased for stemless implant placement, then implant stability is improved, but system complexity increases
Solution Approach 1:
The patent introduces a virtual object as an intermediary between the physical implant and the robotic manipulator. This virtual representation, defined in a coordinate system based on bone density data, serves as a guide for the robotic system, simplifying the control complexity by providing a clear target position and orientation that the robot can accurately achieve without requiring complex real-time decision-making algorithms.
Solution Approach 2:
The system creates a virtual copy or representation of the implant and its ideal position within the patient's anatomy based on pre-operative planning and intra-operative density data. This virtual model allows the robotic system to operate with simplified guidance, following pre-determined trajectories and positions rather than requiring complex adaptive control, thereby reducing system complexity while maintaining high precision.
Data Source
AI summary
Robotic systems and methods for robotic arthroplasty. The robotic system includes a machining station and a guidance station. The guidance station tracks movement of various objects in the operating room, such as a surgical tool, a humerus of a patient, and a scapula of the patient. The guidance station tracks these objects for purposes of controlling movement of the surgical tool relative to virtual cutting boundaries or other virtual objects associated with the humerus and scapula to facilitate preparation of bone to receive a shoulder implant system. The virtual objects are located based on density data of the bone such that, when one or more shoulder implants are fully seated in the bone, distal portions of the implants are located in a first region of the bone having a density characteristic greater than an adjacent second region of the bone.