Integrally Formed Cap Set Screw Vertebral Implant
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Solution Overview
Problem
Existing osteosynthesis implant systems face challenges in aligning set screws with threaded posts, leading to cross-threading issues, and require multiple components and steps, which can result in discomfort for patients and limited use in closely spaced implants, especially in the thorax region.
Innovation Solution
An integrally formed cap and set screw with the set screw free to rotate within the cap, and a rod persuasion instrument with flat recessed sides and a catch basin design that accommodates close spacing and different rod diameters, facilitating easier alignment and securement of rods within implants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate cap and set screw components are used, then the locking mechanism can be formed, but the alignment of set screw with threaded posts becomes difficult leading to cross-threading issues
Solution Approach 1:
The patent combines the cap and set screw into a single integrally formed component. The set screw is formed as an integral extension of the cap, eliminating the need for separate alignment steps. This unified structure ensures proper alignment with the threaded posts while maintaining the locking function, directly resolving the cross-threading issue described in the contradiction.
2Reliability
If multiple components (cap, set screw, anti-splay ring) are used, then the locking and anti-splay functions are achieved, but the number of installation steps increases
Solution Approach 1:
The patent merges multiple functions into fewer components. The integrally formed cap-set screw combines the cap and set screw functions, while the flat bottom surface of the cap provides the anti-splay function that previously required a separate anti-splay ring. This reduction in component count directly reduces installation steps and time.
Solution Approach 2:
The cap is designed with multi-functionality: it provides the locking function through the integrally formed set screw, and simultaneously provides the anti-splay function through its flat bottom surface that contacts the rod. This universal design eliminates the need for separate specialized components, reducing installation complexity.
3Strength
If traditional implant profile is used, then the structural integrity is maintained, but patient discomfort increases due to implant size
Solution Approach 1:
By combining the cap and set screw into one component, the overall height and profile of the implant are reduced. The integral design eliminates the need for additional clearance space between separate components, creating a more compact structure that maintains structural integrity while reducing patient discomfort from implant size.
Data Source
AI summary
A anti-splay and rod securing member for use with vertebral implants of the hook, monoaxial and polyaxial types, in which a pair of arcuate upstanding internally threaded posts define a transverse opening for securing a rod to immobilize bone segments comprises an integrally formed cap and set screw with the cap having opposed curved side walls extending around the posts and flat end walls, the set screw being positioned within the posts and free to rotate within the cap so that rotation of the set screw will advance the cap and set screw in unison along the implant posts to clamp the rod and implant together. The implant may be provided with opposed catch basins for releasably securing the distal end of a rod persuasion instrument.