Clinical effects of combined anteversion and offset on postoperative dislocation in total hip arthroplasty

Clinical effects of combined anteversion and offset on postoperative dislocation in total hip arthroplasty | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Clinical effects of combined anteversion and offset on postoperative dislocation in total hip arthroplasty Kenta Matsuda, Ryo Hidaka, Shigeru Nakamura, Masaki Nakamura, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-1863433/v2 This work is licensed under a CC BY 4.0 License Status: Posted Version 2 posted You are reading this latest preprint version Show more versions Abstract Background Implant impingement and soft tissue tension are factors involved in dislocation after total hip arthroplasty (THA). Combined anteversion (CA) has been used as an indicator for implant placement; however, placing implants optimally remains challenging. Moreover, the effect of changes in offset on dislocation remains unclear. We aimed to clarify the effects of postoperative CA and pre- and postoperative changes in offset on dislocation. Methods We included patients who underwent primary cementless THA performed between 2013 and 2020. The mean values of CA and offset in the dislocation and non-dislocation groups were compared. The CA values within ± 10% of the recommended values were defined as good CA, and those outside the range were defined as poor CA. The dislocation rates in the good and poor CA groups and in the groups with and without increased offset were compared. Results A total of 283 hips were included. The mean values of CA in the dislocation and non-dislocation groups were significantly different (p < 0.001). The dislocation rate was significantly lower in the good CA group (p < 0.05). The dislocation rates in the groups with and without increased total offset were 0.5% and 4.3%, respectively (p = 0.004). There were no dislocations in patients with good CA and increased offset. Conclusions The dislocation rate was significantly lower when implants were placed within ± 10% of the recommended CA value. Our results suggest that dislocation can be avoided by placing the implant in the good CA range and considering the increase in total offset on the operative side. Total hip arthroplasty Dislocation Combined anteversion Offset Figures Figure 1 Figure 2 Figure 3 Background Complications after total hip arthroplasty (THA) are known to include infection, loosening, fracture, and dislocation. Of these, dislocation is one of the most serious complications that may require revision; therefore, preventing dislocation is essential [ 1 ]. Various factors are involved in dislocation after THA, including surgical, patient, and implant factors [ 2 , 3 ]. Patient factors include age, cerebral dysfunction, and range of motion [ 2 , 4 ]; implant factors include head diameter and neck design [ 2 , 4 ]; surgical factors include operative approach, implant and bony impingement, and soft tissue strain [ 5 ]. Several studies have demonstrated that implant impingement because of inadequate implant placement is the main cause of postoperative THA dislocation [ 6 – 8 ]. Combined anteversion (CA), the optimal combination of cup inclination, cup anteversion, and stem anteversion to maximize the range of motion and minimize the risk of cup-neck impingement to reduce the risk of dislocation, has been reported to be a useful index for implant positioning [ 9 – 11 ]. Moreover, the offset is an index for bony impingement and soft tissue tension [ 5 , 12 ]. However, few reports have evaluated THA dislocations based on both CA and offset. Additionally, although differences in offset between the operative and contralateral sides have been reported, the pre- and postoperative offsets on the operative side have not been described. In this study, we aimed to determine if obtaining desired CA and combined offset would lead to a reduction in hip instability in a consecutive series of hip arthroplasties. Methods Participants A total of 428 consecutive hips, which underwent primary cementless THA via posterior approach from 2013 to 2020 at our institution, were included. This retrospective case-control study was conducted in compliance with the Helsinki Declaration and was approved by the institutional ethics board (19–174). The patients provided written informed consent prior to participation. Patients who used non-flatliners (n = 65), those who could not undergo postoperative computed tomography (CT) for any reason (n = 37), and those who could not be followed for more than 1 year (n = 48) were excluded. All hips were followed up for at least 1 year, during which time postoperative dislocations were recorded. Preoperative planning Preoperative planning was performed using a three-dimensional (3D) template (ZedHip™ Lexi Co., Ltd., Tokyo, Japan) based on preoperative CT. For the pelvic coordinates, the functional pelvic plane was used as the reference plane passing through the bilateral anterior iliac spines and parallel to the CT table [ 13 ], and for the femoral coordinates, the retrocondylar plane was used as the reference plane passing through the posterior point of the greater trochanter and the posterior points of the medial and lateral femoral condyle [ 14 ]. The target inclination of the acetabular component (cup radiographic inclination) was set to 43° in all cases. Anteversion of the femoral component (stem anteversion) was predicted by placing a stem along the shape of the proximal femur using a preoperative 3D template. The target anteversion of the acetabular component (cup anatomical anteversion) was determined for each case using Yoshimine’s CA formula (cup anatomical anteversion + cup radiographic inclination + 0.80 × stem anteversion = 90.8°) [ 11 ]. Surgical procedure and postoperative evaluation All surgical procedures were performed in the lateral decubitus position, and a CT-based navigation system (Stryker CT-Hip System V1.1, Stryker-Leibinger GmbH & Co. KG, Freiberg, Germany) was used as the acetabular component. The posterior articular capsule and short external rotator muscles were repaired in all cases [ 15 ]. All surgeries were performed by either of the two senior authors. A CT scan was performed at 1 week postoperatively as a routine protocol to evaluate implant placement and to confirm the presence of fractures. The postoperative CT data were imported into the template for 3D analysis. The postoperative placement angles of the acetabular and femoral components were measured using the template. Matching with the preoperative template data, a template of the same size as the actual implant was overlapped on the postoperative CT for measurement (Fig. 1 ). Based on these placement angles, the postoperative CA values were calculated using the formulas of Widmer et al (cup radiographic anteversion + 0.7 × stem anteversion = 37°) and Yoshimine et al [ 10 , 11 ]. The mean CA values of the dislocated and non-dislocated groups were calculated and compared. Cup radiographic inclination within 35°–55° and CA values within ± 10% of the recommended values (Widmer: 