Variable-Length Compression Screw for Bone Compression and Countersinking
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Solution Overview
Problem
Existing bone screws lack effective mechanisms for providing compression at the bone joint or fracture line to prevent nonunion and malunion, and often require additional instrumentation for countersinking, which can cause soft-tissue irritation and increase surgical complexity.
Innovation Solution
A variable length headless compression screw system comprising a bone screw and a compression sleeve, driven by a driver assembly, which allows for adjustable compression and countersinking without predrilling, using self-tapping and self-drilling features to minimize bone build-up and toggle, and includes a ram driver to lock the screw components during insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If additional instrumentation is used for countersinking, then compression capability is improved, but surgical complexity increases
Solution Approach 1:
The patent combines the compression sleeve and countersinking functions into a single integrated device. The compression sleeve itself serves as the countersinking tool, eliminating the need for separate instrumentation. This merging of functions reduces surgical complexity while maintaining compression capability.
Solution Approach 2:
The compression sleeve is designed to perform multiple functions: it provides compression at the fracture site and simultaneously acts as a countersinking tool. This multi-functionality eliminates the need for additional specialized instrumentation, thereby reducing surgical complexity while maintaining effective compression.
2Ease of operation
If predrilling is performed, then screw insertion is facilitated, but soft-tissue irritation increases
Solution Approach 1:
The compression sleeve is designed with self-drilling and self-tapping features that allow it to create its own insertion path and threads in the bone without requiring predrilling. This self-service capability facilitates screw insertion while avoiding the soft-tissue irritation caused by separate predrilling operations.
Solution Approach 2:
The compression sleeve performs preliminary bone preparation actions (drilling and tapping) as part of its insertion process, creating the necessary path and threads before final seating. This preliminary action is integrated into the insertion itself, facilitating ease of operation while minimizing separate invasive steps that cause soft-tissue irritation.
3Ease of manufacture
If screw length is fixed, then manufacturing is simplified, but adaptability to different fracture types is reduced
Solution Approach 1:
The compression sleeve is designed with variable length capability, allowing it to be adjusted to different lengths based on the specific fracture type and location. This dynamic adjustability provides adaptability to different fracture types while the basic manufacturing process remains relatively simple, requiring only modular construction.
Solution Approach 2:
The compression sleeve can be manufactured in modular segments that can be combined to achieve different lengths. This segmentation allows for adaptability to different fracture types while keeping individual manufacturing units simple and standardized, balancing manufacturing simplicity with clinical versatility.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system provides controlled compression and countersinking, reducing surgical complexity, minimizing soft-tissue irritation, and preventing screw back-out, while ensuring stable fixation of bone fragments.
Implementation Method 1
The bone screw includes a proximal end having an external threading threadably received in the compression sleeve
Implementation Method 2
remove bone build-up (for example, from cutting flutes)
Implementation Method 3
are self-tapping and/or self-drilling
Implementation Method 4
are self-tapping and/or self-drilling
Data Source
AI summary
A variable length headless compression screw insertion system includes a compression screw and a driver assembly for driving the compression screw into a bone. The compression screw has a bone screw and a compression sleeve coupled to the bone screw. The bone screw includes a proximal end having an external threading threadably received in the compression sleeve, and the compression sleeve includes a proximal end having a predefined drive feature and an external threading. The driver assembly includes a sleeve coupler adapted to threadably receive the external threading of the compression sleeve. A ram driver is coupled to the sleeve coupler and has a predetermined length such that its distal end is shaped to contact the proximal end of the bone screw to prevent translation of the bone screw relative to the compression sleeve.