Transverse Connector Radial Compression Locking
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Solution Overview
Problem
Current spinal fixation apparatuses face challenges in securely and adjustably connecting longitudinal rods to bone anchors, particularly in providing a stable and adjustable transverse connector that can accommodate polyaxial movement and secure positioning relative to vertebral bones.
Innovation Solution
A transverse connector system comprising a cross member assembly with first and second connector assemblies, each including a mount, screw, and nut configuration, which securely engages with bone anchors and allows for axial and polyaxial movement, using a cross member with an annular flange and rings that adjust diameters to lock the cross member in position through radial compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transverse connector is designed to securely engage bone anchors, then the connection stability is improved, but the device complexity increases due to multiple components (mount, screw, nut, ring, cross member)
Solution Approach 1:
The transverse connector is divided into multiple functional components: a mount for engaging the bone anchor, a screw that threads through the mount, a nut that secures the screw, a ring that provides radial compression, and a cross member that connects to the other side. This segmentation allows each component to perform its specific function optimally while contributing to overall connection stability.
Solution Approach 2:
The components are nested within each other in a compact arrangement: the screw passes through the mount, the nut threads onto the screw, the ring is compressed between the nut and mount, and the cross member extends from the ring. This nesting minimizes the overall device footprint while maintaining structural integrity and connection strength.
2Adaptability or versatility
If the transverse connector allows for polyaxial movement, then the adaptability is improved, but the positioning precision deteriorates
Solution Approach 1:
The connector transitions from a static rigid connection to a dynamic system that allows polyaxial movement. The ring and cross member assembly can rotate and adjust along multiple axes while maintaining secure engagement with the bone anchor through the screw-nut-rig compression mechanism, enabling adaptation to anatomical variations.
Solution Approach 2:
The system allows changes in orientation parameters (angular position along multiple axes) while maintaining the fundamental engagement parameters through the compressed ring and secured screw-nut assembly. This enables polyaxial adjustment without compromising the security of the bone anchor connection.
3Stability of the object's composition
If the ring is configured to axially lock the cross member, then the positioning stability is improved, but the ease of operation worsens due to requiring radial compression to adjust diameter
Solution Approach 1:
The ring acts as an intermediary component between the nut and the cross member. When the nut is tightened, it applies radial compression to the ring, which then translates this force into axial locking of the cross member. This intermediary mechanism provides stable positioning while allowing adjustment through the nut tightening operation.
Solution Approach 2:
The ring's diameter parameter changes in response to radial compression from the nut, transitioning from an expanded state during installation to a compressed locked state for stable positioning. This parameter change enables the ring to adapt between allowing cross member insertion and securing it in place.
4Strength
If the connector assembly uses multiple fastening components (screw, nut, ring compression), then the connection strength is improved, but the time to assemble increases
Solution Approach 1:
The screw, nut, and ring are pre-configured in a sequential assembly path. The screw is inserted through the mount, the ring is positioned around the cross member, and the nut is threaded onto the screw in advance of final tightening. This preliminary arrangement of components reduces assembly time by eliminating the need to search for or position components during the fastening process.
Solution Approach 2:
The fastening function is segmented into distinct components (screw for threading, nut for tightening, ring for compression) that can be independently prepared and then assembled in a straightforward sequence, reducing the cognitive load and time required for proper assembly while maintaining strong connection through each component's specialized function.
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
Enables secure and adjustable connection of spinal rods to bone anchors, allowing for precise positioning and adjustment, enhancing the stability and flexibility of spinal fixation systems by accommodating polyaxial motion and axial fixation.
Implementation Method 1
The nut may be configured to tighten against the first ring to tighten the first ring around the cross member and fictionally lock the cross member in position relative to the first connector assembly
Implementation Method 2
The first ring may be an open ended ring positioned to move between a first position and second position. The first ring may have a first diameter in the first position and a second diameter in the second position. The second diameter may be less than the first diameter. The first ring may be configured to axially lock the cross member to the rod mount portion of the mount when the first ring is in the second position
Data Source
AI summary
A transverse connector includes a cross member assembly, a first connector assembly, and a second connector assembly. The cross member assembly includes a cross member, a first ring, and a second ring. The cross member has a first end portion and a second end portion. The first ring is receivable on the first end portion of the cross member and the second ring is receivable on the second end portion of the cross member. The first and second connector assemblies are coupled to the first and second rings of the cross member assembly, respectively, to support the cross member between the first and second connector assemblies. The first and second connector assemblies are configured to selectively and releasably secure to bone anchors.