The development and validation of a scoring system for shoulder injuries in rugby players

Background Shoulder injuries are relatively common among professional rugby players and result in a large proportion of days absent from training and competition. No instrument exists that is designed and validated to assess function or outcome following therapeutic interventions in rugby players sustaining shoulder injuries. The objective was to develop and validate an athlete-reported scoring system to assess shoulder function in rugby players following shoulder injuries. Methods Potential items for the scoring system were identified by a literature review of shoulder-specific scoring systems (n=46), and by interviewing professional rugby players (n=38) and medical staff (n=12). Redundant and clinician-assessed items were excluded. A second set of interviews with rugby players (n=8) determined the frequency importance product (FIP) of potential items. The 20 items with the highest FIPs were selected for the provisional Rugby Shoulder Score (RSS) that was tested for internal consistency and reliability by administering to rugby players with stable shoulder injuries (n=11). Results The literature review and interviews identified 575 items, of which 105 items were neither clinician-assessed nor redundant. Twenty items with the highest FIPs were selected for the RSS. The RSS demonstrated excellent internal consistency (Cronbach's =0.96) and reliability (intraclass correlation coefficient=0.941, paired student t test p>0.05). Conclusions A reliable athlete-reported scoring system for assessing shoulder injuries in rugby players has been developed that incorporates the most important factors for rugby players recovering from shoulder injuries. Further prospective testing of the instrument is being undertaken to determine its discriminative and evaluative functions and construct validity.