Porous Implant Fixation With Interlocking Elements
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Solution Overview
Problem
Designing bone implants that balance low stiffness for bone ingrowth with high strength to withstand accidental impacts is challenging, as reducing stiffness to promote bone ingrowth can lead to stress shielding and increased risk of implant failure under load.
Innovation Solution
The development of porous implant fixation systems with integrated interlocking elements that allow for low stiffness under normal loads and high strength under accidental loads, featuring units that combine flexible behavior with internal deformation-restricting elements, and a structure that promotes bone ingrowth while maintaining mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the density of the porous structure is lowered to reduce stiffness and promote bone ingrowth, then bone ingrowth is improved, but the strength of the implant is reduced
Solution Approach 1:
The implant is divided into multiple porous units connected by connection elements, allowing each unit to be optimized for bone ingrowth while the collective structure provides strength through the interconnections
Solution Approach 2:
The implant combines porous structure for bone ingrowth with denser connection elements for strength, creating a composite structure that achieves both low stiffness and high strength
2Strength
If the density of the porous structure is increased to increase strength and survive accidental loads, then implant strength is improved, but stress shielding occurs
Solution Approach 1:
Different regions of the implant have different densities - the porous units have low density for flexibility and bone ingrowth, while the connection elements have higher density for strength, creating local quality variations that resolve the contradiction
3Adaptability or versatility
If the stiffness of the implant is lowered to promote bone ingrowth, then bone ingrowth is improved, but the implant becomes vulnerable to accidental impacts
Solution Approach 1:
The implant structure transitions from a static uniform design to a dynamic system where porous units provide flexibility under normal conditions but connection elements engage to provide strength under accidental loads, allowing the structure to adapt its mechanical properties
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 solution effectively reduces stress shielding, promotes bone ingrowth, and enhances the implant's ability to withstand accidental loads, ensuring both flexibility and strength, thereby improving the fixation and longevity of the implant.
Implementation Method 1
to allow bone ingrowth for better fixation
Implementation Method 2
Stress shielding is the phenomenon in which the implant takes on most of the loading such that less of the loading is carried by the bone
Data Source
AI summary
The present disclosure relates to flexible porous implant fixation systems. Certain aspects provide flexible porous structures including a helicoidal structure and a plurality of interlocking elements coupled to the helicoidal structure, the helicoidal structure being configured to connect the plurality of interlocking elements. Certain aspects provide a body comprising a porous structure, the body configured to interface with a bone perpendicular to an axis of the bone; and a screw comprising a head, wherein the head is configured to lie within a volume of the body while a portion of the screw extends away from the body, wherein the body is configured to restrict movement of the head within the body along the axis of the bone.