Woven Retention Device for Bone Screw Fixation
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Solution Overview
Problem
Current bone screw fixation methods face issues with loss of grip and stripping of bone holes, particularly in osteoporotic bone, leading to reduced holding strength and increased risk of screw loosening or pullout.
Innovation Solution
A woven retention device with a tubular lattice structure made of interwoven monofilaments and multifilaments, featuring protuberances on both interior and exterior surfaces, which adapts to bone density and screw shape to enhance fixation and accommodate variations in bone hole diameter and depth, allowing for bone ingrowth and increased pullout force resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional bone screws are used for fixation, then the procedure is simple and quick, but the holding strength is insufficient and screw loosening or pullout occurs
Solution Approach 1:
The woven retention device is inserted into the bone hole created for the bone screw, nesting the retention device within the bone hole and the bone screw within the retention device. This nested configuration allows the retention device to provide enhanced fixation strength while maintaining a relatively simple overall system structure.
Solution Approach 2:
The retention device is constructed from woven monofilament materials that combine flexibility and strength. This composite material approach enables the device to adapt to bone density variations while providing sufficient holding strength to prevent screw loosening or pullout.
2Reliability
If bone screws are used in osteoporotic bone, then the procedure is straightforward, but the purchase or grip is reduced leading to loss of holding strength
Solution Approach 1:
The woven retention device features varying filament densities and configurations at different locations within the device structure. This local quality variation allows the device to adapt to different bone density conditions, providing reliable fixation in osteoporotic bone while maintaining effectiveness in denser bone structures.
Solution Approach 2:
The retention device utilizes changes in filament arrangement, density, and structural parameters to adapt to varying bone density conditions. These parameter changes enable the device to maintain reliable fixation across different bone quality scenarios, including osteoporotic bone.
3Strength
If bone screws are inserted with high tightening force, then initial fixation is strong, but the bone hole strips resulting in loss of purchase
Solution Approach 1:
The woven retention device is inserted into the bone hole before the bone screw is fully tightened, acting as a cushioning layer between the screw and the bone. This prior cushioning prevents direct high-stress contact that causes bone hole stripping, while still allowing strong initial fixation.
Solution Approach 2:
The retention device serves as an intermediary element between the bone screw and the bone tissue. It mediates the interface by distributing stresses and preventing direct stripping of the bone hole, while maintaining strong fixation through its woven structure.
4Adaptability or versatility
If retention devices with fixed geometry are used, then manufacturing is simple, but they cannot accommodate variations in bone hole diameter and depth
Solution Approach 1:
The woven retention device possesses dynamic characteristics through its flexible monofilament construction, allowing it to adapt its shape and dimensions to accommodate variations in bone hole diameter and depth. This dynamic adaptability is achieved without requiring complex adjustable mechanisms.
Solution Approach 2:
The retention device is constructed from flexible monofilament materials that can bend, stretch, and conform to the specific geometry of the bone hole. This flexibility enables the device to accommodate variations in bone hole diameter and depth while maintaining structural integrity and fixation effectiveness.
Data Source
AI summary
A woven retention device for interfacing with a bone surface is provided that includes a sleeve body that can surround a fastener, a proximal end for receiving the fastener, and a distal end. The sleeve body includes interwoven monofilaments of different diameters forming a substantially tubular lattice with protuberances distributed on interior and exterior surfaces of the lattice at a predetermined spatial relationship. In a first state, the sleeve body has a plurality of combinations of filament cross-section geometries at the intersection points, forming a plurality of protuberance thicknesses as measured in a radial direction of the sleeve body. In a second state when a fastener is inserted into the tubular lattice, pressure from the fastener is transmitted to the tubular lattice such that the spatial relationship of the protuberances changes according to a function of bone density and an interfacing surface shape of the fastener.