Interspinous Implants with Deployable Arms
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Solution Overview
Problem
Current surgical treatments for lumbar spinal stenosis, such as decompressive laminectomy and interspinous process decompression (IPD), often require invasive procedures and incisions for implant placement, which can be less than ideal for patient recovery and procedural efficiency.
Innovation Solution
A spinal implant with a threaded body and deployable engagement arms designed for percutaneous insertion into the interspinous process space, featuring a drive assembly for moving engagement members between stowed and deployed positions, and a tapered nose portion for gradual distraction of spinous processes, allowing for minimally invasive deployment and stabilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional surgical treatments (decompressive laminectomy or IPD) are used to treat lumbar spinal stenosis, then effective treatment of spinal stenosis is achieved, but invasive procedures and incisions are required which increase recovery time and procedural complexity
Solution Approach 1:
The implant features deployable engagement arms that can transition between stowed and deployed positions. During percutaneous insertion, the arms remain retracted to minimize tissue disruption. Once positioned, the arms are deployed to engage the spinous process, providing stable fixation without requiring open surgical exposure. This dynamic configuration allows the implant to achieve effective treatment while minimizing procedural invasiveness.
Solution Approach 2:
The engagement arms are nested within the interior cavity of the implant body during insertion. The drive assembly, which actuates the arms, is also contained within the implant structure. This nested configuration allows the entire implant mechanism to be delivered percutaneously through a small incision, avoiding the need for large surgical openings required by traditional approaches.
2Ease of operation
If percutaneous insertion is used to reduce procedural invasiveness, then recovery time and procedural complexity are reduced, but secure engagement and stabilization of the implant may be compromised
Solution Approach 1:
The implant body includes a tapered nose portion that performs preliminary distraction of the spinous processes during insertion. This preliminary action creates optimal spacing and alignment before the engagement arms are deployed, ensuring that the arms can securely engage the bone surfaces. The threaded body portion also performs preliminary thread formation in the bone, facilitating secure engagement without requiring extensive surgical preparation.
Solution Approach 2:
The engagement arms feature curved surfaces and rounded profiles that conform to the natural curvature of the spinous process. The tapered nose portion also employs curved geometry to gradually distract and align the bone structures. These curved configurations allow the percutaneously inserted implant to achieve reliable mechanical engagement with the bone, compensating for the limited access provided by minimally invasive insertion.
3Reliability
If engagement members are deployed to engage the spinous process for stabilization, then implant security is improved, but device complexity increases
Solution Approach 1:
The drive assembly that actuates the engagement arms is merged with the implant body structure. The main drive shaft extends into the interior cavity and is integrated with the tapered nose portion. The locking mechanism is also integrated into the overall implant structure rather than being a separate component. This merging of functions reduces the number of discrete parts while maintaining the capability for secure spinous process engagement.
Solution Approach 2:
The implant body serves multiple functions: it provides the structural framework, contains the nested engagement arms, houses the drive assembly, provides the tapered nose for distraction, and incorporates threading for bone engagement. The engagement arms themselves serve dual purposes by providing both the actuation mechanism (through their connection to the drive assembly) and the final stabilization function. This multi-functionality reduces overall device complexity while achieving reliable engagement.
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 effective treatment of lumbar spinal stenosis through minimally invasive procedures, reducing recovery time and procedural complexity by allowing percutaneous insertion and stabilization of the implant without the need for open surgery or extensive tissue incisions.
Implementation Method 1
The drive shaft can include a transmission end having a plurality of beveled gear teeth for operatively meshing with the beveled gear teeth on the central hubs of each engagement member to facilitate the transmission of torque therebetween.
Data Source
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AI summary
Spinal implants include an elongated body portion dimensioned and configured for percutaneous introduction into a target interspinous process space, at which interspinous distraction and/or spinal fusion are desired. The body portion can include a threaded outer surface, or alternatively a smooth surface. The body portion can include one or more interior cavities, and can include deployable engagement members adapted and configured to move in tandem between a stowed position retracted within the interior cavity of the body portion and a deployed position extended from the interior cavity of the body for engaging adjacent spinous processes. An internal drive assembly for selectively moving the engagement members from the stowed position to the deployed position can be provided, as can a elements for locking the engagement members in a deployed position.