Subcutaneous Bone Distractor With Ratchet Expansion for Small Bones
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Solution Overview
Problem
Existing bone lengthening techniques are complex, invasive, and unsuitable for small bones, often leading to complications and are not cost-effective for smaller bones such as those in children or adults.
Innovation Solution
A subcutaneous bone distraction device with a push-button expansion system and modular actuators, including a first and second block portion with opposing rails and ratchet sections, allowing incremental and sliding advancement, and optionally using shape memory alloys for remote actuation, to elongate bones without external fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external fixation through complex scaffold arrays is used, then bone segments can be distracted apart, but the procedure becomes invasive and complicated with frequent complications
Solution Approach 1:
The invention extracts and eliminates the complex external scaffold arrays from the bone lengthening system. Instead of using bulky external fixation devices, the patent employs a simple intramedullary distractor that fits within the bone's medullary canal, removing the disturbing external components while maintaining the core function of bone distraction.
Solution Approach 2:
The intramedullary distractor is nested within the bone's medullary canal, utilizing the existing bone structure as a housing. This nesting approach eliminates the need for external scaffolds by placing the distraction mechanism inside the bone itself, reducing overall system complexity and invasiveness.
2Ease of operation
If motorized intramedullary nails with implanted antennas are used, then controlled bone lengthening is achieved, but the surgical procedure becomes more invasive and complex
Solution Approach 1:
The invention replaces complex motorized systems with a purely mechanical intramedullary distractor. Instead of using implanted motors, batteries, and antennas for controlled lengthening, the device uses a mechanical expansion mechanism that can be activated through simple means, eliminating electronic components while maintaining controllability.
Solution Approach 2:
The intramedullary distractor is designed to be self-contained and self-actuating. The device includes an expansion mechanism that can be activated without external power sources or complex control systems, allowing the device to perform its function autonomously once implanted.
3Force
If large intramedullary distractors are used, then sufficient driving distraction force is achieved, but the device cannot be integrated into small bones
Solution Approach 1:
The intramedullary distractor is segmented into multiple expandable sections or struts that can be collapsed during implantation and then expanded sequentially. This segmentation allows the device to be inserted in a compact state into small bones and then expanded to generate sufficient distraction force, adapting to different bone sizes including pediatric and small adult bones.
Solution Approach 2:
The device transitions from a static large-sized distractor to a dynamic system that can change its dimensions. The intramedullary distractor features an expandable structure that allows it to be small during implantation and then grow to the required size for generating adequate distraction force, making it suitable for bones of varying sizes.
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
Provides a less invasive and more affordable method for elongating small bones, reducing complications and improving surgical outcomes by using a subcutaneous device with sensors for controlled bone lengthening.
Implementation Method 1
at least one length of shape memory alloy (2207a) connected to the first floating element (2207') and to the second floating element (2207''); activation of the at least one length of shape memory alloy (2207a) forces the first floating element (2207') to come closer to the second floating element (2207'')
Implementation Method 2
a spring (2208) connected to the first floating element (2207') and to the second floating element (2207''), wherein activation of the at least one length of shape memory alloy (2207a) forces the first floating element (2207') to come closer to the second floating element (2207''), compressing the spring (2208) and wherein the released energy of the spring (2208) causes the second floating element (2207'') to move away the first floating element (2207')
Implementation Method 3
a first block portion (3) including a pair of opposing rails (3a) and a pair of opposing ratchet sections (4); and a second block portion (3') that slidably mates with the first block portion (3) and includes a first locking pawl (5)
Data Source
AI summary
The present disclosure provides implantable bone distraction devices and methods of using same to elongate a bone.