This study aimed to translate and culturally adapt the iHOT12 to Hebrew and test its psychometric properties. From this study it can be concluded that the translation procedure of the English iHOT12 was successful. The results of this study show that the iHOT12-H is a reliable, internally consistent, and valid measurement tool to assess physical functioning and quality of life in an Israeli population of young, physically active individuals between 18 to 60 years of age with hip-related pain.

Hip related pain has become one of the most commonly diagnosed musculoskeletal conditions in young and active adults, leading to increased hip arthroscopic surgery rates. However, until recently, there has been a lack of standardized patient-reported outcome measures for this specific population. The iHOT33, and consequently the iHOT12, have addressed this limitation. The favorable psychometric characteristics of the iHOT12 and the relatively short time for application enables it to be used in research as well as in daily clinical practice. Furthermore, a few systematic reviews questioning which patients reported outcome measures are most responsive in this patient population further reinforce the validity of the iHOT12 in assessing outcome for treatment of young and active patients [9, 30, 31].

Our demographic data included men and women with an average age of 39.8 ± 13.0. Thus, they are comparable with the average age used in the original study of the development of iHOT12 conducted by Griffin et al. [14]. In our study, to have a more heterogenous patient sample, we did not preselect patients according to their diagnosis or intended treatment. Two of the previous translation and validation studies of the iHOT12 evaluated only patients with Femoro-acetabular impingement syndrome (FAIS) [16, 19]. This may have negatively affected the external validity of their study.

The overall assessment of the iHOT12-H yielded remarkably high values. These results prove the quality of the iHOT12-H version and confirm the results of previous validation studies on the iHOT12 [9, 13,14,15,16,17,18,19,20, 22, 23]. The iHOT12-H showed good internal consistency, with a Cronbach alpha of 0.953. This result is comparable with the Cronbach alpha values evaluated in prior studies: Swedish (α = 0.89) [16], Dutch (α = 0.96) [17], German (α = 0.94) [18], Japanese (α = 0.90) [19], Turkish (α = 0.93) [20], and Greek (α = 0.92) [22] versions of the iHOT12. The fact that in the present study we found a Cronbach alpha higher than 0.95, may indicate that the items in this questionnaire are almost the same construct [24]. Future studies may look at the possibility of removing some of the items of the iHOT12.

The iHOT12-H showed excellent test–retest reliability, with an ICC of 0.956 (95% CI 0.924–0.974), which is comparable with the ICC of the English (ICC = 0.89) [14], Swedish (ICC = 0.88) [16], Dutch (ICC = 0.93) [17], German (ICC = 0.94) [18], Japanese (ICC = 0.89) [19], Turkish (ICC = 0.93) [20] and Greek (ICC = 0.98) [22] versions. The French version of the iHOT12 showed lower values of ICC (ICC = 0.84) [23], but these values are still categorized as good test–retest reliability [27].

For the evaluation of construct validity, we chose the WOMAC questionnaire, as it was hip-specific and validated questionnaire in the Hebrew language [25]. We found strong correlation between the iHOT12-H and the WOMAC score (r = -0.82, P < 0.001). To our knowledge, these relationships have been investigated previously only by Attila et al. [20], who found a similar correlation between the iHOT12-T and the WOMAC score (r = 0.815, P < 0.001) [20]. All other studies evaluating the validity of the iHOT12 following a procedure of translation used a variability of PROM forms as the gold standard [14, 16,17,18,19, 22, 23]. Li et al. [32] evaluated the correlation between the iHOT33 and the WOMAC score and found similar correlation coefficient (r = 0.812) to our results.

The factor analysis of the iHOT12-H revealed a two-factor structure: Factor-1 (items 1–5, 7–9) refers to “symptoms and functionality”, while Factor-2 (items 6, and 10–12) refers to “hip related concerns”. The original English version of the iHOT12 has a single factor structure [14]. Likewise, the Dutch and one of the Turkish versions reveled a one-factor structure [17, 20]. However, the Swedish version showed two factors, but with different factor loadings than ours: Factor-1 “Function and symptoms” (items 2–5, 8, 9) and Factor-2 “pain and concern/destruction” (items 1, 6, 7, 10–12) [16]. Another study of a Greak version showed two factors quite similar to our results: factor-1 “symptoms and functionality” (items 1–9) and Factor-2 “hip disorder-related concerns” (items 10–12) [22]. Interestingly, we found a second study validating a Turkish version who revealed 3 factors: “Symptom and functional limitations” (items 1–4), “Social, emotional and lifestyle” (items 8–12), and “Sports and recreational activities” (items 6, 7, 11) [21]. Factor-model variations may result from cross-cultural factors, or from age-related quality of life concerns, as the mean age of the studied population varies among studies [17, 20,21,22]. For the Portuguese, German, Japanese and French versions, no factor analysis has been conducted [15, 18, 19, 23].

Despite very good results concerning validity and reliability, there are a few limitations in this study. First, we included patients with different levels of activity but we did not evaluate the exact activity level of our patients using the Tegner Activity Scale as was evaluated in some of the previous studies [17,18,19]. Thus, future research comparing between different levels of activity of patients is therefore necessary to determine whether the iHOT12 is applicable to such a variety of patients. Secondly, the study sample included patients with a variety of hip pathologies. Including a heterogenous population may also increase the external validity of this study. Thirdly, since the iHOT33 questionnaire has not been officially translated into the Hebrew language we were unable to assess the criterion-related validity of iHOT12-H [24]. Finally, responsiveness was not determined in this study, therefore we could not evaluate the exact minimal important change values. Additional research is needed to determine whether the iHOT12-H is a responsive instrument as was shown in previous studies [16, 18, 19, 22]. Further prospective studies are needed to assess the clinical impact of iHOT12 on patients with hip related pain who underwent conservative management or surgical treatment. Such studies will advance our understanding of the therapeutic processes among those patients and will provide benefits both in clinical practice and in research.