Woven Retention Device for Bone Screw Fixation
Find Innovative SolutionsGenerate Solutions
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 interwoven filaments forming a tubular lattice and protuberances on its surface, which distributes pressure from the fastener to multiple points on the bone surface, accommodating variations in bone density and diameter, and allowing for bone ingrowth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a bone screw is inserted into the bone, then the bone fracture can be secured and motion prevented, but the screw may lose grip or strip the bone hole leading to loss of holding strength
Solution Approach 1:
The retention device serves as an intermediary component between the bone screw and the bone tissue. It is inserted into the bone hole first, then the screw is inserted into the retention device, creating a three-component system (bone-screw-retention device-bone) that distributes stresses and prevents direct stripping of the bone hole while maintaining secure fixation.
Solution Approach 2:
The retention device is constructed from multiple filaments woven together to form a tubular lattice structure, creating a composite material system that combines flexibility and strength. This woven structure allows the device to adapt to bone density variations while providing enhanced grip and preventing screw pullout.
2Strength
If the bone density is reduced (osteoporotic bone), then the purchase or grip of the bone screw is reduced, but using traditional screws still results in loss of holding strength and loosening
Solution Approach 1:
The retention device's woven filament structure allows it to change its mechanical parameters (flexibility, compression resistance) based on the bone density it encounters. In osteoporotic bone, the device can compress more to accommodate lower density while still providing sufficient grip, whereas in denser bone it maintains its structural integrity for optimal fixation.
Solution Approach 2:
The retention device provides different mechanical properties at different locations along its length, with the woven structure allowing varying degrees of compression and expansion to adapt to local bone density variations throughout the bone hole, ensuring optimal engagement regardless of bone quality.
3Ease of operation
If a bone screw is over-tightened, then the hole in the bone may be stripped, but this results in loss of purchase and holding strength
Solution Approach 1:
The retention device acts as a cushioning element inserted into the bone hole before the screw is inserted. It protects the bone hole from the stripping forces that would occur during screw insertion and tightening, distributing the mechanical stresses across the woven structure rather than concentrating them on the bone walls.
Solution Approach 2:
The retention device mediates between the screw insertion process and the bone tissue, absorbing and distributing the forces applied during screw tightening to prevent direct contact forces from stripping the bone hole while still allowing secure screw fixation.
4Strength
If traditional bone screw fixation is used, then simple insertion is possible, but cement or adhesives are needed to enhance fixation which adds complexity
Solution Approach 1:
The retention device provides self-service fixation enhancement through its woven lattice structure that naturally engages with both the screw and bone tissue. The device's protuberances and interwoven filaments create mechanical interlocking and friction-based fixation without requiring additional cement or adhesive materials, eliminating the need for separate fixation enhancement steps.
Data Source
AI summary
A woven retention device for interfacing with a bone surface includes interwoven filaments forming a tubular lattice with protuberances distributed on interior and exterior surfaces of the lattice at a predetermined spatial relationship. The protuberances are formed by intersecting interwoven filaments. The retention device receives and surrounds a fastener. In a first, relaxed state, the retention device has multiple combinations of filament cross-section geometries at the intersection points, and the multiple combinations of filament cross-section geometries form multiple protuberance thicknesses. In a second state when surrounding at least a portion of the fastener, the retention device distributes pressure from the fastener to multiple points of contact on the exterior surface of the retention device such that a spatial relationship of the protuberances changes as a function of bone density of the bone surface and as a function of an interfacing surface shape of the fastener.