Multi-set Screw Inserter with Ratcheted Sleeve
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Solution Overview
Problem
Current surgical instruments for delivering set screws to secure rods or spinal fixation elements to bone anchors during spine surgery require multiple passes between surgeons and assistants, increasing operative time and complexity, and risking mishandling of components.
Innovation Solution
A surgical instrument featuring a shaft with a distal portion for driving set screws, a handle, and a sleeve that allows for relative movement between the inner driver shaft and the outer sleeve to sequentially eject set screws into bone anchor receivers, reducing the number of passes needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple set screws are delivered using separate passes between surgeon and assistant, then each set screw can be securely delivered to the bone anchor, but the operative time increases and the complexity of the procedure increases
Solution Approach 1:
The patent combines multiple set screw delivery functions into a single instrument. The shaft can hold multiple set screws stacked against one another, and the sleeve mechanism allows sequential ejection of multiple set screws during one continuous pass through the bone anchor receiver head, eliminating the need for repeated passes between surgeon and assistant.
Solution Approach 2:
The set screws are pre-loaded onto the shaft in a stacked configuration before the instrument is inserted. The sleeve is positioned to contact the proximal-most set screw, ready for sequential advancement. This preliminary preparation allows immediate sequential delivery without stopping to reload between set screws.
2Reliability
If multiple set screws are delivered using separate passes, then each set screw can be securely delivered, but the complexity of the procedure increases and the risk of component mishandling increases
Solution Approach 1:
The instrument integrates multiple set screw delivery functions into a single device. The shaft holds multiple set screws, the sleeve provides sequential advancement capability, and the ratchet teeth with detent mechanism enable controlled stepwise motion. This integration reduces the number of separate instruments and passes required, thereby reducing procedural complexity and the risk of component mishandling.
3Productivity
If the sleeve is advanced to eject set screws, then set screws can be delivered sequentially, but the sleeve requires precise incremental movement control
Solution Approach 1:
The sleeve is designed with ratchet teeth that engage with a detent mechanism, allowing the sleeve to move in discrete incremental steps rather than continuous motion. Each step corresponds to the thickness of one set screw, enabling precise positioning without requiring high-precision manufacturing. The ratchet mechanism provides mechanical control that compensates for manufacturing tolerances.
Data Source
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AI summary
This disclosure relates generally to surgical instruments used to deliver locking or set screws (110) to secure a rod or spinal fixation element relative to an implanted bone anchor or other spinal fixation construct during spine surgery. In one embodiment, the inserter instrument (100) includes an inner driver shaft (102), a ratcheted outer sleeve (104), and a handle (106) configured to receive the shaft and the sleeve therein. The inner driver shaft can receive a plurality of set screws on a distal end thereof. A side latch, pawl, or button (178) engages with the ratcheted outer sleeve to facilitate step-wise advancement of the sleeve relative to the driver shaft for set screw delivery. Step-wise advancement can be controlled using another button that causes movement of the side latch.