Intramedullary Rod Circumferential Shoulder Targeting Interface
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Solution Overview
Problem
Conventional targeting devices for intramedullary rods attach to the topmost surface, limiting the design and failing to effectively transmit torsional, bending, and impact forces during rod insertion, adjustment, and removal in orthopedic procedures.
Innovation Solution
The design of intramedullary rods features a circumferential flange and shoulder with a head extension made of different materials, allowing for a secure interface with a targeting device that can transmit forces effectively, while the head extension can be formed of a radiolucent material for improved positioning and reduced material strength requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional targeting devices attach to the topmost surface of the intramedullary rod, then the attachment is simple, but the design is limited and cannot effectively transmit high torsional moments, bending moments and impact forces
Solution Approach 1:
The intramedullary rod is divided into multiple segments: a head member with circumferential flange and shoulder, a shaft member, and a head extension. This segmentation allows each component to serve specific functions - the flange and shoulder provide attachment surfaces for force transmission, while the head extension can be made of radiolucent material for imaging, resolving the contradiction between strength and complexity.
Solution Approach 2:
The attachment interface is moved from the topmost surface to a circumferential flange and shoulder structure, adding dimensional complexity to the attachment geometry. This allows the targeting device to attach laterally rather than axially, providing better mechanical leverage for transmitting torsional and bending moments while maintaining design flexibility.
2Measurement precision
If the head extension is made of radiolucent material, then positioning is improved and material strength requirements are reduced, but the material selection is more limited
Solution Approach 1:
Different parts of the intramedullary rod are made from different materials optimized for their specific functions. The head extension is made of radiolucent material (such as PEEK or carbon fiber) to improve imaging and positioning, while the head member and shaft member can use traditional metals for strength. This local differentiation resolves the contradiction between positioning precision and manufacturing ease.
Solution Approach 2:
The intramedullary rod uses composite construction with the head extension made of radiolucent polymer or carbon fiber materials, while other portions use metal alloys. This composite approach allows each material to be selected for its optimal properties - radiolucency for imaging in the head extension region, and mechanical strength in load-bearing regions - thereby improving positioning without overly constraining overall material selection.
3Manufacturing precision
If the circumferential flange and shoulder are used for attachment, then the structural interface is enhanced for precise positioning, but the manufacturing process becomes more complex
Solution Approach 1:
The circumferential flange and shoulder are pre-formed as integral features of the head member during the manufacturing process. By establishing these attachment geometry features in advance rather than adding them later, the patent achieves precise positioning interfaces while minimizing the number of manufacturing steps, thus resolving the contradiction between positioning precision and manufacturing complexity.
Data Source
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AI summary
Intramedullary rods, targeting devices, intramedullary rod systems, intramedullary rod kits, and methods of placing an intramedullary rod in a bone are described. An intramedullary rod comprises a head member having a first end, a second end, and a body extending between the first end of the head member and the second end of the head member. The head member is formed of a first material and defines a circumferential flange and a circumferential shoulder. The circumferential flange extends radially outwardly from the head member and the circumferential shoulder is disposed between the first end of the head member and tire circumferential flange. A shaft member extends from the head member and a head extension is partially disposed over the head member. The head extension is formed of a second material that is different than the first material and has an end contacting the circumferential shoulder of the head member.