Implantable Gear Lock Mechanism to Prevent Back-Driving
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Solution Overview
Problem
Implantable distraction and compression devices experience loss of distraction or compression due to back-driving under load, compromising their efficiency and effectiveness in generating forces.
Innovation Solution
A lock mechanism comprising a keeper and a driven gear system that allows rotational fixation and axial translation, preventing rotation under load and enabling controlled distraction or compression procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a distraction or compression device is used to perform bone lengthening or compression procedures, then the device can generate distraction or compression forces, but the device experiences back-driving under load causing loss of previously achieved distraction or compression
Solution Approach 1:
The lock mechanism transitions between locked and unlocked states dynamically. During distraction/compression procedures, the keeper is in the unlocked state allowing rotation. When procedures are complete, the lock engages to prevent back-driving. This dynamic state change allows the device to perform its function while preventing energy loss during idle periods.
Solution Approach 2:
The lock mechanism is extracted as a separate functional component from the main drive system. The keeper, lock tooth, and biasing element form a distinct subsystem that can engage or disengage independently, allowing the drive gear to rotate freely when needed while providing locking protection when required.
2Reliability
If a lock mechanism is added to prevent back-driving, then loss of distraction or compression is prevented, but the device complexity increases
Solution Approach 1:
The lock mechanism is self-actuating through the biasing element (spring) that automatically pushes the keeper into the locked position. The mechanism locks itself without requiring external actuation, and the simple geometry of the drive gear teeth provides the natural engagement points for the lock tooth, reducing the need for additional complex components.
Solution Approach 2:
The lock mechanism is integrated with the existing drive gear structure. The lock tooth engages with the teeth of the drive gear, combining the locking function with the existing gear geometry. The keeper is positioned to interact with both the drive gear and the biasing element, merging multiple functions into a compact arrangement.
3Reliability
If the keeper is configured to prevent rotation under load, then back-driving is prevented, but the mechanism must allow rotation during distraction or compression procedures
Solution Approach 1:
The lock mechanism transitions between locked and unlocked states dynamically. During distraction/compression procedures, the keeper is in the unlocked state allowing rotation. When procedures are complete, the lock engages to prevent back-driving. This dynamic state change allows the device to perform its function while preventing energy loss during idle periods.
Solution Approach 2:
The biasing element预先 applies force to push the keeper into the locked position, creating a preliminary locking action. This pre-existing bias ensures that as soon as the procedure is complete and rotation stops, the lock immediately engages to prevent any back-driving, countering the potential harmful effect before it can occur.
Data Source
AI summary
Disclosed herein are lock mechanisms configured for locking and unlocking rotation of a driver and a driven gear system in implantable distraction and compression systems, and implantable medical devices and implantable distraction and compression systems including such lock mechanisms. The lock mechanisms include a keeper that is configured to move from a locked position to an unlocked position in response to a rotation of the driver, wherein, in the locked position, the keeper is configured to resist rotation of the driven features and the driver under a load on the driven features, and in the unlocked position, permits rotation of the drive gear and the driver.