Neuromusculoskeletal Interface for Bionic Arms

Not Applicable

Not yet recruiting

• Conditions: Amputation; Amputation, Traumatic; Amputation, Surgical; Upper Limb Amputation Above Elbow (Injury)

• Registration Number: NCT07032753
• Lead Sponsor: Shirley Ryan AbilityLab

Brief Summary

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.

Detailed 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.

Study Timeline

• Study First Submitted: 2025-04-11
• Status Verified: 2025-06
• Study First Submitted QC: 2025-06-12
• Last Update Submitted: 2025-06-12
• Study First Posted: 2025-06-24
• Last Update Posted: 2025-06-24
• Study Start: 2026-01-01
• Primary Completion: 2028-05-31
• Study Completion: 2029-05-31

Recruitment & Eligibility

• Status: NOT_YET_RECRUITING
• Sex: All
• Target Recruitment: 12

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

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Primary Outcome Measures

Name	Time	Method
Effectiveness related: EMG Signal to Noise Ratio Testing	Month 13, Month 16, Month19, Month 22	The investigators will quantify the signal-to-noise ratio (SNR) of EMG signals by comparing activity recorded during maximum voluntary contraction (MVC) to that recorded during rest. SNR will be calculated as the ratio of EMG signal power during contraction to the signal power during rest, using a standardized protocol consistent with our preliminary data. Each trial will consist of three repetitions of three-second MVCs, interleaved with three-second rest periods. From each repetition, the central 30% of both the contraction and rest epochs will be extracted to minimize edge effects and ensure steady-state measurement. These extracted segments will then be concatenated across repetitions to create two signal arrays: one representing active EMG and the other representing baseline noise. This metric will be used to evaluate the quality of EMG signal acquisition from both surface and implanted electrodes, and to ensure adequate fidelity for pattern recognition control.
Effectiveness related: Somatosensory Mapping	Month 13, Month 16, Month19, Month 22	The projected field-the region on the phantom limb where an electrically evoked sensation is perceived-for each contact on the implanted spiral nerve cuff electrodes. This mapping will be performed at three stimulation levels: the detection threshold (the lowest amplitude at which a sensation is first perceived) and two suprathreshold amplitudes that fall within a safe, physiologically relevant, and comfortably perceptible range. These amplitudes will allow us to assess the size, intensity, and location of the perceived sensation change with increased stimulation. Projected fields will be recorded on a schematic of the hand and used to build a subject-specific somatotopic map. This map will inform which sensor signals (from the TASKA CX hand) are routed to which nerve cuff contacts during the sensory feedback phases of the study. Contact-response stability will be evaluated over time, as these experiments will be repeated each time outcomes are collected in the study.
Safety related: Adverse Event reporting	Through study completion for each subject, on average 3 years.	The number/percentage of subjects that successfully demonstrate the absence of any Serious Adverse Device Effects will be summarized along with a 95% confidence interval.

Secondary Outcome Measures

Name	Time	Method
Jebsen Test of Hand Function	Month 11, Month 13, Month 16, Month 19, Month 22	The Jebsen test includes seven subtests, including writing, turning over cards, picking up small objects, etc., in which the time taken to complete each subtask is recorded. The test has been validated for able-bodied subjects, but not for subjects with an amputation. The investigators have used this test previously for transhumeral and transradial amputees.
Southhampton Hand Assessment Procedure (SHAP)	Month 11, Month 13, Month 16, Month 19, Month 22	The SHAP is a clinically validated, objective (self-timed) test of unilateral hand function that can be used to evaluate functionality of passive, mechanical, or myoelectric hands without bias to type-and changes in control ability over time. Abstract objects (some light, some heavy) and activities of daily living that are classified into one (or more) of six hand grips are timed by the subject. Scores are compared to a normalized, able-bodied control score of 100 allowing assessment of functional control of the terminal device compared to an intact hand Although this test has not been validated in prosthesis users, it was recommended for use while undergoing validation for this population.
Assessment of Capacity for Myoelectric Control (ACMC)	Month 11, Month 13, Month 16, Month 19, Month 22	The ACMC is an observational assessment tool that specifically measures the subject's ability to control a myoelectric hand and is the only validated test for subjects with an upper limb amputation. The ACMC uses a Rasch analysis of the subject's ability to control gripping, holding, releasing, and coordinating 30 items, and is scored on a four-point capability scale: 0, not capable; 1, sometimes capable; 2, capable on request; and 3, spontaneously capable. The prosthetic hand is used normally (i.e., in an active assist or passive support role). The test can detect small differences in ability to perform daily bimanual tasks and takes as little as 10-15 minutes to administer, although scoring takes significantly longer.
Patient-Specific Functional Scale (PSFS):	Month 11, Month 13, Month 16, Month 19, Month 22	A questionnaire that asks patients to list up to five tasks they have difficulty with and rate the difficulty on an 11-point numerical scale. Difficulty ratings can be averaged for each participant.
Clothespin Relocation Task	Month 11, Month 13, Month 16, Month 19, Month 22	A test of prosthetic function that requires the user to move three clothespins from a vertical bar to a horizontal bar (thereby requiring use of the elbow, terminal device, and wrist rotator). This test has been in use by the Center for Bionic Medicine as a measure of prosthesis function for over a decade.
Orthotics and Prosthetics User Survey-Upper Extremity Functional Status (OPUS-UEFS):	Month 11, Month 13, Month 16, Month 19, Month 22	A 19-item, self-reported measure of an individual's ability to perform self-care and upper limb-based daily living tasks (e.g. button shirt, tie shoelaces) using a 5-point scale. Rasch analysis of the questionnaire ratings is used to calculate an overall measure of each subject's functional ability.
Modified Box and Block Test	Month 11, Month 13, Month 16, Month 19, Month 22	This test involves counting the number of blocks a patient can move from one side of a box, over a barrier, to the other side of the box, usually in a 2-min test period. This test requires elbow and hand function.

Trial Locations

Locations (1)

Shirley Ryan Abilitylab; 🇺🇸 Chicago, Illinois, United States