Two-Part Tubular Elements for Spinal Deformity Correction
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Solution Overview
Problem
Current spinal correction techniques for severe deformities like scoliosis require multiple stages and result in loss of correction due to the need to dismantle tubular elements to fix the implantable rod on the opposite side of the spine, leading to inefficiency and loss of correction.
Innovation Solution
A surgical device with two-part tubular elements that can be coupled externally to the pedicle screw heads without disassembly, allowing for simultaneous straightening of vertebrae and positioning of the implantable rod, using a ring for vertical displacement and angular indexing, and spacers for maintaining alignment, enabling unilateral assembly and reducing unit pressure on screws.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the implantable rod is fixed on the opposite side of the spine after tubular element alignment, then the correction can be completed, but the tubular elements must be dismantled causing loss of correction and time
Solution Approach 1:
The device separates the alignment function (tubular elements) from the final fixation function (rod with nuts), allowing the tubular elements to remain in place as permanent structural components rather than temporary guides that must be removed
Solution Approach 2:
The rod and nuts are nested within the tubular elements during insertion, then the nuts are tightened against the pedicle screw heads while the tubular elements remain in position, eliminating the need to dismantle the alignment structure
2Reliability
If the implantable rod is fixed on the opposite side of the spine, then the correction can be completed, but the relative position of tubular elements is lost requiring re-alignment
Solution Approach 1:
The fixation system is segmented into rod, nuts, and tubular elements, where each component has a specific function and the tubular elements serve as permanent reference structures rather than temporary guides
Solution Approach 2:
The tubular elements are pre-aligned to establish the correct spinal curvature, then the rod and nuts are inserted and tightened within this pre-established framework, eliminating the need for re-alignment after rod fixation
3Reliability
If multiple stages are used for correction, then the implantable rod can be fixed, but the process becomes inefficient and time-consuming
Solution Approach 1:
The alignment and fixation operations are merged into a single stage where the tubular elements perform both functions simultaneously, eliminating the need for separate alignment and fixation steps
Solution Approach 2:
The tubular elements serve multiple functions: they guide rod insertion, maintain alignment during tightening, and remain as permanent structural components, eliminating the need for separate temporary alignment devices
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
The device comprises tubular elements (1) and rods (4) and (5). Each tubular element (1) is in two parts, the ends thereof having arrangements (1a1) and (1b1) for coupling said parts to each other and to the corresponding pedicle screw head (2). The rods are inserted into slots (1e) and (1d) defined by the two parts of the tubular elements, such that they can move parallel to the axis of the tubular elements (1). The insertion of one of the rods (4) triggers the alignment of the tubular elements, corresponding to the correction of the spinal column. The other rod (5) acts on a means (7) for moving a curved rod (3), previously inserted into the slots (1e) and (1d), in the direction of the heads (2). Said rod (5) is intended to be removed and subsequently coupled to the exterior of the tubular elements (1) in order to allow: the removal of the other rod (4), and the insertion into each tubular element of a member (11) for manoeuvring a nut (10) for securing the curved rod (3) in each of the heads (2).