Percutaneous Targeting Device for Parallel Screw Placement
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Solution Overview
Problem
The minimally invasive chevron osteotomy procedure for correcting hallux valgus deformity requires multiple X-ray images for correct screw placement, leading to increased radiation exposure and time, as well as potential bone weakening from oblique screw insertion.
Innovation Solution
A percutaneous targeting device with a target guide and guide pins for precise screw placement, ensuring screws are in a plane with the target pin, allowing for parallel insertion and preventing oblique angles, using markings and adjustable extensions to align guide pins and screws accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple X-ray images are used for screw placement, then screw placement accuracy is improved, but radiation exposure and time increase
Solution Approach 1:
The patent introduces a targeting device as an intermediary tool that includes a target pin inserted into the bone and a guide pin positioned relative to the target pin. This mechanical guide system serves as a mediator between the surgeon and the bone structure, providing physical guidance for screw insertion without requiring multiple X-ray images. The guide pin acts as a mediator that transfers the desired screw trajectory directly to the bone, eliminating the need for repeated radiation exposure while maintaining placement accuracy.
Solution Approach 2:
The patent replaces the radiological system (X-ray images) with a mechanical guidance system consisting of the target pin and guide pin assembly. Instead of using electromagnetic radiation to visualize bone structure and plan screw paths, the invention uses a purely mechanical approach where the guide pin physically defines the screw trajectory through direct contact with the bone. This substitution eliminates radiation exposure while providing equally accurate screw placement guidance through tactile and geometric constraints.
2Measurement precision
If multiple X-ray images are used for screw placement, then screw placement accuracy is improved, but surgical time increases
Solution Approach 1:
The patent applies preliminary action by inserting the target pin and guide pin into the bone before making any incisions or preparing for screw insertion. The targeting device is set up in advance with the guide pin positioned at the exact location where the screw will be inserted. This preliminary positioning eliminates the need for multiple X-ray images during the surgical procedure, as the mechanical guide is already in place to define the precise screw trajectory, thereby reducing surgical time while maintaining accuracy.
Solution Approach 2:
The guide pin serves as an intermediary that bridges the planning phase and the execution phase of the surgery. Once the guide pin is positioned relative to the target pin, it becomes a permanent reference for screw insertion. This intermediary mechanical guide eliminates the need for real-time X-ray verification during surgery, as the guide pin physically constrains the screw path, thereby reducing surgical time without compromising placement accuracy.
3Adaptability or versatility
If oblique screw insertion is performed, then screw placement flexibility is improved, but bone weakening occurs
Solution Approach 1:
The patent incorporates feedback through the geometric relationship between the target pin and guide pin. The guide pin is positioned at a specific distance and angle relative to the target pin, creating a feedback mechanism that ensures the screw is inserted at the correct oblique angle. This feedback system provides real-time geometric constraint during surgery, ensuring that the screw follows the optimal path that maintains bone strength while still allowing for the necessary flexibility in screw placement to accommodate different bone geometries and surgical requirements.
Data Source
AI summary
A percutaneous targeting device comprises a body holding an extension. The body has a target guide holding a target pin which may be a K-wire. The extension has two guide sleeves, holding a guide wire. All wires are held in a common plane. The guide wires serve as a guide for cannulated fixation screws. The extension is movable against the body to adjust the angle between the target pin and the guide wires.