Meniscal Repair Device Push Rod Segmentation and Ratchet Retraction
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Solution Overview
Problem
Existing meniscal repair devices lack a user-manipulated retraction mechanism for the push rod, leading to failure in deploying the second implant due to excessive force or breach of the needle slot, and the suture tensioning process is strenuous and prone to slippage.
Innovation Solution
The tissue repair device incorporates a push-pull delivery mechanism with a ratchet and advancement member that allows independent retraction of the push rod, and a compliant push rod optimized for needle curvature, along with a suture featuring a bifurcated section for easier tensioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid push rod is used to maintain structural strength for expelling implants, then the compressive strength is sufficient, but the push rod cannot conform to needle curvature and may breach the needle slot or fail to retract
Solution Approach 1:
The push rod is divided into two distinct segments: a proximal segment that is rigid for maintaining structural strength during implant expulsion, and a distal segment that is flexible to conform to needle curvature. This segmentation allows each portion to perform its specific function optimally without compromising the other.
Solution Approach 2:
The push rod is constructed as a composite structure combining rigid and flexible materials. The proximal portion uses rigid material for compressive strength, while the distal portion uses flexible material for curvature compliance. This composite approach resolves the contradiction between strength and adaptability.
2Ease of operation
If spring force is used for push rod retraction, then the mechanism can retract passively, but friction forces may exceed spring force and prevent retraction
Solution Approach 1:
Instead of relying on spring force to pull the push rod back (passive retraction), the system uses a user-manipulated mechanism that actively pulls the push rod proximally. This inversion of the retraction approach ensures reliable operation by applying direct user control rather than relying on insufficient spring force to overcome friction.
Solution Approach 2:
The push rod retraction mechanism is designed to be self-operating through user manipulation. The user directly controls the retraction process, ensuring that the push rod returns to its initial position regardless of friction forces, thereby making the system self-sufficient and reliable.
3Productivity
If traditional suture tensioning is used, then the repair can be closed, but the process is strenuous and the suture may slip during reduction
Solution Approach 1:
A suture tensioning device is introduced as an intermediary tool between the surgeon and the suture. This device provides a mechanical advantage system that converts small user inputs into the necessary tension forces, making the suture tensioning process easier and more controlled while preventing slippage through secure engagement features.
Data Source
AI summary
Tissue repair devices include an advancement assembly comprising a rod portion configured to advance through a needle to expel first and second implants from the needle, a ratchet coupled to a proximal section of the rod portion and configured to advance the rod through the needle by axial and rotational movement, and an advancement member having a linear travel axis including a first bore connected to a second bore. A diameter of the first bore is smaller than a diameter of the second bore such that the first bore and the second bore comprise a stop. The rod portion has mechanical properties optimized to both conform to a needle curvature and provide sufficient compressive strength to expel implants from the devices.