Osmotic Expandable Bone Implant for Predictable Lengthening
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Solution Overview
Problem
Existing expandable bone implant systems require multiple invasive surgical interventions to lengthen as the patient grows, lacking a predictable and efficient method for distraction over time.
Innovation Solution
An expandable bone implant system comprising a first body with an internal cavity and osmotic chamber, a perforated cap, a semi-permeable member, a second body, and a restrictor, which allows fluid flow to facilitate movement of the second body relative to the first body, enabling controlled expansion without the need for repeated surgeries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If manually movable plates or rods with distraction instruments are used, then the implant can be lengthened, but multiple invasive surgical interventions are required
Solution Approach 1:
The patent replaces manual mechanical distraction systems with an osmotic-driven fluid absorption system. The implant contains an osmotic chamber that absorbs body fluids through a semi-permeable membrane, generating internal pressure that automatically drives the distraction mechanism to lengthen the implant over time without requiring external mechanical intervention or repeated surgical procedures.
Solution Approach 2:
The implant incorporates an osmotic mechanism that automatically absorbs interstitial fluid from the surrounding bone tissue through a semi-permeable membrane. This self-powered system converts the osmotic pressure gradient into mechanical work, enabling the implant to lengthen itself continuously as the patient grows, eliminating the need for repeated surgical interventions.
2Length of moving object
If magnets and motors are used for distraction, then the implant can be lengthened, but the device complexity increases
Solution Approach 1:
The patent eliminates complex electrical actuation systems (motors, magnets, batteries, control circuits) by replacing them with a passive osmotic mechanism. The distraction force is generated automatically through fluid absorption across a semi-permeable membrane, converting chemical osmotic energy directly into mechanical expansion without requiring any active control systems or power sources.
Solution Approach 2:
The patent uses a hydraulic/osmotic principle where body fluids are absorbed through a semi-permeable membrane into an osmotic chamber, creating internal fluid pressure. This pressure acts as the actuating force to drive the distraction mechanism, replacing complex mechanical or electrical systems with a simple fluid-pressure-based expansion mechanism.
3Adaptability or versatility
If expandable bone implant systems are used, then the implant can accommodate growth, but predictable distraction control is difficult to achieve
Solution Approach 1:
The patent incorporates a restrictor mechanism that can be adjusted to control the rate of fluid absorption by the osmotic chamber. By regulating the fluid flow through the semi-permeable membrane, the system provides controlled and predictable distraction rates that can be tailored to match the patient's growth rate, enabling precise adaptation without over- or under-expansion.
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 system allows for predictable and continuous expansion of the implant, accommodating patient growth without the need for multiple surgical interventions, thereby improving the efficacy and reducing the morbidity associated with traditional expandable bone implant systems.
Implementation Method 1
a semi-permeable member disposed between the cap and the internal cavity... fluid flow through the cap from the semi-permeable member to the osmotic chamber
Data Source
AI summary
An expandable bone implant system comprises a first body defining an internal cavity, a perforated cap configured to attach to a first side of the first body to enclose the internal cavity, a semi-permeable member disposed at least partially between the cap and the internal cavity, a second body having a sealing end positioned within the internal cavity of the first body, a free end extending from a second side of the first body, the second body being moveable relative to the first body, and a restrictor controlling fluid flow through the perforated cap. The first body includes an osmotic chamber defined within the internal cavity which is fluidly connected to the semi-permeable member such that fluid flow through the cap from the semi-permeable member to the osmotic chamber in a first direction facilitates movement of the second body in the first direction relative to the first body.