Bone Anchor Suture Attachment via Peg and Friction
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Solution Overview
Problem
Existing methods for attaching sutures to bone screws or anchors, such as interference screws and cross-pins, face issues with knot slippage and mechanical damage leading to failure, particularly in ACL prosthesis anchorage, due to bone resorption and wear at the edge of the hole.
Innovation Solution
A bone anchor assembly featuring a central axis hole with a cylindrical and angled portion, combined with a peg that can be inserted to hold the suture in place, utilizing a suture with longer filaments fused to form a loop and passed through the hole, and a knot tied around the peg to secure the suture and peg within the hole.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a knot is tied in the end of the ACL prosthesis to retain it within the central hole, then the prosthesis can be anchored, but the knot may pass through the central hole causing the ACL prosthesis to loosen or fail
Solution Approach 1:
A peg is introduced as an intermediary element between the suture and the bone anchor. The peg is inserted through the central hole and has a diameter that prevents the suture knot from passing through, while still allowing the suture to be tied around it for secure retention
Solution Approach 2:
The central hole is divided into two functional segments: a first portion that receives the peg, and a second portion that receives the suture. This segmentation allows the peg to be positioned first to prevent slippage, followed by the suture being tied around the peg for secure anchorage
2Reliability
If the central hole is sized to prevent the knot from pulling through, then knot slippage is prevented, but tying the knot becomes difficult while retaining the ACL prosthesis taut
Solution Approach 1:
The peg serves as a mediator that facilitates knot tying. By inserting the peg through the central hole first, the surgeon can then tie the knot around the peg with easier manipulation, and the peg's presence keeps the suture taut during the tying process
Solution Approach 2:
The peg is inserted into the central hole before the suture is tied. This preliminary action prepares the anchorage site by establishing a reference point and preventing slippage before the knot is tied, making the subsequent knot-tying operation easier and more reliable
3Strength
If interference screws or cross-pins are used to anchor the prosthesis, then initial fixation is achieved, but bone loss due to contact resorption and mechanical damage leads to prosthesis failure
Solution Approach 1:
The invention replaces the traditional interference screw or cross-pin mechanical anchoring system with a suture-based anchoring system. The suture is tied around a peg in the central hole, creating a different mechanical mechanism that distributes forces more favorably and eliminates the edge loading that causes bone resorption and prosthesis failure
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 solution effectively prevents knot slippage and mechanical damage by utilizing friction between the central axis hole, peg, and suture to maintain secure anchorage of the ACL prosthesis, enhancing the longevity and stability of the attachment.
Implementation Method 1
utilizing friction between the central axis hole, peg, and suture to maintain secure anchorage
Data Source
Figure 1~7
Figure 8~10
AI summary
A bone anchor has a central bore allowing for uniquely attaching a suture thereto. The bore is shaped so that it is wider at the bottom of the anchor than at the top of the anchor. A peg fits within the bore. The suture is looped around the peg and the peg is inserted into the bore. Friction between the bore, peg and suture holds the suture in place. A suture for use with the bone anchor may be formed by fusing together the ends of a plurality of fibers to form a loop.