Universal Pedicle Screw Removal Tool Tapered Shaft Design
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Solution Overview
Problem
Current methods for removing pedicle screws during spinal surgery are challenging due to screws becoming incarcerated in bone, leading to difficulty in removal, potential tissue damage, and contamination risks, especially when bone growth fills the screw socket or the screw's integrity is compromised.
Innovation Solution
A pedicle screw removal tool with a tapered shaft and right-angle removal tip, designed to expand and fit within the screw channel, allowing for secure engagement and rotation without the need for removing bone tissue, featuring a square head for attaching a ratchet or T-handle, and optional prongs for enhanced access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional removal tools are used on incarcerated screws, then screw removal may be achieved, but the channel and body socket are often stripped, bent, or broken
Solution Approach 1:
The removal tool is divided into distinct functional segments: a tapered shaft for expansion and engagement, a right angle removal tip for inserting into the channel, and a square head for torque application. This segmentation allows each part to perform its specific function optimally without compromising other components.
Solution Approach 2:
The shaft is designed with a tapered geometry that allows it to expand in diameter along its length. This parameter change enables the shaft to progressively engage the channel walls, distributing the removal forces evenly and preventing localized damage to the body socket while maintaining reliable screw extraction.
2Ease of operation
If bone tissue is removed to access the screw socket, then screw removal may be facilitated, but tissue damage and contamination risks increase
Solution Approach 1:
The design extracts the need for bone removal entirely. The tapered shaft is engineered to expand and fit within the existing channel dimensions, allowing direct engagement with the screw mechanism without requiring any preparatory bone resection or socket clearance.
Solution Approach 2:
The tool incorporates a right angle removal tip that is pre-configured to insert directly into the channel opening. This preliminary geometric configuration ensures that the tool can engage the screw mechanism immediately upon insertion, eliminating the need for preliminary bone removal actions.
3Manufacturing precision
If multiple custom tools are used for different screw sizes and shapes, then precise fit may be achieved, but device complexity and surgical time increase
Solution Approach 1:
The removal tool is designed as a universal instrument that can accommodate various pedicle screw sizes and configurations. The tapered shaft provides a range of engagement diameters, while the right angle tip and square head configuration work with standard screw geometries, eliminating the need for multiple specialized tools.
Solution Approach 2:
The tapered geometry of the shaft creates a dynamic engagement mechanism that adapts to different screw sizes. As the shaft is inserted and expanded, it naturally conforms to the channel dimensions, providing a precise fit for various screw configurations without requiring multiple fixed-size tools.
4Productivity
If force is applied to rotate incarcerated screws, then screw removal may be achieved, but surrounding tissue damage and bleeding increase
Solution Approach 1:
The right angle configuration of the removal tip creates an asymmetric force application geometry. This asymmetric design allows torque to be applied at a right angle to the screw axis, optimizing the mechanical advantage for unscrewing while directing forces away from surrounding soft tissues, thereby reducing damage and bleeding.
Data Source
AI summary
Disclosed is a universal pedicle screw removal tool comprising a tapered shaft having an “L” shaped tip on one end and a generally square head on an opposite end. A lower section leads to a tapered section which is connected to a handle. The handle may include a set of serrations to provide increased grip. The handle is connected to the head. The tip is sized to engage the channel of a tuliped pedicle screw while the head is sized to engage a ratchet or other torque producing tool. In an alternate embodiment, the tip is “T” shaped. In another alternate embodiment, the handle section includes opposing members extending from the shaft to form a “T” shaped handle. In use, the tip is inserted into the channel of a tuliped pedicle screw while the shaft is rotated to unscrew the pedicle screw from a patient's bone.