Screw-Based Retractor for Minimally Invasive Spine Surgery
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Solution Overview
Problem
Current minimally invasive spine surgery techniques face challenges in maintaining small incisions and achieving complete access for rod insertion, often requiring additional incisions or larger incisions, which limits the procedure's minimally invasive nature and flexibility, especially for multi-level fusions.
Innovation Solution
A minimally invasive screw-based retractor system co-molded with a pedicle bone screw, featuring frangible blades and a living hinge, allows for flexible tissue retraction and instrument guidance, maintaining access and visibility without the need for additional incisions, and can be easily assembled and removed during surgery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If standard hand-held surgical retractors are used, then the incision can be kept small, but manual manipulation is required which occupies the physician's hand and requires assistance
Solution Approach 1:
The retractor is integrated with the pedicle screw as a single unit, combining the fixation function of the screw with the retraction function of the blades. This eliminates the need for separate hand-held retractors and reduces the number of components the surgeon must manipulate.
Solution Approach 2:
The retractor blades are automatically positioned and maintained through the screw's threading action on the bone. Once the screw is inserted, the blades self-adjust to maintain retraction without requiring continuous manual manipulation or assistance.
2Area of stationary object
If typical retractors are positioned into soft tissue and levered back, then the wound can be held open, but they frequently require re-positioning if they dislodge, obstruct view, or interfere with access
Solution Approach 1:
By integrating the retractor with the pedicle screw that is firmly anchored in the vertebral body, the retraction system gains stable fixation. The screw-bone anchorage prevents dislodgement and maintains consistent retraction position throughout the procedure.
Solution Approach 2:
Instead of leveraging the retractor back against tissue to maintain position, the design uses the screw's forward insertion motion to actively push the blades into the retracted position, where they are then maintained by the screw's fixed anchorage.
3Area of stationary object
If a single small incision is used for rod insertion in spine fusion, then minimally invasive benefits are achieved, but access and visibility are limited especially for multi-level fusions
Solution Approach 1:
The retractor system uses multiple independent blades that can be individually adjusted and positioned. This segmentation allows each blade to be optimized for specific anatomical structures and surgical needs, providing versatile access through a single small incision.
Solution Approach 2:
The retractor blades are designed to be dynamically adjustable during the procedure, allowing the surgeon to modify the retraction configuration to accommodate different rod sizes, insertion angles, and multi-level fusion requirements through the same incision.
4Adaptability or versatility
If additional incisions are made to improve access for rod insertion, then surgical flexibility is improved, but the minimally invasive nature of the procedure is compromised
Solution Approach 1:
The integrated screw-retractor unit serves multiple functions: it provides vertebral fixation, maintains tissue retraction, guides rod insertion, and allows instrument passage. This multi-functionality eliminates the need for additional incisions that would otherwise be required for separate retraction and instrumentation.
Solution Approach 2:
The retractor blades act as an intermediary structure that creates a working channel through the tissue, allowing rods and instruments to be passed through the single small incision. The blades mediate between the limited incision access and the requirements for instrument manipulation and rod insertion.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The retractor system enables more efficient and flexible minimally invasive spine surgery by maintaining access and visibility, reducing tissue retraction, and accommodating various surgical needs, including multi-level fusions, while minimizing scarring and post-operative pain.
Implementation Method 1
The retractor blades are frangible from the tulip of the pedicle screw. In one embodiment, the retractor has a 'living hinge' joining the retractor arm to a blade.
Implementation Method 2
The retractor has a 'living hinge' joining the retractor arm to a blade. The proximal end of the retractor is flexible and flexes away from the radial center.
Data Source
AI summary
A device, system and method for orthopedic spine surgery using a novel screw-based retractor, disclosed herein, that allows for access to the spine through a minimally or less invasive approach. The retractor device is designed as a co-molded part of the tulip of a pedicle screw assembly with opposed arms of the retractor spread apart to open the wound proximally. The arms are removed by separating the arms from the tulip and removing them from the incision. The retractor device is intended to be made of a relatively stiff material, sterile packaged and disposable after one use. A system and method for using the retractor and performing a minimally invasive spine surgical procedure are also disclosed.