Clinical Research Directory

Adjustable Prosthetic Sockets

Each year, around 1500 Veterans join the 623,000 Americans who live with a lower limb amputation. Many of these Veterans choose the arduous path of rehabilitation to remain ambulatory, a process that includes the prescription of a lower limb prosthesis. Much relies on the goodness of fit of their prosthesis. A good fit feels comfortable and enables a variety of ambulatory activities. A poor fit results in discomfort, often accompanied by chronic skin issues, and activities of daily living are curtailed. Conventional prosthetic sockets are custom-built by a skilled prosthetist, carefully formed to fit the Veteran's residual limb, and good fits can usually be obtained. These sockets are rigid, fixed shape structures with the robustness of a bulldozer, built for sustained, heavy-duty action. Unfortunately, the shape of an individual's residual limb can change over time, such that a good fit eventually becomes poor. One estimate suggests a new below-knee socket is needed every three and a half years. The expense of replacing sockets that no longer fit is not insignificant. Medicare expenditures for replacement of existing below-knee sockets and associated components were estimated at $50M in 2017. Importantly, Medicare is estimated to be only 20% of the market, suggesting the estimated expenditure for the entire population with lower limb amputations is likely to be meaningfully larger. A good fitting prosthesis that maintains its fit over time would serve Veterans well. A potential solution that could make a good fit last longer is an adjustable prosthetic socket. While little evidence is available to support prescription practice, the Centers for Medicare and Medicaid Services (CMS) recently authorized reimbursement for adjustable prosthetic sockets, suggesting a compelling need for such a product. To investigate the potential for deleterious effects and how Veterans might use adjustable prosthetic sockets, the aim of this research is to determine the pressure applied to the residual limb by an adjustable prosthetic socket during activities of varying intensity and the activities that induce adjustments. A laboratory-based human subject experiment will be conducted using a custom sensor placed inside the adjustable panel of a study-provided adjustable prosthetic socket. Participants will acclimate to the adjustable prosthetic socket for two weeks in the field, then return to the laboratory to perform seven activities. The pressure inside the prosthesis will be measured during these activities. Participants will also report how tight their socket feels after each activity.

Improving Prosthetic Provision in Rural Communities: Limb Scanning With Caregiver Assistance

When the prosthetic socket of a Veteran with a lower limb amputation no longer fits or is damaged beyond repair, a new prosthetic socket is warranted. The provision of a new socket requires multiple clinical visits which can place a high travel burden and potential pandemic exposure stress on Veterans who live in rural communities far from VA Medical Centers or alternative prosthetic clinics. This research seeks to determine if one of the in-person visits traditionally needed to obtain a well-fitting prosthesis can be performed remotely with the assistance of a helper. The investigators seek to discover if an untrained individual (a helper) can wield inexpensive, easy to use, digital technology to capture the shape of a residual limb to see if it can be used to fabricate a prosthetic socket that fits at least as well as one fabricated by a prosthetist using traditional, hand casting methods in the clinic. The expected result of this research is an evidence-based prosthetic fabrication process that reduces Veteran travel burden while providing a prosthesis that fits at least as well as the current standard-of-care. The upshot is a clear improvement in prosthetic provision for Veterans, particularly for those who live in rural communities. To make this determination, the investigators will perform a between-subject experiment with two specific aims. To determine differences in goodness of fit between the two study sockets, the investigators will use both patient reported outcomes, and measurements of the pressure applied to the distal end of the residual limb. Specific Aim 1: Determine if patient reported outcomes, by subjects wearing a prosthetic socket whose shape was captured with study helper assistance, are at least as good as those reported by subjects wearing a socket whose shape was captured by a prosthetist. The investigators propose to recruit Veterans with a below knee amputation and their study helpers to participate in a human subject experiment. Participants will be randomly assigned and fit with either a prosthesis made with study helper assistance and digital methods, or one made wholly by a prosthetist using traditional methods. Patient reported outcome metrics will be collected while the subject is still wearing their as-prescribed socket at the beginning of the study (baseline), and again after wearing the study prosthesis for two weeks. Specific Aim 2: Determine if distal end residual limb pressure, measured from a group of individuals fit with a prosthetic socket whose shape was captured with study helper assistance using digital methods, are no worse than those measured from a group of individuals fit with a prosthetic socket whose shape was captured by a prosthetist using traditional methods. Concurrent with the human subject procedures briefly described above, the investigators propose to fabricate duplicates (copies) of the two prosthetic sockets used by each subject in Specific Aim 1. A novel sensor will be embedded in these duplicate sockets which can measure the pressure applied to the distal end of the residual limb. Measurements of distal end residual limb pressure while standing and walking for both the as-prescribed and study sockets will be collected at the beginning of the study (baseline), and again after two weeks. The data from the investigators' experiments will be used to determine if residual limb shape capture by a helper using digital technologies can be used to make prosthetic sockets that fit at least as well as those made by a prosthetist using traditional, hand casting techniques. One third of all Veterans live in rural communities far from VA Medical Centers. When Veterans with a lower limb amputation need a new prosthetic socket, attending in-person clinical visits can be a challenge. If the hypotheses are supported, this research will provide evidence to support the use of digital technology as part of clinical practice, enabling a remote, study helper enabled alternative to one of the in-person clinical visits needed to fabricate a well-fitting prosthesis.

