Smart Intramedullary Implant for Controlled Bone Lengthening
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Solution Overview
Problem
Existing limb lengthening techniques using external fixation frames are bulky, painful, and prone to infection, while intramedullary devices lack efficient control and monitoring mechanisms.
Innovation Solution
An adjustable implant with smart electronics, including a housing, movable adjustable portion, load cell, actuator, sensor, and controller, that allows precise, non-invasive adjustment and monitoring of bone lengthening, using magnetic drives and ultrasonic communication for real-time data exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external fixation frames are used for limb lengthening, then bone lengthening can be achieved, but the device becomes bulky and causes patient discomfort
Solution Approach 1:
The implant places the actuator, load cell, battery, and control electronics nested within the intramedullary canal space, with the actuator housed inside a compact motor housing that fits within the bone marrow cavity. This nesting approach consolidates all distraction mechanisms into a space-efficient configuration that eliminates external frame components.
Solution Approach 2:
The patent replaces the mechanical external fixation system with an intramedullary device that uses electromagnetic actuators (motor-driven or shape memory alloy-based) to produce distraction forces. This substitution eliminates the need for external pins, rods, and adjustment mechanisms, thereby improving patient comfort while maintaining bone lengthening capability.
2Reliability
If external fixation frames are used for limb lengthening, then bone lengthening can be achieved, but infection risk increases due to pin tracts
Solution Approach 1:
The implant extracts the distraction mechanism entirely from the external environment and places it within the intramedullary canal. By removing the need for skin-penetrating pins and external connection points, the design eliminates the primary infection pathways associated with external fixation while preserving the bone lengthening function.
Solution Approach 2:
The patent converts the previously harmful external pin tracts into a beneficial closed intramedullary system. The intramedullary placement transforms the infection risk from external pin sites into a protected internal environment, where the bone and implant interface is shielded from external contaminants while still allowing controlled distraction.
3Ease of operation
If intramedullary lengthening devices are used, then patient comfort is improved, but control and monitoring mechanisms become insufficient
Solution Approach 1:
The implant integrates multiple functions into a single device: the actuator provides distraction, the load cell measures forces, the battery supplies power, and the control electronics manage operation. This multi-functional integration achieves comprehensive control and monitoring capabilities within the constrained intramedullary space, preventing device complexity from becoming a limiting factor.
Solution Approach 2:
The patent incorporates a load cell that continuously measures distraction and compression forces, providing real-time feedback to the control system. This feedback enables closed-loop control where the actuator adjustments are based on actual measured forces, achieving precise control and monitoring despite the compact intramedullary configuration.
4Measurement precision
If precise control and monitoring are implemented in intramedullary devices, then treatment efficacy improves, but device complexity increases
Solution Approach 1:
The patent merges the actuator and load cell into a closely integrated assembly where the load cell is positioned to directly measure forces generated by the actuator. This merging reduces the number of separate components and connections needed, simplifying the overall device architecture while maintaining precise measurement capabilities through the close coupling of sensing and actuation elements.
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 controlled, precise, and minimally invasive bone lengthening with reduced patient discomfort and risk of infection, providing real-time data for medical professionals to optimize treatment.
Implementation Method 1
a load cell within the housing for measuring a load imparted on the implant during movement of the adjustable portion relative to the housing or during movement of a bone relative to the housing
Implementation Method 2
a sensor positioned adjacent to the actuator and configured to monitor an angular position of the actuator
Implementation Method 3
an actuator positioned within the housing and configured to cause movement of the adjustable portion relative to the housing
Data Source
AI summary
Aspects of the disclosure relate to an adjustable implant configured to be implanted into a patient that includes an adjustable portion moveable relative to a housing. The adjustable implant may include various smart components for enhancing operation of the implant. Smart components may include a controller for managing operations and a transducer for communicating ultrasound data with an external interface device. Additional smart components may include a load cell within the housing for measuring an imparted load; a sensor for measuring angular position of the adjustable portion; a dual sensor arrangement for measuring imparted forces; a reed switch; a half piezo transducer; and an energy harvester.