Femur Fixation Adjuster with Nested Rotation and Sliding Parts
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Solution Overview
Problem
Existing femur fixation apparatuses face challenges such as limited adjustability, complex manufacturing processes, and reliability issues due to specialized tools required for assembly, and difficulty in securely fixing fractured femurs with varying fracture types.
Innovation Solution
A femur fixation apparatus with an intramedullary nail and lag screw, featuring an adjuster with a sliding part and rotation part that allows for increased length without increasing the overall adjuster length, using engaging protrusions and receiving holes with inward flanges for stable connection, and interference prevention parts to accommodate different rotation prevention members and angles, simplifying manufacturing and enhancing operability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the sliding part length is increased to accommodate different rotation prevention members and angles, then the adjustability is improved, but the overall adjuster length increases
Solution Approach 1:
The rotation part is nested within the sliding part, allowing the rotation prevention member to be received inside the rotation part while the sliding part extends along the intramedullary nail. This nested configuration enables the sliding part to provide extended adjustability along the nail without requiring a proportional increase in the overall adjuster length, as the rotation mechanism is contained within the sliding structure.
Solution Approach 2:
The rotation part provides rotational adjustment in a circumferential dimension while the sliding part provides linear adjustment along the longitudinal dimension of the intramedullary nail. By utilizing both dimensional directions, the apparatus achieves comprehensive adjustability for different fracture types and angles without requiring excessive length in a single direction.
2Reliability
If specialized tools are used for assembling the head part and body part, then the connection reliability is improved, but the manufacturing complexity increases
Solution Approach 1:
The engaging protrusion on the body part automatically engages with the corresponding recess on the head part through simple axial insertion, allowing the components to self-align and self-secure without requiring specialized assembly tools. This self-service mechanism maintains connection reliability through the geometric constraint of the engaging features while dramatically simplifying the manufacturing and assembly process.
3Ease of manufacture
If the fitting groove and fitting piece structure is used, then the assembly is simplified, but the resistance between parts is reduced leading to potential detachment
Solution Approach 1:
The engaging protrusion features an asymmetric cross-sectional shape that corresponds to a matching asymmetric recess. This asymmetric geometry creates a mechanically interlocked connection where the protrusion fits into the recess with high resistance to detachment forces, while still allowing for simple tool-free assembly. The asymmetric shape ensures proper orientation and provides inherent mechanical engagement without requiring additional fastening elements.
Data Source
AI summary
A femur fixation apparatus includes an intramedullary nail, a lag screw that is inserted through the intramedullary nail, and an adjuster 4 fitted in the intramedullary nail. The adjuster includes a sliding part unrotatable and slid-movable in a longitudinal direction relative to the intramedullary nail and a rotation part rotatably connected to the sliding part. A lower end of the rotation part is formed with an inward flange part and a cutout. An engaging part of an engaging protrusion formed to the sliding part is inserted into the rotation part via the cutout from the radial direction, and the engaging part is supported by the inward flange part from the bottom, rotatably connecting the sliding part to the rotation part.