Spinal Screw Drive Portion with Guide Grooves for Alignment
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Solution Overview
Problem
In spinal and orthopedic surgeries, particularly in minimally invasive procedures, locating and adjusting the insertion depth of screw elements can be challenging due to limited visibility at the operation site.
Innovation Solution
The screw element features a drive portion with torx-shaped drive grooves and guide grooves that facilitate easy alignment and engagement with a screw driver, even when visibility is restricted, allowing for quick and precise adjustment of insertion depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a small incision is made for minimally invasive surgery, then patient trauma and recovery time are reduced, but visibility and access to the operation site are restricted
Solution Approach 1:
The patent introduces a specialized drive portion with drive grooves and guide grooves as an intermediary mechanism that mediates between the limited access through small incisions and the need for precise screw insertion. The guide grooves act as visual and mechanical guides that can be seen and accessed through the small incision, enabling the surgeon to locate and engage the drive portion even with restricted visibility.
Solution Approach 2:
The drive portion is designed with specific geometric features (drive grooves and guide grooves) that create visual contrast and landmarks visible through the small incision. The grooves provide visual cues that allow the surgeon to detect and locate the drive portion without requiring wide visibility, effectively using visual differentiation to overcome the visibility limitation.
2Manufacturing precision
If the drive portion is made complex to enable precise engagement, then insertion accuracy is improved, but ease of operation deteriorates
Solution Approach 1:
The guide grooves are designed to preliminarily guide the screw driver into the correct position before the drive grooves engage. This preliminary guidance action ensures that even if the screw driver is inserted at a slight incline, it will be automatically aligned with the screw axis, providing insertion accuracy without requiring complex engagement mechanisms or high skill from the operator.
Solution Approach 2:
The drive portion is segmented into two distinct functional elements: guide grooves for alignment and drive grooves for engagement. This segmentation allows each element to perform its specific function optimally - the guide grooves handle alignment to ensure accuracy, while the drive grooves handle torque transmission for operation, simplifying the overall operation while maintaining precision.
3Ease of operation
If the screw driver is inserted at a slight incline, then ease of insertion is improved, but alignment accuracy deteriorates
Solution Approach 1:
The guide grooves perform the preliminary action of aligning the screw driver with the screw axis before the drive grooves engage. When the screw driver is inserted at a slight incline, the guide grooves guide the engagement protrusions into proper alignment, automatically correcting the angular deviation. This allows easy insertion at an incline while ensuring accurate alignment through the guiding action of the grooves.
Data Source
AI summary
A screw element includes a screw axis, a shank for inserting in a bone, and a drive portion for engaging a screw driver. The drive portion includes a first wall defining a first recess and a second wall defining a second recess. Drive grooves are formed in the first wall and extend parallel to the screw axis. The second wall extends axially from a free end portion of the screw element to the first wall and has an inner diameter that continuously increases from the first wall towards the free end portion. A plurality of guide grooves are formed in the second wall at circumferential positions corresponding respectively to circumferential positions of the drive grooves. The guide grooves extend further radially from the screw axis than the drive grooves and guide the screw driver from the free end portion of the screw element to the drive grooves.