Spinal Closure Top Depth Limiter Tool
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Solution Overview
Problem
The challenge in spinal stabilization procedures is the over-torqueing of closure tops into pedicle screws, which can compress connecting members, making proper tensioning impossible and potentially causing movement issues with pedicle screws.
Innovation Solution
A depth limiter tool is introduced, featuring a housing with pins and a driver that transfers torque to the closure top, limiting its insertion depth by disengaging from the driver when a predetermined depth is reached, preventing further torque transmission and thus avoiding compression of the connecting member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If closure top is inserted deeper into pedicle screw to secure connecting member, then securing reliability is improved, but connecting member compression occurs making tensioning impossible
Solution Approach 1:
The patent applies preliminary action by pre-setting a depth limiter on the driver that automatically stops the closure top insertion at the correct depth. This prevents over-insertion before it occurs, ensuring the connecting member is not compressed while still achieving proper securing of the closure top to the pedicle screw.
2Strength
If higher torque is applied to secure closure top, then fastening strength is improved, but connecting member compression occurs
Solution Approach 1:
The patent implements feedback through the depth limiter mechanism that provides real-time monitoring of insertion depth. When the predetermined depth is reached, the limiter automatically prevents further torque transmission, creating a feedback loop that stops the process before harmful compression occurs while still achieving adequate fastening strength.
3Ease of operation
If closure top insertion depth is not controlled, then installation simplicity is maintained, but pedicle screw movement issues occur
Solution Approach 1:
The patent applies self-service through the automated depth limiter mechanism that independently controls insertion depth without requiring manual measurement or calculation by the surgeon. The system self-regulates the insertion process, maintaining simplicity of operation while ensuring stable positioning of the pedicle screw assembly.
Data Source
AI summary
An apparatus to limit a seating depth of a fastener can include a cylindrical housing, a pin, a driver, and a biasing element. The cylindrical housing can include a proximal portion couplable to a tool, a distal portion engageable with a workpiece, and a bore extending from an opening on the distal portion towards the proximal portion along a longitudinal axis of the housing. The pin can be secured to the housing and can extend radially inward into the bore. The driver can be translatable within the bore of the housing and can extend beyond the opening on the distal portion to engage the fastener. The driver can include a slot that can be engageable with the pin to receive a torque from the pin and can rotate with the housing to transfer the torque to a fastener when the pin engages the slot.