Tethers for Spinal Fastener Assemblies to Reduce Stress
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Solution Overview
Problem
Uninstrumented levels of the spine adjacent to the spinal framework experience significant stresses due to the interconnection of spinal rods and fastener assemblies, necessitating a method to mitigate these stresses and create desirable tension for therapeutic purposes.
Innovation Solution
The use of tethers with fastener assemblies, where screws are inserted into vertebrae on either side of the spinous process, with the tether extending over a spinous process of an uninstrumented vertebrae and tensioned between screws of fastener assemblies to stabilize and apply force to adjacent vertebrae, thereby reducing stress and creating therapeutic tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If spinal rods and fastener assemblies are used to form a framework for correcting spinal deformities, then spinal alignment and stability are improved, but significant stresses are transmitted to uninstrumented levels of the spine causing potential damage
Solution Approach 1:
A tether is introduced as an intermediary element that connects fastener assemblies at different spinal levels. The tether spans across uninstrumented vertebrae, distributing mechanical loads and reducing stress concentration on these vulnerable levels while maintaining overall framework stability.
Solution Approach 2:
The spinal stabilization system is segmented into multiple independent fastener assemblies connected by tethers, allowing localized stress distribution. Instead of a continuous rigid rod, the segmented tether-fastener configuration allows flexible load management across different spinal segments.
2Stability of the object's composition
If multiple fastener assemblies are attached to vertebrae to stabilize the spine, then spinal stability is improved, but the complexity of the surgical procedure and device assembly increases
Solution Approach 1:
The tether serves multiple functions simultaneously: it connects fastener assemblies, spans across uninstrumented vertebrae, distributes mechanical loads, and provides tensile stabilization. This multi-functionality reduces the need for additional specialized components, simplifying the overall device configuration.
3Reliability
If tethers are tensioned over spinous processes to reduce stress on uninstrumented levels, then therapeutic effect is improved, but precise positioning and tensioning control becomes more difficult
Solution Approach 1:
The tether system allows adjustment of tension parameters and positioning after implantation. By modifying tension levels and anchor point positions, optimal therapeutic effects can be achieved while accommodating variations in patient anatomy and surgical outcomes.
Data Source
AI summary
One or more tethers for use with fastener assemblies and a method for use of the one or more tethers with the fastener assemblies is provided. The one or more tethers can be attached between a first fastener assembly positioned with respect to a first vertebrae adjacent a first side of a spinous process of a second vertebrae and a second fastener assembly positioned with respect to the vertebrae adjacent a second side of the spinous process of the second vertebrae. The one or more tethers can be tensioned against the spinous process of the second vertebrae to mitigate stresses on an uninstrumented level of the spine.