Western Ontario Shoulder Instability Index (WOSI)

June 01, 2016


Western Ontario Shoulder Instability Index (WOSI)

The Western Ontario Shoulder Instability index (WOSI), a validated PRO measure developed in 1998 as an outcome measure to be used specifically for use in shoulder instability. It is thought that instability of the shoulder joint leads to special problems of assessment that traditional shoulder patient-reported outcome measures may fail to capture as instability of the shoulder has symptoms that are often intermittent and characterized less by pain than by the anticipation of problems arising in association with certain activities.

The WOSI has proven to be a useful outcome measure in several clinical studies and has been translated and validated in multiple languages.

The WOSI questionnaire consists of 21 items, each scored on a 100 mm Visual Analogue Scale (VAS). Each item falls into one of the domains of physical function, sports/recreation/work, lifestyle and emotional well-being. Each question is scored between 0-100 points and the summation of all the questions results in a final WOSI score. The final score ranges from 0 (best possible score – the patient is experiencing no decrease in shoulder related quality of life) to 2100 (worst score – signifies extreme distress in shoulder related quality of life).

The WOSI is a valid, reliable and sensitive assessment for patients with shoulder problems that are associated with instability and it is widely recommended for use in the evaluation of these patients.


The WOSI index is a patient-friendly survey with excellent test-retest reliability. It is also designed for clinical trials and is valid for comparing and even aggregating cohort studies.

Studies have found the WOSI to be more responsive and sensitive to change than other measures for shoulder instability including DASH, Constant, ASES and UCLA.


The WOSI takes about ten minutes for patients to complete which compares unfavorably to other shoulder and upper extremity outcome measures that take a considerably shorter amount of time (2-5 minutes). There is also comparatively little validity and responsiveness information for the WOSI. Its 0-2100 scale is not comparable to other outcome measures (although it may be converted to a 0-100 point scale).

There is much consensus amongst clinicians that the Western Ontario Shoulder Instability Index is the preferred PRO measure when evaluating treatments of shoulder instability. It is easy to administer and has good reliability and responsiveness.

Licensing and Cost

The Western Ontario Shoulder Instability Index does not require a license. To view the measure, please visit: www.orthopaedicscore.com/scorepages/oxford_wosi_score.html


The Western Ontario Shoulder Instability Index (WOSI): validity, reliability, and responsiveness retested with a Swedish translation     |  The Responsiveness and Minimal Important Change of the Western Ontario Shoulder Instability Index and Oxford Shoulder Instability Score   |   The development and evaluation of a disease-specific quality of life measurement tool for shoulder instability. The Western Ontario Shoulder Instability Index (WOSI)The use of the Oxford hip and knee scores. Bone & Joint Journal

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