Rotational Spinal Instrument for Secure Intervertebral Implant Positioning
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Solution Overview
Problem
Existing instruments for positioning intervertebral implants in spinal fusion surgeries are complex, often cause tissue damage due to linear movement, and lack a simple and stable locking mechanism, making them unsuitable for minimal invasive procedures.
Innovation Solution
A positioning instrument with a handle, a cannulated locking shaft, and a grasping head with prongs or clamps that can be easily rotated to grip and secure the implant using a 90° oval locking mechanism, allowing for secure gripping and minimal tissue disruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a linear movement mechanism is used to fix the implant, then the implant can be positioned, but tissue damage occurs and the mechanism becomes complex
Solution Approach 1:
The patent replaces the linear movement mechanism with a rotational locking mechanism. The instrument shaft rotates relative to the handle, and this rotation is converted into angular movement of the grasping head through a gear mechanism. This substitution eliminates the need for extensive linear movement, thereby reducing tissue damage while maintaining reliable implant fixation through a 90° lock/unlock mechanism.
2Reliability
If a complex locking mechanism is used, then the implant can be secured, but the instrument becomes difficult to operate
Solution Approach 1:
The patent divides the locking mechanism into distinct functional segments: the handle, the instrument shaft, the gear mechanism, and the grasping head. Each segment performs a specific function, and the 90° rotation of the shaft relative to the handle engages corresponding features (such as a keyway or gear teeth) to secure the implant. This segmentation allows for a simple rotational operation that reliably secures the implant without requiring complex multi-step procedures.
3Reliability
If the instrument is permanently connected to the implant, then the implant can be fixed, but the instrument cannot be engaged in-situ
Solution Approach 1:
The patent employs a dynamic locking mechanism where the instrument shaft can rotate relative to the handle, allowing the grasping head to be angularly adjusted. This dynamic capability enables the instrument to be engaged in-situ by rotating the shaft to the appropriate angle, while still providing reliable implant fixation through the 90° lock mechanism. The connection is not permanent or rigid, but rather adaptable to different engagement scenarios.
4Adaptability or versatility
If a friction lock interface is used, then the instrument can be fixed at different angles, but the stability is inferior compared to a positive lock
Solution Approach 1:
The patent replaces the friction lock interface with a positive lock mechanism. The 90° rotation of the instrument shaft relative to the handle engages with corresponding features (such as a keyway, gear teeth, or cam mechanism) that provide a definite mechanical stop. This positive locking action ensures stable fixation at the desired angle, eliminating the instability associated with friction-based locking while maintaining the ability to position the instrument at different angles through rotational adjustment.
Data Source
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AI summary
The present invention relates to an instrument (1) for positioning an intervertebral implant for the fusion between two vertebral bodies of a vertebral column, comprising: - a handle (3) having a proximal and a distal end; - a locking shaft (7) extended from the distal end of the handle (3); - a grasping head (10) at the distal end of said shaft (7). Advantageously, the locking shaft (7) is cannulated and a stem (15) is hosted inside the cannulated shaft (7) passing through the handle (3); the stem (15) is free to rotate with respect to the locking shaft (7), or viceversa; while the grasping head (10) is formed at the distal end of said stem (15) with a couple of prongs or clamps coming close or far one toward the other according to an angular relative rotation of said stem (15) with respect to the locking shaft (7). The instrument allows to the surgeon to grip a corresponding implant with a simple rotation movement of his hand.