Spinal Fixation Guide Wire for Minimally Invasive Rod Insertion
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Solution Overview
Problem
Minimally invasive spinal fixation techniques face challenges in aligning and inserting fixation rods through pedicle screws due to misalignment and lack of proper guidance, leading to excessive tissue damage and prolonged recovery.
Innovation Solution
A guide wire is connected to an outermost pedicle screw, pulled through all screws, and used to guide a fixation rod into position, with optional use of a malleable template rod to determine alignment and length, allowing for minimally invasive incisions and reduced tissue disruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional open surgical techniques are used with long incisions and muscle retraction, then access to vertebrae is achieved, but muscle damage and recovery time are excessive
Solution Approach 1:
The surgical approach is segmented into multiple percutaneous incisions rather than a single long inciction, allowing targeted access to specific vertebrae while preserving surrounding muscle tissue. Each inciction is made through the muscle belly rather than requiring muscle stripping.
Solution Approach 2:
Tubular cannulas serve as intermediary devices that provide a protected pathway through the muscle and soft tissue to reach the vertebrae. These cannulas maintain the percutaneous approach while facilitating screw insertion and rod passage without requiring direct muscle retraction.
2Object-affected harmful factors
If percutaneous MIS techniques with tubular cannulas are used, then muscle damage is reduced, but alignment and insertion of fixation rods becomes difficult due to misalignment of pedicle screws
Solution Approach 1:
A flexible guide wire acts as an intermediary element that is first inserted through the tubular cannulas and pedicle screws. This guide wire provides a physical pathway and alignment reference that facilitates subsequent rod insertion, overcoming the misalignment problem while preserving the percutaneous approach.
Solution Approach 2:
The system allows for adjustment of the guide wire and rod parameters (flexibility, diameter, surface properties) to accommodate variations in pedicle screw alignment while maintaining the minimally invasive approach. The guide wire's flexibility allows it to conform to slight misalignments.
3Ease of operation
If a swinging rod inserter is used to deliver the rod through skin and tissue, then rod insertion is achieved, but the rod is not restrained or guided along the insertion path
Solution Approach 1:
The guide wire serves as a reliable intermediary that provides both guidance and restraint for the rod during insertion. The rod is passed over or alongside the guide wire, which constrains its path and ensures accurate positioning within the pedicle screws, eliminating the unrestrained motion problem.
Solution Approach 2:
The guide wire is inserted and positioned in advance before rod insertion. This preliminary action establishes the correct pathway and alignment, ensuring that when the rod is subsequently inserted, it follows the predetermined accurate path without requiring complex real-time guidance mechanisms.
4Ease of operation
If the rod is inserted in a non-axial direction through sleeve extenders, then rod connection is achieved, but excessive tissue damage and prolonged recovery occur
Solution Approach 1:
Instead of inserting the rod through a lateral approach requiring slit creation in the muscle, the guide wire and rod are inserted in an axial direction through the same percutaneous incisions used for screw insertion. This inverted approach sequence eliminates the need for additional tissue disruption.
Solution Approach 2:
The same percutaneous incisions and tubular cannulas used for pedicle screw insertion are also used for guide wire and rod insertion. This multi-functional approach eliminates the need for separate incisions or tissue disruption for rod insertion, reducing overall tissue damage.
Data Source
AI summary
An improved method and guide wire assembly used in a system, set of instrumentation and method comprising the combination and use of plural pedicle screws, a rod for connecting pedicle screws in a relatively rigid manner, and instrumentation to optimize insertion of the rod into the pedicle screws, the assembly having a guide wire and instrumentation to grasp a medial portion of the guide wire to pull the medial portion through all the pedicle screws and connecting the loop to the end of a fixation rod, whereby one end of the guide wire is mounted to a pedicle screw, all the screws are implanted into the vertebrae, and the rod subsequently guided into the pedicle screws by pulling the guide wire loop back through the pedicle screws, all using minimally invasive surgical incisions.