Expandable Bone Fixation Housing with Expansion Bolt
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Solution Overview
Problem
Current bone fixation technologies face challenges in achieving durable long-term fixation, especially in scenarios with short bone segments or cortical bone, due to limited osseointegration surface area and potential for surgical error in reproducing pressure between the device and bone, leading to high risks of early failure and prolonged weight-bearing restrictions.
Innovation Solution
An expandable osseointegration bone fixation apparatus with a metallic housing containing diametrically opposed sections and an expansion bolt, allowing for incremental expansion and compression against both the inside and leading edge of the bone, utilizing microscopic pores and angled tapers for enhanced osseointegration, along with optional features like grooves, threaded collars, and transverse bolts for increased stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If manual impaction is used to produce pressure between the device and host bone, then compression force is achieved, but surgical precision and reliability deteriorate due to difficulty in reproducing consistent pressure
Solution Approach 1:
The device transitions from a static implant to a dynamic system that actively generates and adjusts compression force through spring-loaded mechanisms and expandable components, allowing the force to be applied consistently without relying on manual impaction precision
Solution Approach 2:
The implant self-regulates compression force through internal spring mechanisms and expandable structures that automatically adjust to achieve optimal contact pressure between the device and bone, eliminating the need for precise manual force application
2Force
If spring-loaded mechanisms are used to produce compression, then compression force is achieved, but osseointegration surface area deteriorates because compression is limited to only the leading edge of the bone
Solution Approach 1:
The compression mechanism is divided into multiple independent spring-loaded sections distributed along the length of the device, allowing compression force to be applied at multiple locations simultaneously, thereby expanding the osseointegration surface area beyond just the leading edge
Solution Approach 2:
The device transitions from applying compression in one dimension (leading edge only) to applying compression across multiple dimensions along the bone interface, utilizing distributed springs and expandable structures to engage a larger surface area
3Device complexity
If fixed-size housing is used for bone fixation, then device simplicity is maintained, but adaptability deteriorates when dealing with varying bone configurations such as short segments or cortical bone
Solution Approach 1:
The housing transitions from a fixed-size structure to a dynamic, expandable structure that can adjust its dimensions to accommodate different bone configurations, including short segments and cortical bone, while maintaining a relatively simple base design
Solution Approach 2:
The device employs nested components including telescoping sections and expandable structures that allow the housing to adapt to various bone sizes and shapes while maintaining a compact stored configuration
4Device complexity
If limited osseointegration surface area is used, then device simplicity is maintained, but fixation reliability deteriorates leading to high risk of early failure and prolonged weight-bearing restrictions
Solution Approach 1:
The device incorporates porous metallic surfaces with optimized pore structures that significantly increase the osseointegration surface area, allowing bone progenitor cells to migrate into and form bone within the porous structure, thereby enhancing fixation reliability while maintaining a relatively simple overall device design
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 apparatus enables durable and reliable bone fixation by promoting osseointegration across a larger surface area, reducing surgical errors, and allowing for earlier weight-bearing and lower risk of early failure, while accommodating various bone configurations and applications.
Implementation Method 1
An expansion bolt 110 at the centerline axis CL produces a sliding motion between the two sections 106, 108
Implementation Method 2
The apparatus 102 is compressed against the affected bone B by twisting the expansion bolt 110 causing horizontal expansion of the housing 102 while simultaneously advancing the tapers 118 further into the affected bone
Implementation Method 3
a plurality of microscopic pores along the leading end 120 of the housing 102 and along the outer aspect of the tapers 118 enable osseointegration between the bone B and the several metallic surfaces of the apparatus 100
Data Source
AI summary
A cortical shaft bone fixation apparatus includes a housing having a leading portion and a trailing portion, the leading portion configured to fit within a diameter of an affected cortical shaft bone, the leading portion having first and second sections. The apparatus further includes an expansion mechanism adapted to transition the first and second sections from a first position to a second position, the first and second sections providing an outward force against the inside surface of the cortical shaft bone when the first and second sections transition from the first position to the second position, the trailing portion of the housing abutting a leading end of the affected cortical shaft bone. The trailing portion of the housing includes a pair of angled tapers extending inwardly toward each other to a minimum separation distance at an extreme end of the housing.