37°±4°, Yoshimine: 90.8°±9°) were defined as good CA, and those outside the range were defined as poor CA. The dislocation rates in the good and poor groups were compared. The absolute values of the difference between the CA values calculated for each case and the recommended CA values using the formulas of Widmer et al and Yoshimine et al (37° and 90.8°, respectively) were calculated. Moreover, the cutoff values of CA for dislocation were examined. All offset measurements were made by projecting the distance on a horizontal plane using the template based on the preoperative and postoperative CT findings. The horizontal distance from the pubic symphysis to the center of the femoral head was measured as the acetabular offset, and the horizontal distance from the center of the femoral head to a line passing through the center of the femoral shaft was measured as the femoral offset [ 16 ]. The sum of these offsets was defined as the total offset (Fig. 2 ). The mean values of the total, acetabular, and femoral offsets on the operated side were compared between the dislocated and non-dislocated groups. The difference between the preoperative and postoperative values of each of these three offsets was divided into the postoperative increase and non-increase groups, and their dislocation rates were compared. The number of dislocations in each combination of the total offset increased/non-increased group and the CA good/poor group was investigated. The dislocation rates were also compared in cases with inner heads < 32 and ≥ 32 mm. Statistical assessment Demographic variables are described as means, standard deviations, and ranges for continuous data. We used the Mann–Whitney U test to compare the averages of continuous variables and Fisher’s exact test to compare the proportions of categorical variables between the groups. Receiver operator coefficient (ROC) curves were created to calculate the cutoff value of CA for dislocation. The Youden method was used to calculate the optimal threshold scores to obtain the best balance between sensitivity and specificity [ 17 ]. All statistical analyses were conducted using JMP (version 15.1.0; SAS Institute Inc., Cary, NC), with statistical significance defined as p < 0.05. Results The mean follow-up period was 5.3 ± 1.8 (2.5–9) years. Patient demographics are presented in Table 1 . A total of 283 hips (256 patients) were included. There were nine dislocated hips (3.2%) and 274 non-dislocated hips. Dislocation was found in nine out of 238 cases treated by the surgeon SN and in zero out of 45 cases treated by KM. There was no difference in the dislocation rates between the cases treated by these surgeons (p = 0.363). The mean CA values, as calculated by both Widmer et al’s and Yoshimine et al’s equations, were significantly different between the dislocation and non-dislocation groups. The good CA group included 158 hips according to the study of Widmer et al and 233 hips according to the study of Yoshimine et al, and dislocation was significantly lower in the good CA group for both Widmer and Yoshimine (Table 2 ). Based on the ROC curve analysis, the cutoff values for dislocation in Widmer’s CA and Yoshimine’s CA were 37°±3.3° and 90.8°±10.3°, respectively (Fig. 3 a, 3 b). The area under the ROC curve for Widmer’s CA was 0.696, the sensitivity was 0.889, the specificity was 0.471, and the Youden index was 0.36; for Yoshimine’s CA, the area under the ROC curve, sensitivity, specificity, and Youden index were 0.676, 0.556, 0.873, and 0.4, respectively. The mean total, acetabular, and femoral offsets on the operated side were not different between the dislocation and non-dislocation groups. The number of increased offsets was 169 (59.7%), 64 (22.6%), and 223 (78.8%) for total, acetabular, and femoral offsets on the operated side, respectively. Regarding the number of dislocations, the increased and non-increased groups were only significantly different in the total offset. Concerning the mean of the preoperative and postoperative differences in offset, the offsets were not significantly different between the dislocation and non-dislocation groups (Table 2 ). In the evaluation of dislocation using total offset and CA simultaneously, using both equations, dislocations were observed in cases with poor CA or no increase in offset, but no dislocations were observed in cases with good CA and increased offset (Table 3 ). The used femoral heads had sizes of 28, 32, and 36 mm; femoral heads of 28 mm were used in 57 cases, of which three were dislocated, with no significant difference in dislocation compared to cases of ≥ 32 mm (Table 4 ). Discussion The investigation was performed to determine the effect of CA and offset on dislocation after THA. It was demonstrated that both Widmer’s and Yoshimine’s CA values showed a significant difference in the mean values between the dislocation and non-dislocation groups, supporting the effectiveness of CA. However, many researchers have reported that some degree of difference between preoperative target values and postoperative measured values of implant placement angle is inevitable in THA [ 18 – 20 ]. Considering these previous reports, it is difficult to place the cup precisely at the generally recommended combined anteversion value. Moreover, Widmer et al assume that the radiographic inclination of the cup should be in the range of 40°–45° for CA; however, it is also difficult to place the implant within this range. In this study, only 155 implants were placed within this range. Therefore, based on the aforementioned reports and considering possible CA errors in surgery, we defined good CA as a cup radiographic inclination within the range of 35–55° and within ± 10% of the recommended CA value. The results of the present study demonstrated that dislocation was significantly lower in the good CA group and the cutoff values of CA for postoperative dislocation were 37°±3.3° and 90.8°±10.3° for Widmer and Yoshimine, respectively. This range is almost the same as our definition of good CA, and it covers the pre- and postoperative differences in implant placement angles in previous reports. Significantly fewer dislocations occurred when implants were placed within this range, which is useful as an indicator of dislocation prevention. However, as cases of dislocation occurred even when implants were placed within this range, it would be difficult to prevent dislocation after THA using CA alone as an indicator of implant placement. CA has been reported to be effective only in the prevention of implant impingement, but not in bony impingement [ 21 ]. Previous studies have shown the importance of not only implant impingement but also bony impingement and soft tissue tension in the prevention of dislocation after THA [ 5 , 21 , 22 ]. Studies on bony impingement have shown that increased acetabular offset provides increased range of motion for flexion and internal rotation by decreasing the effect of impingement of the greater trochanter on the anterior acetabulum [ 23 – 25 ]. Increased femoral offset improves hip abductor strength by lengthening the