Anchor Assembly Shape Transition for Bone Fixation
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Solution Overview
Problem
Current soft tissue anchors face issues such as incomplete engagement with bone holes, complex insertion procedures, unreliable tensioning, and unsuitability for small bones due to the 'piston effect' and deeper drill holes required for deployment.
Innovation Solution
An anchor assembly featuring an elongate, flexible anchoring implant with woven suture segments and a bridging loop that changes shape from radially narrow to axially shortened and radially extended when tensioned, preventing the 'piston effect and reducing the working distance, allowing secure deployment in smaller bones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If soft anchors are used to enable less-invasive implantation, then the invasiveness is reduced, but the anchors fail to fully engage with the bore walls resulting in dislodgement
Solution Approach 1:
The anchor is designed to transition from a compressed delivery configuration to an expanded deployed configuration. The expandable body dynamically changes shape to engage the bore walls, providing secure anchoring while maintaining less-invasive delivery through a catheter.
Solution Approach 2:
The anchor utilizes shape memory alloy materials that change their physical parameters (shape, rigidity) in response to temperature changes. The anchor is delivered in a compressed state at body temperature, then expanded by applying heat (e.g., from a heating element or ice slurry), causing the material to transform and engage the bore walls reliably.
2Reliability
If soft anchors are used to reduce risk of lodging, then the risk profile is lowered, but the insertion instruments become highly mechanized and complex
Solution Approach 1:
The delivery catheter and anchor expansion mechanism are merged into a single integrated device. The catheter itself serves as the delivery and deployment mechanism, eliminating the need for separate complex insertion instruments. The anchor is simply loaded into the catheter and deployed by expanding it within the catheter.
Solution Approach 2:
The anchor is self-deploying through its shape memory properties. Once positioned in the bore, the anchor autonomously transforms from its compressed to expanded configuration when exposed to the triggering stimulus (heat or cold), eliminating the need for complex mechanical actuation systems.
3Strength
If soft anchors are used to generate larger surface area, then the strength is increased, but the anchors piston in the bone tunnel resulting in unreliable tensioning
Solution Approach 1:
The anchor provides dynamic tensioning through its expandable structure. As the anchor expands within the bore, it progressively engages the walls and maintains continuous contact, ensuring reliable tensioning throughout the deployment process and eliminating the piston effect seen in rigid anchors.
Solution Approach 2:
The anchor utilizes composite construction combining shape memory alloy with other materials to achieve both the desired surface area for strength and the controlled expansion characteristics needed for reliable tensioning without pistoning.
4Ease of manufacture
If soft anchors are used to improve ease of manufacture, then the manufacturing simplicity is increased, but deeper drill holes are required which makes them unsuitable for small extremity bones
Solution Approach 1:
The anchor is designed as a compact, segmented structure that can be fully deployed within a short bone tunnel. The expandable configuration allows the anchor to achieve its full functional dimensions within a compressed delivery profile, making it suitable for shallow bores in small extremity bones while maintaining manufacturing simplicity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The anchor assembly provides reliable tissue-to-bone fixation with reduced working distance, improved usability, and enhanced stability, making it suitable for orthopedic surgeries involving small extremity bones.
Implementation Method 1
applying tension to the terminal ends of the suture, when the anchoring implant is located in the bone or the tissue, causes the flexible anchoring implant to change shape from an elongate and radially narrow configuration into an axially shortened and radially extended configuration
Data Source
AI summary
An anchor assembly includes: an elongate and flexible anchoring implant for inserting into a bore of bone or tissue, the implant having proximal and distal ends with sidewalls extending therebetween, a suture having: first and second segments between the proximal and distal ends of the implant and, passed through a first and second side wall portions of the implant, respectively; A bridging loop between the two segments, and at or adjacent an in-use upper portion of the implant that includes the proximal end; wherein each of the segments has respective terminal ends of the suture extending from the implant; Applying tension to the terminal ends, when implant is in bone or tissue, causes the proximal end to be drawn towards the distal end to effect change of the implant shape from elongate and radially narrow into axially shortened and radially extended configurations to deploy the implant in the bore.