Cannulated Bone Screw Insertion With Integrated Stylet Guidance
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Solution Overview
Problem
Existing spinal fixation techniques, particularly the use of pedicle screws, face challenges in surgical efficiency, safety, and accuracy during screw insertion, especially when dealing with complex spinal alignments and small pedicles.
Innovation Solution
The use of cannulated and non-cannulated fasteners with integrated stylets that allow for one-step insertion by creating a pilot hole and engaging threads simultaneously, along with oscillating and retracting mechanisms to maintain accuracy and prevent skiving, optionally assisted by robotic end effectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional multi-step screw insertion methods are used, then surgical safety and accuracy are maintained, but surgical efficiency is reduced due to multiple steps
Solution Approach 1:
The patent combines multiple functions (pilot hole creation, thread engagement, and screw insertion) into a single integrated fastener device. The stylet with cutting edges at its distal end allows simultaneous pilot hole formation and screw insertion in one continuous motion, eliminating the need for separate drilling and insertion steps, thereby improving surgical efficiency without compromising safety
Solution Approach 2:
The stylet is pre-positioned within the cannulated fastener before insertion, with its cutting edges already prepared to create the pilot hole. This preliminary positioning allows the surgeon to perform both pilot hole creation and screw insertion in a single coordinated motion, reducing the number of surgical steps while maintaining precision and safety
2Productivity
If cannulated fasteners with stylets are used for single-step insertion, then surgical efficiency is improved, but risk of skiving and loss of accuracy increases
Solution Approach 1:
The stylet acts as an intermediary element between the surgeon and the bone, performing the pilot hole creation function while the cannulated fastener follows along its created path. This intermediary approach ensures that the screw insertion path is pre-established with accurate positioning, preventing skiving and maintaining placement precision even during single-step insertion
Solution Approach 2:
The insertion process is segmented into distinct functional zones: the stylet's distal cutting edges create the pilot hole, while the cannulated fastener's threads engage the bone separately. This functional segmentation allows each component to perform its specific task optimally, maintaining accuracy while enabling single-step insertion
3Manufacturing precision
If oscillating rotation of the stylet is used during insertion, then accuracy is maintained and skiving is prevented, but device complexity increases
Solution Approach 1:
The insertion mechanism transitions from static to dynamic operation, allowing the stylet to oscillate between clockwise and counter-clockwise rotation during insertion. This dynamic oscillating motion prevents the stylet from becoming stuck and maintains accurate path following, while the simple ratchet-based mechanism keeps the overall device complexity manageable
Data Source
AI summary
A method of inserting a fastener includes positioning a portion of a stylet within a cannulated shaft of the fastener, advancing a tip of the stylet through a first bone and into a second bone, advancing a leading end of the fastener along the stylet through the first bone and into the second bone, and removing the stylet from the cannulated shaft of the fastener and the bone. In another embodiment, a method of inserting a fastener includes positioning a portion of a stylet within a cannulated shaft of the fastener, advancing a tip of the stylet into a bone to a first depth without advancing the fastener into the bone, advancing a leading end of the fastener along the stylet into the bone to a second depth without further advancing the stylet into the bone, and removing the stylet from the cannulated shaft of the fastener and the bone.