Spinal Prosthesis Rod Insertion Using a Flexible Pull Element
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Solution Overview
Problem
Existing percutaneous fusion surgery methods face difficulties in inserting long fusion rods due to limitations in rotation joint mechanisms and space within towers, particularly in the 'inside' approach, which complicates the procedure and limits rod length.
Innovation Solution
A flexible element, such as a wire or strip, is integrated with the fusion rod and guided through insertion guide members to facilitate rod insertion, allowing for controlled orientation and length adjustment using a rod inserter, enabling the rod to be installed perpendicular or parallel to the inserter for ease of insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a rigid connection between insertion tool and fusion rod is used with rotation mechanism, then the fusion rod can be inserted through the tower, but the rod length is limited due to rotation joint mechanism limitations and space inside the tower
Solution Approach 1:
Instead of pushing the rod through the tower using a rotation mechanism from the proximal end, the invention inverts the approach by pulling the rod through the tower using a flexible element attached to the distal end. This allows the rod to be drawn through the tower length without being constrained by rotation joint limitations or internal tower space, enabling insertion of longer rods.
Solution Approach 2:
The invention replaces the complex rotation mechanism and rigid push-based insertion system with a flexible element-based pull system. The flexible element (wire or strip) runs through the tower and attaches to the rod, allowing the rod to be pulled through the tower along the flexible element's path, eliminating the need for rotation joints and rigid mechanical manipulation within the tower.
2Object-affected harmful factors
If the 'inside' approach is used for rod insertion, then soft tissue management is improved and stress on soft tissues is reduced, but it becomes particularly difficult to insert long fusion rods
Solution Approach 1:
The flexible element serves as an intermediary that bridges the insertion tool and the fusion rod. It passes through the tower and attaches to the rod, allowing the rod to be pulled through the tower without direct manipulation. This intermediary approach maintains the benefits of the inside technique for soft tissue management while eliminating the operational difficulties of inserting long rods through confined tower space.
3Adaptability or versatility
If a complicated rotation mechanism is used at the distal end of the insertion tool, then the fusion rod can be rotated during insertion, but the mechanism complexity increases and space requirements increase
Solution Approach 1:
The invention extracts and removes the complex rotation mechanism from the insertion tool. Instead of incorporating a rotation joint mechanism at the distal end of the insertion tool, the system uses a simple flexible element that can be manipulated externally to guide the rod through the tower, eliminating the need for complex internal rotation mechanisms while retaining orientation control capability.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 2C
AI summary
A spinal prosthesis comprising a first and second spinal prosthetic members (82, 84), each of which comprises attachment members (86, 88), comprising prongs that are fastenable to polyaxial pedicle screws, and central articulating members (90) that allow said first and second spinal prosthetic members (82, 84) to articulate in more than one degree of freedom including rotating about rotation axes (92, 94) parallel to the prongs, wherein said first and second spinal prosthetic members (82, 84) are pivotable about said rotation axes (92, 94) to pivot with respect to one another between expanded and contracted positions.