Vertebral Body Derotation Towers for 3D Spinal Alignment
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Solution Overview
Problem
Existing spinal fixation constructs face challenges in effectively correcting spinal curvature, particularly in conditions like adolescent idiopathic scoliosis, as they struggle to maintain vertebral alignment during fusion surgery, which is essential for bone growth and stability.
Innovation Solution
A vertebral body derotation system comprising derotation towers, transverse connectors, and clamps is used to correct spinal alignment by coupling bone anchors across vertebrae, allowing for simultaneous reduction and fixation of fixation rods to maintain alignment until fusion is achieved.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional rod-based fixation constructs are used to correct spinal curvature, then the spine can be stabilized, but the ability to achieve precise 3-dimensional correction including vertebral derotation is limited
Solution Approach 1:
The fixation construct is divided into modular components: anchors with receiver assemblies, separate rod reduction assemblies, and derotation towers. Each component performs a specific function and can be independently positioned and adjusted, enabling precise 3-dimensional spinal correction while maintaining manageable system complexity through standardized interfaces.
Solution Approach 2:
The system adds rotational correction capability (axial plane) to the traditional two-plane (sagittal and coronal) correction system. Derotation towers provide a third dimension of correction by enabling vertebral body derotation, transforming the system from planar to spatial correction and achieving comprehensive 3-dimensional alignment.
2Stability of the object's composition
If multiple anchors are coupled to vertebrae and connected by fixation rods for spinal stabilization, then bone fusion can be facilitated, but maintaining vertebral alignment during surgery becomes difficult
Solution Approach 1:
Rod reduction assemblies are used to pre-position and reduce fixation rods into the receiver assemblies before final tightening. This preliminary action establishes proper vertebral alignment and spacing early in the procedure, making it easier to maintain stability throughout the remainder of surgery without requiring complex real-time adjustments.
Solution Approach 2:
The receiver assembly acts as an intermediary mechanism between the anchor and fixation rod, providing a controlled interface that facilitates rod insertion and positioning. This intermediary structure enables precise alignment control during rod reduction while simplifying the overall operation of maintaining vertebral stability.
3Measurement precision
If fixation rods are reduced and locked in traditional constructs, then spinal stability is achieved, but precise control over rod positioning and vertebral derotation is lost
Solution Approach 1:
The derotation tower integrates multiple functions into a single component: it provides structural support, enables vertebral derotation, and facilitates rod reduction. This multi-functional design achieves precise rod positioning and derotation control without requiring multiple separate instruments, thereby maintaining surgical efficiency while improving measurement precision.
Solution Approach 2:
The rod reduction assembly is designed to be self-contained, with all necessary reduction and locking functions integrated into the assembly itself. This self-service mechanism allows the surgeon to perform precise rod positioning and locking without requiring additional specialized tools or complex procedural steps, maintaining productivity while achieving high precision.
Data Source
AI summary
One aspect of the disclosure relates to vertebral body derotation (VBD) system. In one embodiment, the VBD system includes a first pair of derotation towers and a second pair of derotation towers, a first transverse coupler coupled to the first pair of derotation towers and a second transverse coupler coupled to the second pair of derotation towers, and at least one clamp configured to couple the first and second transverse connectors in the cranial-caudal direction or a first derotation tower of the first pair of derotation towers and a second derotation tower of the second pair of derotation towers in the cranial-caudal direction.