Biomechanical Assessment of Gait in Lower-Extremity-Amputees
Condition: Prosthesis User
Study type: Interventional

Summary: 
      This study is investigating the influence of several simulated real life conditions on the
      symmetry of gait with trans-tibial prostheses

      Hypotheses: It is hypothesized that the observable differences in gait pattern between
      amputees can be detected by a combination of forces and moments that are measured internally
      in the prosthesis, and electromyography data. It is further hypothesized that changing
      conditions such as uneven walking surface, prosthetic misalignment or user fatigue are
      characterized by typical values in the measured data or combinations thereof.
    

Detailed description: 
      In amputee walking, an optimal static alignment of the artificial leg is important in order
      to achieve the best possible performance. Comfort, energy expenditure, mobility and walking
      speed should ideally be similar to those of able bodied persons. Of course, amputation level,
      overall health status and other factors often pose certain individual limitations that may
      prevent an amputee from reaching this goal.

      Irrespective of that, the artificial leg must be aligned properly to eliminate unnecessary
      inhibitions. Apart from manufacturing a well fitting socket, and selecting the appropriate
      functional components of the prosthesis, the prosthetist has to routinely optimize the static
      alignment during the fitting process. Hereby, objective measures and guidelines are scarce.
      Despite various more or less useful tools that are available, the alignment optimization in
      praxis is often based on subjective gait assessment and rules of thumb. Commonly accepted is
      the notion, that the gait pattern should be most symmetrically, that is step lengths, stance
      times, knee angles etc. should be identical between sound and prosthetic leg.

      There are different questions that our study wants to address: Is gait symmetry indeed a
      valid measure of prosthetic performance (e.i. is it the most energy efficient way to walk)?
      How does the gait pattern change when the prosthesis user walks on different surfaces,
      becomes tired or tries to compensate for a less-than-optimal prosthesis fit? How can gait
      symmetry be objectively assessed without using an expensive motion analysis laboratory? We
      hope that our findings will provide practically useful information that can help improve
      prosthetic fittings in the field.

      The study will be based on data from up to 15 trans-tibial prosthesis users. Participants
      will walk with their standard prosthesis, which will be equipped with a small sensor unit for
      the measurement of forces and moments during walking. The muscle activity of the thigh
      muscles will be measured using surface EMG sensors. All of the data collection will take
      place at the USR facilities (115 E Reindl Way, Milwaukee), where a multi camera motion
      analysis system is set up. Trials will require an overall time commitment of 5 hours at most,
      and will include normal walking, walking on carpet and gravel, walking up and down stairs,
      walking with fatigued thigh muscles.
    

Intervention name(s): Alignment perturbations
Intervention type(s): Device
Intervention description(s): Increased foot plantar flexion, increased foot dorsal flexion, increased foot supination, increased foot pronation (always 2 degrees from the neutral position)
Intervention model: Single Group Assignment
Masking: None (Open Label)