Effects of Microprocessor-controlled Prosthetic Knees on Fall-related Health Outcomes in Limited Community Ambulators

This study aims to assess the effects of microprocessor-controlled prosthetic knees on fall-related health outcomes in prosthesis users classified as limited community ambulators. This study also seeks to expand the existing research on the potential microprocessor-controlled prosthetic knees (MPKs) have on improving health outcomes for patients who are classified as limited community ambulators (i.e., Medicare Functional Level K2). The investigators will examine whether the anticipated reduction in falls in K2 users is accompanied by improvements in fall-related health outcomes like fall-related anxiety, fall-related self-efficacy, fall-related avoidance behaviors, fall-related interference, and fewer falls. Investigators will also examine whether MPK use in the K2 population leads to increased mobility, increased walking speed, and improvements in health-related quality of life.

A 12-month, pragmatic randomized control trial (pRCT) will be conducted to assess whether MPKs improve fall-related health outcomes in unilateral, transfemoral or knee disarticulation prosthesis users classified as limited community ambulators.

Patients will be invited to participate in the trial as a part of their routine prosthetic care. If a patient agrees to participate and is eligible, a follow-up appointment will be scheduled, and the patient will be consented by the research study team. Participants will then be randomized to the intervention or control group. Participants in the control arm of the trial will remain in their prescribed prosthesis with a non-microprocessor knee (nMPK). Participants randomized to the intervention arm of the trial will have their nMPK exchanged for either a stance-and-swing MPK (Ottobock C-Leg 4) or a stance-only MPK (Ottobock Kenevo). The MPK provided to each participant in the intervention arm will be determined by the manufacturer's recommended patient-selection criteria. Transfemoral prosthesis users walking up to 0.83m/s (3km/hr) in the 2-minute walk test (2MWT) will receive a stance-only MPK (Kenevo), while participants walking more than 0.83m/s in the 2MWT will receive a stance-and-swing MPK (C-Leg 4). Study participants will wear the knee for 12 months.

Each participant will be assessed at baseline (after enrollment and randomization), and 1-, 3-, 6-, 9-, and 12-months after baseline. The baseline and 12-month assessments will be the primary study time points. T-scores on the Prosthetic Limb Users Survey of Fall-Related Health (PLUS-F) and number of fall events experienced over the prior year will serve as the primary endpoints. Participants will complete a selected set of performance-based tests and standardized self-report surveys. In addition to the outcome measures noted, investigators will collect sociodemographic, health, amputation, fall history, and prosthesis information by self-report in order to characterize study participants and assess the comparability of the study groups. Fall-related health outcomes (e.g. fall-related self-efficacy and fall-related interference) will be measured using new PLUS-F instruments as well as existing measures that measure fall-related outcomes. We will also co-administer the Prosthetic Limb Users Survey of Mobility (PLUS-M) to assess participants' prosthesis-related mobility. Walking speed, mobility, endurance, and quality of life will be measured. For the 6- and 12-month assessments, we will also collect the hours of wear and hours of activity in the prosthesis.

Participants in both groups will receive education and training specific to their prosthetic knee between assessment 1 (baseline) and assessment 2 (one-month follow-up). Training will consist of 1 to 4 sessions to facilitate participants' use of their assigned prostheses. The number of sessions will be determined by the ability of each participant to explain and/or perform specified tasks. A standardized protocol and training checklist will be developed by our team Physical Therapist specific to each condition in collaboration with the knees' manufacturer (Ottobock). Every 2 weeks, throughout the 12 months of patient participation, the number of falls and near-fall events, including the event, injury, treatment and/or hospitalization, and whether the falls occurred while wearing the prosthesis, will be collected.

Inclusion criteria

• Unilateral transfemoral or knee disarticulation limb loss.
• 6 months or longer since time of limb loss.
• Current user of a prosthesis with a non-microprocessor-controlled prosthetic knee.
• Received a replacement prosthesis with a non-microprocessor knee in the past 4-24 months.
• Clinician has deemed patient limited community ambulator (Medicare functional classification level K2).
• In addition, Medicare functional classification level K2 as determined by at least one of the following criteria:

• Houghton Score: 5-10
• Prosthetic Limb Users Survey of Mobility (PLUS-M) T-Score: if amputation etiology is vascular disease/diabetes <49.45, otherwise, <36.75.
• Amputee Mobility Predictor (AMPPRO) score: 27-42 collected within the last 24 months
• Ability to read, write, and understand English.

Exclusion criteria

• Any health condition that would prevent safely completing trial activities.
• Any individuals that weigh 275 lbs or more.
• Any individuals who wear their prosthesis less than 3 days a week or less than a total of 24 hours a week
• Individuals with a history of acute or chronic residual limb breakdown
• Individuals with declining health status such that he/she subsequently reports reduced activity over the past 6 months