Two-part screw system eliminates guide wire puncture risk
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Solution Overview
Problem
Minimally invasive spinal surgery techniques require multiple steps and tools, increasing the risk of misplacement and malfunction due to the use of guide wires, which can puncture vital structures and result in weaker cannulated screws.
Innovation Solution
A two-part screw system comprising an inner and outer member that are pre-assembled with drivers, eliminating the need for a guide wire, with the inner member acting as a guide for the outer member to form a solid implant upon final alignment, reducing the number of steps and enhancing screw strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a guide wire is used to guide the cannulated screw, then the screw can be inserted accurately, but the guide wire may puncture vital structures such as the aorta or abdomen
Solution Approach 1:
The patent removes the guide wire from the surgical system entirely. Instead of using a separate guide wire to establish the trajectory, the system uses a pre-assembled inner member that is directly advanced into the vertebra under imaging guidance, eliminating the harmful intermediate step of guide wire insertion that could puncture vital structures.
Solution Approach 2:
The screw system is divided into two separate parts: an inner member that establishes the trajectory and a cannulated outer member that provides the final implant. The inner member acts as a self-contained guide that eliminates the need for a separate guide wire, while the outer member is advanced over the inner member to form the final solid implant.
2Reliability
If multiple steps are used to insert and remove various parts including guide wire, then the screw can be implanted, but the surgical process becomes complex and time-consuming
Solution Approach 1:
The patent combines the guide function and the implant function into a single integrated system. The inner member serves both as the trajectory guide and as part of the final implant structure. The pre-assembly of the inner member with its driver and the outer member with its driver creates a unified surgical assembly that reduces the number of separate manipulation steps required.
Solution Approach 2:
The inner member and outer member are pre-assembled into a surgical assembly before the surgical procedure begins. This pre-assembly eliminates the need to sequentially remove and apply different drivers and implant parts during surgery, streamlining the implantation process into fewer steps.
3Ease of operation
If a cannulated screw is used, then the surgical procedure can be performed, but the implanted screw is weaker compared to a solid screw
Solution Approach 1:
The patent uses a nested structure where the inner member is inserted into the cannulated outer member. The inner member fills the hollow space of the outer member, and when fully advanced, the two members integrate to form a substantially solid body. This nested approach allows the screw to maintain structural strength comparable to a solid screw while still enabling minimally invasive surgical techniques.
Data Source
AI summary
A two-part screw system includes an inner member and a cannulated outer member that may be pre-assembled with an inner member driver and an outer member driver to form a surgical assembly. A method of inserting the two-part screw system includes advancing the inner member into the bone by using the inner member driver, and advancing the outer member into the bone by using the outer member driver. The inner member acts as a guide for the outer member, and eliminates the need for a separate guide wire. The pre-assembled nature of the surgical assembly eliminates the need to sequentially remove and apply drivers and implant parts. The inner member and the outer member are configured to integrate into a substantially solid body when in a final alignment, thus forming a stronger implant than a cannulated screw.