functional lever arm, reducing impingement, and increasing postoperative joint stability [ 22 , 26 ] and hip range of motion [ 27 , 28 ]. Thus, dislocation after THA is influenced not only by CA but also by acetabular offset and femoral offset, and all of these indicators should be considered during surgery. In this study, the results revealed no significant difference in the dislocation rate between the groups with and without increased acetabular and femoral offsets but a significant difference in the dislocation rate between the groups with and without increased total offset. In THA of patients with osteoarthritis, medialization by reaming is often necessary to place the acetabular component in an anatomically normal acetabulum [ 29 ]. The femoral offset should be increased to compensate for the decrease in acetabular offset due to the medialization. Thus, both offsets need to be evaluated [ 30 ], and avoiding a decrease in the total offset is important [ 31 ], which supports our results. In this study, the distance from the pubic symphysis to the femoral shaft was measured as the total offset; therefore, both the femoral and acetabular offsets were used in the evaluation. In both Widmer’s and Yoshimine’s CA, there were dislocations under the condition of good CA alone but not in cases with good CA and increased total offset. This suggests that dislocation can be further avoided by considering not only CA to prevent implant impingement but also the increase in total offset on the operated side to avoid soft tissue hypotension and bony impingement. Although a previous report showed no difference in the risk of dislocation between the increased and non-increased global offset groups [ 32 ], all previous reports on offset for dislocation after THA have compared the offset between the healthy and the operative sides. Krishnan et al reported that the mean difference between the right and left sides of the normal hip offset was 2.54 ± 2.31 mm and that hip offsets are not always symmetrical even in normal hips [ 33 ]. Additionally, determining the appropriate center of rotation of the hip joint in patients with bilateral morbidity or severe dysplasia is difficult [ 34 ]. In our study, we found a significant difference in the pre- and postoperative total offset changes on the operative side between the dislocation and non-dislocation groups. This method of evaluating offset has a great advantage in that it is not affected by the condition of the contralateral hip joint. Our findings also suggest that when postoperative offset on the operative side is reduced from the preoperative offset, soft tissue tension is reduced, thus, resulting in bony impingement and increased susceptibility to dislocation. To our knowledge, no other study has compared the pre- and postoperative offsets on the affected side. In this study, regarding the occurrence of pain on the lateral side of the hip, there was no significant difference between patients with > 5 mm of postoperative femoral offset on the operated side compared with the healthy side and those with < 5 mm. Many studies have reported that pain does not increase with increasing offset, which supports our results [ 23 , 35 – 38 ]. The limitations of this study should be noted. First, three types of femoral head sizes were used in this study. Regarding the effect of different head sizes on dislocation, many reports have shown that there was less dislocation in those sized ≥ 32 mm compared to those sized 28 mm [ 39 ]. However, in this study, no difference in dislocation was observed after comparing head sizes of 28 and ≥ 32 mm. Similar results were obtained for CA and offset for dislocation only in cases with a head size of ≥ 32 mm. Second, we used a non-flatliner to prevent dislocation in patients with inadequate intraoperative stability. These cases were excluded from the study because postoperative CT could not accurately measure the angle of placement of the non-flatliner, which may overestimate the effect of CA on dislocation. Third, the small sample size of nine patients with dislocations prohibited a multi-factor analysis. More dislocation cases should be evaluated to improve the accuracy of the analysis. Fourth, long-term adverse effects in cases of excessively increased femoral offset were not evaluated. Polyethylene wear reportedly increases when femoral offset increases by more than 5 mm compared with the normal hip joint [ 40 ]. In this study, there were 22 cases, in which femoral offset increased by ≥ 5 mm compared with the healthy side in 112 patients with unilateral disease, and the patients need to be carefully monitored in the future. Fifth, the proportion of female individuals in this study was larger than that of male individuals, showing a substantial sex bias. The reason for this is that most of the indications for total hip arthroplasty in Japan are of osteoarthritis associated with acetabular dysplasia, and the prevalence of this disease is approximately three times higher in women [ 41 ]. In the present study, the incidence of dislocation was not significantly different between men and women. Conclusions The dislocation rate was significantly lower when implants were placed within ± 10% of the recommended CA value, suggesting that placement within this range can prevent postoperative dislocation. In addition, an increase in the total offset on the operative side may prevent more dislocations. List Of Abbreviations THA Total hip arthroplasty CA Combined anteversion ROC Receiver operator coefficient 3D Three-dimensional Declarations Ethics approval and consent to participate This retrospective case-control study was conducted in compliance with the Helsinki Declaration and was approved by Teikyo University Medical Research Ethics Committee (19-174). The patients provided written informed consent prior to participation. Consent for publication All individuals have given general consent in the use of their data, including imaging, for analysis and publication. Availability of data and materials The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. Competing interests The authors declare that they have no competing interests. Funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Authors’ contributions All authors contributed to the study conception and design. Material preparation and data collection and analysis were performed by KM and RH. The first draft of the manuscript was written by KM , and all authors commented on the previous versions of the manuscript. All authors read and approved the final manuscript. Acknowledgments We would like to thank Editage (www.editage.com) for English language editing. References Bozic KJ, Kurtz SM, Lau E, Ong K, Vail TP, Berry DJ. The epidemiology of revision total hip arthroplasty in the United States. J Bone Joint Surg Am. 2009;91:128–33. https://doi.org/10.2106/JBJS.H.00155 . Berry DJ, von Knoch M, Schleck CD, Harmsen WS. The cumulative long-term risk of dislocation after primary Charnley total hip arthroplasty. J Bone Joint Surg Am. 2004;86:9–14. https://doi.org/10.2106/00004623-200401000-00003 . Malkani AL, Ong KL, Lau E, Kurtz SM, Justice BJ, Manley MT. 