Tissue Dilation System with Serrated Dilator for Pedicle Screw Placement
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Solution Overview
Problem
Minimally invasive spinal fusion surgeries face challenges with guide wires detaching or breaking during pedicle screw insertion due to insufficient depth insertion and foreign object interference, leading to prolonged procedures and contamination risks.
Innovation Solution
A tissue dilation system comprising a trocar with a threaded distal region, a stylet, and sequential dilators with serrated edges for engaging bone, along with a handle and temporary fixation pin, facilitating precise bone engagement and minimizing tissue displacement during surgical procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a guide wire is inserted through tissue toward a pedicle of the vertebral body, then the surgeon can accurately attach a pedicle screw to the vertebral body, but the guide wire may not be inserted to a sufficient depth resulting in detachment prior to insertion of the pedicle screw
Solution Approach 1:
The system divides the guide wire into multiple segments: a removable stylet for initial insertion and positioning, and a permanent guide wire that remains in place. The stylet is inserted first to establish the trajectory, then the guide wire is advanced over it. This segmentation allows the stylet to be removed after serving its purpose, while the guide wire remains secured to the bone surface through the dilator system.
Solution Approach 2:
The dilator system acts as an intermediary between the guide wire and the bone surface. The dilator is inserted through the guide wire and engages the bone surface with its engagement feature (serrated edge or threads). This intermediary structure provides stable anchoring to the bone, preventing guide wire detachment while allowing the guide wire itself to maintain proper insertion depth.
2Reliability
If a guide wire is used during surgical procedure, then pedicle screw attachment is enabled, but the guide wire may deflect or break as a result of catching on a foreign object such as a surgeon's clothing
Solution Approach 1:
The dilator is inserted and engaged with the bone surface before the guide wire is fully utilized for screw placement. This preliminary action secures the guide wire system to the bone, eliminating the guide wire's vulnerability to external forces such as clothing interference. The guide wire becomes part of a fixed assembly rather than a loose, deflectable element.
Solution Approach 2:
The guide wire and dilator assembly is designed to be contained within the bore of the dilator, which protects it from external interference. The cylindrical geometry of the dilator bore shields the guide wire from catching on foreign objects like surgeon's clothing, while still allowing the guide wire to perform its function of guiding the pedicle screw.
3Ease of operation
If minimally invasive spinal fusion surgery is performed, then surgical trauma is reduced, but guide wire detachment or breakage leads to prolonged procedures and contamination risks
Solution Approach 1:
The system merges the guide wire function with the dilator function into a single integrated assembly. The guide wire is advanced over the stylet, and the dilator is inserted through the guide wire, creating a combined structure that performs multiple functions: guiding the pedicle screw, securing to the bone surface, and protecting the guide wire from detachment or breakage. This integration eliminates the need for separate securing mechanisms.
Solution Approach 2:
The engagement feature on the dilator (serrated edge or threads) provides beforehand cushioning by securing the assembly to the bone surface before any potential guide wire failure can occur. This preventive measure ensures that even if the guide wire encounters foreign objects or experiences stress, the dilator-bone engagement prevents detachment and maintains procedural integrity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system ensures stable and secure engagement of pedicle screws by maintaining the guide wire in place, reducing the risk of detachment and breakage, thus shortening surgical time and minimizing contamination.
Implementation Method 1
A distal region of the elongated body has threads for engaging bone
Implementation Method 2
sequential dilators with serrated edges for engaging bone
Data Source
AI summary
Disclosed herein are systems and methods for dilating tissue for placement of a pedicle screw without the use of guide wires. The tissue dilation system includes, generally, a stylet and trocar which are used for the initial placement of the tissue dilation system. A second dilator is passed over the first. A second dilator is passed over the first dilator, and further includes a serrated edge for engaging with a target surface. The second dilator may be secured to the target surface by the serrated edge alone, or may additional be secured using one or more temporary fixation pins, which operably couple to the second dilator.