Shape Memory Orthopedic Implant Retainer Mechanism

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Solution Overview

Problem

Current orthopedic fixation systems using shape memory implants face challenges in simplifying the removal of shape memory implants after implantation and preloading before surgery, as well as preventing premature activation due to external heat sources.

Innovation Solution

An orthopedic fixation system with an implant that transitions between a natural shape and an insertion shape, utilizing an implant retainer to constrain the implant in the insertion shape, allowing for controlled energy delivery to bone fragments, and featuring a mechanism for progressive energy release to facilitate bone fusion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a shape memory implant is mechanically constrained during implantation, then the implant can be preloaded and sterilized prior to surgery, but the complexity of the device increases due to additional constraining instrumentation

Engineering Contradiction:

Improvepreload and sterilize implant before surgeryVSAvoidconstraining instrumentation

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent extracts the constraining function from complex external instrumentation and integrates it into a simple retainer device that is part of the implant assembly. The retainer mechanically constrains the implant during implantation and can be easily removed after deployment, eliminating the need for complex external constraining instruments while enabling preloading and sterilization.

Inventive Principle:

Principle #2Taking out (Extraction)

2Ease of operation

If the shape memory implant is activated by body temperature, then no external heating source is required, but premature activation may occur before implantation if the implant is exposed to heat sources

Engineering Contradiction:

Improvethermal activation without external heatingVSAvoidprevent premature activation

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The retainer serves as a preliminary protective measure that prevents premature activation of the shape memory implant before implantation. By mechanically constraining the implant in its loaded configuration, the retainer ensures that the implant will not activate prematurely due to exposure to heat sources during storage or handling, while still allowing thermal activation to occur after implantation when the retainer is removed.

Inventive Principle:

Principle #9Preliminary anti-action

3Reliability

If the shape memory implant delivers mechanical energy continuously, then bone fragments are maintained in desired orientation, but the implant cannot be easily removed after implantation

Engineering Contradiction:

Improvemaintain bone fixationVSAvoidremove implant after implantation

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The system transitions from a static constraint to a dynamic one. The retainer provides mechanical constraint during implantation and initial healing, but can be easily removed after the bone has healed. The shape memory implant itself transitions from a constrained state to an active energy-delivering state, and finally to a passive maintained state after retainer removal, allowing easy removal while maintaining reliable fixation during the critical healing period.

Inventive Principle:

Principle #15Dynamics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system effectively simplifies the removal of shape memory implants, prevents premature activation, and ensures consistent energy delivery to promote bone fusion, enhancing surgical efficiency and healing outcomes.

Implementation Method 1

shape memory implants typically are composed of a shape memory material such as Nitinol that allows a shape memory implant to have a first final shape and the ability to transition into a second shape

Methodology Applied

Scientific EffectShape memory: Shape Memory Alloy

Implementation Method 2

A shape memory implant that requires mechanical constraint stores mechanical energy due to elastic (recoverable) deformation, and then releases the stored mechanical energy when the constraining instrument is removed

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 3

the shape memory implant, which has been mechanically deformed to the second shape, is maintained in instrumentation

Methodology Applied

Scientific EffectMechanical constraint: Mechanical Force

Data Source

PatentUS20230225774A1Orthopedic fixation systems and methods of use thereof

Publication Date: 2023.07.20 DEPUY SYNTHES PROD INC

AI summary

An orthopedic fixation system includes an implant transitionable between a natural shape and an insertion shape and an implant retainer. The implant includes a transition section deformable to move the implant between the natural shape and the insertion shape. The implant includes a first post and a second post protruding therefrom across the transition section. The first post and second post each include an opening therethrough, whereby, when the implant resides in the insertion shape, the opening of the first post and the opening of the second post align. The implant retainer being configured to insert in the openings of the first and second posts when the implant resides in the insertion shape such that the implant retainer interconnects the first post and second post while spanning the transition section, thereby constraining the implant in the insertion shape.