Fatigue-Resistant Neuromuscular Stimulation Lead with Coiled Conductors
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Solution Overview
Problem
Conventional medical leads used for neuromuscular electrical stimulation in the lower back are prone to fracture and dislodgement due to mechanical stresses from highly mobile muscles, leading to ineffective therapy delivery and potential complications during implantation.
Innovation Solution
A lead design featuring a fatigue-resistant zone with coiled conductors to withstand shear forces, combined with fixation elements and an insulated tube to secure the lead, ensuring durability and stability during muscle movement, and a method for manufacturing and implanting the lead to target the lumbar spine effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional straight conductors are used in leads for neuromuscular electrical stimulation, then the lead structure is simple and easy to manufacture, but the lead is prone to fracture and dislodgement due to mechanical stresses from highly mobile lower back muscles
Solution Approach 1:
The patent applies local quality by differentiating the conductor configuration along the lead length. The distal portion (within the active zone) uses a coiled configuration to withstand shear forces from muscle movement, while the proximal portion maintains a straight configuration for simplicity and ease of connection. This localized differentiation resolves the contradiction by providing enhanced reliability only where mechanically stressed, without unnecessarily complicating the entire lead structure.
Solution Approach 2:
The conductor is segmented into two distinct portions: a coiled distal portion and a straight proximal portion. This segmentation allows each segment to be optimized for its specific functional requirements - the coiled segment absorbs mechanical stress from muscle movement while the straight segment provides structural simplicity and ease of manufacturing, thereby resolving the contradiction between reliability and device complexity.
2Reliability
If the lead is made flexible to accommodate muscle movement, then the lead can withstand mechanical stress, but the lead may dislodge from the implantation site
Solution Approach 1:
The fixation elements are applied locally at the distal end of the lead where implantation occurs, rather than along the entire lead length. This localized anchoring provides strong attachment to surrounding tissue at the critical implantation site while allowing the rest of the lead to remain flexible enough to accommodate muscle movement without dislodgement, resolving the contradiction between stability and flexibility.
3Reliability
If fixation elements are added to secure the lead, then the lead resistance to dislodgement is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The fixation elements are merged with the lead body as an integrated structure rather than separate components. The coiled conductor itself serves dual functions: providing electrical conductivity and acting as a fixation mechanism through its anchoring to surrounding tissue. This merging reduces manufacturing complexity by eliminating separate assembly steps for attaching fixation elements while still providing reliable anchoring.
Data Source
AI summary
A lead for providing neuromuscular electrical stimulation that enhances fatigue-resistance, as well as methods of use thereof, and methods for manufacturing the same, are provided. The lead has a proximal region, a distal region, a fatigue-resistant zone disposed between the proximal region and the distal region, and one or more conductors comprising individual strands that extend from the distal region to the proximal region substantially parallel to a longitudinal axis of the electrostimulation lead outside of the fatigue-resistant zone. The individual strands of one or more conductors are wound in a coiled configuration within the fatigue-resistant zone to enhance fatigue-resistance. Moreover, the fatigue-resistant zone is configured to be disposed at a location within the patient that experiences fracture-inducing shear forces caused by movement of the patient's lower back muscles.