Spinal Implant Inserter With Torque Limiting for Angled Placement
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Solution Overview
Problem
Current spinal implant instrumentation lacks increased functionality and durability for multiple uses, particularly in procedures requiring angled implant placement, such as TLIF techniques, where existing instruments may not provide sufficient access and stability to the intervertebral disc space.
Innovation Solution
A surgical instrument featuring a body with a lumen and an anchor rod that secures the implant at both ends, utilizing a torque limiting mechanism and articulating joint to allow for angled placement and secure fixation, reducing the risk of breakage and failure during insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a straight instrument is used for implant insertion, then the instrument structure is simple, but the access to intervertebral disc space is limited and angled placement is difficult
Solution Approach 1:
The instrument is divided into multiple segments including a body, an articulating distal end with junction block, and an anchor rod. This segmentation allows the distal end to articulate independently relative to the body, enabling angled access to the intervertebral disc space while keeping the proximal handling portion simple and straight.
Solution Approach 2:
The distal end of the instrument is made dynamic through the articulating joint (junction block) that allows relative movement between the body and the anchor rod insertion path. This dynamic capability enables angled implant placement without requiring the entire instrument to be angled, maintaining simplicity at the proximal end.
2Reliability
If torque is applied to secure the implant, then the implant is fixed in place, but the instrument may break or fail due to excessive force
Solution Approach 1:
A spring mechanism is incorporated into the instrument that acts as a torque-limiting feature. When excessive torque is applied during implant insertion, the spring compresses to absorb the excess force, preventing instrument breakage or failure while still allowing sufficient torque to secure the implant in place.
Solution Approach 2:
The spring acts as an intermediary element between the torque application point and the implant. It mediates the force transmission by allowing controlled deformation under excessive load, thereby protecting the instrument structure from damage while maintaining the ability to apply necessary securing torque.
3Manufacturing precision
If the anchor rod is allowed to move freely in the lumen, then the instrument is easy to assemble, but the anchor rod cannot maintain precise positioning during insertion
Solution Approach 1:
The anchor rod is preliminarily positioned within the lumen of the body at a predetermined location before final implant insertion. This preliminary positioning ensures precise alignment and placement during the critical insertion phase, while the anchor rod remains removable for assembly and disassembly purposes.
Solution Approach 2:
Different portions of the anchor rod have different properties: the distal end features threading for implant engagement, while the proximal end has a non-circular cross-section for engagement with the body's drive shaft. This local differentiation enables precise positioning at the insertion site while maintaining ease of assembly through the non-circular drive interface.
Data Source
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AI summary
A surgical instrument (100) includes a body having a proximal end and a distal end and defining a lumen extending from the proximal end to the distal end along an axis, the distal end configured to abut an implant (101), and an anchor rod (106) disposable within the lumen of the body for contacting the implant (101) to secure the implant (101) at the distal end of the body. When the anchor rod (106) is disposed within the lumen of the body in a working configuration, the anchor rod (106) is connected to the body at the proximal end of the body and at the distal end of the body to substantially fix the anchor rod (106) from moving along the axis of the lumen. The body includes a handle (102), a shaft (104) extending distally from the handle (102), and a torque limiting mechanism (160).