Adjustable External Fixation Struts for Extreme Frame Angulation
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Solution Overview
Problem
Current hexapod bone fixation systems require frequent and time-consuming changes of struts of varying lengths to achieve the necessary adjustments, which is cumbersome and costly, especially in situations requiring extreme initial angulations or rotations.
Innovation Solution
The development of adjustable strut assemblies for external fixation systems, which include an elongate tubular first end member, an intermediate member rotationally fixed and axially translatably within the first end member, and a second end member received within an axial cavity of the intermediate member, allowing for quick and easy length adjustments over a large range without the need for strut replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple struts of differing lengths are used to accommodate various clinical situations, then the system can handle extreme initial angulations or rotations, but the device complexity and inventory requirements increase significantly
Solution Approach 1:
The strut is divided into multiple segments (first end member, intermediate member, second end member) that can move relative to each other. This segmentation allows a single strut to provide multiple effective lengths and configurations, eliminating the need for multiple different struts in inventory while maintaining the ability to handle extreme angulations and rotations.
Solution Approach 2:
The strut transitions from a static fixed-length component to a dynamic adjustable-length component. The intermediate member can translate axially within the first end member, and the second end member can translate within the intermediate member, allowing the strut to dynamically adapt its length and configuration during bone correction procedures.
2Measurement precision
If struts are frequently swapped to achieve necessary adjustments, then the correct strut length can be selected for each stage, but the time and cost associated with strut changes increases
Solution Approach 1:
The adjustable length mechanism allows continuous or discrete adjustment of strut length without disassembly or replacement. The intermediate and end members can be repositioned along the strut's length, providing precise length selection for each correction stage while eliminating the time-consuming process of swapping entire struts.
Solution Approach 2:
Instead of discarding struts after use, the same strut can be recovered and reconfigured for subsequent correction stages. The adjustable mechanism allows the strut to be reused multiple times with different effective lengths, reducing both time and cost while maintaining precision in length selection.
3Adaptability or versatility
If a large inventory of struts with differing lengths is maintained, then all clinical situations can be accommodated, but the cost and confusion in utilization increases
Solution Approach 1:
A single adjustable strut design serves multiple functions that previously required multiple specialized struts. By incorporating axial translation mechanisms for both the intermediate member and the second end member, one strut can provide the functionality of multiple struts with different lengths, eliminating the need for large inventories and reducing utilization confusion.
Solution Approach 2:
The strut structure employs nesting where the intermediate member is received within the first end member, and the second end member is received within the intermediate member. This nested configuration allows compact storage and easy reconfiguration, replacing the need to store and manage multiple separate struts of different lengths.
4Length of moving object
If the minimum distance between platforms is reduced, then the platforms can be positioned closer together, but the adjustable range (maximum length) of struts is limited
Solution Approach 1:
The adjustable length mechanism allows the strut to dynamically change its effective length by translating the intermediate and end members. This enables the same physical strut to accommodate both minimum distances (when members are retracted) and maximum distances (when members are extended), providing a wide adjustable range without limiting either extreme.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The adjustable strut assemblies provide a significant reduction in the time and cost associated with strut changes, allowing for more efficient and precise adjustments during bone or tissue correction procedures, while also minimizing the need for inventory and reducing the complexity of the system.
Implementation Method 1
a second adjustment mechanism provided at the second free end portion of the intermediate member that is configured to selectively rotate the second end member with respect to the intermediate member and the threaded rod to axially translate the second end member relative to the intermediate member
Data Source
AI summary
Length-adjustable strut assemblies for external fixation systems, and corresponding external fixation systems, are disclosed. The strut assemblies include an elongate first and second end members, an elongate intermediate member, and first and second adjustment mechanisms. The intermediate member comprises a threaded rod fixedly coupled within an axial cavity thereof, and is rotatably fixed and axially translatably within an axial cavity of the first end member. An end portion of the second end member is received within the axial cavity of the intermediate member, and the second end member comprises an axial cavity threadably coupled with the threaded rod. The first adjustment mechanism is configured to selectively axially fix the intermediate member relative to the first end member. The second adjustment mechanism is configured to selectively rotate the second end member with respect to the threaded rod to axially translate the second end member relative to the intermediate member.