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Innmann MM, Maier MW, Streit MR, Grammatopoulos G, Bruckner T, Gotterbarm T, et al. Additive influence of hip offset and leg length reconstruction on postoperative improvement in clinical outcome after total hip arthroplasty. J Arthroplasty. 2018;33:156–61. https://doi.org/10.1016/j.arth.2017.08.007 . Sayed-Noor AS, Sjoden GO. Greater trochanteric pain after total hip arthroplasty: the incidence, clinical outcome and associated factors. Hip Int. 2006;16:202–6. https://doi.org/10.5301/hip.2008.4186 . Jameson SS, Lees D, James P, Serrano-Pedraza I, Partington PF, Muller SD, et al. Lower rates of dislocation with increased femoral head size after primary total hip replacement: a five-year analysis of NHS patients in England. J Bone Joint Surg Br. 2011;93:876–80. https://doi.org/10.1302/0301-620X.93B7.26657 . Little NJ, Busch CA, Gallagher JA, Rorabeck CH, Bourne RB. Acetabular polyethylene wear and acetabular inclination and femoral offset. Clin Orthop Relat Res. 2009;467:2895–900. https://doi.org/10.1007/s11999-009-0845-3 . Jingushi S, Ohfuji S, Sofue M, Hirota Y, Itoman M, Matsumoto T, et al. Multiinstitutional epidemiological study regarding osteoarthritis of the hip in Japan. J Orthop Sci. 2010;15:626–31. https://doi.org/10.1007/s00776-010-1507-8 . Tables Table 1 Patient demographics Characteristic Value Number of patients (hips/cases) 283/256 Gender (hips/cases) Male 68/58 Female 215/198 Age at THA * (years) 63.3 ± 11.1 (33–85) BMI (kg/m 2 ) * 24.5 ± 4.4 (15.8–39.6) Diagnosis (hips/cases) OA ONFH FNF RA RDC 216/196 51/44 8/8 3/3 5/5 * Values are presented as mean ± standard deviation (range) BMI , body mass index; OA , osteoarthritis; ONFH , osteonecrosis of the femoral head; FNF, femoral neck fracture; RA , rheumatoid arthritis; RDC , rapidly destructive coxopathy; THA , total hip arthroplasty Table 2 Results of the univariate analysis of factors for dislocation after total hip arthroplasty Variable Dislocation (+) n = 9 Dislocation (-) n = 274 p- value Age at THA * (years) 61.7 ± 14.2 (40–79) 63.4 ± 11 (33–85) 0.652 Sex (hips/cases) Male 2/2 66/56 1.000 Female 7/7 208/191 BMI (kg/m 2 ) * 25 ± 5.5 (17.2–36.6) 24.5 ± 4.4 (15.8–39.6) 0.722 Mean CA * (degree) Widmer 30.4 ± 8.5 (15.1–41.2) 37.1 ± 5.9 (19.8–62.1) 0.001 a Yoshimine 81.3 ± 12 (60–95) 90.6 ± 7.4 (66.7–118.7) < 0.001 a Widmer CA (hips) Good 2 156 0.0469 a Poor 7 118 Yoshimine CA (hips) Good 4 229 0.01 a Poor 5 45 Total offset (hips) Increase (+) 1 168 0.004 a Decrease (-) 8 106 Acetabular offset (hips) Increase (+) 2 62 1.000 Decrease (-) 7 212 Femoral offset (hips) Increase (+) 6 217 0.406 Decrease (-) 3 57 Total offset D * (mm) -3.5 ± 8.0(-15.9〜12.7) 1.1 ± 8.9 (-31.7〜43.4) 0.124 Acetabular offset D * (mm) -6.1 ± 8.0 (-22.3〜3.2) -5.1 ± 6.6 (-30.8〜26) 0.67 Femoral offset D * (mm) 1.6 ± 5.4 (-4.7〜12.6) 5.3 ± 7.0 (-14.1〜29.9) 0.103 a * Values are presented as mean ± standard deviation (range) a Statically significant p -value < 0.05 BMI , body mass index; CA , combined anteversion: D , the value obtained by subtracting the preoperative value from the postoperative value for each offset; THA , total hip arthroplasty Table 3 Dislocation rate of each group of combined anteversion and total offset (dislocated cases/total cases) 3- A Widmer Widmer TO decrease TO increase CA good 3.2% (2/62) 0% (0/96) CA poor 11.5% (6/52) 1.4% (1/73) 3-B Yoshimine Yoshimine TO decrease TO increase CA good 4.8% (4/84) 0% (0/126) CA poor 20% (4/20) 3.6% (1/28) CA, combined anteversion: TO, total offset Table 4 Number of dislocations by femoral head size Dislocation (+) Dislocation (-) p- value Femoral head size ≥ 32 mm 6 220 0.392 < 32mm 3 54 Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-1863433","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":153855136,"identity":"1efb4929-5ef2-46d6-832b-b01489315307","order_by":0,"name":"Kenta Matsuda","email":"","orcid":"","institution":"Teikyo University School of Medicine","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Kenta","middleName":"","lastName":"Matsuda","suffix":""},{"id":153855137,"identity":"3d5cb239-0b2e-40e0-bc6b-ed5173ea0d6c","order_by":1,"name":"Ryo Hidaka","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA50lEQVRIiWNgGAWjYHACA+YfFQyM/QwMbDCRBMJaGM4wMM5sIEkLYxsD44YDCC34Ad/x5G2fC9usZTffSH724EMFgzw/A8OzB/i0SJ55Vjx7xrl042030swNZ5xhMAS6MN0Ar6tu5Bgz8JQdTtx2I8FMmreNIcHgAEOaBGEtbIcTN89I/0a8FmaetsOJGyRyiLQF5BfGGWfSjWeceVMmOeOMhOHMZgJ+AYbYZoYPFday/e3p2yQ+VNjI87P3pD3Ap4XhQAKIZGZgEAAzgE5i5knDqwOhhf8ATIj9GH4to2AUjIJRMNIAAE9PTTTQDrtvAAAAAElFTkSuQmCC","orcid":"","institution":"Teikyo University School of Medicine","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Ryo","middleName":"","lastName":"Hidaka","suffix":""},{"id":153855138,"identity":"5deb653c-00b9-4071-904b-da2aac3ee1e9","order_by":2,"name":"Shigeru Nakamura","email":"","orcid":"","institution":"Nishitokyo Chuo General Hospital","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Shigeru","middleName":"","lastName":"Nakamura","suffix":""},{"id":153855139,"identity":"08d130ce-daea-4972-b05b-08800bfa8060","order_by":3,"name":"Masaki Nakamura","email":"","orcid":"","institution":"Toranomon Hospital","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Masaki","middleName":"","lastName":"Nakamura","suffix":""},{"id":153855140,"identity":"1d920b56-61b1-48ef-8d65-337af5b61278","order_by":4,"name":"Hirotaka Kawano","email":"","orcid":"","institution":"Teikyo University School of Medicine","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Hirotaka","middleName":"","lastName":"Kawano","suffix":""}],"badges":[],"createdAt":"2022-07-16 04:14:11","currentVersionCode":2,"declarations":"","doi":"10.21203/rs.3.rs-1863433/v2","doiUrl":"https://doi.org/10.21203/rs.3.rs-1863433/v2","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":29394734,"identity":"d564bbb6-e421-4471-9eb9-20d7c6f15e55","added_by":"auto","created_at":"2022-11-22 15:52:18","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1143794,"visible":true,"origin":"","legend":"\u003cp\u003eMeasurement of the postoperative acetabular component and femoral component placement angles\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-1863433/v2/fc4b9ab92cd6b5c122537f45.png"},{"id":29394049,"identity":"d50047e8-cfd6-411a-ae87-066beee22819","added_by":"auto","created_at":"2022-11-22 15:44:18","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":872671,"visible":true,"origin":"","legend":"\u003cp\u003eMeasurement method for offsets\u003c/p\u003e\n\u003cp\u003eAcetabular offset: the horizontal distance from the pubic symphysis to the center of the femoral head.\u003c/p\u003e\n\u003cp\u003eFemoral head: the horizontal distance from the center of the femoral head to a line passing through the center of the femoral shaft. The sum of these offsets was defined as the total offset.