Frustoconical Screw Extractor Tip for Stripped Bone Screws
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Solution Overview
Problem
Conventional orthopedic screw extractors fail to effectively remove damaged or stripped bone screws due to insufficient grip, leading to excessive bone loss during extraction.
Innovation Solution
An orthopedic screw extractor with a frustoconical screw extracting tip featuring multiple threads and flutes, designed to securely engage and remove damaged screws by applying counter-clockwise torque, utilizing a narrow taper angle and buttress thread configuration for enhanced grip and torque application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional orthopedic screw extractors are used, then the extraction procedure can be performed, but the grip on damaged or stripped screws is insufficient leading to excessive bone loss
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the extractor tip including the taper angle (5-15 degrees), thread pitch (0.02-0.04 inches), thread depth (0.01-0.02 inches), and lead (0.07-0.12 inches). These specific parameter adjustments optimize the bite and grip on damaged screws while minimizing bone loss during extraction.
Solution Approach 2:
The extractor tip features localized quality variations with different thread depths, pitches, and angles at different locations along the tip. The flutes are strategically positioned to concentrate cutting and gripping forces at specific locations, providing enhanced local engagement with the damaged screw while protecting surrounding bone tissue.
2Ease of operation
If conventional screw extractors are used on stripped screws, then extraction can be attempted, but the extractor cannot sufficiently lock onto the damaged fastener
Solution Approach 1:
The extractor tip is segmented into multiple functional zones with three different thread pitches and three flutes circumferentially spaced around the tip. This segmentation allows different portions of the tip to engage different regions of the damaged screw, providing distributed locking and extraction force that reliably secures even severely stripped fasteners.
Solution Approach 2:
The extractor tip combines multiple thread configurations (different pitches, depths, and angles) and flute patterns in a single integrated structure. This composite design creates multiple engagement mechanisms that work together to reliably lock onto damaged screws, providing both cutting action and gripping force simultaneously.
Data Source
AI summary
An orthopedic screw extractor device including a shaft, an end portion about a first end of the shaft for securing to a handle, and a screw extracting tip about a second end of the shaft opposite the first end. The screw extracting tip further includes a generally frustoconical shape having a side at an angle of about 5 to 15 degrees relative to a longitudinal axis of the screw extracting tip. The screw extracting tip further includes first, second and third screw threads and first, second and third flutes circumferentially spaced about the screw extracting tip and extending across an entire length of the screw extracting tip. Each of the screw threads has a lead of about 0.07 to 0.12 inches, a pitch of about 0.02 to 0.04 inches, a thread angle of about 40 to 50 degrees, and a depth of about 0.01 to 0.02 inches.