Self-locking Loop Constructs for Bone Block Fixation
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Solution Overview
Problem
Securing a bone block to cortical bone in bone-tendon-bone (BTB) grafts is challenging due to the inability to fold the graft through a loop, requiring techniques that minimize material removal and compressive forces while ensuring secure fixation without damaging compressive forces and promoting easy self-locking adjustability.
Innovation Solution
A knotless, self-locking, adjustable tensionable construct is used, comprising a flexible closed loop and a splicing device, allowing customization and secure fixation within a bone tunnel or socket, minimizing compressive forces and enabling easy adjustability without knotting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bone block is secured using traditional cortical button fixation, then the tissue can be fixed to bone, but the bone block is subjected to damaging compressive forces and requires material removal
Solution Approach 1:
Instead of pushing the bone block through the loop with compressive force, the loop is passed through the bone block and the button is pulled through the loop from the opposite side, inverting the direction of force application to achieve secure fixation without compression damage
2Reliability
If a bone-tendon-bone graft is used for ACL reconstruction, then the graft can be secured to cortical bone, but the rigid bone block cannot be folded through a loop like soft tissue grafts
Solution Approach 1:
The fixation system is segmented into three distinct components: the bone block, the flexible loop, and the cortical button. This segmentation allows each component to perform its specialized function - the loop passes through the rigid bone block without requiring folding, while the button provides secure cortical fixation
Solution Approach 2:
The flexible loop serves as an intermediary element between the bone block and the cortical button, enabling the rigid bone block to be secured to cortical bone without direct contact or compression between these two components
3Reliability
If traditional suture-button constructs are used, then fixation can be achieved, but the constructs require knotting which increases complexity and prevents easy adjustment
Solution Approach 1:
The knotting function is extracted from the fixation system and replaced with a friction-based self-locking mechanism. The button's geometry and the loop's material properties create sufficient friction to maintain fixation without requiring knots, thereby reducing device complexity and enabling easy adjustment
4Reliability
If material is removed from the bone block to facilitate fixation, then the graft can be secured, but the structural integrity of the bone block is compromised
Solution Approach 1:
Rather than removing material from the entire bone block, the solution creates a localized interaction zone where the loop passes through a small portion of the bone block. This preserves the overall structural integrity of the bone block while providing sufficient anchorage for secure fixation
Data Source
AI summary
Systems and methods for bone to bone, or soft tissue to bone, repairs without knot tying. The repair systems include self-cinching constructs which are tensionable and which include a flexible strand with a knotless, adjustable loop with at least one splice and a shuttle/pull device attached to the flexible strand. A final splice is formed by pulling on the shuttle/pull device subsequent to the knotless, adjustable loop being assembled with or secured to tissue (for example, a soft tissue graft or BTB graft), to allow desired tensioning of the graft to be fixated relative to the bone.