Construct: OPRO-M™ instruments measure orthosis users’ mobility (i.e., the ability to move from one place to another without help from another person). Individual OPRO-M™ questions assess respondents’ perceived ability to carry out specific activities that require use of lower limbs. OPRO-M™ questions cover movements that range from basic ambulation (e.g., walking a short distance in their home) to complex activities (e.g., going for an all-day hike). OPRO-M™ response options reflect the degree of difficulty with which respondents report they can carry out these activities.

Intended applications: OPRO-M™ instruments are intended for use in research and clinical care.

Intended population: OPRO-M™ instruments are intended for use with adults (ages 18 and older) who use an orthosis that extends from the foot to the ankle or higher.

Current version: The current version of the OPRO-M™ item bank is Version 1.0, as of July 1, 2022. We recommend Version 1.0 for measuring mobility in people who use an orthosis for ambulation.

Formats: OPRO-M™ instruments are based on a set of calibrated questions called the OPRO-M™ item bank. The OPRO-M™ short forms included in this guide are subsets of questions in the OPRO-M™ item bank. Short forms are available in different lengths depending on the purpose and reliability required by the researcher or clinician. All short forms are suited to measuring mobility across a range of orthosis users. OPRO-M™ Version 1.0 short forms are available in either a 20-item or 12-item. The OPRO-M™ Computer Adaptive Test (CAT) will be made available soon on the OPRO-M™ website (https://OPRO-M.org). The OPRO-M™ CAT will offer an optimal combination of high measurement precision and low administrative burden.

Administration and scoring time: OPRO-M™ short forms require approximately 2-3 minutes to administer and 1-2 minutes to score.

Score: OPRO-M™ Version 1.0 instruments provide a T-score that ranges from 17.5 to 81.7, depending on the form of the instrument selected:

• 20-item mobility short form: 19.4 to 79.7
• 12-item mobility short form: 22.3 to 78.9

Score interpretation: OPRO-M™ Version 1.0 T-scores are referenced to the development sample (n=1036 lower limb orthosis users) described in the OPRO-M™ User Guide. A T-score has a mean of 50 and a standard deviation (SD) of 10. A OPRO-M™ T-score of 50 represents the mean mobility reported by the development sample (i.e., people who use an orthosis). A higher OPRO-M™ T-score corresponds to greater mobility.