Composite Interference Screw with Open Helical Coil
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Solution Overview
Problem
Current interference screws used in ligament reconstruction limit bone-to-ligament integration due to their size and material properties, leading to incomplete absorption and inferior tissue growth, which affects the strength of the graft-bone junction.
Innovation Solution
A novel anchor system featuring a suture bridge with a bulbous distal end and open helical coil design, which allows for greater suture load capacity and improved bone integration by reducing the anchor's footprint within the bone tunnel, promoting superior bone-to-ligament in-growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional interference screws are used to secure the graft ligament, then the graft ligament is firmly fixed in the bone tunnel, but the screw occupies substantial space that limits bone-to-ligament integration surface area
Solution Approach 1:
The interference screw is designed with a porous structure that allows bone ingrowth through the screw body. This porous architecture enables bone cells to penetrate and grow within the screw's internal framework, creating a biological integration pathway that increases the effective bone-to-ligament contact area while maintaining mechanical fixation strength.
Solution Approach 2:
The interference screw utilizes composite material construction combining bioabsorbable polymer matrix with reinforcing elements or surface coatings. This composite approach provides the necessary mechanical strength for initial fixation while allowing gradual degradation and bone ingrowth, effectively resolving the contradiction between maintaining fixation strength and enabling bone integration.
2Stability of the object's composition
If absorbable materials are used for interference screws, then the screw can eventually disappear to allow complete bone-to-ligament in-growth, but the absorption process takes substantial time (e.g., three years)
Solution Approach 1:
The screw design incorporates parameters that control degradation rate, such as porous structure geometry, material composition ratios, and surface area-to-volume ratio. These parameter optimizations enable accelerated bone ingrowth and modified absorption kinetics, reducing the time required for complete absorption while ensuring adequate initial mechanical support.
Solution Approach 2:
Different regions of the screw exhibit different material properties and degradation rates. The proximal and distal portions may have varying porosity, density, or material composition to optimize local bone ingrowth patterns and control the temporal sequence of absorption, allowing faster overall absorption while maintaining structural integrity during the critical healing period.
3Strength
If absorbable interference screws are made large to provide adequate strength, then mechanical support is sufficient, but the foreign mass remaining in the body is substantial
Solution Approach 1:
The porous structure reduces the effective volume of foreign material by creating void spaces that allow bone ingrowth. This internal architecture decreases the amount of non-biological material remaining in the body while maintaining mechanical strength through the optimized porous framework that provides both structural support and biological integration pathways.
Data Source
Figure 1
Figure 2~3
Figure 2A~4
AI summary
The present disclosure relates to an anchor (400). The anchor includes a suture bridge (405) having a proximal end and distal end. The distal end of the suture bridge has a thickness greater than a thickness of the proximal end of the suture bridge. At least two ribs (406) extend from the proximal end of the suture bridge to a proximal end of the anchor. At least one open helical coil (403) wraps around the at least two ribs and extends, substantially, from the proximal end of the suture bridge to the proximal end of the anchor. The at least one open helical coil defines an internal volume communicating with a region exterior to the anchor through apertures between turns of the at least one open helical coil. The at least two ribs are engagable with a grooved shaft of a driver (30).