Biodegradable Magnesium Bone Anchor with Polymer Sleeve

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Solution Overview

Problem

Existing fixation devices for soft tissue to bone and bone fixation often damage small or thin bones during insertion, making it difficult or impossible to implant a revision device, and require a second procedure for removal.

Innovation Solution

A bone anchor with a biodegradable metal or metal alloy core and a thermoplastic polymer sleeve that can be inserted without pre-drilling, using a pointed tip to penetrate the bone and then expanding into the bone tissue with electromagnetic radiation to secure itself, eliminating the need for a second procedure and reducing migration risk.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a fixation device is inserted by drilling and tapping into bone, then secure fixation is achieved, but bone damage or splitting occurs that may prevent revision implant insertion

Engineering Contradiction:

Improvefixation securityVSAvoidbone damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the traditional mechanical drilling and tapping system with a biodegradable magnesium core that is inserted without pre-drilling. The core gradually degrades through biocorrosion in the body, eliminating the need for aggressive bone preparation that causes damage and splitting.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the material parameter from permanent metal to biodegradable magnesium alloy, which has controlled degradation properties. This allows the implant to maintain structural integrity during healing then gradually resorb, avoiding the bone damage associated with traditional permanent implants requiring drilling and tapping.

Inventive Principle:

Principle #35Parameter changes

2Duration of action of stationary object

If a permanent fixation device is used, then long-term fixation is maintained, but a second procedure is required for removal

Engineering Contradiction:

Improvefixation durationVSAvoidsecond procedure time

Core Design Contradiction:

Duration of action of stationary objectVSLoss of time

Solution Approach 1:

The biodegradable magnesium core is designed to be temporarily implanted and then naturally discarded by the body through biocorrosion. The core resorbs over time, converting to harmless degradation products that are eliminated by the body's natural processes, eliminating the need for a second surgical procedure to remove the implant.

Inventive Principle:

Principle #34Discarding and recovering

Solution Approach 2:

The invention uses a disposable biodegradable magnesium core that serves its fixation purpose temporarily then degrades naturally. This single-use approach eliminates the need for removal procedures, reducing overall treatment time and surgical interventions.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Ease of operation

If a biodegradable core is used, then no second removal procedure is needed, but the material must withstand mechanical loads during degradation

Engineering Contradiction:

Improveimplant removalVSAvoidmechanical strength during degradation

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The invention employs composite construction with a biodegradable magnesium core providing initial mechanical strength and a thermoplastic polymer sleeve providing additional structural support. The composite structure allows the core to degrade while maintaining sufficient mechanical integrity throughout the healing process.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The magnesium core's mechanical properties dynamically change over time as it degrades. The core maintains high strength initially to support mechanical loads, then gradually reduces in strength as it biocorrodes, transitioning the load-bearing function to the surrounding bone and soft tissue.

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 bone anchor fully resorbs, leaving no trace and reduces the risk of implant migration, allowing for effective fixation without damaging the bone and eliminating the need for a second surgical procedure.

Implementation Method 1

heating the sleeve by applying electromagnetic radiation through the sleeve

Methodology Applied

Scientific EffectElectromagnetic radiation heating: Dielectric Heating

Implementation Method 2

the core comprise one of a biodegradable metal, metal alloy and glass-metal... the implant to fully resorb leaving no trace in the body

Methodology Applied

Scientific EffectBiocorrosion: Crevice Corrosion

Data Source

PatentUS9357996B2Fixation device with magnesium core

Publication Date: 2016.06.07 DEPUY SYNTHES PROD INC

AI summary

A fixation device comprises a biodegradable inner core extending along a longitudinal axis from a distal tip to a proximal end in combination with a sleeve surrounding the core along a portion of a length thereof and comprising a thermoplastic polymer formed of a material which softens and expands into surrounding bone tissue when activated by an energy source.