Motor-Driven Fracture Fixator With Closed-Loop Micromotion Control
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Solution Overview
Problem
Current fracture fixation methods using relative stability implants lack controllable micromotion parameters, leading to inconsistent clinical results, high nonunion rates, and delayed union due to improper micromotion application.
Innovation Solution
An external fixator system utilizing an electronic linear servo motor actuator and micromotional unit to produce controllable and programmable micromotion at the fracture site, adjusted by a closed-loop controller based on displacement sensors, ensuring accurate micromotion parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If relative stability implants are used to induce micromotion at fracture site, then callus formation is promoted and bone healing is accelerated, but micromotion parameters are uncontrollable leading to high nonunion rates and delayed union
Solution Approach 1:
The patent applies dynamics by transitioning from static fixation to dynamic micromotion. The micromotional unit with motor actuator enables controlled dynamic movement between fracture fragments, allowing the system to adapt micromotion parameters (amplitude, frequency, waveform) to optimal healing conditions while maintaining reliability through programmable control
Solution Approach 2:
The patent implements feedback control through displacement sensors that monitor actual micromotion at the fracture site and feed this information back to the controller. This closed-loop feedback system ensures micromotion parameters remain within optimal ranges, preventing both excessive movement (causing nonunion) and insufficient movement (delaying healing), thereby resolving the reliability-productivity contradiction
2Ease of operation
If conventional dynamic fixators rely on patient bearing weight to produce micromotion, then micromotion is generated, but micromotion is uncontrollable and inconsistent
Solution Approach 1:
The patent replaces the passive mechanical system (relying on patient weight-bearing) with an active electromechanical system. The motor actuator in the micromotional unit provides controlled micromotion independent of patient activity, while sensors and controllers precisely measure and regulate micromotion parameters, resolving the contradiction between ease of operation and measurement precision
3Stability of the object's composition
If absolute stability is provided by dynamic compression plate, then primary fracture healing occurs without callus formation, but healing time is extended and re-fracture rate increases
Solution Approach 1:
The patent applies periodic action by implementing cyclic micromotion at the fracture site. The motor actuator produces rhythmic movement with controlled amplitude and frequency, creating optimal mechanical stimulation for callus formation while maintaining overall stability. This periodic micromotion accelerates healing compared to absolute stability, resolving the contradiction between stability and healing duration
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
Facilitates controlled micromotion that accelerates bone healing, reduces nonunion rates, and provides real-time feedback for optimal healing conditions, reducing patient burden by being demountable.
Implementation Method 1
an electronic linear servo motor actuator and micromotional unit are designed to transform electric energy into reciprocating displacement between two fracture fragments
Implementation Method 2
adjusted by a closed-loop controller based on displacement sensors
Data Source
Figure 1~2
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Figure 5~6
AI summary
Devices and methods for treating bone fractures involving a micromotional unit (6) that produces reciprocating displacement between two fracture fragments (1) to thereby apply controllable micromotion to a fracture site.