Polyaxial Bone Anchor Clamping Ring for Repeatable Rod Adjustment
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Solution Overview
Problem
In spinal surgery, repeated adjustments of bone anchoring elements and spinal rods relative to polyaxial bone anchoring devices are necessary, often requiring large forces that can damage surrounding tissue, and existing systems lack versatility and efficiency in handling during such procedures.
Innovation Solution
A polyaxial bone anchoring device with a receiving part, pressure member, and clamping ring that allows independent locking and releasing of the bone anchoring element relative to the receiving part, enabling multiple adjustments without damaging surrounding tissue, and a modular system for combining various anchoring elements based on clinical needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If repeated adjustments of bone anchoring elements and rod relative to receiving part are performed, then positioning accuracy is improved, but tissue damage increases due to large forces required
Solution Approach 1:
The device transitions from a static locked state to a dynamic adjustable state through the instrument. The receiving part can dynamically change between allowing adjustment movements and maintaining fixed positioning, enabling repeated repositioning without permanent tissue damage from forceful adjustments
Solution Approach 2:
The instrument acts as an intermediary mechanism between the surgeon's control and the bone anchoring element. It provides a controlled interface for applying minimal forces during adjustment, mediating the interaction to achieve positioning accuracy while protecting surrounding tissue from harmful forces
2Stability of the object's composition
If existing locking mechanisms are used, then structural stability is improved, but ease of operation deteriorates due to complexity of releasing and repositioning
Solution Approach 1:
The locking mechanism is segmented into independent functional components: the clamping ring for locking the bone anchoring element, the pressure member for maintaining structural stability, and the instrument for controlled release. This segmentation allows each component to perform its specific function efficiently, enabling easy repositioning without compromising overall structural stability
Solution Approach 2:
The device incorporates self-contained locking and releasing functionalities within the receiving part structure. The clamping ring and pressure member work together to automatically maintain stability during use, while the instrument provides self-service release capability without requiring complex external mechanisms or sacrificing structural integrity
3Reliability
If fixation element is used to lock bone anchoring element, then reliability is improved, but device complexity increases due to multiple components
Solution Approach 1:
The clamping ring integrates multiple functions into a single component: it locks the bone anchoring element in the receiving part, maintains positional stability, and works cooperatively with the pressure member. This merging of functions reduces the number of separate fixation components needed while maintaining or improving locking reliability through coordinated action
Data Source
AI summary
A bone anchoring device includes a receiving part with a recess for receiving a rod and a flexible head receiving portion for pivotably holding a head of a bone anchoring element, a pressure member configured to exert pressure on the head when the head is held in the head receiving portion, and a clamping ring positionable around the head receiving portion and movable from a first position where the head is pivotable relative to the receiving part, to a second position where the clamping ring exerts a radial force on the head receiving portion to lock the head relative to the receiving part. When the clamping ring is at the first position, the clamping ring abuts the receiving part to restrict upward movement, while a surface of the clamping ring that faces upwards is exposed for engaging an instrument to move the clamping ring to the second position.