Wearable sensors reveal how prosthetics perform in the real world

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: Target Populations: * Participants with amputation must have used a prosthesis for more than 6 months, and wear it for at least 8 hours per day. * Participants must be more than 6 months past their most recent surgery (if any). * Participants must be free of musculoskeletal and cardiovascular conditions that would limit their ability to safely complete testing. * Participants should consider themselves in good health; be able to wear their prostheses or orthoses all day long; be able to perform all of their activities of daily living (ADL) with their prostheses or orthoses as appropriate; have a comfortably fitting functional prosthesis (if applicable) that does not cause any skin problems; and have a stable residual limb (or impaired limb). * Participants may use a narrow-base cane (single point, narrow tripod base, etc.) as an ambulatory aid but not a small-base quad cane or walker. * Participants must be able to walk with their prostheses or orthoses for 30 minutes (total) and stand for 30 minutes (total), in individual bouts of at least 6 minutes, without becoming fatigued, feeling dizzy, having chest pain or shortness of breath, or experiencing claudication symptoms. * Participants involved in running tests must be able to run for 30 minutes (total) in bouts of at least 6 minutes, without becoming fatigued, feeling dizzy, having chest pain, or experiencing claudication symptoms. * Participants must have no known cognitive disability. * Participants must be fluent in spoken and written English. * Running portions of the study will be limited to participants who self-report regular engagement in recreational or competitive running. * Participants in the branch that uses only their own prostheses must have at least a daily use prosthesis and a running-specific prosthesis; additional prostheses may also be included Multiple Sclerosis group: * For the specific subgroup targeting Multiple Sclerosis, participants must have a clinical diagnosis of Multiple Sclerosis and a clinician must determine they are experiencing foot drop. * Participants must be able to comfortably wear and ambulate with both study devices with effective management of foot-drop, without significant discomfort * Participants must be able to perform all of their activities of daily living (ADL) with only minimal use of ambulatory aids. Subjects may use a narrow-base cane (single point, narrow tripod base, etc.) as an ambulatory aid in any amount. Use of more comprehensive ambulatory aids (e.g. a small-base quad cane, wide-base quad cane or walker) must be limited to no more than 20% of their walking time when not at home. Participants who do use an assistive device occasionally should report a threshold for use of greater than 100 feet, i.e., they are unlikely to use their device unless they anticipate ambulating greater than this distance. Exclusion Criteria: Target Populations: * Allergy to electrode gel, surgical tape and metals. * Participants who currently use the Bioness L300 Go or similar neuro-orthoses or use a carbon fiber ankle-foot orthosis at the time of the study will be excluded to avoid biasing results for one device or the other. Participants with past experience not currently using these devices will be eligible. * Participants enrolled in physical therapy or other rehabilitative care for treatment of gait, balance, or lower extremity strength or coordination at the time of the study will be excluded to avoid confounding effects from therapy and device-based management of their condition. * For the orthotics study, participants with peripheral neuropathy impacting control of the tibialis anterior muscle via the peroneal nerve will be excluded. * Participants under treatment for infectious diseases will be excluded from the study. * Women who are pregnant or planning to become pregnant during the course of the study will be excluded. * Symptomatic musculoskeletal conditions that prevent unaided walking, such as back pain or knee arthritis. * Cardiovascular conditions that make moderate exercise unsafe, including (but not limited to) history of angina, peripheral vascular disease, congestive heart failure, history of myocardial infarction, and history of stroke. Potential participants will be excluded if they self-report that a physician has told them to avoid moderate exercise. * History of chest pain, shortness of breath, or claudication symptoms during ambulation * History of significant neuropathy with altered balance * History of serious residual limb pain or phantom limb pain within the past six months. * History of chronic skin breakdown. * Inability to perform the tasks involved in the study.