We have added the radiographic image of an exemplary case (Figure 5).

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1 Author s response to reviews Title: Ten-year survival rate after rotational acetabular osteotomy in adulthood hip dysplasia Authors: Masamitsu Tomioka (kyoken5@msn.com) Yutaka Inaba (yute0131@med.yokohama-cu.ac.jp) Naomi Kobayashi (naomik58@aol.com) Taro Tezuka (tettu59@hotmail.com) Hyonmin Choe (hyonmin@hotmail.com) Hiroyuki Ike (sle9999mds@gmail.com) Tomoyuki Saito (t_stito@med.yokohama-cu.ne.jp) Version: 1 Date: 07 Apr 2017 Author s response to reviews: to Reviewer #1, Dr. Dirk Zajonz We are grateful to Dr. Dirk Zajonz for the critical comments and useful suggestions that have helped us improve our manuscript considerably. As indicated in the responses that follow, we have taken all of these comments and suggestions into account in revising our manuscript. 1 With an exemplary case (radiological images in progress), the surgical procedure and the development over the 10 years could be better illustrated. We have added the radiographic image of an exemplary case (Figure 5). 2 The colleagues showed that, in particular, the age at the of surgery is essential for outcome (OA and THA). The work of Yuasa et al. from February 2017 was able to confirm these results for 178 joints over a follow up period of median 20 years. However, Yuasa et al lead the cause rather in the pre-existing OA and not in the age alone. Perhaps the authors can show a correlation between the age at surgery and the existing OA- grade at surgery and the resulting outcome.

2 Rotational acetabular osteotomy for acetabular dysplasia and osteoarthritis: a mean follow-up of 20 years; Takahito Yuasa, Katsuhiko Maezawa, Kazuo Kaneko, Masahiko Nozawa; Arch Orthop Trauma Surg, 14 February 2017 DOI /s As the reviewer mentioned, Yuasa et al. reported that pre-existing OA was a significant predictor of failure of RAO. In the current study, we classified all hips into 4 stages according to the JOA classification (Page 8, Line 123; Page 10, Line 171). We calculated the correlation coefficient between the patients age and JOA classification. There was a weak positive correlation (r = 0.31, p < 0.01), which indicated that older patients tended to reveal a severe preexisting OA. However, based on the Cox regression analysis, the JSW itself was not a risk factor of THA or OA progression. One of the reasons why pre-existing OA or the JSW did not reveal any significance might be that the current study did not include cases of hips with severe OA (Page 14, Lines ). 3 From my point of view, it is hardly conceivable that an additional intertrochanteric valgus or varus osteotomy on the femur should no influence on the outcome. Perhaps the authors will be able to discuss this in more detail in the discussion. Eleven hips of 10 patients had a simultaneous intertrochanteric osteotomy. One had a varus osteotomy, and the other 10 hips had a valgus osteotomy. We have included the procedure in the methods section (Page6, Line 97, Page 7, Line ). We also performed a log-rank test to compare the survival rates among the three groups, i.e., hips treated with RAO alone, RAO with valgus osteotomy of the femur, and RAO with varus osteotomy. The figures below show the results of the log-rank test. There was no significant difference among the three groups (Page 12, Lines ). We have also added the figure showing the hip treated with RAO and simultaneous intertrochanteric osteotomy (Figure 6).

3 to Reviewer #2, Dr. Mostafa Ayoub We are grateful to Dr. Mostafa Ayoub for the critical comments and useful suggestions that have helped us improve our manuscript considerably. As indicated in the responses that follow, we have taken all these comments and suggestions into account in revising our manuscript. 1 The title: it is too long; I suggest its correction to "ten-year survival rate after rotational acetabular osteotomy in adulthood hip dysplasia" We have changed the title of the manuscript as per your recommendation. Introduction: 2 I think it is better to exchange developmental dysplasia of the hip (DDH) by adulthood hip dysplasia (AHD), as all cases were adults with defective head femur coverage without subluxation or dislocation of the hip and one case had spastic hip dysplasia. We have changed the term DDH to ADH as per your recommendation. Materials and methods: 3 Did the authors have preoperative CT scans evaluation to facilitate the defective area coverage after osteotomy? We have currently evaluated the three-dimensional morphology of the hips using CT scans; however, because preoperative CT scan evaluation was not performed more than 10 years ago, we do not have preoperative CT scan data of the patients enrolled in the current study, unfortunately. 4 How did they guide resection of the acetabulum without penetration of the socket or the medial walls of the iliac, ischeal, and pubic bones?

4 We used the intraoperative fluoroscopic image to detect the acetabular rim or resect the acetabulum. 5 How did they fix the rotated acetabulum to the iliac bone? Two to three absorbable screws (4.5 mm in diameter) were used to fix the rotated acetabulum to the iliac bone (Page 7, Lines ). 6 Was it through the socket itself or through its outer shell of bone? What were the screw lengths and directions? The screws were fixed through the outer shell of the bone. We inserted the screws 15 cranially and fixed them bicortically to obtain a rigid fixation. As a result, 40- to 50-mm screws were often used. 7 How many screws were used to fix the greater trochanter? In cases of the hips treated with RAO alone, we used 2 absorbable screws to fix the greater trochanter. One was 6.5 mm and the other was 4.5 mm in diameter (Page 7, Lines ). In cases of the hips treated with RAO and valgus/varus osteotomy, we used 2 pairs of pins and wires (Figure 6). 8 Were they bicortical or unicortical? They were bicortical (Page 7, Line 112). 9 In page 8 lines represented a discussion paragraph? Similarly page 9 lines

5 We moved such sentences to the discussion section, accordingly (Page 14, Line 246; Page 15, Line 263). Results: 10 Ten cases had simultaneous intertrochanteric osteotomy? The authors did not mention this procedure in the method section and how they did it in the presence of greater trochanter osteotomy? And how did they fix both osteotomies among those cases? It is better to add cases figures for better understanding of both simultaneous osteotomies and their fixation. Eleven hips of 10 patients had a simultaneous intertrochanteric osteotomy. One had a varus osteotomy, and the other 10 hips had a valgus osteotomy. We have added the procedure in the methods section (Page 6, Line 97; Page 7, Line 110). We have also added the figure showing the hip treated with RAO and simultaneous intertrochanteric osteotomy (Figure 6). Discussion: 11 It is short, somewhat superficial and added few to the literature. We have included a more detailed discussion section in the revised manuscript.