Low Profile Orthopedic Fastener with Polyaxial Locking
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Solution Overview
Problem
Existing orthopedic fasteners face challenges in resisting migration due to rotational and translational forces in spinal surgery, and they often 'back out' over time, leading to implant disconnection and migration from the treatment area.
Innovation Solution
A low profile fastening assembly with a polyaxial locking mechanism that securely connects orthopedic devices to bone tissue, featuring a fastener with a neck portion matching the diameter of the head and shank, and a locking mechanism using modified buttress threads and a polyaxial locking head to prevent disengagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional orthopedic fasteners are used to secure implants to bone tissue, then the implants can be fixed to bone, but the fasteners may back out over time due to rotational and translational forces from spinal loading and movement
Solution Approach 1:
The locking mechanism applies a preliminary counteracting force to prevent the fastener from backing out. The lock engages with the fastener shaft to provide resistance against rotational and translational forces before they can cause disengagement, thereby maintaining fastener retention and position stability over time
Solution Approach 2:
The locking mechanism is pre-configured to engage with the fastener shaft at a predetermined position. This preliminary engagement ensures that the fastener is secured against migration forces before clinical use begins, preventing backout due to spinal loading and movement
2Strength
If standard profile fasteners are used for spinal fixation, then adequate fixation strength can be achieved, but patient comfort and anatomic compatibility are reduced
Solution Approach 1:
The fastener design implements local quality by creating a low-profile head portion that minimizes the protruding dimensions while maintaining the threaded shaft strength for adequate fixation. The head diameter is reduced to improve patient comfort and anatomic compatibility, while the shaft maintains sufficient thread engagement to provide required fixation strength
Data Source
AI summary
A fastener assembly that can be used for the fixation or anchoring of orthopedic devices or instruments to bone tissue. In particular, a low profile variable angle or fixed angle fastener assembly is able to securely connect the orthopedic device to bone tissue. The fastener assembly may have a locking mechanism that will quickly and easily lock the fastener assembly with respect to the orthopedic device.