Expandable Percutaneous Sheath for Minimally Invasive Spinal Fixation
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Solution Overview
Problem
Current methods for stabilizing and repositioning displaced vertebrae in the spine are invasive, costly, and associated with significant morbidity, pain, and lengthy hospital stays, with a need for minimally invasive procedures that can accommodate large diameter instruments through small tissue tracts.
Innovation Solution
A percutaneous access sheath that can be inserted in a small configuration and expanded to a larger size using a deployment catheter with a balloon, allowing for the passage of orthopedic fixation devices and implants through a minimally invasive approach, while resisting tissue forces and facilitating procedures like XLIF and TLIF.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If open reduction with screw fixation is used to stabilize displaced vertebrae, then stable fixation is achieved, but the procedure causes significant morbidity, pain, and lengthy hospital stays
Solution Approach 1:
The procedure is divided into separate stages: first creating a small percutaneous access tract, then progressively dilating to accommodate fixation devices. This segmentation allows stable fixation to be achieved through multiple small incisions rather than one large open incision, reducing tissue damage and patient morbidity while maintaining fixation reliability
Solution Approach 2:
The patent employs nested structures where smaller devices are inserted through progressively larger dilators through the same percutaneous access tract. The fixation devices are nested within the dilator system, allowing them to pass through a small initial incision. This nesting approach enables open-reduction-level fixation stability while avoiding the need for large open incisions that cause significant patient morbidity
2Object-affected harmful factors
If a small diameter puncture is made to minimize tissue damage, then tissue trauma is reduced, but the available space for diagnostic or therapeutic instruments is limited
Solution Approach 1:
The access tract dynamically changes size during the procedure. It begins as a small puncture to minimize tissue trauma, then progressively dilates to accommodate larger fixation devices. This dynamic expansion allows the same access tract to serve multiple functions - initially minimizing trauma, then accommodating various sized instruments and implants as needed
Solution Approach 2:
The physical parameters of the access tract are changed during the procedure. The tract starts with small diameter parameters to reduce tissue trauma, then undergoes controlled dilation to increase diameter parameters. This parameter transformation enables the tract to accommodate instruments of varying sizes while initially minimizing tissue damage from the small entry puncture
3Length of moving object
If the sheath is inserted in a small configuration to minimize incision size, then the incision is smaller, but the sheath must be expanded to accommodate large diameter instruments
Solution Approach 1:
The sheath employs flexible, expandable wall structures that can transition from a compressed small-diameter configuration for insertion through a minimal incision to an expanded large-diameter configuration to accommodate fixation devices. This flexible shell design allows the incision to remain small while the sheath internally expands, avoiding the need for a large incision but requiring the sheath to overcome its structural resistance to expansion
Solution Approach 2:
The sheath is pre-compressed or pre-formed in a small-diameter configuration that facilitates insertion through a minimal incision. This preliminary preparation of the sheath in a compact state allows it to be introduced through a small opening, after which it can be expanded to its functional diameter to accommodate the fixation devices
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 minimally invasive stabilization and repositioning of vertebrae with reduced pain and complications, allowing for the use of large instruments through small incisions, thereby reducing hospital stay and improving patient outcomes.
Implementation Method 1
The percutaneous access sheath is configured to be inserted in a first, smaller cross-sectional configuration and then be expanded to a second, larger cross-sectional configuration
Implementation Method 2
allowing for the passage of orthopedic fixation devices and implants through a minimally invasive approach, while resisting tissue forces
Data Source
AI summary
Disclosed is an expandable percutaneous sheath, for introduction into the body while in a first, low cross-sectional area configuration, and subsequent expansion to a second, enlarged cross-sectional configuration. The sheath is maintained in the first, low cross-sectional configuration by a removable tubular restraint or by structural elements built into the wall of the expandable portion of the sheath. In one application, the sheath is utilized to introduce a formed in place orthopedic fixation rod such as for use in spinal fixation procedures, preparation of a spinal segment, or placement of a vertebral body spacer. The sheath can further comprise structural elements to permit re-collapse of the sheath under fluid pressure following completion of the procedure and prior to removal from the patient.