Orthopedic Dynamization Device with Threaded Adjustment Mechanism
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Solution Overview
Problem
Existing external fixation devices face challenges in achieving controlled destabilization for bone healing, as current methods often result in wide variations in instability and fail to effectively limit dynamization to a desired direction or degree of displacement axis of movement.
Innovation Solution
A dynamization device with a sleeve, shaft, and biasing member that allows for varying degrees of compressive movement, featuring a dial with internal and external threads, a contact feature, and a biasing member that can be adjusted to provide specific amounts of dynamization, ensuring controlled movement and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dynamization methods are used (removing bars, sliding bars away, removing pins, releasing tension), then destabilization for bone healing is achieved, but wide variations in instability level occur and control over direction/degree of displacement is lost
Solution Approach 1:
The connection rod transitions from a static rigid structure to a dynamic system with controlled mobility. The rod allows axial compression and expansion movements through the interaction of the biasing member (spring) and threaded engagement mechanisms, enabling controlled destabilization while maintaining directional control along the rod's axis.
Solution Approach 2:
The system controls the degree of dynamization by adjusting parameters such as the pre-compression force of the biasing member, the threaded engagement depth, and the clearance between rod sections. These parameter adjustments allow precise control over the amount of displacement and instability introduced during bone healing.
2Reliability
If rigid fixation is maintained for complete bone consolidation, then structural stability is ensured, but controlled destabilization needed for accelerated healing is prevented
Solution Approach 1:
The system enables periodic adjustment of fixation stability. Initially, the rod provides rigid fixation for immediate post-operative stability. As healing progresses, the biasing member can be adjusted to introduce controlled micro-movements and instability, creating a periodic transition from stable to dynamically unstable states that stimulate callus formation while maintaining overall structural integrity.
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 dynamization device enables precise control over the degree of dynamization, allowing for targeted bone healing by providing adjustable compressive movement, thereby enhancing the stability and effectiveness of bone healing processes.
Implementation Method 1
a biasing member disposed within the inner recess of the sleeve and around the shaft, wherein the biasing member is compressed between the contact feature and a shoulder within the inner recess of the sleeve
Implementation Method 2
a dial having a body configured to be disposed at least partially within the inner recess; an annular lip having a diameter greater than a diameter of the inner recess of the sleeve; and a plurality of internal threads, wherein the plurality of internal threads are configured to mate with the plurality of external threads of the shaft
Data Source
Figure 1~2
Figure 3A~4
Figure 5A
AI summary
A dynamization device may comprise a sleeve, a shaft, a dial, a contact feature, and a biasing member. The shaft may comprise an interior section partially within an inner recess of the sleeve; a flat surface on the interior section of the shaft; and a plurality of external threads on the interior section of the shaft. The dial may comprise a body disposed partially within the inner recess; an annular lip; and internal threads secured to external threads of the shaft. The contact feature has an annular geometry disposed within the inner recess of the sleeve. The biasing member may be disposed around the interior section of the shaft, and disposed between the contact feature and a shoulder within the inner recess of the sleeve. Rotation of the annular lip may provide for compressive movement of the biasing member relative to the sleeve and shaft.