Low Profile Bone Screw Extender for Minimally Invasive Spinal Fixation
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Solution Overview
Problem
Conventional spinal surgeries often require large incisions and extensive tissue retraction, leading to long recovery times, patient discomfort, increased risk of infection, and high expenses due to the need to address facet joint and intervertebral disc degeneration, which frequently occur together.
Innovation Solution
A percutaneous surgical assembly comprising a subcutaneous screw, a tissue extender, and a setscrew is used to secure adjacent vertebrae, where the tissue extender is coupled to the screw head to retract soft tissue and allow for the insertion of a tether, which is then locked into the screw head using a setscrew, minimizing the need for extensive tissue manipulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional spinal surgery methods are used with large incisions and extensive tissue retraction, then secure stabilization of vertebrae can be achieved, but patient recovery time increases and surgical risk increases
Solution Approach 1:
The surgical system is divided into separate modular components: a screw with head, a separate extender device, and a tether. This segmentation allows the extender to be attached to the screw head to provide percutaneous access while the tether is secured inside, enabling stable fixation through minimal incisions without requiring extensive tissue retraction
Solution Approach 2:
The extender device acts as an intermediary component between the screw head and the external environment. It provides a pathway for inserting and securing the tether through the skin without requiring large incisions, thus maintaining reliable vertebrae stabilization while minimizing tissue disruption and accelerating patient recovery
2Reliability
If conventional spinal surgery with extensive tissue retraction is performed, then vertebrae can be stabilized, but the risk of infection increases
Solution Approach 1:
By segmenting the surgical system into a screw component, extender component, and tether component, the procedure can be performed through small separate incisions rather than one large incision. This reduces the open wound surface area and exposure to contaminants, lowering infection risk while maintaining effective vertebrae stabilization
Solution Approach 2:
The extender serves as an intermediary that creates a controlled access pathway through the skin. This allows the tether to be inserted and secured with minimal tissue disruption and reduced exposure to external contaminants, thereby stabilizing vertebrae effectively while minimizing infection risk
3Loss of time
If percutaneous method with tissue extender is used, then patient recovery time is shortened, but the complexity of the surgical assembly increases
Solution Approach 1:
The surgical assembly is segmented into distinct functional components (screw, extender, tether) that can be manufactured using standard orthopedic techniques and assembled during surgery. This modular approach manages complexity by allowing each component to be optimized independently while working together to achieve rapid patient recovery through minimal incisions
Data Source
AI summary
A tissue extender includes a ring defining a proximal end opening to engage a head of a subcutaneous screw, a first extender portion coupled to the ring at a proximal end of the first extender portion, and a second extender portion coupled to the ring at a proximal end of the second extender portion. The first extender portion includes a first coupling portion disposed at a distal end of the first extender portion, and the second extender portion includes a second coupling portion at a distal end of the second extender portion. The first and second extender portions define two side openings disposed on opposite sides of the tissue extender. The distal ends of the first and second extender portions together define a distal end opening. The first coupling portion engages the second coupling portion when the tissue extender is in an extended state. The distal end opening is larger in the extended state than in an unextended state.