Spinal Anchor D-Shaped Interface for Rotational Control
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Solution Overview
Problem
Existing spinal fixation systems experience loose rotational and axial engagement between instruments and anchors, leading to undesirable torque application and shear stress, and often require multiple instruments for installation, which can complicate the top loading of stabilization system elements.
Innovation Solution
A spinal stabilization system with a driving tool and vertebral anchor design that includes a top portion with a perimeter and engaging elements, such as trapezoidal slots and protrusions, to restrict rotation and facilitate secure engagement, allowing for top loading and minimally invasive procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional interface between instrument and anchor is used, then installation can be performed, but loose rotational and axial engagement occurs leading to undesirable torque application and shear stress
Solution Approach 1:
The patent employs asymmetric geometric features including a D-shaped outer surface on the anchor and corresponding D-shaped inner surface in the instrument, along with trapezoidal slots and protrusions. These asymmetric interfaces eliminate loose rotational engagement by providing a unique orientation fit, preventing unwanted rotation and axial play while distributing loads more effectively during installation.
Solution Approach 2:
The patent inverts the traditional engagement approach by using a male-female interface configuration where the instrument contains trapezoidal slots (female) that receive trapezoidal protrusions (male) from the anchor. This inverted geometry ensures tight engagement with minimal clearance, reversing the typical loose-fit design to achieve precise rotational and axial control during anchor installation.
2Adaptability or versatility
If multiple instruments are used for anchor engagement and rotation, then installation functionality is provided, but top loading of stabilization system elements is complicated
Solution Approach 1:
The patent merges multiple instrument functions into a single integrated driving tool that simultaneously provides anchor engagement, rotation capability, and top loading functionality. The unified instrument features both the D-shaped interface for rotational control and the slot configuration for receiving stabilization elements, eliminating the need for separate instruments and simplifying the surgical procedure.
Solution Approach 2:
The driving tool is designed as a universal instrument that performs multiple functions: it engages the anchor through the D-shaped interface, rotates the anchor for proper orientation, and accepts top loading of connecting elements through its slot structure. This multi-functional design reduces the total number of instruments required while maintaining full installation capability.
Data Source
AI summary
A system for implantation of a spinal stabilization system includes a vertebral anchor having a top portion. The top portion has a perimeter and a first engaging element. The first engaging element has a first longitudinal axis that is generally parallel to a second longitudinal axis of the top portion. The perimeter extends around the second longitudinal axis. The system also includes a driving tool that has a second engaging element that is configured to cooperate with the first engaging element to substantially restrict rotation of the driving tool relative to the top portion about the second longitudinal axis. The first engaging element is configured to slidably receive the second engaging element in a direction along the first longitudinal axis, and the second engaging element is configured to extend substantially within the perimeter of the top portion.