Woven Retention Device for Bone Screw Fixation
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Solution Overview
Problem
Current bone screw fixation methods face challenges such as loss of grip, stripping of bone holes, and reduced holding strength due to osteoporotic bone or infections, which can lead to loosening or pullout of screws, and hinder bone healing by preventing bony ingrowth.
Innovation Solution
A woven retention device with a tubular lattice structure comprising interwoven filaments that maintain pore sizes within a range of 200-1000 μm, allowing for dynamic adjustment to accommodate varying diameters and promoting bone ingrowth while impeding biofilm formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a bone screw is inserted into bone tissue, then fixation is achieved, but loss of grip and stripping of bone holes occurs leading to reduced holding strength
Solution Approach 1:
A woven retention device acts as an intermediary between the bone screw and the bone tissue. The device is inserted into the bone hole first, then the screw is inserted into the device, creating a three-component system (bone-screw-device-bone) that distributes mechanical stresses and prevents direct stripping of the bone hole while maintaining secure fixation.
Solution Approach 2:
The retention device is made with a porous woven structure having pore sizes of 200-1000 μm that promote bone ingrowth. This porous structure allows bone cells to penetrate and integrate with the device, creating a biological anchor that enhances long-term fixation stability and prevents screw loosening or pullout.
2Strength
If osteoporotic bone or disease states are present, then bone purchase is reduced, but this increases likelihood of screw loosening and pullout
Solution Approach 1:
The porous woven structure with 200-1000 μm pores facilitates bone ingrowth into the device, creating a biological interlock that compensates for reduced mechanical purchase in osteoporotic bone. As bone grows into the pores, it forms a structural integration that anchors the device securely within weakened bone tissue.
Solution Approach 2:
The system creates a composite structure combining the woven retention device material with ingrown bone tissue. This composite construction leverages the mechanical properties of the device material while incorporating the biological bonding capability of bone, resulting in enhanced retention strength that overcomes the limitations of osteoporotic bone density.
3Reliability
If pore size is maintained within 200-1000 μm range, then bone ingrowth is promoted, but device complexity increases to maintain dynamic pore size adjustment
Solution Approach 1:
The woven structure is designed to be dynamically adjustable, allowing the pore size to change as the device is compressed during insertion and then expands to its relaxed state within the bone hole. This dynamic behavior enables the same device to accommodate varying bone hole diameters while maintaining the optimal 200-1000 μm pore size range for bone ingrowth without requiring complex active control mechanisms.
Solution Approach 2:
The device utilizes changes in physical parameters (compression and expansion) to maintain consistent pore size characteristics across different device diameters. By designing the woven structure with specific geometric parameters and material properties, the pore size remains within the optimal 200-1000 μm range regardless of the overall device size or compression level, eliminating the need for complex active regulation systems.
Data Source
AI summary
A woven retention device that is configured to receive a fastener in a bone hole can be configured to promote bone ingrowth and impede biofilm formation. The woven retention device can be made of woven filaments that outline apertures of varying sizes and shapes and can serve as an interface between the fastener and the bone material. In a first relaxed state, the interwoven filaments can outline apertures of varying sizes and shapes within a predetermined range and in a second constricted state inside the bone hole with the fastener the interwoven filaments can outline apertures of decreased area that still fall within the predetermined range. The woven retention device can be configured to allow for optimal bone growth while at the same time minimizing the likelihood that biofilm forms thereon.