Vertebra Manipulation Instrument for Spinal Rod Derotation
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Solution Overview
Problem
Conventional spinal deformity surgical procedures face challenges in rotating vertebrae relative to each other, leading to stress on bone anchors and potential failure, necessitating improved instruments and methods for manipulating vertebrae angular relationships.
Innovation Solution
The development of instruments featuring an inner shaft with a lumen and an outer sleeve, along with a pair of fingers that can capture a spinal rod receiving member of a bone anchor, allowing for controlled rotation of the vertebra, and a connector system for connecting instruments to facilitate cooperative movement of vertebrae manipulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional rod derotation procedures are used to correct angular relationship of vertebrae, then the curvature of the spine can be corrected, but significant stress is placed on the interface between bone anchors and vertebrae causing potential failure
Solution Approach 1:
The patent introduces a vertebra manipulation instrument as an intermediary device between the spinal rod and the bone anchor. This instrument engages with the bone anchor's receiving member and provides a controlled mechanism for rotating the vertebra, thereby mediating the force application and reducing direct stress on the bone anchor-vertebra interface during derotation procedures
Solution Approach 2:
The vertebra manipulation instrument is divided into distinct functional segments: an engagement mechanism that interfaces with the bone anchor's receiving member, a manipulation shaft for transmitting rotational force, and control elements. This segmentation allows each component to be optimized for its specific function while distributing mechanical stresses across multiple interfaces rather than concentrating them at the bone anchor-vertebra interface
2Manufacturing precision
If conventional rod derotation is performed by rotating the spinal rod directly, then angular relationship correction is achieved, but the procedure lacks precision and control
Solution Approach 1:
The vertebra manipulation instrument incorporates dynamic elements including a movable manipulation shaft that can be advanced and retracted, and engagement mechanisms that can be selectively activated. This dynamic design allows the operator to control the timing and progression of vertebra rotation, enabling precise angular correction while managing the complexity of the procedure through staged manipulation
Solution Approach 2:
The instrument design includes features that provide tactile and visual feedback to the operator during the manipulation process, such as engagement indicators and controlled resistance mechanisms. This feedback allows the surgeon to monitor the rotation progress and adjust the applied force in real-time, improving precision while simplifying the operational complexity through intuitive control
3Adaptability or versatility
If the bone anchor receiving member is made adjustable in multiple directions, then versatility is improved, but stability and control during manipulation are reduced
Solution Approach 1:
The bone anchor receiving member is designed with dynamic adjustment capabilities that allow it to be movable in certain directions during the surgical procedure to accommodate different rod positions and angles, while incorporating stabilization mechanisms that lock the receiving member in the desired position once adjustment is complete, thereby maintaining both versatility and stability
Solution Approach 2:
The receiving member employs a periodic action mechanism where it transitions between movable and fixed states. During the adjustment phase, the receiving member is movable to allow positioning, then it transitions to a locked, stable state for the manipulation and healing phases, creating a periodic cycle of adjustability and stability that satisfies both requirements
Data Source
AI summary
A method for manipulating a vertebra includes connecting a first bone anchor to a first vertebra, connecting a second bone anchor to a second bone anchor, positioning a spinal rod in a receiving member of the first bone anchor and in a receiving member of the second bone anchor, connecting a first instrument to the receiving member of the first bone anchor, and manipulating the first instrument to rotate first bone anchor and the first vertebra relative to the second vertebra.