Bone Fusion Device with Adjustable Screw and Washer
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Solution Overview
Problem
Conventional bone fusion surgeries, particularly in the lumbar region, often result in excessive displacement at adjacent segments leading to secondary lesions and the need for reoperation, with existing methods like sacroiliac joint fusion implants facing issues of loosening and tissue damage due to screw penetration.
Innovation Solution
A bone fusion device comprising a bone screw with an elongated shank and adjustment threads, a washer with a larger cross-sectional area and wedges for stable fixation, and an adjustment screw with anti-rotation features to prevent loosening, allowing for controlled pulling of distant bone bodies towards each other during fusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the screw is rotated until it contacts the washer, then the bone bodies are fused, but the screw may penetrate the distant bone body and damage other tissues
Solution Approach 1:
The washer acts as an intermediary element between the bone screw and the distant bone body. It provides a stopping surface that prevents the screw from penetrating through the bone body and damaging surrounding tissues, while still allowing the screw to achieve sufficient contact pressure for bone fusion.
2Object-affected harmful factors
If the screw is tightened only to a position where it does not penetrate the distant bone body, then tissue damage is prevented, but the bone bodies cannot be sufficiently adhered
Solution Approach 1:
The washer serves as a mediator that enables the screw to be tightened to the point of contacting the washer, providing sufficient compression force for bone adhesion without requiring the screw to penetrate the distant bone body. This resolves the contradiction by allowing full tightening while preventing tissue damage.
3Manufacturing precision
If screws of required length are prepared based on differences in bone structure, then accurate contact with washer is achieved, but the treatment efficacy becomes uncertain due to complexity
Solution Approach 1:
The washer provides a universal stopping surface that works with screws of various lengths. Instead of requiring precise customization of screw length for each patient's bone structure, the washer serves as a standardized reference point that enables accurate bone fusion while preventing tissue damage across different anatomical variations.
4Device complexity
If simple screw fixation is used for sacroiliac joint fusion, then the procedure is simple, but loosening occurs after long period requiring reoperation
Solution Approach 1:
The invention merges the bone screw with a washer to create a combined fixation system. This combination provides both the simplicity of screw insertion and the reliability of distributed load bearing, preventing loosening while maintaining procedural simplicity.
Solution Approach 2:
The washer is pre-positioned against the bone surface before the screw is fully tightened. This preliminary positioning ensures that the screw will contact the washer at the correct point, distributing forces evenly and preventing future loosening while maintaining the simplicity of the insertion procedure.
Data Source
AI summary
The present invention provides a bone fusion device which allows a distant bone body in a surgery direction to be pulled toward an adjacent bone body in the surgery direction while fusing the adjacent bone bodies. The bone fusion device includes a bone screw which includes a shank having an elongated shape with a circular cross-section, a screw thread formed on one end portion of the shank, and an adjustment female thread formed in the other end portion of the shank; a washer which includes a through hole into which the other end portion of the shank is inserted, and has a cross-sectional area larger than that of the bone screw; and an adjustment screw having an adjustment male thread screwed with the adjustment female thread of the bone screw through a through hole of the washer.