Development of Adaptive Vacuum Suspension to Improve Prosthetic Fit and Residual Limb Health
Condition: Lower Limb Amputation
Study type: Interventional

Summary: 
      The purpose of the study is to evaluate residual limb circulation and skin health associated
      with the use of a prosthetic vacuum socket. A conventional non-vacuum prosthetic socket will
      be compared to a vacuum prosthetic socket.

      The prosthetic suspension plays a pivotal role in an amputee's comfort. It can also
      significantly impact an amputee's limb health. If the prosthesis is not held securely to the
      amputee's limb, relative movement between the limb and prosthetic interface can cause
      bruising, skin irritation and skin breakdown. These poor outcomes are uncomfortable and can
      lead to much more serious health conditions. A positive solution to creating secure and
      comfortable suspension is the use of a vacuum suspension socket. The vacuum pressure assists
      in preventing movement in the socket. The clinical benefits associated with vacuum suspension
      include volume retention, increased proprioception, secure suspension, and frequently
      reported observations of wound healing. However, the long term effects of vacuum suspension
      on circulation remain undetermined or undocumented. This study examines a vacuum suspension
      system on the health of the residual limb (amputated limb). A vacuum socket creates a vacuum
      between the rigid prosthetic socket and prosthetic liner which is sealed to the socket.
      Therefore, vacuum is not directly applied to the skin of the residual limb.
    

Detailed description: 
      There are a total of 3 study visits, (some visits may be broken into separate visits per
      preference of subject), including socket fitting visits (which could be 2 separate visits), a
      baseline visit, and a final visit. During the socket visit, which may consist of a three
      visits plus socket adjustments (as needed by the participant) on separate days (up to 4
      weeks), limb shape capture, measurement or tracing, diagnostic static fitting and diagnostic
      static fitting, and delivery of a definitive "research" socket will be done. At the baseline
      visit, participants will perform seated tasks, standing tasks, and treadmill walking tasks.
      Residual limb health measurements will be taken before and after the activity period,
      including surface electrical capacitance, Transepidermal Water Loss (TEWL) measurement,
      hyperspectral imaging, Hitachi Aloka ultrasound imaging, Blood Flow, and digital imaging
      during the baseline visit as well. The final visit, using the research socket, will consist
      of the same tasks and measurements as the baseline visit and questionnaires will be
      completed. The subject may choose to break up the final visit tasks into 2 different visits
      if desired.

      After completion of the study, participants will be given the choice to keep the research
      socket or return to using their original prosthesis as normal. The study prosthetist will be
      available to review and adjust the fit of their standard of care prosthesis at this time.
      Note: Due to physical change and limb volume fluctuation over the study period, it is
      possible that at the end of the study the standard of care prosthesis will not fit your
      residual limb as it does at the beginning of the study. At the completion of the study, it is
      recommended that the subject follow up with their primary care prosthetist for socket
      evaluation and fitting.

      There may be risks that are not known about at this time. Side effects, risks, and
      discomforts may result from study participation .While the goal of this project is to create
      a more comfortable prosthesis, it is possible that the subject could experience discomforts
      commonly associated with prosthesis use, such as perspiration, dry skin, rash, itching,
      blisters, high pressure in the socket, looseness in the socket, and mechanical rubbing that
      leads to ulceration which may lead to infection and additional surgery. Subjects with low
      levels of arterial blood flow have an additional risk of ulceration.

        -  Prosthesis placement: While the goal of this project is to create a more comfortable
           prosthesis, it is possible that the subject could experience discomforts commonly
           associated with prosthesis use, such as perspiration, dry skin, rash, itching, blisters,
           high pressure in the socket, looseness in the socket, and mechanical rubbing that leads
           to ulceration.

        -  Treadmill task:There is a risk of falling during the research activities. This risk is
           mitigated by the ability of participants to self-select pace for the treadmill task and
           observation of treadmill activities by research staff.

        -  Transcutaneous Oxygen Measurement (TcOM) and skin temperature: The PeriFlux System 5000
           uses non-invasive probes that will measure the skin temperature and transcutaneous
           Oxygen Measurement and poses minimal risk to the subject. The probe head is affixed to
           the residual limb by an adhesive sticker. Removal of the sticker after data acquisition
           may cause minor discomfort similar to removing a small band-aid.

        -  Hyperspectral Imaging: This non-invasive imaging technique poses minimal risk to the
           subject. A small fiduciary marker sticker is placed on the subject's limb to calibrate
           camera settings. Removal of the sticker after imaging may cause minor discomfort similar
           to removing a small band-aid.

        -  Hitachi Aloka Ultrasound:Ultrasound imaging is a noninvasive technique and is a minimal
           risk procedure.

        -  TEWL and Surface Electrical Capacitance Measurements: TEWL and Surface Electrical
           Capacitance measurements are noninvasive and propose less than minimal risk.

      Subjects will be queried on self-reported measures of user comfort and performance. Briefly,
      four subjective measures will be completed: VR-36, PEQ, SCS, and measures from the NIH PROMIS

      The CHAMP test will be used to assess overall amputee performance and the effect of the
      socket suspension intervention over time. The conglomeration of clinical assessment tools
      into the CHAMP was specifically done to measure high-level mobility in service members with a
      lower limb amputation. CHAMP consists of the Single Leg Stance Test (SLS), the Edgren Side
      Step Test (ESST), Illinois Agility Test (IAT), and T Test.

      IU Neuroscience Gait lab will be used to collect kinematic data. The laboratory is equipped
      with an instrumented treadmill and infrared camera system. A harness system will be used to
      provide support and safety for the amputees while study participants walk on the treadmill
      for 6 minutes.
    

Intervention name(s): Active vacuum test prosthesis
Intervention type(s): Device
Intervention description(s): The adaptive vacuum prosthesis is sold as a commercial device by the company Willow Wood with suggested U.S. L-Code L5781. The device is designated as a Class 1 Medical Device and 510(K) Exempt. This category is part of a low or moderate risk to patient safety and health. The Prosthetic socket system uses an active vacuum pump to push air out of the socket. The level of vacuum is controlled by hardware that automatically detects the socket fit based on in-socket motion and adjusts vacuum as needed to eliminate this motion.
Other intervention name(s): Limb logic system
Intervention model: Single Group Assignment
Intervention model description: This is a 16 weeks longitudinal study where subjects will serve their own control. A baseline measurement will be done prior to start of intervention that will continue for 16 weeks and a final measurement will be taken at the end of 16 weeks.
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: Transfemoral Amputees; Transtibial Amputees; Prosthesis