Button-and-post fixation device for shear stability in shoulder grafts
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Solution Overview
Problem
Current fixation devices for bone grafts in shoulder joint procedures, such as the Latarjet procedure, lack sufficient shear and rotational stability, especially when using suspension fixation, which can lead to instability and dislocation of the shoulder joint.
Innovation Solution
A fixation device with a solid, cylindrical post attached to a flat button provides enhanced shear stability and rotational stability, allowing for easier arthroscopic placement and using sutures to secure the bone graft, offering greater stability than traditional screws.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If solid screws are used for fixation, then shear stability is improved, but ease of arthroscopic operation deteriorates
Solution Approach 1:
The fixation device is segmented into distinct functional components: a button portion for arthroscopic placement and a post portion for bone engagement. This segmentation allows the button to be easily inserted arthroscopically while the post provides the necessary shear stability through its solid cylindrical structure that resists shear forces across the fracture line.
Solution Approach 2:
Instead of using a traditional screw that must be driven in with significant torque and precise alignment, the invention inverts the approach by using a button-and-post configuration where the post is inserted through the button and secured with sutures. This inversion makes the procedure arthroscopically accessible while maintaining shear stability through the solid post structure.
2Ease of operation
If flat button fixation devices are used for suspension fixation, then ease of arthroscopic operation is improved, but shear stability deteriorates
Solution Approach 1:
The device separates the suspension fixation function (performed by the flat button with suture holes) from the shear resistance function (performed by the solid cylindrical post). The button provides ease of arthroscopic placement and suspension capability, while the solid post extends through the bone to provide the necessary shear stability that flat buttons alone cannot provide.
3Reliability
If fixation devices provide strong shear stability, then reliability of bone graft fixation is improved, but device complexity increases
Solution Approach 1:
The invention merges two previously separate fixation approaches (suspension fixation with flat buttons and compression fixation with screws) into a single integrated device. The button portion handles suspension and soft tissue attachment, while the solid post portion provides shear stability and compression, eliminating the need for multiple separate devices and procedures.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A
AI summary
A surgical fastener comprising a generally flat, circular body and a generally cylindrical post fixedly coupled to a center of the body extending perpendicular to the body. Both of the body and the post include through holes configured for passage of a suture. A length of the post is selected to extend through both of a bone graft and at least a portion of bone for providing shear and/or anti-rotational support to the surgical fastener across a fracture line in the bone.