Curved Wire RF Spinal Probe with Integrated Suction and Irrigation
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Solution Overview
Problem
Current electrosurgical instruments are not well-suited for minimally invasive surgical (MIS) procedures to remove spinal tissue, such as the disc nucleus pulposus, efficiently and safely, particularly for replacing spinal tissue with an artificial disc prosthesis.
Innovation Solution
An intervertebral electrosurgical electrode designed for use within a cannula, featuring a flexible curved wire electrode flanked by irrigation and suction ports, utilizing 4 MHz radiofrequency energy to create a precise void in spinal tissue with minimal lateral heat and tissue damage, allowing for efficient removal and coagulation of excised tissue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional electrosurgical instruments are used for spinal tissue removal, then tissue excision can be achieved, but the procedure is not suitable for minimally invasive surgical (MIS) approaches and causes excessive tissue damage
Solution Approach 1:
The electrosurgical instrument is nested within a cannula, with the active electrode contained inside the tubular member. This nesting enables the instrument to be inserted through a small incision for minimally invasive access to spinal tissue, eliminating the need for large open incisions while maintaining electrosurgical functionality.
Solution Approach 2:
The active electrode is designed to concentrate RF energy precisely at its tip where it contacts the tissue, creating localized heating and ablation only at the treatment site. The tubular member provides electrical isolation, ensuring that energy is delivered only where intended, minimizing collateral tissue damage.
2Manufacturing precision
If RF electrosurgical currents are applied to spinal tissue, then a void can be formed for prosthesis placement, but lateral heat spread can damage endplates and violate the annulus
Solution Approach 1:
The instrument operates at 4 MHz radiofrequency, a specific parameter choice that provides self-limiting energy penetration. This frequency enables precise tissue interaction with controlled heating depth, allowing accurate void formation while preventing excessive lateral heat spread that could damage surrounding structures.
Solution Approach 2:
Irrigation fluid is introduced through the tubular member as an intermediary cooling medium. The fluid flows across the active electrode during operation, absorbing lateral heat and preventing thermal damage to the endplates and annulus while allowing the RF energy to effectively ablate the nucleus pulposus.
3Productivity
If tissue is removed to form a cavity, then space for prosthesis is created, but tissue removal and cavity formation is time-consuming and inefficient
Solution Approach 1:
The instrument enables continuous RF energy delivery to the tissue while irrigation fluid continuously cools the electrode and removes debris. This continuous action allows efficient, uninterrupted ablation and removal of the nucleus pulposus, significantly reducing procedure time compared to intermittent or mechanical removal methods.
Solution Approach 2:
Hydraulic pressure from the irrigation fluid system is used to flush removed tissue debris away from the surgical site through the tubular member. This hydraulic removal mechanism efficiently clears the cavity during formation, eliminating the need for separate removal steps and improving overall procedural efficiency.
4Ease of operation
If a cannula is used for MIS access, then minimally invasive approach is achieved, but the instrument must be elongated and confined within the cannula limits
Solution Approach 1:
The tubular member serves multiple functions: it acts as the cannula for minimally invasive access, provides electrical insulation for the active electrode, delivers irrigation fluid to cool the electrode and flush debris, and serves as a stop to position the electrode at the correct depth. This multi-functionality reduces the need for separate components, simplifying the overall instrument design.
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
Enables precise and safe excision of spinal tissue with reduced tissue damage and bleeding, facilitating MIS procedures that are cost-effective and result in superior outcomes compared to other voiding devices, with the ability to accommodate replacement substances or devices.
Implementation Method 1
The wire electrode is electrically active and is capable of applying electrosurgical currents to human tissue... cutting is accomplished by volatilizing intracellular fluids at the point of the transmitting electrode contact
Implementation Method 2
use of radio-frequency (RF) electrosurgical currents, in a frequency range preferably above 3 MHz, with 4 MHz being preferred
Implementation Method 3
in front of the electrode is a receiving port for the suction... the tissue removed to form the cavity under pressure from the exiting irrigation fluid is then easily aspirated via the suction port
Implementation Method 4
the wire electrode is flanked in front by the exiting irrigation fluid and behind by the suction, with the result that suction causes fluid flow across the wire electrode creating pressure forces that direct removed tissue to the suction entrance
Implementation Method 5
the far end of the tubular member is constructed of a radio-opaque material such that the instrument end is visible during fluoroscopic examination
Implementation Method 6
It is believed that 4 MHz radiofrequency energy has been proven to be a self-limiting, minimal penetration energy source capable of precise tissue interaction... Since lateral heat is typically not a byproduct of 4 MHz RF currents, damage to endplates can be minimized or avoided
Data Source
AI summary
An electrosurgical instrument for spinal procedures comprises an elongated tubular member configured to fit within and be extended down a standard sized cannula. The instrument comprises a proximal end including a handle for the surgeon and supplied with fittings for connection to a source of irrigation fluid and a source of suction. The distal end of the instrument has an active end comprising a slightly-flexible curved wire electrode that extends in the plane of the tubular member. Beyond the wire electrode is an exit port for irrigation fluid, and in front of the electrode is a receiving port for suction. The wire electrode is thus flanked in front by the exiting irrigation fluid and behind by the suction, with the result that fluid flow is drawn by the suction across the wire electrode creating pressure forces that direct removed tissue to the suction entrance and its removal from the surgical site.