Bone Distraction System Asymmetric Torque Ratchet
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Solution Overview
Problem
Current bone distraction systems lack the ability to efficiently and precisely control the directional adjustment of bone segments post-osteotomy, often requiring high torque values for rotation in both directions, which can be cumbersome for surgeons and may lead to incorrect adjustments during the healing process.
Innovation Solution
A bone distraction system featuring a distractor with a screw and sleeve configuration that allows rotation in one direction with a first torque value and in the opposite direction with a higher second torque value, utilizing a ratchet mechanism to prevent unintended rotation until sufficient torque is applied, ensuring precise control over bone segment adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a typical distractor is used that allows adjustment in both directions with equal ease, then the device is easy to operate, but it increases the risk of incorrect adjustments by patients or surgeons
Solution Approach 1:
The screw mechanism is designed with asymmetric torque requirements: a first torque value for rotation in a first direction and a second torque value (greater than the first) for rotation in a second direction. This asymmetry prevents accidental or incorrect adjustments while still allowing intentional adjustments when sufficient torque is applied. The ratchet mechanism embodies this asymmetry by having different engagement characteristics for clockwise versus counter-clockwise rotation.
2Reliability
If a ratchet mechanism with different torque values for different directions is implemented, then the reliability of adjustment control is improved, but the device complexity increases
Solution Approach 1:
The ratchet mechanism is integrated into the existing distractor body structure, merging the directional control function with the overall device architecture. The screw threads and ratchet teeth are incorporated as integral components rather than separate add-on mechanisms, reducing overall device complexity while maintaining the differential torque control capability.
3Reliability
If high torque values are required for rotation in both directions, then the reliability of preventing unintended movement is improved, but the ease of operation deteriorates
Solution Approach 1:
The mechanism applies different torque thresholds locally for different rotational directions: a lower first torque value for the first direction of rotation and a higher second torque value for the second direction. This local differentiation allows easy intentional adjustments in the primary direction while providing stronger protection against unintended movements in the opposite direction.
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
This system enables precise and controlled adjustments of bone segments, reducing the risk of incorrect manipulations and improving surgical outcomes by ensuring that rotations occur only when appropriate torque is applied, thus enhancing the efficacy of bone distraction procedures.
Implementation Method 1
the screw is rotatable relative to the sleeve about an axis of rotation in a first direction of rotation only upon application of a first torque to the screw in the first direction of rotation
Implementation Method 2
a ratchet mechanism to prevent unintended rotation until sufficient torque is applied
Data Source
AI summary
Instrumentation and methods are provided for orthopedic surgery, including bone distraction. The application describes a bone distraction system that can be used to both distract and retract, or increase and decrease, a gap between first and second bone segments. The instrumentation can include any one of, or any combination of, a distractor, a ratchet, a first footplate, a second footplate, a first torque application instrument, and a second torque application instrument.