' COMMENTS AND OUR REPLY Reviewer : Tanja

Results: Please insert “Test-retest reliability correlation coefficient obtained was rho= 0.95.” Also “the correlations coefficient versus the five subscales of FAOS ranged from rho= 0.80-0.86.” Reply The rho has been inserted as suggested Background Page 2, Line 1-2: please delete word “now” Reply The text has been changed as suggested Reviewer’s comments Did the OMAS score have been proven for responsiveness in patients with ankle fractures? Reply We have now calculated the effect size using the values of OMAS at six-month and 12-month follow-up. The effect size was found to be 0.44. At the end of the Background section information about effect size has been shortly inserted, Statistics has been completed as well as Results and Discussion sections. Reviewer’s comments The author’s state: “few methodological studies regarding OMAS have been performed. Please specify and include the results or main outcomes. Reply The results from a few methodological studies have been described in the paper and one more new study has been published in 2012 (Wees et al.) and has now been included and referred to. The references have been written once more and hopefully this makes it clearer. Methods Reviewer’s comments The authors described the results (tables) with median and range, so they also have to do in the methods section, describing the anthropometrics. Where the authors did recruit the patients? Are they all from the same cohort? Explain the different numbers of subjects included in the different reliability and validity steps. Please also insert the inclusion and exclusion criteria’s. Reply As OMAS is a non-parametric instrument, the points go from 0-5-10-15-20-25 (ordinal scale), and to our knowledge it should therefore be more correct to use median and range. Age and number of days in plaster cast should be regarded as parametric data (ratio scale) and by then the mean value and the standard deviation should be used. The patients were all recruited at the University Hospital of Lund, Sweden (ref 29) as now has been described in the section Design/Participants and were from the same cohort. This has now been clarified. We have also described that this validity and reliability study was a part of an intervention study (ref 29). At six-month follow-up, all 106 subjects filled in OMAS and global selfrated function and of those 99 showed up at 12-month and by then filled in the same questionnaires. However, we also wanted to study the validity and reliability of OMAS as this had not been done before. Therefore a part of the cohort was asked to fill in OMAS once more and FAOS at the clinic as described. There were no particular inclusionor exclusion criteria (age, gender, fracture types and surgical techniques and immobilization routines were all the same as we have described) and we estimated that about 40 individuals should be enough. From ethical point of view no more subjects than necessary should be involved in studies. Reviewer’s comments Test-retest reliability of the OMAS -Participants-> 19 had a bi-or trimalleolar fracture. Please implement also how many patients had a bimalleolar fracture and how many patients had an trimalleolar fracture. -Please implement how many patients were treated with a non-rigid surgical technique and how many patients underwent a rigid surgical technique -Did the kind of fracture influence the convalescence? Are they differences regarding the length of convalescence? If yes, it would be influence the results at 6 month post-surgery Reply Fracture types and surgical techniques that were used have been described in detail elsewhere (29). This information has now been added to the text as suggested. As the aim of this study was to evaluate the reliability and validity of OMAS the convalescence or recovery in relation to fracture type was not focused on this time. Furthermore, all questionnaires were filled in at the same time and each person was compared to him/herself so the length of convalescence should not be assumed to influence the results. Reviewer’s comments Validity of OMAS using global self –rated function -Please implement how many patients had a bimalleolar fracture and how many patients a trimalleolar fracture. Validity of OMAS using the FAOS -Please implement how many patients had a bimalleolar fracture and how many patients a trimalleolar fracture. Reply Fracture types and surgical techniques that were used are described in detail elsewhere (29). This information has now been added as described above and is now referred to. Reviewer’s comments Statistics Did the variables been tested for normal distribution? Reply The OMAS was almost normal distributed at six-month. At twelve-month the distribution was slightly shifted which means some more subjects scored higher at that time. This could be expected as more individuals improve over time. Of the same reason we found it relevant to evaluate the validity of OMAS both at six-and 12 month follow-up. The distribution curves did not differ between the two measurements at 12-month. Reviewer’s comments Further statistical analyses are wanted to demonstrate the reliability of the OMAS questionnaire. Please implement the Intraclass coefficient and calculate the minimal detectable change as well as the SEM. Reply The ICC as well as SEM, SEM% and SRD, 95%SRD and SRD% has now been calculated. Statistics has been completed and the figures have been added in the Results and discussed in the Discussion section. Reviewer’s comments Results Test retest reliability Please insert significance range (e.g: “no significant differences were found between the two tests (p= xx-xx) Reply The p-value has now been added as suggested Reviewer’s comments Discussion Page 6, line 7 #Please implement the kind of ankle fractures, were the OMAS questionnaire seems to be a reliable and valid tool. Reply The sentence has now been revised as suggested: The results of this study showed that the testretest reliability and concurrent validity of the OMAS were good for patients surgically treated due to an unibi or trimalleolar ankle fracture. We thank the reviewer for the comments and for the time spent reviewing our work.