Graft Fixation Device for Anatomic ACL Reconstruction
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Solution Overview
Problem
Current ACL reconstruction techniques face challenges in achieving a highly accurate anatomic reconstruction due to uncontrolled rotation and positioning of graft bundles during interference screw fixation, leading to non-anatomic reconstructions, reduced pull-out strength, and altered knee motion.
Innovation Solution
The use of a graft fixation device comprising a graft separator with guide ribs and an interference screw, which is designed to secure the graft bundles in the true anatomic locations of the native ACL insertions, eliminating micro-movement within the bone tunnels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional interference screw fixation is used, then the graft can be secured in the bone tunnel, but the graft bundles experience uncontrolled rotation and positioning leading to non-anatomic reconstruction
Solution Approach 1:
The fixation device is segmented into distinct functional components: a graft separator element that divides the bone tunnel into separate compartments for each graft bundle, and an interference screw element that provides fixation. This segmentation allows independent control and positioning of each graft bundle, preventing uncontrolled rotation and ensuring anatomic reconstruction while maintaining reasonable device complexity through modular design.
Solution Approach 2:
The graft separator acts as an intermediary element between the bone tunnel and the graft bundles. It mediates the positioning process by creating defined pathways that guide each graft bundle to its correct anatomic location, eliminating the need for complex external positioning mechanisms while ensuring precise graft placement.
2Ease of operation
If graft bundles are allowed to rotate during fixation, then the interference screw can be easily inserted, but the graft bundles end up in non-anatomic positions reducing pull-out strength
Solution Approach 1:
The graft separator is inserted and positioned within the bone tunnel before the interference screw is inserted. This preliminary action establishes the correct spatial configuration and anatomic positioning of the graft bundles in advance, creating predetermined pathways that constrain subsequent screw insertion to follow the same anatomic trajectory, thereby maintaining both ease of operation and high pull-out strength.
3Stability of the object's composition
If the graft is secured tightly in the bone tunnel, then stability is improved, but micro-movement within the tunnel cannot be eliminated
Solution Approach 1:
The graft separator provides localized structural support and positioning at specific critical locations within the bone tunnel, particularly at the interface between the graft and bone. This localized quality enhancement ensures precise graft positioning and eliminates micro-movement at the fixation interface, while the overall fixation stability is maintained through the combined action of the separator and interference screw.
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
This approach ensures that the graft bundles are accurately positioned and secured, resulting in a more stable ACL reconstruction, improved graft tension, and reduced risk of tunnel widening and osteoarthritis.
Implementation Method 1
securing the tissue graft in the femoral and tibial tunnels with interference screws or other fixation devices
Implementation Method 2
interference screw comprising a body having screw threads formed thereon
Data Source
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AI summary
A graft fixation device comprising: a graft separator comprising a distal end, a proximal end, a cavity disposed between the distal end and the proximal end, and at least one guide rib disposed radially outboard of the cavity and extending between the distal end and the proximal end; and an interference screw rotatably mountable within the cavity, the interference screw comprising a distal end, a proximal end, and a screw thread disposed intermediate thereof, the screw thread disposed radially outboard of at least a portion of the graft separator and radially inboard of the at least one rib.