Validation of the Dutch version of the Hip Outcome Score; validity, reliability, and responsiveness in patients with femoroacetabular impingement syndrome

Due to a lack of a validated Dutch version of the Hip Outcome Score (HOS) considering functional outcome after hip arthroscopy for femoroacetabular impingement syndrome, we validated the Dutch version of the HOS (HOS-NL) in patients with femoroacetabular impingement syndrome for reliability, internal consistency, construct- and content validity. Furthermore, the smallest detectable change (SDC) and minimal clinically important difference (MCID) were determined. All consecutive patients scheduled for an arthroscopic procedure for FAIS were selected. Five questionnaires covering groin and hip pain were filled in at three moments in time (two pre-operatively with a maximum two-week interval and 6 months postoperatively). Main endpoints were reliability (test re-test, SDC), internal consistency (Cronbach alpha), construct validity (construct validity was considered sufficient if a least 75% of a-priori made hypotheses were confirmed), content validity (floor and ceiling effects) and responsiveness (MCID). The intraclass correlation coefficient (ICC) was 0.86 for the HOS ADL-NL and 0.81 for the HOS Sports-NL. SDC for the HOS ADL-NL was 21 and for the HOS Sports-NL 29 Cronbach alpha score was 0.882 for HOS ADL-NL and 0.792 for HOS Sports-NL. Construct validity was considered sufficient since 91% of the hypotheses were confirmed. No floor effects were determined. A small ceiling effect was determined for the HOS AD-NL postoperatively. The MCID for HOS ADL-NL and HOS Sports-NL were 14 and 11.0, respectively. The HOS-NL is a reliable and valid patient reported outcome measure for measuring physical function and outcome in active and young patients with femoroacetabular impingement syndrome.