\u003c/p\u003e","description":"","filename":"Figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-1863433/v2/f4f7f2fca6af2c3548703e2a.png"},{"id":29394050,"identity":"9f61ee17-8ef3-4068-a375-a72d49876a5a","added_by":"auto","created_at":"2022-11-22 15:44:18","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":520092,"visible":true,"origin":"","legend":"\u003cp\u003eReceiver operating characteristic coefficient curve for dislocation\u003c/p\u003e\n\u003cp\u003ea: Widmer (area under the curve: 0.696); b: Yoshimine (area under the curve: 0.676)\u003c/p\u003e","description":"","filename":"Figure3.png","url":"https://assets-eu.researchsquare.com/files/rs-1863433/v2/142245dc794644ae7ebe83dc.png"},{"id":32450865,"identity":"e013d6fb-7bdf-4db6-aed4-eeaec8aa6812","added_by":"auto","created_at":"2023-02-03 18:59:32","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2796681,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-1863433/v2/165b4c37-0414-4c25-92ca-f9c5f7961db9.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Clinical effects of combined anteversion and offset on postoperative dislocation in total hip arthroplasty","fulltext":[{"header":"Background","content":"\u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eComplications after total hip arthroplasty (THA) are known to include infection, loosening, fracture, and dislocation. Of these, dislocation is one of the most serious complications that may require revision; therefore, preventing dislocation is essential [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Various factors are involved in dislocation after THA, including surgical, patient, and implant factors [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Patient factors include age, cerebral dysfunction, and range of motion [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]; implant factors include head diameter and neck design [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]; surgical factors include operative approach, implant and bony impingement, and soft tissue strain [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Several studies have demonstrated that implant impingement because of inadequate implant placement is the main cause of postoperative THA dislocation [\u003cspan additionalcitationids=\"CR7\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eCombined anteversion (CA), the optimal combination of cup inclination, cup anteversion, and stem anteversion to maximize the range of motion and minimize the risk of cup-neck impingement to reduce the risk of dislocation, has been reported to be a useful index for implant positioning [\u003cspan additionalcitationids=\"CR10\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Moreover, the offset is an index for bony impingement and soft tissue tension [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. However, few reports have evaluated THA dislocations based on both CA and offset. Additionally, although differences in offset between the operative and contralateral sides have been reported, the pre- and postoperative offsets on the operative side have not been described. In this study, we aimed to determine if obtaining desired CA and combined offset would lead to a reduction in hip instability in a consecutive series of hip arthroplasties.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eParticipants\u003c/h2\u003e \u003cp\u003eA total of 428 consecutive hips, which underwent primary cementless THA via posterior approach from 2013 to 2020 at our institution, were included. This retrospective case-control study was conducted in compliance with the Helsinki Declaration and was approved by the institutional ethics board (19\u0026ndash;174). The patients provided written informed consent prior to participation. Patients who used non-flatliners (n\u0026thinsp;=\u0026thinsp;65), those who could not undergo postoperative computed tomography (CT) for any reason (n\u0026thinsp;=\u0026thinsp;37), and those who could not be followed for more than 1 year (n\u0026thinsp;=\u0026thinsp;48) were excluded. All hips were followed up for at least 1 year, during which time postoperative dislocations were recorded.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003ePreoperative planning\u003c/h2\u003e \u003cp\u003ePreoperative planning was performed using a three-dimensional (3D) template (ZedHip\u0026trade; Lexi Co., Ltd., Tokyo, Japan) based on preoperative CT. For the pelvic coordinates, the functional pelvic plane was used as the reference plane passing through the bilateral anterior iliac spines and parallel to the CT table [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e], and for the femoral coordinates, the retrocondylar plane was used as the reference plane passing through the posterior point of the greater trochanter and the posterior points of the medial and lateral femoral condyle [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. The target inclination of the acetabular component (cup radiographic inclination) was set to 43\u0026deg; in all cases. Anteversion of the femoral component (stem anteversion) was predicted by placing a stem along the shape of the proximal femur using a preoperative 3D template. The target anteversion of the acetabular component (cup anatomical anteversion) was determined for each case using Yoshimine\u0026rsquo;s CA formula (cup anatomical anteversion\u0026thinsp;+\u0026thinsp;cup radiographic inclination\u0026thinsp;+\u0026thinsp;0.80 \u0026times; stem anteversion\u0026thinsp;=\u0026thinsp;90.8\u0026deg;) [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eSurgical procedure and postoperative evaluation\u003c/h2\u003e \u003cp\u003eAll surgical procedures were performed in the lateral decubitus position, and a CT-based navigation system (Stryker CT-Hip System V1.1, Stryker-Leibinger GmbH \u0026amp; Co. KG, Freiberg, Germany) was used as the acetabular component. The posterior articular capsule and short external rotator muscles were repaired in all cases [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. All surgeries were performed by either of the two senior authors.\u003c/p\u003e \u003cp\u003eA CT scan was performed at 1 week postoperatively as a routine protocol to evaluate implant placement and to confirm the presence of fractures. The postoperative CT data were imported into the template for 3D analysis. The postoperative placement angles of the acetabular and femoral components were measured using the template. Matching with the preoperative template data, a template of the same size as the actual implant was overlapped on the postoperative CT for measurement (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Based on these placement angles, the postoperative CA values were calculated using the formulas of Widmer et al (cup radiographic anteversion\u0026thinsp;+\u0026thinsp;0.7 \u0026times; stem anteversion\u0026thinsp;=\u0026thinsp;37\u0026deg;) and Yoshimine et al [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. The mean CA values of the dislocated and non-dislocated groups were calculated and compared. Cup radiographic inclination within 35\u0026deg;\u0026ndash;55\u0026deg; and CA values within \u0026plusmn;\u0026thinsp;10% of the recommended values (Widmer: 37\u0026deg;\u0026plusmn;4\u0026deg;, Yoshimine: 90.8\u0026deg;\u0026plusmn;9\u0026deg;) were defined as good CA, and those outside the range were defined as poor CA. The dislocation rates in the good and poor groups were compared. The absolute values of the difference between the CA values calculated for each case and the recommended CA values using the formulas of Widmer et al and Yoshimine et al (37\u0026deg; and 90.8\u0026deg;, respectively) were calculated. Moreover, the cutoff values of CA for dislocation were examined. All offset measurements were made by projecting the distance on a horizontal plane using the template based on the preoperative and postoperative CT findings.