Intuitive Control of a Hybrid Prosthetic Leg During Ambulation

The objective of this research is to determine the clinical benefits of an innovative and lightweight powered leg controlled using our intent recognition framework in laboratory and community environments.

The hypothesis of this study is that using the Hybrid Leg with seamless, automatic transitions will result in participants choosing to become more active and improve their community participation compared to when using their own passive prosthetic leg.

The Hybrid Leg is an an innovative and lightweight powered leg that has 2 operating modes: active and passive. When in active mode, the Hybrid Leg is capable of supplying 120 NM of knee torque and actively repositioning the ankle during non-weight bearing phases of gait. When in passive mode, the motor and transmission are decoupled from the knee, which then behaves like an Ottobock 3R95 passive prosthetic knee, and the non-backdriveable mechanism of the ankle allows it to behave as an energy return foot. Allowing the device to behave passively if the battery becomes depleted or the actuators become damaged is an important enabling safety factor that will allow us to complete our study.

Phase 1: We will enroll 20 subjects a clinical trial of the leg and control system who will be fit with the Hybrid Leg and receive in-lab therapy to learn how to ambulate with the device.

Phase 2: Subjects will be randomized into a clinical trial of the leg and control system with an AB-BA design; condition A - subjects own device; condition B - Hybrid Leg. Subjects will complete an extensive ambulation and community mobility training to learn optimal use of their own passive device or the Hybrid Leg. After training the subjects will complete a full biomechanical analysis for each device as they complete ambulation circuits that include standing, level-ground walking, walking on slopes and on stairs, sit-stand transitions and transitions between these activities.

Phase 3: After completing phase 2 subjects will complete 4-week trials using their assigned prosthesis (Condition A or B) at home and within their community. During the trials subjects will be monitored using mobile phone based sensors and socket mounted activity monitor to determine how often the user performs the ambulation activities.

Eligibility Criteria:
Inclusion Criteria:

* A unilateral or bilateral lower limb amputation
* K2/K3/K4 ambulator with a prosthesis
* 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 useable, reliable data. The ability to obtain relevant user feedback through questionnaires and informal discussion adds significant value to this study.

  * 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.