Two-Part Bone Anchor With Wedging Clamp for Suture Protection
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Solution Overview
Problem
Existing medical anchors cause damage to suture threads due to friction during placement and have uncertain pull-out resistance, particularly when reattaching rotator cuff tendons in the shoulder joint.
Innovation Solution
A two-part anchor design with wedging surfaces that securely engage suture threads, protecting them from damage during placement and ensuring strong anchoring to the bone, featuring an outer part with anchoring ribs and an inner part that moves to clamp the threads between wedging surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a transverse passage through the anchor is used to insert the suture thread, then the suture thread can be connected to the anchor, but friction between the anchor and the bone causes damage to the thread during anchor placement
Solution Approach 1:
The anchor is divided into two separate parts: an outer part that is inserted into the bone wall and an inner part that contains the suture thread engagement mechanism. This segmentation allows the suture thread to be engaged within the inner part without passing through the outer part, thereby eliminating friction between the thread and the bone during placement.
Solution Approach 2:
The inner part is inserted into the outer part, with the suture thread engaged within the inner part. The inner part can move relative to the outer part between a distal position (where the thread is not blocked) and a proximal position (where the thread is clamped). This nested structure protects the suture thread from external friction while allowing secure engagement.
2Reliability
If a proximal ring on the anchor is used to tie the suture thread, then the thread can be secured to the anchor, but there is a significant risk of thread breakage at the knot
Solution Approach 1:
The invention eliminates the proximal ring structure entirely, replacing it with a wedging mechanism between the inner and outer parts. The suture thread is engaged by the wedging action of the two parts rather than by tying a knot around a ring, thereby removing the stress concentration and breakage risk associated with knots.
Solution Approach 2:
The traditional knot-tying mechanism is replaced with a wedging mechanism. The inner part moves relative to the outer part to create a wedging action that secures the suture thread through friction and geometric interlocking, rather than through a knot that creates stress concentrations.
3Reliability
If the anchor is screwed in, then the anchor can be fixed to the bone, but there is a risk of the line being cut or damaged during installation
Solution Approach 1:
The anchor is segmented into an outer part for bone insertion and an inner part for suture engagement. The suture thread is engaged within the inner part, which is protected from the insertion process. The outer part can be screwed or pressed into the bone without exposing the suture thread to damaging forces.
Solution Approach 2:
The inner part containing the engaged suture thread is nested within the outer part during insertion. This nesting protects the suture thread from mechanical damage during the anchoring process, whether the outer part is screwed in or pressed into the bone wall.
4Ease of operation
If existing anchor designs are used, then the anchor can be inserted into the bone wall, but the pull-out resistance is relatively uncertain under significant tendon tension
Solution Approach 1:
The anchor employs a composite structure with an outer part for bone engagement and an inner part for suture engagement. This composite design allows optimization of each part for its specific function: the outer part provides stable bone anchoring while the inner part provides secure suture retention, resulting in predictable and reliable pull-out resistance.
Solution Approach 2:
The inner part is designed to move relative to the outer part between distal and proximal positions. This dynamic mechanism allows the anchor to adapt to loading conditions: during insertion the inner part is in the distal position for easy engagement, and under tendon tension it moves to the proximal position to maximize clamping force and pull-out resistance.
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 effectively prevents suture thread breakage and shearing, providing secure fixation to the bone with reduced risk of damage and enhanced pull-out resistance.
Implementation Method 1
the inner piece forms at least a second wedging surface located on the proximal side with respect to the transverse conduit which it comprises, this second wedging surface being disposed in the longitudinal direction of the inner piece; said at least one suture thread is intended to extend along said first wedging surface and along said second wedging surface
Data Source
Figure 1~3
Figure 4~5
Figure 6~8
AI summary
This anchor (1) comprises two parts (2, 3) intended to be assembled together, namely: - an outer part (2), forming at least a first clamping surface (16a) for suture thread (100); and - an inner part (3), intended to be inserted and retained in the outer part (2), which forms a transverse conduit (21) and at least a second clamping surface (25) for suture thread (100).