Tendon Fixation Anchor with Expanding Sheath
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Solution Overview
Problem
Current tendon-to-bone fixation techniques in orthopedic surgery are cumbersome, often requiring multiple drill holes, external guides, and assistants, and do not effectively replicate the native ACL's anatomy or physiology, leading to suboptimal fixation strength and increased surgical time.
Innovation Solution
A system comprising two sheath portions with a hinge mechanism and a tapered screw for expanding laterally to compress the tendon against the bone tunnel aperture, providing strong and secure fixation with minimal surgical effort and no additional accessories, suitable for single or double tendon bundles, and accommodating autografts or allografts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional bone tunnel techniques are used for tendon fixation, then fixation strength can be achieved, but the surgical procedure becomes time-consuming and complex requiring multiple drill holes and assistants
Solution Approach 1:
The device divides the fixation function into two separate components: an anchor implanted in the bone tunnel and a button on the tendon graft. This segmentation allows each component to be optimized independently and simplifies the surgical procedure by eliminating the need for complex tunnel creation and suture passage.
Solution Approach 2:
The invention extracts the compression function from the traditional single-unit fixation system and places it directly at the bone-tendon interface through the anchor's compression element. This provides direct tendon-to-bone compression without requiring the tendon to pass through complex tunnel structures.
2Stress or pressure
If interference screws are used for tendon fixation, then axial compression is provided, but the tendon can be cut or compromised during implantation and the procedure remains complex
Solution Approach 1:
The compression element acts as an intermediary between the anchor and the tendon graft, providing controlled compression force. This intermediary mechanism distributes the compression force evenly across the tendon-bone interface, avoiding the concentrated stress that can cut or compromise the tendon during screw implantation.
Solution Approach 2:
The device provides localized compression precisely at the bone-tendon interface where it is most needed for healing, rather than applying compression throughout the entire tendon length. This localized approach maintains tendon integrity while providing sufficient compression for fixation.
3Ease of operation
If ENDOBUTTON technique is used for tendon fixation, then secondary incisions are eliminated, but fixation strength is limited to suture strength without direct tendon to bone compression
Solution Approach 1:
The invention merges the advantages of both ENDOBUTTON and interference screw techniques into a single device. The anchor provides the secure bone fixation and compression capability of interference screws, while the button provides the easy implantation and retention of the ENDOBUTTON technique. This combination achieves both direct tendon-to-bone compression and ease of operation.
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 system achieves pull-out strengths greater than 1000 N, replicates the native ACL's anatomy, and reduces surgical complexity by allowing single-person operation with a single drill hole, enhancing graft stiffness and aperture compression.
Implementation Method 1
An insertion member, preferably a tapered screw, is insertable into the space for expanding the sheath portions laterally outwardly in order to urge a soft tissue graft against an adjacent bone surface
Data Source
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AI summary
A material fixation system is particularly adapted to improve the tendon- to-bone fixation of hamstring autografts, as well as other soft tissue ACL reconstruction techniques. The system is easy to use, requires no additional accessories, uses only a single drill hole, and can be implanted by one person. Additionally, it replicates the native ACL by compressing the tendons against the aperture of the tibial tunnel, which leads to a shorter graft and increased graft stiffness. It is adapted to accommodate single or double tendon bundle autografts or allografts. It also provides pull out strength measured to be greater than 1000 N.