Implantable Bone Adjustment Device Dynamic Segment
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Solution Overview
Problem
Current implantable reconfigurable bone adjustment devices, such as limb lengthening nails, face limitations in weight-bearing capability and can experience excessive stress shielding due to increased stiffness, which hinders bone regeneration and consolidation.
Innovation Solution
Incorporation of a dynamic segment, such as a metallic spring or compressible member, between the first and second members of the device to enable compression and axial movement, stimulating bone growth while preventing stress shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the LLN nail is designed to withstand greater weight bearing, then the strength and stiffness of the nail are improved, but the stiffness may increase beyond an optimal point causing excessive stress shielding that prevents bone regeneration
Solution Approach 1:
The patent applies the dynamics principle by incorporating a dynamic segment with a compressible member that allows controlled movement between the proximal and distal body portions. This dynamic mechanism enables the nail to adapt its stiffness characteristics - providing sufficient strength for weight bearing while allowing micro-movements that prevent excessive stress shielding and promote bone regeneration through controlled mechanical stimulation.
2Strength
If the LLN nail is made more rigid to increase strength, then the weight bearing capability is improved, but bone regeneration and consolidation are hindered due to excessive stress shielding
Solution Approach 1:
The dynamic segment with compressible member enables the nail to maintain structural strength while introducing controlled flexibility. This allows the system to simultaneously achieve high weight bearing capability and promote bone regeneration by permitting beneficial micro-movements that stimulate osteogenesis without compromising mechanical support.
Solution Approach 2:
The patent employs parameter changes by utilizing a compressible member that can dynamically adjust the mechanical properties of the nail. The compressible member allows the system to transition between stiffer and more compliant states, optimizing both strength for weight bearing and flexibility for bone regeneration at different phases of the healing process.
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 dynamic segment enhances the device's strength for weight-bearing while promoting bone regeneration by allowing axial compression, reducing the risk of non-union and accelerating consolidation.
Implementation Method 1
Incorporation of a dynamic segment, such as a metallic spring or compressible member, between the first and second members of the device to enable compression and axial movement
Data Source
AI summary
A reconfigurable bone adjustment device includes a first member configured for attachment to a first bone fragment, portion, etc., a second member configured for attachment to a second bone fragment, portion, etc., a drive mechanism configured to move the second member relative to the first member, a threaded rod having a proximal end operatively coupled to the drive mechanism and a distal end operatively coupled to the second member so that rotation of the drive mechanism rotates the threaded rod and moves the second member relative to the first member, and a dynamic segment positioned between the first and second members to enable compression of the second member relative to the first member to stimulate bone growth. The dynamic segment may be a silicone/rubber compressible member or assembly, a metallic spring, a non-metallic shock absorbing material or washer, or the like.