Clinical evaluation of the Modular Electromechanical Lock Actuator (MELA) for above-elbow prostheses: a final report

The Modular Electromechanical Lock Actuator (MELA) is the result of research and development (R&D) conducted under the direction of Dudley S. Childress, PhD, at the Northwestern University Prosthetics Research Laboratory (NUPRL), Chicago, Illinois. NUPRL, based upon experience with prostheses for persons with high-level, above-elbow amputations, developed the MELA to assist those persons with amputation who experience difficulty in operating existing manual elbows, whether with a conventional harness, nudge control, excursion amplifier, or other arrangement. Technology Transfer Section, VA Rehab R&D, with collaboration from Frederick Downs, Jr., Director, and John Clements, Prosthetic Regional Manager, VA National Prosthetic and Sensory Aids Service, managed a multicenter clinical evaluation of the MELA. The purpose was to objectively assess and affirm its performance, safety, clinical application, and commercial readiness. The following VA Prosthetic Treatment Centers served as evaluation sites: Baltimore, MD, Huntington, WV, and New York, NY. A VA-wide screening process yielded 10 candidates for review. A total of seven subjects met the selection criteria and were accepted for participation. In addition, several prosthetists provided their comments on the MELA. Overall, the performance of the MELA demonstrated that it could be fit to existing body-powered arms and used as an alternative control method for manual elbows. Consensus of participant feedback indicated general satisfaction and improved elbow lock function. In addition, several modifications were identified for the commercial version. The primary issues focused on 1) increasing speed (alternating response time); 2) unloading forearm (sometimes required to cycle the MELA); 3) providing mechanical back-up in case of unit failure; 4) reducing gear-motor noise; 5) improving integrity of wiring and retaining clip; and 6) marketing the MELA as a stand-alone product. Hosmer-Dorrance Corp., in collaboration with the developer, has indicated that resolution for most of the identified issues is readily achievable. Increasing speed (response time) and unloading forearm will require more investigation and consumer feedback from the commercial market. Based upon the clinical findings, the MELA was recommended for commercial production and availability, upon prescription, to appropriate veteran beneficiaries.