Strike Instrument Rotating Abutment Locking Mechanism
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Solution Overview
Problem
Existing intramedullary nail insertion systems face challenges with secure attachment of strike instruments to insertion handles, as threaded connections can loosen under impaction force, potentially damaging the connection and compromising the stability of the nail insertion process.
Innovation Solution
A strike instrument with a shaft and abutment that rotates between two orientations, securely locking into the insertion handle via a non-threaded connection, ensuring stability during impact and preventing accidental removal, utilizing a lock mechanism to maintain engagement with the handle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a threaded connection is used to attach the strike instrument to the insertion handle, then the attachment can be easily assembled and disassembled, but the connection can loosen under impaction force, compromising stability
Solution Approach 1:
The connection system is divided into separate functional components: an abutment with locking features on the strike instrument, a corresponding recess in the insertion handle, and a separate lock component. This segmentation allows each element to perform its specific function - the abutment provides structural engagement, while the lock provides secure fixation resistant to impaction forces.
Solution Approach 2:
The abutment is designed with locking features that preliminarily engage with the recess before the final locking action. This preliminary engagement positions the components correctly and prepares the connection for the subsequent locking step, ensuring proper alignment and reducing the risk of misassembly.
Solution Approach 3:
The connection system transitions from a static threaded interface to a dynamic two-stage process: initial insertion of the abutment into the recess, followed by rotation or engagement of the lock component. This dynamic approach allows the connection to evolve from a preliminary state to a fully secured state capable of withstanding impaction forces.
2Reliability
If a non-threaded connection with lock mechanism is used, then the connection stability during impaction is improved, but the device complexity increases
Solution Approach 1:
The abutment and lock features are merged into an integrated system where the abutment on the strike instrument combines with the recess in the insertion handle to form a unified connection interface. This merging reduces the need for separate complex components while maintaining connection stability during impaction.
Solution Approach 2:
The abutment and recess are designed to self-align and self-engage during assembly. The geometric features guide the components into proper alignment automatically, eliminating the need for complex alignment mechanisms or adjustment procedures, thereby reducing overall device complexity while ensuring reliable connection.
3Reliability
If the abutment is designed to rotate between two orientations, then the secure locking is achieved, but the ease of operation decreases
Solution Approach 1:
The abutment and recess feature asymmetric geometric shapes that only fit together in specific orientations. This asymmetry provides tactile and visual cues to the operator about the correct orientation, making the rotation and locking action intuitive rather than arbitrary, thereby reducing the operational complexity despite the additional rotation step.
Solution Approach 2:
The asymmetric locking features may incorporate visual indicators such as color coding, alignment marks, or contrasting surface finishes that change appearance or become visible only in the correct orientation. This helps the operator quickly identify when proper alignment is achieved, simplifying the attachment process despite the rotational requirement.
Data Source
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AI summary
In one embodiment, a strike instrument that couples to an insertion handle of an intramedullary nail has a shaft that extends along a shaft axis, and an abutment that extends outward relative to the shaft. The abutment is rotationally fixed to the shaft such that the shaft can rotate the abutment between a first orientation, where the abutment can be removed or inserted into the insertion handle, and a second orientation, where the abutment forms an interference with the insertion handle that prevents the abutment from being removed from the handle. The strike instrument includes a strike surface that can transfer an impaction force to the insertion handle, and a lock that engages the insertion handle so as to prevent the abutment from rotating from the second orientation to the first orientation after the abutment is rotated within the insertion handle from the first orientation to the second orientation.