Kinematics of Ewing Amputees

The agonist-antagonist myoneural interface (AMI) construct, known as the Ewing amputation at the trans-tibial level, has been shown to create a bi-directional neural communication platform as a means of controlling and interpreting proprioceptive feedback from a prosthetic joint. In AMI constructs, agonist-antagonist muscles are mechanically coupled within the residual limb, and volitional contraction of an agonist passively stretches that muscle's antagonist. The natural neural responses from muscle spindles within both muscles are then interpreted by the central nervous system as sensations of joint position and speed, associated with movement of the prosthesis. The aim of this research protocol is to evaluate the electromyographic and kinematic patterns of participants who have undergone unilateral lower extremity Ewing Amputation in order to determine how similar their residual limb data is when compared to their intact limb data. A secondary aim of this research may include comparison of the Ewing participant cohort's biomechanical patterns to a similar cohort of participants who have undergone standard amputation. The investigators hypothesize that the affected limb of patients with the Ewing procedure will demonstrate a pattern of electromyographic activation of their AMI constructs and kinematic data that recapitulates the pattern seen in their intact limb. The investigators secondarily hypothesize that the kinematic assessment of Ewing Amputation patients will demonstrate patterns that are significantly more physiologic than those witnessed in similar assessments of standard amputees.

Instrumental Analysis of Walking in People With Osseointegrated Prostheses for Lower Extremity Amputation: Comparative Evaluation With Traditional Socket Prostheses

The currently accepted standard for rehabilitation and mobility following amputation is a socket-mounted prosthesis. Osseointegration is an alternative method that has gradually gained greater acceptance in the last 30 years. It is defined as a procedure in which a metal implant is directly anchored to the residual bone, attached to a prosthetic limb using a transcutaneous connector. The advantages of osseointegrated prostheses over conventional socket prostheses include stable fixation, significant increases in walking ability, range of motion and control of the prosthesis, and health-related quality of life. Moreover, bodyweight distribution results more similar to physiological conditions. No formal consensus exists for osseointegration surgery. However, based on the positive clinical experience, surgeons currently indicate this surgery for those patients who show poor tolerance of socket prostheses. The present study investigates neuro-physiologic and mechanical parameters of walking and balance in patients with lower limb amputation and osseointegrated prostheses and in matched patients with traditional socket prostheses to highlight strengths and weaknesses of the alternative technique with respect to the present standard of care. The primary endpoint is the investigation of the neurologic and mechanic adaptation in terms of a) kinematic and dynamic segmental analysis of walking and transfer of the body center of mass during walking; b) capacity to retain balance in response to different conditions of oscillation, tilt, and translation of a posturographic platform. The secondary endpoint is investigating of adaptation to walking on a split-belt treadmill mounted on force sensors with the belts running at different velocities. We hypothesize that: * the deficit in joint power of the prosthetic limb is associated with a phenomenon of "learned non-use" both in balance and during gait. This behavior looks automatic and unconscious. It consists of the under recruitment of the impaired side as a form of unconscious protection, which is adopted when the contralateral side may be exploited to carry out the function; * the joint power provided by the prosthetic limb may increase both by increasing treadmill velocity and by walking in split-belt modality with the prosthetic limb on the faster belt; * an "after-effect" will be evidenced after the split-belt walking test when the two belts will return to the same velocity; patients with osseointegrated prostheses and patients with socket prostheses may show different behaviors in the adaptation to split-belt walking and the following post-adaptation, as a result of the residual proprioception of the amputated limb. Results from the present study will allow: * the identification of the possible advantages in walking and balance symmetry in patients with osseointegrated prostheses with respect to patients with socket prostheses; * the estimate of the sample size for future experimental protocols and new rehabilitative programs.