Cannulated Bone Screw Insertion With Stylet-Guided Pedicle Accuracy
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Solution Overview
Problem
Existing spinal fixation techniques, particularly involving 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 bone screws with integrated stylets that allow for one-step insertion by creating pilot holes and engaging threads simultaneously, combined with oscillating and rotating mechanisms to maintain accuracy and prevent skiving, and the use of robotic end effectors for precise placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional multi-step insertion methods are used for pedicle screws, then safety and accuracy can be maintained, but surgical efficiency is reduced and procedure time increases
Solution Approach 1:
The patent combines multiple traditional steps (reaming, broaching, screw insertion) into a single integrated operation. The reamer-screw assembly allows the reamer to create the pedicle canal while the screw is simultaneously inserted and secured in one continuous motion, eliminating the need for separate reaming and screwing steps that traditionally required multiple instruments and sequential operations.
Solution Approach 2:
The reamer-screw assembly serves multiple functions simultaneously: the reamer portion creates the pedicle canal while the screw portion is inserted and secured in the same operation. This multi-functional design eliminates the need for separate reaming instruments, broaches, and screwdrivers, thereby reducing procedure time and improving surgical efficiency.
2Loss of time
If single-step insertion is used to improve surgical efficiency, then procedure time is reduced, but accuracy and safety during insertion may be compromised
Solution Approach 1:
The reamer portion of the assembly performs preliminary action by creating the pedicle canal before the screw is fully inserted. This preliminary reaming establishes the correct pathway and depth, ensuring that when the screw is inserted in the same operation, it follows the pre-established accurate trajectory rather than requiring post-insertion adjustment.
Solution Approach 2:
The integrated design provides real-time feedback during insertion as the reamer and screw work together in one operation. The surgeon can feel and observe the interaction between the reamer cutting edges and bone, as well as the screw engagement with the pedicle, allowing immediate adjustment if deviation from the planned trajectory occurs, thereby maintaining accuracy despite the single-step approach.
3Device complexity
If conventional screw insertion without stylet is used, then device complexity is reduced, but the ability to prevent skiving and maintain accuracy in small pedicles is limited
Solution Approach 1:
The stylet acts as an intermediary tool inserted through the lumen of the screw to provide internal support during insertion. This intermediary element prevents the screw from bending or skiving (rubbing against the bone surface) by providing a rigid core that maintains the screw's structural integrity throughout the insertion process, especially important in small pedicles where the screw is more prone to deformation.
Solution Approach 2:
The stylet is nested within the lumen of the screw, creating a concentric structure where the stylet is inserted through the center of the screw shaft. This nested arrangement allows the stylet to provide internal support without adding external complexity to the overall device, as the stylet occupies the existing internal space of the screw rather than requiring additional external components.
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.