Mis Cross-Connector Rotational Locking for Spinal Alignment
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Solution Overview
Problem
Existing bone fixation systems face challenges in accommodating variations in geometrical alignment of elongate members during spinal stabilization, often requiring invasive procedures that damage anatomical structures and lack sufficient adjustability.
Innovation Solution
A bone fixation system comprising a connector assembly with adjustable locking caps and a connector member that includes a cap portion and a hook portion, allowing for rotational adjustment of the cap while keeping the hook stationary, to secure elongate members to bone fasteners, thereby providing stability and minimizing tissue damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If typical cross connectors are inserted through fully open or mini-open procedure, then the elongate members can be connected, but resection of spinal ligaments and bone occurs causing damage to anatomical structures
Solution Approach 1:
The connector system is divided into separate components: a connector body, a connector arm, and a bone fastener assembly. This segmentation allows the connector to be inserted through a minimally invasive trajectory without requiring resection of spinal ligaments and bone, while still achieving connection of the elongate members.
Solution Approach 2:
The connector arm acts as an intermediary element that bridges the connector body and the bone fastener assembly. This intermediary structure enables the connector to engage with the elongate member through a minimally invasive approach without directly damaging the anatomical structures.
2Stability of the object's composition
If pedicle screws and rods are used to stabilize adjacent spinal segments, then stability is provided, but the system cannot accommodate variations in geometrical alignment of elongate members
Solution Approach 1:
The connector system incorporates adjustable components that allow dynamic adaptation to different geometrical alignments. The connector arm can be positioned at various angles relative to the connector body, and the bone fastener assembly can be adjusted to accommodate variations in pedicle orientation, enabling the system to maintain stability despite alignment variations.
Solution Approach 2:
The system allows change in geometric parameters such as the angle between the connector arm and connector body, and the orientation of the bone fastener assembly. These parameter adjustments enable the connector to accommodate variations in elongate member alignment while maintaining the stability required for spinal fixation.
3Stability of the object's composition
If multiple sizes and shapes of pedicle screws are used to accommodate varying pedicle size and angulation, then stable fixation is achieved, but the device complexity increases
Solution Approach 1:
The connector system is designed as a universal assembly that can accommodate various pedicle sizes and angulations through a single standardized interface. The bone fastener assembly integrates multiple functions (anchoring to bone, connecting to elongate member, accommodating angular variation) within one component, eliminating the need for multiple specialized pedicle screw types.
Solution Approach 2:
The system uses adjustable parameters within the bone fastener assembly and connector arm to adapt to different pedicle geometries. Rather than requiring multiple fixed designs, the components can be adjusted within a range of motion to accommodate variations in pedicle size and angulation, reducing device complexity.
4Strength
If cross connectors are used to intercoupling elongate members, then strength and stability are increased, but the procedure becomes more invasive
Solution Approach 1:
The connector system extracts the connection function from the traditional open surgical approach. By using a minimally invasive insertion trajectory and a connector design that engages elongate members through existing tissue planes, the system achieves the same strength and stability without requiring resection of spinal ligaments and bone.
Solution Approach 2:
The connector arm serves as an intermediary that transmits the connection force from the connector body to the bone fastener assembly through a minimally invasive path. This intermediary structure enables the cross-connector function to be achieved with reduced tissue damage compared to traditional open procedures.
Data Source
AI summary
A bone fixation system for implanting in bone, the system comprising a plurality of bone fastener assemblies that attach to bone, a pair of elongate members that attach to the plurality of bone fastener assemblies, a connector member that contacts the pair of elongate members, and a plurality of locking caps that secure the connector member and the elongate members to the plurality of bone fastener assemblies, wherein at least one of the plurality of locking caps comprises a cap portion and a hook portion, where the cap portion is adapted to rotate while the hook portion is stationary.