Minimally Invasive Pedicle Screw Assembly with Slotted Rod
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Solution Overview
Problem
Traditional open pedicle screw instrumentation causes significant muscle and ligament damage during spinal fusion surgery, leading to post-operative pain, extended recovery times, and potential additional surgical procedures due to the need for muscle stripping to achieve accurate screw placement.
Innovation Solution
A pedicle screw and rod assembly for minimally invasive percutaneous instrumentation, featuring ball-shaped pedicle screws with cannulated posts and a lordotic slotted rod system that allows for secure multi-axial engagement and easy removal of components post-surgery, maintaining anatomical integrity and reducing tissue damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional open pedicle screw instrumentation is used to achieve accurate screw placement, then manufacturing precision is improved, but object-affected harmful factors worsen due to significant muscle and ligament damage
Solution Approach 1:
A guide tube is introduced as an intermediary device that directs the pedicle screw along a predetermined safe trajectory through the pedicle and into the vertebral body. The guide tube acts as a mediator that protects surrounding soft tissues from direct surgical manipulation while ensuring accurate screw placement through its pre-positioned pathway, thereby resolving the contradiction between placement accuracy and tissue preservation
2Object-affected harmful factors
If minimally invasive percutaneous instrumentation is used to reduce tissue damage, then object-affected harmful factors are improved, but manufacturing precision worsens due to challenges in achieving accurate screw placement
Solution Approach 1:
The guide tube serves as a mediator that bridges the gap between minimally invasive access and precise screw placement. By pre-positioning the guide tube through percutaneous access and using it to direct the screw trajectory, the system achieves both tissue preservation and placement accuracy without requiring extensive muscle stripping
Solution Approach 2:
The guide tube is pre-positioned through percutaneous access before screw insertion, establishing a predetermined safe trajectory in advance. This preliminary action ensures that when the screw is subsequently inserted through the guide tube, accurate placement is achieved without requiring complex real-time adjustments during the minimally invasive procedure
3Ease of operation
If muscle stripping is performed to expose the spine for accurate instrumentation, then ease of operation is improved, but object-affected harmful factors worsen due to significant post-operative pain and extended recovery
Solution Approach 1:
The guide tube acts as an intermediary that provides the necessary surgical access and directional control without requiring muscle stripping. By establishing percutaneous access to the guide tube and using it to direct screw placement, the system maintains ease of operation while avoiding the harmful effects of muscle and ligament damage
Solution Approach 2:
The surgical approach is segmented into distinct steps: percutaneous guide tube insertion, screw insertion through the guide tube, and guide tube removal. This segmentation allows for minimal tissue disruption at each stage while maintaining surgical control, thereby reducing post-operative pain and recovery time compared to traditional en bloc muscle stripping
Data Source
AI summary
A pedicle screw and rod assembly that has particular application for minimally invasive percutaneous pedicle screw instrumentation. The assembly includes pedicle screws having ball-shaped heads that are threaded through pedicles of adjacent vertebra into the vertebral body. The assembly also includes two cannulated posts that extend above a cannulated pedicle screw to allow placement over a K-wire. A head portion accepts the head of the pedicle screw in a secure and multi-axial engagement. The assembly further includes a tube portion that is coupled to the head portion and extends above the patient's skin. The assembly also includes a lordotic slotted rod that is slid down the tube portions to be positioned on top of the head portions of the posts so that the portions are locked within the slot. Bolts are then slid down the tube portions and are threaded to a threaded portion on the portion.