Expandable Tendon-Bone Fixation Device for ACL Reconstruction
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Solution Overview
Problem
Current tendon-to-bone fixation systems for ACL reconstruction, particularly using hamstring autografts, face challenges such as increased anterior knee pain, invasive harvest procedures, and insufficient fixation strength, with existing devices requiring additional accessories, drill holes, and personnel for implantation, and failing to replicate the native ACL's stiffness and compression.
Innovation Solution
A novel tendon-bone fixation device that provides active compression at the femoral tunnel aperture, requiring only one drill hole and one person for implantation, with outwardly expandable wedge and wing portions that deploy to engage the bone, replicating the native ACL's stiffness and strength by compressing the tendon against the bone, and featuring a breakaway connection and anti-rotation keys for secure deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If cortical-only fixation devices (EndoButton, TightRope) are used, then ease of operation is improved, but graft stiffness is reduced by up to 56% compared to native ACL
Solution Approach 1:
The invention transitions from cortical-only fixation to subchondral bone fixation, utilizing the denser, more rigid subchondral bone layer beneath the articular cartilage. This dimensional change in fixation depth enables direct tendon-to-bone compression at the aperture while anchoring in the highly dense subchondral bone, thereby restoring native ACL stiffness without compromising ease of operation
Solution Approach 2:
Instead of compressing the tendon against the cortical bone surface as with traditional devices, this invention inverts the approach by expanding the implant within the tunnel to compress the tendon directly against the subchondral bone interface, achieving superior graft stiffness through reversed compression mechanics
2Strength
If interference screw fixation is used, then fixation strength is improved, but additional drill holes and accessories are required
Solution Approach 1:
The invention merges the functions of multiple components into a single expandable implant device. The implant integrates the anchoring function, tendon compression function, and fixation function into one unified structure that expands within the existing tunnel, eliminating the need for additional drill holes, interference screws, and other accessories
Solution Approach 2:
The expandable implant is self-contained and self-deploying within the tunnel. Once inserted in a compressed state, it expands autonomously to engage the subchondral bone and compress the tendon, requiring no additional instruments or accessories for deployment, thereby simplifying the overall device system
3Object-affected harmful factors
If hamstring tendon autograft is used, then post-surgical pain is reduced, but fixation strength is insufficient compared to BTB autograft
Solution Approach 1:
The invention changes the fixation mechanism parameters from passive cortical anchoring to active subchondral bone engagement with direct tendon-to-bone compression. This parameter change in the fixation approach enables hamstring tendons to achieve fixation strength exceeding 1,000 N while maintaining the pain-free advantages of hamstring harvest
4Strength
If BTB autograft with interference screw is used, then fixation strength is improved, but anterior knee pain increases and harvest procedure becomes more invasive
Solution Approach 1:
The invention extracts the problematic interference screw component and its associated additional drill holes from the fixation system. By using a single expandable implant that provides equivalent or superior fixation strength, it eliminates the sources of anterior knee pain while maintaining strong fixation
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 device achieves high tendon-bone fixation strength greater than 1,000 N, reduces graft length and stiffness, and minimizes bone removal, enabling effective ACL reconstruction with reduced post-surgical pain and less invasive procedures, suitable for various ligament reconstruction techniques.
Implementation Method 1
provides active compression at the femoral tunnel aperture... compressing the tendon against the bone
Implementation Method 2
outwardly expandable wedge and wing portions that deploy to engage the bone
Data Source
AI summary
A system and method for making an orthopedic repair by fixing a soft tissue graft to bone, utilizes an implant including a body wedge having first and second outwardly expandable wedge portions, a wing portion having outwardly expandable wings, and a deployment member which is movable distally into the implant to deploy the wedge portions and the wings into an expanded deployed orientation.