Prosthetic Fit Assessment in Transtibial Amputees Secondary to Trauma
Condition: Traumatic Amputation of Lower Extremity
MeSH terms: Amputation, Traumatic
Study type: Observational

Summary: 
      The aims of this study address an exploratory endpoint in the Major Extremity Trauma Research
      Consortium (METRC) Transtibial Amputation Outcomes Study (TAOS; NCT01821976) that is
      investigating prosthesis fit, alignment and condition of the residual limb. As there are no
      validated measures of fit and alignment (factors known to impact comfort, function and
      performance among amputees) the TAOS study includes a provision in the protocol for
      acquisition of photographs, video and radiographs in order to help develop uniform
      assessments of the residual limb. The goal of the ProFit study is to validate and refine the
      prosthetic assessment tool (ProFit) that was developed by an expert panel of certified
      orthotist prosthetistis (CPOs) in collaboration with orthopaedic trauma investigators, a
      measurement scientist and a biomedical engineer from the BADER consortium.
    

Detailed description: 
      Specific Aim 1: To test the reliability of the ProFit.

      Patients enrolled in the TAOS trial returning for their eighteen month final visit will
      undergo radiographic, video, and photographic assessment. A blinded prosthetist panel (PP)
      will view these remotely and complete a 42 item assessment based on x-ray, photo and video.
      We will examine two aspects of reliability for the ProFit, inter-rater reliability and
      internal consistency.

      Specific Aim 2: To examine the validity and responsiveness of the ProFit.

      This study aims to examine the validity of the ProFit by specifically evaluating factor
      validity, construct validity and discriminant validity. This will be accomplished by
      correlating ProFit scores with measures of self-reported pain (Brief Pain Inventory),
      function (Short Musculoskeletal Functional Assessment), and satisfaction (Orthotics and
      Prosthetics User's Survey). Moreover, a subset of subjects will undergo quantitative
      measurement of fit and alignment using a novel prosthesis-mounted socket reaction moment
      sensor. Responsiveness of the ProFit will be based on repeated measurements at 6 and 18
      months.

      Specific Aim 3: To develop a shorter version of the ProFit.

      Based on findings from Aim 1 and 2 at the individual item level, we will remove items that:
      1) have poor inter-rater agreement; 2) demonstrate weak relationships with clinician and
      patient report of overall fit; or 3) exhibit strong ceiling or floor effects.

      Study design: The ProFit study is a prospective validation study of an assessment of
      prosthetic fit and alignment among patients with a transtibial amputation.

      Study duration: 3 years Sample size: 120 TAOS patients will provide adequate power to detect
      important differences in fit and alignment 18 months following amputation. A subset of 60
      patients is necessary to detect significant differences in alignment using the Smart Pyramid.

      Number of study sites: Up to 35 centers including 24 Core METRC sites, 4 MTFs, and 7 METRC
      satellite sites.

      Study population: Patients enrolled in the METRC TAOS study.

      Outcome measure: This ancillary project to the TAOS trial is designed to study the validity
      reliability and validity of the ProFit, a 42-item tool for assessing prosthetic fit and
      alignment among patients with a transtibial amputation.

      Statistical analysis: Inter-rater reliability and internal consistency will be examined to
      test the reliability of the ProFit. The validity of this assessment will be evaluated using a
      variety of construct validity tests. Based on findings from the reliability and validity
      analysis, a shorter version of the ProFit will be developed. The performance of the shorter
      version will be determined based on correlation with the original assessment.

      Randomization: Not applicable

      Safety monitoring: Not applicable
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Participants will be drawn from the TAOS study which enrolls patients with below the knee
        amputations from trauma centers participating in the Major Extremity Research Consortium
        (METRC).
      
Keywords: Transtibial amputation; Prosthetic fit; Prosthetic alignment