Stemless Shoulder Implant Locking for Bone-Preserving Arthroplasty

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Solution Overview

Problem

Current robotic systems for surgery lack precision and accuracy in preparing the shoulder joint for arthroplasty, particularly for stemless implants, which require secure placement without a humeral stem, posing challenges in stability and bone preservation.

Innovation Solution

A robotic surgery system comprising a robotic manipulator, cutting tool, localizer, and controller that tracks movement to form precise cavities for shoulder implants, including a locking member that secures the implant by rotating into an undercut in the bone, ensuring stable placement and minimal bone removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a stemmed implant is used to enhance stability, then implant stability is improved, but bone removal is increased

Engineering Contradiction:
Improveimplant stabilityVSAvoidbone removal
Core Design Contradiction:
Stability of the object's compositionVSLoss of substance

Solution Approach 1:

The implant is divided into separate components: a humeral head portion and a locking member that can be inserted independently into the humeral canal. This segmentation allows the locking member to provide stability without requiring a traditional stem, thereby reducing bone removal while maintaining implant stability through the locking mechanism that engages with the humeral canal.

Inventive Principle:
Principle #1Segmentation

2Loss of substance

If a stemless implant is used to preserve bone, then bone preservation is improved, but implant stability is worsened

Engineering Contradiction:
Improvebone preservationVSAvoidimplant stability
Core Design Contradiction:
Loss of substanceVSStability of the object's composition

Solution Approach 1:

The locking member acts as an intermediary element between the humeral head and the humeral canal. It provides the necessary mechanical interlocking and stability without requiring a traditional stem, enabling bone preservation while maintaining implant stability through its engagement with the humeral canal and locking mechanism.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If traditional robotic systems are used for hip and knee procedures, then those procedures are improved, but shoulder arthroplasty precision is insufficient

Engineering Contradiction:
Improveprocedure efficiencyVSAvoidshoulder arthroplasty precision
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The robotic system is configured with specific end effectors and cutting tools designed for shoulder anatomy, allowing precise cavity formation in the humeral head and accurate positioning of the locking member. This localized adaptation of the robotic system provides the precision needed for shoulder arthroplasty while maintaining overall system productivity.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3479792B1Robotic system for shoulder arthroplasty using stemless implant components
Publication Date: 2022.09.28 HOWMEDICA OSTEONICS CORP
  • EP3479792B1 patent drawingFigure 1
  • EP3479792B1 patent drawingFigure 2~3
  • EP3479792B1 patent drawingFigure 4~5

AI summary

A 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 displaying their relative positions and orientations to the surgeon and, in some cases, 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.