Cam Lock Setscrew Retention for Spine Plate Implants
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Solution Overview
Problem
Existing spine plate implants face the issue of bone screw backout, compromising the integrity of the orthopedic implant and its ability to perform its intended function, as previous designs have been deficient in addressing this problem effectively.
Innovation Solution
The spine plate implant utilizes cam lock setscrews, which are configured to allow bone screws to pass through in an unlocked position and retain them in a locked position, preventing backout, with external threads and teeth providing rotational stability and engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional spine plate implants are used, then the implant can be installed and initially functions, but bone screws back out compromising the integrity and reliability of the implant
Solution Approach 1:
The retention mechanism is segmented into distinct functional elements: cam lock setscrews with external teeth, bone screw bores with recesses, and complementary engagement features. This segmentation allows each component to perform its specific function while maintaining overall system reliability and preventing bone screw backout.
Solution Approach 2:
The cam lock setscrew is nested within the bone screw bore structure, with the setscrew positioned inside the bore and its external teeth engaging with the bone screw head. This nested configuration allows the retention mechanism to be integrated within the existing plate architecture without significantly increasing external complexity.
2Reliability
If cam lock setscrews with external teeth are used to prevent bone screw backout, then reliability improves, but manufacturing complexity increases
Solution Approach 1:
The cam lock setscrew combines multiple functions into a single component: the threaded body provides rotational engagement with the bone screw, while the external teeth provide anti-backout retention. This merging of functions into one integrated part simplifies manufacturing compared to using separate retention components, and allows for economical production through standard threading and tooth formation processes.
3Reliability
If the cam lock setscrew has external teeth for engagement, then bone screw retention is improved, but the complexity of the setscrew design increases
Solution Approach 1:
The external teeth are positioned locally at specific regions of the cam lock setscrew where engagement with the bone screw head is required. This localized feature concentration means the complex toothed structure exists only where needed for retention, while the rest of the setscrew maintains simple threaded geometry for easy installation and removal, thereby limiting the increase in overall device complexity.
Data Source
AI summary
A spine plate implant utilizes cam lock setscrews to retain bone screws in the plate once implanted. A cam lock setscrew is received in a setscrew pocket adjacent a configured bone screw bore of the plate and is configured to allow a bone screw to be received in the plate when in an unlocked rotational position, and to retain the received bone screw when in a locked rotational position. The bone screw may include a tang that allows engagement with external teeth of the cam lock setscrew when the cam lock setscrew is rotated into the locked position. Once the cam lock setscrew is in the locked position, the bone screw is inhibited from backing out of the bone screw bore. When the cam lock setscrew is in the unlocked position, a flat of the cam lock setscrew is adjacent the bone screw tang so the bone screw may be removed.