Two-Piece Bone Compression Screw Assembly
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Solution Overview
Problem
Existing bone compression screws lack stability and effectiveness in preventing rotation and ensuring proper bone mending, as they can shift in position and do not adequately contribute to the bone healing process.
Innovation Solution
A two-piece compression screw assembly comprising a screw component with external threading and a sleeve component that can be independently driven to provide compression and resistance to rotational forces, featuring expandable segments or tangs to secure the screw in place within the bone anatomy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-piece compression screw is used, then the device is simple to manufacture, but it lacks stability and is susceptible to shifts in position once installed
Solution Approach 1:
The compression screw is divided into two separate components: a screw component and a sleeve component. The screw component includes a proximal threaded portion for bone engagement and a distal smooth portion, while the sleeve component includes a proximal smooth portion and a distal threaded portion. This segmentation allows each component to be optimized for its specific function and enables independent installation and adjustment, improving stability while maintaining manufacturing simplicity.
Solution Approach 2:
The sleeve component is designed to be positioned over the screw component, creating a nested configuration where the sleeve's internal diameter accommodates the screw's external diameter. This nesting arrangement provides mutual support between components, prevents positional shifts, and enhances overall stability without requiring complex external fixation structures.
2Reliability
If conventional compression screws are used, then installation is straightforward, but they rotate or shift in position once installed
Solution Approach 1:
The screw component and sleeve component are designed with asymmetric geometries that prevent rotational movement. The screw component may include a non-circular cross-section or asymmetric thread pattern, while the sleeve component has corresponding asymmetric features that mate with the screw. This asymmetry creates a mechanically locked configuration that resists rotation while maintaining straightforward installation through sequential component placement.
3Force
If greater compression force is applied, then bone mending is improved, but the screw may shift or rotate under the increased force
Solution Approach 1:
The two-component design allows for dynamic load distribution between the screw component and sleeve component. The threaded portions engage with bone tissue to distribute compression forces, while the nested configuration between components provides mechanical interlocking that prevents shifting. This dynamic system maintains positional stability even under high compression forces required for effective bone mending.
Data Source
AI summary
Bone compression screws are characterized by a two-piece compression screw assembly comprising a screw component and a sleeve component. The screw component has external male bone screw threading at a distal end, external male machine screw threading on a proximal end, and a smooth shank between the threaded distal and proximal ends. The screw component may be solid, cannulated, slotted, fenestrated, fluted, helically fluted, or any combination thereof. The sleeve component has external male bone screw threading with a pitch that can be equal to, smaller than, or greater than the thread pitch of the screw component, an internal bore extending from a proximal end of the sleeve component to the distal end of the sleeve component and sized for reception over the proximal end of the screw component. Internal female machine screw threading is configured to mate with the external male machine screw threading of the screw component.