Uni-planar Taper Lock Bone Screw for Spinal Alignment
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Solution Overview
Problem
Conventional bone screws fail to provide a flexible, uni-planar connection for securing connecting rods to vertebrae not on the same plane, limiting surgical manipulation and alignment in conditions like scoliosis, and often require additional torque or locking mechanisms.
Innovation Solution
A novel uni-planar taper lock screw with a slidable outer housing and a spherically configured, pivotable screw head allows for easy insertion, alignment, and locking of connecting rods to vertebrae without additional torque, featuring a complementary tool for locking and unlocking, and restricting movement to a single plane for precise spinal column manipulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional bone screws are used to secure connecting rods to vertebrae, then the connection is rigid and stable, but the surgical manipulation and alignment flexibility is limited
Solution Approach 1:
The screw head is designed with a spherical configuration that allows dynamic movement and rotation during surgical manipulation, enabling alignment flexibility. After positioning, the connection is locked to provide stability, thus transitioning from a static rigid connection to a dynamic adjustable connection that achieves both flexibility and stability.
Solution Approach 2:
The connecting rod connection is divided into two functional segments: a spherical screw head portion that provides rotational freedom for alignment adjustment, and a locked portion that provides stable fixed connection. This segmentation allows the system to exhibit both flexible manipulation capability and stable final positioning.
2Adaptability or versatility
If additional locking mechanisms are added to provide flexibility, then the adaptability improves, but the device complexity increases
Solution Approach 1:
The locking mechanism is merged with the screw structure itself, where the spherical screw head integrates both the movement capability and the locking function. The compression force from screw insertion directly engages the spherical surface to lock the connecting rod, eliminating the need for separate locking components and reducing overall device complexity while maintaining adaptability.
3Adaptability or versatility
If a spherical screw head configuration is used, then the uni-planar movement flexibility is improved, but the control over multiplanar movement may be compromised
Solution Approach 1:
The spherical screw head is designed with an asymmetric configuration where the spherical surface geometry and the connecting rod interface are configured to permit rotation only in the desired surgical plane. This asymmetric design inherently restricts multiplanar movement while maintaining uni-planar flexibility, providing both adaptability and reliable movement control through its geometric constraints.
4Ease of operation
If the screw head is made accessible for tool engagement, then the ease of operation improves, but the device complexity increases
Solution Approach 1:
The spherical screw head configuration serves multiple functions: it provides the rotational flexibility for alignment adjustment, acts as the locking surface when compressed, and presents a accessible geometry for tool engagement. This multi-functional design achieves ease of operation without requiring additional specialized components, thereby avoiding increased device complexity.
Data Source
AI summary
Provided is a novel uni-planar taper lock screw for connecting a connecting rod to bone. The screw is capable of being secured to the underlying bone while the screw head adapted to securely hold a connecting rod is articulated in a uni-directional manner to facilitate a stable connection to the connecting rod. After the screw had been articulated and properly positioned, it can be partially locked such that the connecting rod will remain in relative position to the bone while permitting flexibility of the screw head relative to the bone along a single plane. The screw head can then be fully locked securing the connecting rod into a selected position. The screw is configured for easy insertion and connection as well as easy removal and disconnection from the connecting rod. Also provided is a system for fixing two or more bones or bone fragments and a kit for fixing bones or bone fragments. A method of fixing bones or bone fragments is also provided.