Nested Screw Assembly for Simultaneous Bone Compression and Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing screw-based constructs for bone-to-bone fixation face a trade-off between achieving optimal compression and stability, with compression screws providing better compression but not stability, and full-threaded screws offering more stability but less compression.
Innovation Solution
A nested screw assembly comprising a cannulated outer screw and an inner screw with matching thread pitches, allowing for the formation of a nested screw construct that enables simultaneous compression and stability by threading the inner screw into the outer screw to compress the joint and then driving the outer screw across the joint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If compression screws are used for bone fixation, then optimal compression is achieved, but stability is insufficient
Solution Approach 1:
The patent employs a nested screw configuration where an inner compression screw is placed inside an outer stability screw. The inner screw provides compression force to the bone joint, while the outer screw provides structural stability. The inner screw's shaft is received within the outer screw's hollow body, allowing both functions to be achieved simultaneously through nested arrangement.
2Stability of the object's composition
If full-threaded constant-pitch screws are used for bone fixation, then stability is improved, but compression is insufficient
Solution Approach 1:
The nested screw design allows the outer screw with full threading to provide stability while the inner screw provides compression. The coordinated action of both screws within the nested structure enables simultaneous achievement of stability and compression that neither screw could achieve alone.
Solution Approach 2:
The fixation system is divided into two functional segments: the outer screw dedicated to stability and the inner screw dedicated to compression. This segmentation of functions allows each component to optimize its specific role while working together as an integrated system.
3Device complexity
If a single screw is used for bone fixation, then device complexity is low, but it cannot achieve both compression and stability simultaneously
Solution Approach 1:
By nesting the inner screw within the outer screw, the patent achieves dual functionality (compression and stability) while maintaining a relatively compact and integrated device structure. The nested arrangement allows two functional screws to work together without requiring separate fixation elements, thus balancing complexity with versatility.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3~4
AI summary
Provided is a nested screw assembly and a related method for fusing a joint between two bones using the nested screw assembly, where the nested screw assembly includes a cannulated outer screw and an inner screw.