Neuromusculoskeletal Interface for Bionic Arms
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About
The overall objective of this proposal is to perform a first-in-human home trial of the Electronic Osseoanchored Prostheses for the Rehabilitation of Amputees (e-OPRA) implant system in individuals with transhumeral amputations who have had Targeted Muscle Reinnervation (TMR) surgery and use a pattern recognition-controlled myoelectric prosthesis. The purpose of the study is to capture preliminary safety and effectiveness information on the e-OPRA device when used with the prosthetic systems. The investigators expect that the e-OPRA implant system will be safe and provide clinically and statistically significant improvements in control and comfort.
Specifically, the investigators hypothesize that the e-OPRA system will (1) allow for training of more functional prosthesis controllers, (2) provide more stable electromyographic (EMG) signals, reducing the need to recalibrate the prosthetic control system, and (3) be more comfortable, as it does not require a tethered arm-band to record surface EMG signals.
Phase 1: Perform TMR and e-OPRA surgeries in 8 persons with transhumeral amputations.
Phase 2: Perform a randomized cross-over study to compare the OPRA and e-OPRA system (without sensory feedback) in 8 transhumeral amputees who have received TMR.
Phase 3: Perform a randomized cross-over study to compare the e-OPRA system with and without sensory feedback in 8 transhumeral amputees who have received TMR.
Full description
In the past decade, progress has been made in creating stronger, more capable prosthetic devices, with improved control. Similar improvements have been made in prosthesis suspension, which is a critically important factor in both comfort and function of a prosthetic device. While skin-fit suction sockets were considered the state of the art for many years, custom-rolled silicon and instrumented gel-liners are now becoming more common, as they provide improved comfort. However, these approaches still require use of an external socket worn on the residual limb.
The Osseoanchored Prostheses for the Rehabilitation of Amputees (OPRA) implant system (Integrum AB, Mölndal, Sweden) uses osseointegration (OI) (i.e., a metal implant is placed in the residual bone, which then grows into and integrates with the implant) to provide mechanical attachment of the prosthesis to the skeleton in the residual limb, thus eliminating the need for a socket.
However, obtaining electromyographic (EMG) control signals to enable myoelectric control of a prosthesis, whether it is attached through OI or a conventional socket, requires placement of surface electrodes over residual limb muscles, which has many practical limitations. Surface EMG signals are a complex blend of all local muscle activations and as such have low fidelity. It is difficult to isolate EMG signals from large surface muscles, and it is impossible to separate out signals from small or deep muscles. In addition, surface EMG signals are contaminated by several sources of noise, including ambient electromagnetic interference, motion artifact, and even electrocardiogram signals.
The limitations of surface electrodes may be overcome by surgically implanting the electrodes into the residual limb and placing them directly onto/into the tissue of the target muscle so that the EMG can be recorded directly at the source with improved signal to noise ratio and without disturbances from the external environment. Typically, such an approach would require skin-penetrating leads to convey the EMG signals from the implanted electrodes to the outside of the body to enable myoelectric prosthesis control, making it unsuitable as a permanent solution.
However, in the e-OPRA (electronic OPRA) device, the percutaneous interface of the OPRA Implant is utilized as a conduit for the wired communication between the inside and the outside of the body, eliminating the need for permanent skin penetrating leads and enabling a permanent solution for myoelectric prosthesis control using implanted electrodes. The e-OPRA system (which is not yet commercially available) developed by Integrum AB (Mölndal, Sweden), is built on decades of developing the OPRA system (which is commercially available).
In addition to electrodes placed on muscle tissue, the e-OPRA device also contains implanted electrodes which are placed directly around peripheral nerves, which may be used for neurostimulation to generate sensory feedback to the user. The e-OPRA device constitutes the only available technology that provides a bidirectional neuromusculoskeletal interface in whichimplanted electrodes both record EMG signals and provide peripheral nerve stimulation for sensory feedback.
Use of the e-OPRA device with the well-documented neuro-electronic capabilities of EMG control systems provides an alternative to traditional socket prostheses by establishing a load-bearing coupling between the patient's skeleton and prosthesis, including wired connection between muscles and nerves in the residual limb and the prosthesis.
The investigators first propose to secure an investigational device exemption (IDE) from the FDA to implant an e-OPRA system. After implantation of the device and targeted muscle reinnervation (TMR) surgery in eight subjects with transhumeral amputations, we propose two clinical trials to (i) compare comfort and function with implanted electrodes (e-OPRA) or surface electrodes (OPRA) and (ii) evaluate the effects of providing sensory feedback.
Enrollment
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Inclusion criteria
- Between the ages of 18 and 70 years old
- Unilateral transhumeral level absence
- Candidate for a myoelectric prosthesis (can generate mV level electromyographic EMG signals as detected by surface electrodes).
- Candidate for TMR surgery as verified by surgical team
- Candidate for OPRA surgery as verified by surgical team
- English speaking
Exclusion criteria
- Significant new injury that would prevent use of a prosthesis: The ability to consistently wear a prosthesis and perform activities of daily living and specific performance tasks is necessary to evaluate the relative benefits of the interventions.
- Cognitive impairment sufficient to adversely affect understanding of, or compliance with, study requirements, ability to communicate experiences, or ability to give informed consent: The ability to understand and comply with requirements of the study is essential in order for the study to generate usable, reliable data. The ability to obtain relevant user feedback through questionnaires and informal discussion adds significant value to this study. These cognitive impairments would be confirmed with the Mini-Mental State exam.
- Proximal nerve injury that would prevent TMR or sensory feedback
- Significant other comorbidity: Any other medical issues or injuries that would preclude completion of the study, use of the prostheses, or that would otherwise prevent acquisition of useable data by researchers. Examples include: injuries to the shoulder, cervical spine or sound side joint pain that would prohibit the participants from being able use a prosthesis. Medical conditions including unregulated high blood pressure or advanced heart disease that would exclude the participant as an appropriate surgical candidate.
- Individuals who smoke. This may interfere with the OPRA process from both bone healing and soft tissue standpoints.
- Individuals with active implants. This has been a restriction of prior FDA IDE to investigate e-OPRA.
- Pregnant women
- Non-English speaking
Trial design
Primary purpose
Allocation
Interventional model
Masking
12 participants in 4 patient groups
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Central trial contact
Suzanne B Finucane, MS
Data sourced from clinicaltrials.gov
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