\u003c/p\u003e \u003cp\u003eThe horizontal distance from the pubic symphysis to the center of the femoral head was measured as the acetabular offset, and the horizontal distance from the center of the femoral head to a line passing through the center of the femoral shaft was measured as the femoral offset [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. The sum of these offsets was defined as the total offset (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe mean values of the total, acetabular, and femoral offsets on the operated side were compared between the dislocated and non-dislocated groups. The difference between the preoperative and postoperative values of each of these three offsets was divided into the postoperative increase and non-increase groups, and their dislocation rates were compared. The number of dislocations in each combination of the total offset increased/non-increased group and the CA good/poor group was investigated. The dislocation rates were also compared in cases with inner heads\u0026thinsp;\u0026lt;\u0026thinsp;32 and \u0026ge;\u0026thinsp;32 mm.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eStatistical assessment\u003c/h2\u003e \u003cp\u003eDemographic variables are described as means, standard deviations, and ranges for continuous data. We used the Mann\u0026ndash;Whitney U test to compare the averages of continuous variables and Fisher\u0026rsquo;s exact test to compare the proportions of categorical variables between the groups. Receiver operator coefficient (ROC) curves were created to calculate the cutoff value of CA for dislocation. The Youden method was used to calculate the optimal threshold scores to obtain the best balance between sensitivity and specificity [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. All statistical analyses were conducted using JMP (version 15.1.0; SAS Institute Inc., Cary, NC), with statistical significance defined as p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eThe mean follow-up period was 5.3\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8 (2.5\u0026ndash;9) years. Patient demographics are presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. A total of 283 hips (256 patients) were included. There were nine dislocated hips (3.2%) and 274 non-dislocated hips. Dislocation was found in nine out of 238 cases treated by the surgeon SN and in zero out of 45 cases treated by KM. There was no difference in the dislocation rates between the cases treated by these surgeons (p\u0026thinsp;=\u0026thinsp;0.363). The mean CA values, as calculated by both Widmer et al\u0026rsquo;s and Yoshimine et al\u0026rsquo;s equations, were significantly different between the dislocation and non-dislocation groups. The good CA group included 158 hips according to the study of Widmer et al and 233 hips according to the study of Yoshimine et al, and dislocation was significantly lower in the good CA group for both Widmer and Yoshimine (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Based on the ROC curve analysis, the cutoff values for dislocation in Widmer\u0026rsquo;s CA and Yoshimine\u0026rsquo;s CA were 37\u0026deg;\u0026plusmn;3.3\u0026deg; and 90.8\u0026deg;\u0026plusmn;10.3\u0026deg;, respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb). The area under the ROC curve for Widmer\u0026rsquo;s CA was 0.696, the sensitivity was 0.889, the specificity was 0.471, and the Youden index was 0.36; for Yoshimine\u0026rsquo;s CA, the area under the ROC curve, sensitivity, specificity, and Youden index were 0.676, 0.556, 0.873, and 0.4, respectively. The mean total, acetabular, and femoral offsets on the operated side were not different between the dislocation and non-dislocation groups. The number of increased offsets was 169 (59.7%), 64 (22.6%), and 223 (78.8%) for total, acetabular, and femoral offsets on the operated side, respectively. Regarding the number of dislocations, the increased and non-increased groups were only significantly different in the total offset. Concerning the mean of the preoperative and postoperative differences in offset, the offsets were not significantly different between the dislocation and non-dislocation groups (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). In the evaluation of dislocation using total offset and CA simultaneously, using both equations, dislocations were observed in cases with poor CA or no increase in offset, but no dislocations were observed in cases with good CA and increased offset (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The used femoral heads had sizes of 28, 32, and 36 mm; femoral heads of 28 mm were used in 57 cases, of which three were dislocated, with no significant difference in dislocation compared to cases of \u0026ge;\u0026thinsp;32 mm (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e "},{"header":"Discussion","content":"\u003cp\u003eThe investigation was performed to determine the effect of CA and offset on dislocation after THA. It was demonstrated that both Widmer\u0026rsquo;s and Yoshimine\u0026rsquo;s CA values showed a significant difference in the mean values between the dislocation and non-dislocation groups, supporting the effectiveness of CA. However, many researchers have reported that some degree of difference between preoperative target values and postoperative measured values of implant placement angle is inevitable in THA [\u003cspan additionalcitationids=\"CR19\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Considering these previous reports, it is difficult to place the cup precisely at the generally recommended combined anteversion value. Moreover, Widmer et al assume that the radiographic inclination of the cup should be in the range of 40\u0026deg;\u0026ndash;45\u0026deg; for CA; however, it is also difficult to place the implant within this range. In this study, only 155 implants were placed within this range. Therefore, based on the aforementioned reports and considering possible CA errors in surgery, we defined good CA as a cup radiographic inclination within the range of 35\u0026ndash;55\u0026deg; and within \u0026plusmn;\u0026thinsp;10% of the recommended CA value. The results of the present study demonstrated that dislocation was significantly lower in the good CA group and the cutoff values of CA for postoperative dislocation were 37\u0026deg;\u0026plusmn;3.3\u0026deg; and 90.8\u0026deg;\u0026plusmn;10.3\u0026deg; for Widmer and Yoshimine, respectively. This range is almost the same as our definition of good CA, and it covers the pre- and postoperative differences in implant placement angles in previous reports. Significantly fewer dislocations occurred when implants were placed within this range, which is useful as an indicator of dislocation prevention. However, as cases of dislocation occurred even when implants were placed within this range, it would be difficult to prevent dislocation after THA using CA alone as an indicator of implant placement.