Open Architecture Anchor Thread Profile Reduces Bone Removal
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Solution Overview
Problem
Structurally weaker bioabsorbable composite materials in open construct anchors face issues with maintaining structural integrity due to thread separation or breakage, which is exacerbated by the need to increase thread cross-sectional area, leading to reduced bone stock and compromised anchor fixation.
Innovation Solution
An open construct anchor with a thread profile smaller than the standard triangle profile, featuring a base with non-linear side walls circumscribed within a triangle, reducing the cross-sectional area while maintaining structural integrity and preserving bone stock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thread cross-sectional area is increased to maintain structural integrity with bioabsorbable materials, then thread strength is improved, but the amount of bone stock remaining after implant insertion is reduced
Solution Approach 1:
The thread structure is segmented into multiple components: the thread body, the base, and internal ribs. This segmentation allows the load to be distributed across multiple structural elements rather than relying solely on thread cross-sectional area, enabling reduced thread size while maintaining strength
Solution Approach 2:
The invention moves from a two-dimensional thread cross-section to a three-dimensional structure by adding internal ribs that extend into the internal volume. This dimensional transition allows strength to be derived from vertical rib structures rather than horizontal thread area, preserving bone stock
2Reliability
If the thread profile is enlarged to prevent thread breakage in bioabsorbable anchors, then reliability is improved, but bone displacement increases
Solution Approach 1:
The thread profile features local quality variations with non-linear side walls that are concave in the viewing direction of the base. This localized geometric modification concentrates structural strength at critical stress points while reducing overall thread profile size, thereby minimizing bone displacement during insertion
Solution Approach 2:
The thread structure functions as a composite system combining the thread body material with internal ribs, creating a multi-component structure that achieves high reliability without requiring increased profile size, thus reducing harmful bone displacement
3Strength
If the thread cross-sectional area is increased to maintain structural integrity, then thread strength is improved, but the thread separates from anchor rib(s)
Solution Approach 1:
The internal ribs are nested within the internal volume defined by the thread, creating a nested doll configuration. The ribs connect to multiple turns of the thread, forming an integrated structure where the thread and ribs support each other, preventing separation while allowing reduced thread cross-sectional area
Solution Approach 2:
The internal ribs are pre-positioned within the thread structure during manufacturing, creating preliminary structural support that prevents thread-rib separation under load, eliminating the need for increased thread cross-sectional area
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5B
AI summary
The disclosure provides examples of an open architecture anchor (100) for securing soft tissue to bone, for example, to repair a torn rotor cuff. The anchor includes a helical screw thread (105) having a base (125) and two sidewalls (135a, 135b) that are non-linear. The non-linear sidewalls extend from opposing ends of the base and meet at a peak (140). The non-linear sidewalls are circumscribed within a triangle (145) defined by the peak and ends of the base. Compared to the standard triangle profile, the helical screw thread profile has a smaller cross-sectional surface area and, consequently, removes less bone. The helical screw thread having the reduced cross-sectional area preserves bone stock and enhances the holding strength of the anchor in bone.