Implementation of an implantable joint-angle transducer.

Area of Science:

• Biomedical Engineering
• Neuroprosthetics
• Implantable Sensors

Background:

• Functional neuromuscular stimulation (FNS) neuroprostheses require reliable control signals.
• Existing control methods may lack precision or long-term stability.
• Wrist joint-angle data is crucial for intuitive hand grasp control.

Purpose of the Study:

• To evaluate the chronic functionality, safety, biocompatibility, and clinical feasibility of an implantable joint-angle transducer (IJAT).
• To assess the IJAT's performance as a command-control input for FNS neuroprostheses.
• To determine the long-term viability and efficacy of the IJAT in human subjects.

Main Methods:

• Development of an IJAT utilizing the Hall effect for joint-angle sensing.
• Accelerated bench testing to project device lifespan.
• Chronic implantation in animal models to assess performance and biocompatibility.
• Clinical implantation in human subjects for evaluating control signal quality and feasibility.

Main Results:

• Accelerated testing projected an operational lifespan exceeding 50 years.
• Chronic animal studies showed stable output from three of four IJATs for 10-19 months.
• Histological analysis confirmed acceptable osseointegration.
• Human implantation for over 2 years yielded an excellent control signal for hand grasp.

Conclusions:

• The implantable joint-angle transducer (IJAT) is safe and effective for chronic human use.
• The IJAT provides a reliable control input for implanted hand neuroprostheses.
• The device demonstrates significant clinical feasibility for improving FNS neuroprosthetic control.