Bone Anchoring Device Torque Application
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Solution Overview
Problem
Existing bone anchoring devices in spine surgery lack an efficient mechanism for applying high torque during insertion and adjustment, which can complicate procedures and reduce precision.
Innovation Solution
A bone anchoring device with a separate shank and head, where the head features an enlarged drive structure for increased torque application, and a receiving part that allows for polyaxial movement and fixation, enhancing the device's robustness and usability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a ball-shaped head is used in existing bone anchoring devices, then the device structure is simple, but the torque application capability during insertion and adjustment is insufficient
Solution Approach 1:
The device is divided into separate modular components: a shank with threaded portion for bone anchoring, a head with enlarged drive structure for torque application, and a receiving part for rod connection. This segmentation allows the head to be optimized for torque application while maintaining overall device functionality.
Solution Approach 2:
The head transitions from a simple ball-shaped structure to an enlarged drive structure with internal cavities and engagement features. This dimensional expansion provides space for enhanced torque transmission mechanisms while maintaining external spherical geometry for receiving part connection.
2Ease of operation
If the shank and head are integrated as one piece, then the device structure is simple, but the flexibility for selecting different shank lengths and the ability to facilitate insertion are reduced
Solution Approach 1:
The bone anchoring device is segmented into a shank component and a head component that can be separately manufactured and selected based on specific surgical requirements. The shank can be inserted first, followed by attachment of the appropriate head, providing flexibility in configuration.
Solution Approach 2:
The shank can be inserted into the bone first, establishing the anchor point before the head is attached. This preliminary action facilitates the procedure by separating the insertion step from the torque application and rod connection steps.
3Force
If the drive structure is enlarged, then the torque application capability is improved, but the size of the head increases
Solution Approach 1:
The drive structure is nested within the head, with internal cavities and engagement features contained within the overall spherical head geometry. This nesting allows the drive structure to be enlarged for better torque application while keeping the external head dimensions compatible with the receiving part.
4Adaptability or versatility
If a polyaxial receiving part is added, then the angular adjustment capability is improved, but the device complexity increases
Solution Approach 1:
The polyaxial functionality is isolated to the receiving part, which is designed as a separate component with spherical seats and fixation members. This segmentation allows the shank and head to remain relatively simple while the receiving part provides the angular adjustment capability through its internal geometry and locking mechanisms.
Data Source
AI summary
An anchoring element includes a shank for anchoring to bone and a separate head that is connectable to the shank. The head has an exterior surface with a spherically-shaped section and an unthreaded tool engagement surface that is engageable with a drive tool when the head and the shank are connected to one another.