Ratcheting Strut for Fracture Fixation Length Adjustment
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Solution Overview
Problem
Current fracture fixation devices lack effective mechanisms for length adjustment during fracture reduction, which is crucial for proper alignment and healing of bones, especially in complex fractures spanning long bones or crossing joints like the knee.
Innovation Solution
A ratcheting strut system comprising a ratchet box, a first tube with ratchet teeth, a second tube optionally coupled to a fixation adapter, and a threaded rod with a nut, allowing for precise longitudinal adjustment by engaging and disengaging ratchet teeth to incrementally change the length of the fixation device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed-length fixation device is used, then the device structure is simple, but the device cannot accommodate various fracture configurations and cannot provide proper alignment for different bone distances
Solution Approach 1:
The fixation device is divided into multiple telescopic segments (first tube, second tube, third tube) that can slide relative to each other along the longitudinal axis. Each segment contains ratchet teeth that engage with corresponding teeth on adjacent segments, allowing the device to be adjusted to different lengths while maintaining structural integrity. This segmentation enables the device to adapt to various fracture configurations without requiring completely different device designs.
Solution Approach 2:
The device transitions from a fixed-length structure to a dynamic, adjustable-length structure through the telescopic mechanism. The tubes can slide relative to each other to change the overall length of the device, and the ratchet locking mechanism allows the device to be locked at specific lengths. This dynamic capability enables the same device to accommodate different fracture types and bone distances.
2Adaptability or versatility
If a telescopic adjustment mechanism is added to allow length adjustment, then the device can accommodate various fracture configurations, but the device complexity increases
Solution Approach 1:
The telescopic mechanism employs a nested structure where the second tube is positioned inside the first tube, and the third tube is positioned inside the second tube. This nested arrangement allows multiple adjustment stages within a compact space, reducing the overall device complexity compared to using separate adjustment mechanisms for each tube. The ratchet locking features are also integrated into the nested structure, with each tube having its own locking mechanism that engages with the adjacent tube.
3Manufacturing precision
If ratchet teeth are used for incremental length adjustment, then precise length control is achieved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The ratchet teeth are designed to engage with each other in a self-locking manner, where the inclined surfaces of the teeth automatically lock when the tubes are pushed together, and allow incremental adjustment when force is applied in the opposite direction. This self-service mechanism eliminates the need for additional locking components such as screws or clips, simplifying the manufacturing process while maintaining precise length control. The ratchet mechanism provides inherent feedback and locking action without requiring complex control systems.
4Measurement precision
If multiple tubes with ratchet teeth are used for incremental adjustment, then precise and incremental length control is achieved, but the device complexity increases
Solution Approach 1:
The device combines multiple functional elements into an integrated telescopic structure. The three tubes are merged in a nested configuration, sharing common longitudinal axes and integrated ratchet locking mechanisms. The fixation adapters at each end combine the functions of connection to bone and provision of the telescopic interface. This merging reduces the number of separate components compared to using independent adjustment mechanisms, while still achieving precise incremental length control through the coordinated action of the ratchet teeth on all three tubes.
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
Enables precise and incremental length adjustment of fracture fixation devices, facilitating better alignment and stabilization of bones during healing, accommodating various fracture configurations and providing flexibility in treatment.
Implementation Method 1
The ratchet box includes a first lever repositionable between an engaged position and a disengaged position, the first lever comprising the second set of ratchet teeth of the ratchet box, the second set of ratchet teeth on the first lever engage the first set of ratchet teeth on the first tube in the engaged position
Implementation Method 2
a threaded rod operatively coupled to a nut and a first fixation adapter, the threaded rod repositionably mounted to the first tube, where the nut is operatively coupled and repositionable with respect to the first tube
Data Source
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AI summary
A ratcheting strut comprising: (a) a ratchet box including a through passage; (b) a first tube sized to extend at least partially through the passage, the first tube including teeth that engage corresponding teeth of the ratchet box; (c) a second tube mounted to the ratchet box in parallel with the first tube, the second tube operatively coupled to a second fixation adapter; and, (d) a threaded rod operatively coupled to a nut and a first fixation adapter, the threaded rod repositionably mounted to the first tube, where the nut is operatively coupled and repositionable with respect to the first tube.