Spinal Implant Cap with Tactile Feedback and Guidance
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Solution Overview
Problem
Spinal implant screws face issues with cross-threading, difficulty in thread engagement due to small thread dimensions, and lack of tactile and visual feedback during surgical procedures, which complicates the fixation of spinal stabilizing elements.
Innovation Solution
The design incorporates a cap with truncated leading edge threads and a deformable ring for enhanced tactile and visual feedback, along with a guiding surface to facilitate easy alignment and locking, providing improved fixation and reduced torque requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If standard threading is used with small thread dimensions to limit implant size, then implant size is reduced, but tactile feedback and thread engagement identification become difficult
Solution Approach 1:
The patent applies visual indicators (color changes or contrasting markings) on the thread surfaces to enhance visibility and identification of thread engagement status. This allows surgeons to easily identify when threads are properly engaged despite the small size of the implant components.
2Strength
If high torque loading is applied to bear thread forces during rod seating, then fixation strength is improved, but cross-threading and thread failure increase
Solution Approach 1:
The patent incorporates a lead-in surface that guides the cap into proper alignment with the receiver before thread engagement begins. This preliminary alignment action prevents cross-threading and ensures reliable thread engagement from the start, allowing high torque to be applied safely without causing thread failure.
Solution Approach 2:
The lead-in surface acts as an intermediary element between the cap and receiver threads. It mediates the engagement process by providing a guidance path that ensures proper alignment before the actual threading begins, thereby preventing cross-threading while maintaining fixation strength.
3Strength
If thread depth is increased to improve connection strength, then thread strength is improved, but cross-threading difficulty increases
Solution Approach 1:
The lead-in surface provides preliminary alignment guidance before the deep threads engage. This ensures that even though the threads are deep and provide strong connection, the engagement process remains easy by preventing cross-threading through proper alignment established by the lead-in surface.
Data Source
AI summary
An implant having a receiver that is adapted to receive a polyaxial screw in the bore and either an internal or external cap. The cap can be an external or internal cap and the implant further has at least one locking aid in the form of at least one of a tactile feedback, a visual feedback or an enhanced fixation between the cap and a rod that is received in the receiver.