\u003c/p\u003e \u003cp\u003eCA has been reported to be effective only in the prevention of implant impingement, but not in bony impingement [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Previous studies have shown the importance of not only implant impingement but also bony impingement and soft tissue tension in the prevention of dislocation after THA [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Studies on bony impingement have shown that increased acetabular offset provides increased range of motion for flexion and internal rotation by decreasing the effect of impingement of the greater trochanter on the anterior acetabulum [\u003cspan additionalcitationids=\"CR24\" citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Increased femoral offset improves hip abductor strength by lengthening the functional lever arm, reducing impingement, and increasing postoperative joint stability [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e] and hip range of motion [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Thus, dislocation after THA is influenced not only by CA but also by acetabular offset and femoral offset, and all of these indicators should be considered during surgery. In this study, the results revealed no significant difference in the dislocation rate between the groups with and without increased acetabular and femoral offsets but a significant difference in the dislocation rate between the groups with and without increased total offset. In THA of patients with osteoarthritis, medialization by reaming is often necessary to place the acetabular component in an anatomically normal acetabulum [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. The femoral offset should be increased to compensate for the decrease in acetabular offset due to the medialization. Thus, both offsets need to be evaluated [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e], and avoiding a decrease in the total offset is important [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e], which supports our results. In this study, the distance from the pubic symphysis to the femoral shaft was measured as the total offset; therefore, both the femoral and acetabular offsets were used in the evaluation. In both Widmer\u0026rsquo;s and Yoshimine\u0026rsquo;s CA, there were dislocations under the condition of good CA alone but not in cases with good CA and increased total offset. This suggests that dislocation can be further avoided by considering not only CA to prevent implant impingement but also the increase in total offset on the operated side to avoid soft tissue hypotension and bony impingement.\u003c/p\u003e \u003cp\u003eAlthough a previous report showed no difference in the risk of dislocation between the increased and non-increased global offset groups [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e], all previous reports on offset for dislocation after THA have compared the offset between the healthy and the operative sides. Krishnan et al reported that the mean difference between the right and left sides of the normal hip offset was 2.54\u0026thinsp;\u0026plusmn;\u0026thinsp;2.31 mm and that hip offsets are not always symmetrical even in normal hips [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. Additionally, determining the appropriate center of rotation of the hip joint in patients with bilateral morbidity or severe dysplasia is difficult [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. In our study, we found a significant difference in the pre- and postoperative total offset changes on the operative side between the dislocation and non-dislocation groups. This method of evaluating offset has a great advantage in that it is not affected by the condition of the contralateral hip joint. Our findings also suggest that when postoperative offset on the operative side is reduced from the preoperative offset, soft tissue tension is reduced, thus, resulting in bony impingement and increased susceptibility to dislocation. To our knowledge, no other study has compared the pre- and postoperative offsets on the affected side. In this study, regarding the occurrence of pain on the lateral side of the hip, there was no significant difference between patients with \u0026gt;\u0026thinsp;5 mm of postoperative femoral offset on the operated side compared with the healthy side and those with \u0026lt;\u0026thinsp;5 mm. Many studies have reported that pain does not increase with increasing offset, which supports our results [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan additionalcitationids=\"CR36 CR37\" citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe limitations of this study should be noted. First, three types of femoral head sizes were used in this study. Regarding the effect of different head sizes on dislocation, many reports have shown that there was less dislocation in those sized\u0026thinsp;\u0026ge;\u0026thinsp;32 mm compared to those sized 28 mm [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. However, in this study, no difference in dislocation was observed after comparing head sizes of 28 and \u0026ge;\u0026thinsp;32 mm. Similar results were obtained for CA and offset for dislocation only in cases with a head size of \u0026ge;\u0026thinsp;32 mm. Second, we used a non-flatliner to prevent dislocation in patients with inadequate intraoperative stability. These cases were excluded from the study because postoperative CT could not accurately measure the angle of placement of the non-flatliner, which may overestimate the effect of CA on dislocation. Third, the small sample size of nine patients with dislocations prohibited a multi-factor analysis. More dislocation cases should be evaluated to improve the accuracy of the analysis. Fourth, long-term adverse effects in cases of excessively increased femoral offset were not evaluated. Polyethylene wear reportedly increases when femoral offset increases by more than 5 mm compared with the normal hip joint [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]. In this study, there were 22 cases, in which femoral offset increased by \u0026ge;\u0026thinsp;5 mm compared with the healthy side in 112 patients with unilateral disease, and the patients need to be carefully monitored in the future. Fifth, the proportion of female individuals in this study was larger than that of male individuals, showing a substantial sex bias. The reason for this is that most of the indications for total hip arthroplasty in Japan are of osteoarthritis associated with acetabular dysplasia, and the prevalence of this disease is approximately three times higher in women [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]. In the present study, the incidence of dislocation was not significantly different between men and women.