Deformable Tip Bone Implant Resists Cut-Out
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Solution Overview
Problem
Existing bone implants, such as screws and fixation devices, face issues like 'cut-out' and migration due to stress shielding and aseptic loosening, particularly in osteoporotic bone, leading to instability and potential failure, as they fail to securely anchor within weak bone tissue.
Innovation Solution
The development of bone implants with dynamically expanding structures, such as elastomeric polymer materials or mechanisms, that deform to increase contact area with bone tissue, resist penetration, and translate forces into lateral friction, preventing unwanted migration and stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rigid mechanisms are used to firmly anchor implants to bone tissue, then penetration resistance is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by utilizing the elastic properties of polymer materials to create a deformable tip that changes its mechanical behavior under load. The tip transitions from a compliant state during insertion to an expanded state under compressive force, increasing contact area and penetration resistance without requiring complex mechanical mechanisms.
Solution Approach 2:
The patent employs composite materials by combining a rigid implant body with a deformable polymer tip. This composite structure allows the implant to leverage both the strength of rigid materials for structural integrity and the flexibility of polymer materials for adaptive expansion, achieving reliable anchoring without complex mechanisms.
2Ease of operation
If implant screws are used in osteoporotic bone, then fracture fixation is achieved, but cut-out occurs due to weak bone tissue
Solution Approach 1:
The patent applies dynamics by creating a tip that is static during insertion but becomes dynamic under load. The deformable polymer tip automatically expands when subjected to compressive forces from bone tissue, adapting its configuration to increase contact area and prevent cut-out in osteoporotic bone without requiring external actuation.
Solution Approach 2:
The patent uses parameter changes by exploiting the stress-dependent deformation behavior of polymer materials. Under the compressive stress experienced during normal bone loading, the tip material undergoes elastic deformation and expansion, transforming the contact parameters to prevent penetration into weak bone tissue.
3Strength
If implants are implanted in bone tissue, then fracture fixation is provided, but stress shielding causes bone resorption and loosening
Solution Approach 1:
The patent applies local quality by concentrating the deformable, stress-distributing characteristics specifically at the tip region that interfaces with bone tissue. This localized approach allows the implant to maintain overall structural strength while creating a specific zone that adapts to bone morphology and distributes stress evenly, preventing stress shielding and bone resorption.
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
These implants effectively reduce the incidence of 'cut-out' and migration, enhance bone stability, and minimize stress shielding, thereby improving the longevity and effectiveness of bone fixation by dynamically adapting to bone structure and load conditions.
Implementation Method 1
the deformable tip may be formed from a material such that upon compressive force being applied to the deformable tip, the deformable tip translates the compressive force into expansion
Implementation Method 2
the deformable tip may be formed from a material such that upon compressive force being applied to the deformable tip, the deformable tip translates the compressive force into expansion which increases frictional force with the bone
Implementation Method 3
The deformable tip may be formed from an elastomeric polymer material
Data Source
Figure 1A~2B
Figure 3A~4H
Figure 5A~8B
AI summary
A device for engagement with a bone includes a dynamically expandable tip (12), a dynamically expandable ring (40), or other dynamically expandable insert (60, 62, 401L) that reacts to forces pushing the implant into bone tissue. The tip (12), ring (40) or insert (60, 62, 401L) expands at least normal to the direction of motion, increasing contact area between the surrounding bone tissue and the material and thereby reducing the occurrence of high areas of contact stress in the adjacent bone tissue. The tip (12), ring (40) or insert (60, 62, 401L) translates forces along an axis of motion into lateral frictional forces that can resist penetration into the bone tissue without the need for additional operator or patient interaction. A method of reducing migration of the device for engagement includes the steps of providing the device and inserting the device within bone tissue.