Cortical Rim-Supporting Interbody Device for Vertebral Subsidence
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Solution Overview
Problem
Subsidence of implanted interbody cages is a risk, particularly in patients with lower bone density, due to inadequate support and stress distribution across the vertebral endplates, which existing fusion techniques fail to adequately address.
Innovation Solution
A percutaneous method involving a central inflatable distractor and a perimeter balloon is used to create a horseshoe-shaped structural support, where the perimeter balloon is filled with a curable material that contacts the vertebral endplates, allowing for the removal of the distractor and subsequent grafting for fusion, providing sustained load-bearing capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional interbody cage is implanted, then fusion is achieved, but subsidence occurs due to inadequate support and stress distribution
Solution Approach 1:
The support structure is divided into multiple components: a central distractor for spacing, a perimeter balloon for lateral support, and a horseshoe-shaped structural support for load distribution. This segmentation allows each component to address specific stress distribution issues, preventing subsidence while maintaining fusion.
Solution Approach 2:
The horseshoe-shaped structural support provides enhanced support at the cortical rim (peripheral region) where subsidence is most likely to occur, while the central region allows for graft placement. This local differentiation of support quality addresses the specific problem of subsidence without compromising overall fusion.
2Ease of operation
If minimally invasive techniques are used to insert fusion cage, then invasiveness is reduced, but adequate support and stress distribution are not achieved
Solution Approach 1:
The device utilizes inflatable balloons (central distractor and perimeter balloon) that can be inserted minimally invasively and then inflated to provide mechanical support. The pneumatic expansion allows the device to achieve adequate stress distribution and support while being delivered through small incisions, resolving the contradiction between minimally invasive delivery and effective support.
Solution Approach 2:
The device transitions from a compressed delivery state to an expanded support state through inflation. This parameter change (volume expansion) allows the same device to provide adequate stress distribution and support after minimally invasive insertion, achieving both low invasiveness and effective mechanical support.
3Ease of operation
If the central distractor is removed after distraction, then access for grafting is improved, but support is reduced
Solution Approach 1:
The central distractor is extracted (removed) after serving its temporary function of spacing the vertebrae and providing access for graft placement. The permanent support function is then assumed by the horseshoe-shaped structural support and perimeter balloon, maintaining strength while enabling grafting access.
Solution Approach 2:
The central distractor performs a preliminary action of spacing the vertebrae and creating access pathways during the procedure. After this preliminary function is complete, it is removed, and the permanent support structure is activated to maintain the spacing and provide ongoing support, allowing grafting to proceed.
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
This method effectively stabilizes the intervertebral space by distributing loads across the cortical rim of the vertebrae, reducing the risk of subsidence and promoting successful fusion, even in patients with lower bone density.
Implementation Method 1
the perimeter balloon is filled with a curable material that contacts the vertebral endplates
Implementation Method 2
a central inflatable distractor and a perimeter balloon are inserted into the disc space in uninflated configurations. The central inflatable distractor is then expanded, thereby distracting the vertebral endplates
Data Source
AI summary
A central inflatable distractor and a perimeter balloon are inserted into the disc space in uninflated configurations. The central inflatable distractor is then expanded, thereby distracting the vertebral endplates to the controlled height of the central inflatable distractor. The perimeter balloon is then inflated with a curable substance. The perimeter balloon expands as it is filled with the curable substance and conforms to the void remaining in the disc space around the central inflatable distractor, thereby creating a horseshoe shape. Once the flowable material in the perimeter balloon has cured, the central inflated distractor can be deflated and removed. The remaining void (or inner space) is then packed with graft for fusion.