Resorbable Self-Tapping Bone Screw With Torque-Activated Distal Tip
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Solution Overview
Problem
Resorbable screws used in cranio-maxillofacial surgeries often provide inadequate fixation and may weaken or dislodge over time, leading to post-surgical complications and the need for additional surgery, and require pilot hole tapping, increasing surgical time and complexity.
Innovation Solution
A fastener with a shaft that changes configuration under predetermined torque, featuring a distal portion that transforms from a static to a movable state, allowing self-tapping into bone without pre-drilling, and is designed to improve anchorage and load-bearing capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If resorbable screws are used for fixation, then the need for removal surgery is avoided, but the fixation strength and reliability deteriorate over time
Solution Approach 1:
The screw transitions from a static structure to a dynamic one through the breakable bridge design. The bridge connects the threaded portion to the distal tip and is designed to break under specific torque conditions, allowing the screw to adapt its structural configuration during installation and provide enhanced fixation reliability while maintaining resorbability.
Solution Approach 2:
The screw is segmented into distinct functional portions: a threaded portion for bone engagement, a breakable bridge connecting the threaded portion to the distal tip, and a distal tip for insertion. This segmentation allows each portion to perform its specific function optimally, with the bridge acting as a controlled weak point that enhances overall fixation strength.
2Ease of operation
If pilot hole tapping is performed prior to screw installation, then screw installation is facilitated, but surgical time and procedural complexity increase
Solution Approach 1:
The screw is designed as a self-tapping fastener with threads on the shaft that automatically create the pilot hole during insertion. The breakable bridge and distal tip configuration enable the screw to tap its own path into the bone without requiring pre-drilling, thereby simplifying the surgical procedure and reducing surgical time while maintaining ease of installation.
3Adaptability or versatility
If resorbable materials are used for screws and plates, then tissue integration is achieved, but anchorage and load bearing capacity are reduced
Solution Approach 1:
The screw is designed with a composite structural configuration combining a threaded portion for load distribution, a breakable bridge for structural reinforcement, and a distal tip for insertion. This composite design maintains the resorbable material property for tissue integration while enhancing load bearing capacity through optimized structural architecture.
Solution Approach 2:
Different portions of the screw have different structural qualities optimized for their specific functions: the threaded portion has a specific thread pitch and depth for bone engagement, the breakable bridge has controlled thickness for torque-based breaking, and the distal tip has a specific geometry for insertion. This local quality optimization ensures adequate anchorage and load bearing capacity throughout the screw structure.
Data Source
AI summary
In one embodiment, the present disclosure relates to fastener for use in a bone. The fastener includes a head and a shaft extending from the head. The shaft includes a threaded surface. When the shaft is subject to less than a predetermined torque, a distal portion of the shaft has a first configuration. When the shaft is subject to the predetermined torque, a distal portion of the shaft has a second configuration with the second configuration being different from the first configuration.