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThe dislocation rate was significantly lower when implants were placed within \u0026plusmn;\u0026thinsp;10% of the recommended CA value, suggesting that placement within this range can prevent postoperative dislocation. In addition, an increase in the total offset on the operative side may prevent more dislocations.\u003c/p\u003e"},{"header":"List Of Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eTHA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eTotal hip arthroplasty\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eCombined anteversion\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eROC\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eReceiver operator coefficient\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e3D\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eThree-dimensional\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003e\u003cem\u003eEthics approval and consent to participate\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis retrospective case-control study was conducted in compliance with the Helsinki Declaration and was approved by Teikyo University Medical Research Ethics Committee (19-174). The patients provided written informed consent prior to participation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll individuals have given general consent in the use of their data, including imaging, for analysis and publication.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAvailability of data and materials\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eCompeting interests\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eFunding\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAuthors\u0026rsquo; contributions\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors contributed to the study conception and design. Material preparation\u0026nbsp;and\u0026nbsp;data collection and analysis were performed by KM and RH. The first draft of the manuscript was written by KM\u003cins cite=\"mailto:Author\"\u003e,\u003c/ins\u003e and all authors commented on the previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAcknowledgments\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe would like to thank Editage (www.editage.com) for English language editing.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eBozic KJ, Kurtz SM, Lau E, Ong K, Vail TP, Berry DJ. The epidemiology of revision total hip arthroplasty in the United States. 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J Arthroplasty. 2009;24:646\u0026ndash;51. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.arth.2008.02.008\u003c/span\u003e\u003cspan address=\"10.1016/j.arth.2008.02.008\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKurtz WB, Ecker TM, Reichmann WM, Murphy SB. Factors affecting bony impingement in hip arthroplasty. J Arthroplasty. 2010;25:624\u0026ndash;34. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.arth.2009.03.024\u003c/span\u003e\u003cspan address=\"10.1016/j.arth.2009.03.024\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBourne RB, Rorabeck CH. Soft tissue balancing: the hip. J Arthroplasty. 2002;17:17\u0026ndash;22. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1054/arth.2002.33263\u003c/span\u003e\u003cspan address=\"10.1054/arth.2002.33263\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCharles MN, Bourne RB, Davey JR, Greenwald AS, Morrey BF, Rorabeck CH. Soft-tissue balancing of the hip: the role of femoral offset restoration. Instr Course Lect. 2005;54:131\u0026ndash;41. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2106/00004623-200405000-00030\u003c/span\u003e\u003cspan address=\"10.2106/00004623-200405000-00030\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiebs TR, Nasser L, Herzberg W, R\u0026uuml;ther W, Hassenpflug J. The influence of femoral offset on health-related quality of life after total hip replacement. Bone Joint J. 2014;96:36\u0026ndash;42. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1302/0301-620X.96B1.31530\u003c/span\u003e\u003cspan address=\"10.1302/0301-620X.96B1.31530\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMerle C, Innmann MM, Waldstein W, Pegg EC, Aldinger PR, Gill HS, et al. High variability of acetabular offset in primary hip osteoarthritis influences acetabular reaming-a computed tomography-based anatomic study. J Arthroplasty. 2019;34:1808\u0026ndash;14. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.arth.2019.03.065\u003c/span\u003e\u003cspan address=\"10.1016/j.arth.2019.03.065\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDastane M, Dorr LD, Tarwala R, Wan Z. Hip offset in total hip arthroplasty: quantitative measurement with navigation. Clin Orthop Relat Res. 2011;469:429\u0026ndash;36. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s11999-010-1554-7\u003c/span\u003e\u003cspan address=\"10.1007/s11999-010-1554-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eClement ND, S Patrick-Patel R, MacDonald D, Breusch SJ. Total hip replacement: increasing femoral offset improves functional outcome. Arch Orthop Trauma Surg. 2016;136:1317\u0026ndash;23. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00402-016-2527-4\u003c/span\u003e\u003cspan address=\"10.1007/s00402-016-2527-4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMahmood SS, Mukka SS, Crnalic S, Wretenberg P, Sayed-Noor AS. Association between changes in global femoral offset after total hip arthroplasty and function, quality of life, and abductor muscle strength. A prospective cohort study of 222 patients. Acta Orthop. 2016;87:36\u0026ndash;41. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3109/17453674.2015.1091955\u003c/span\u003e\u003cspan address=\"10.3109/17453674.2015.1091955\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKrishnan SP, Carrington RW, Mohiyaddin S, Garlick N. Common misconceptions of normal hip joint relations on pelvic radiographs. J Arthroplasty. 2006;21:409\u0026ndash;12. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.arth.2005.10.021\u003c/span\u003e\u003cspan address=\"10.1016/j.arth.2005.10.021\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTakamatsu T, Shishido T, Takahashi Y, Masaoka T, Tateiwa T, Kubo K, et al. Radiographic determination of hip rotation center and femoral offset in Japanese adults: a preliminary investigation toward the preoperative implications in total hip arthroplasty. BioMed Res Int. 2015;2015:610763. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1155/2015/610763\u003c/span\u003e\u003cspan address=\"10.1155/2015/610763\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFlecher X, Ollivier M, Argenson JN. Lower limb length and offset in total hip arthroplasty. Orthop Traumatol Surg Res. 2016;102:S9\u0026ndash;20. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.otsr.2015.11.001\u003c/span\u003e\u003cspan address=\"10.1016/j.otsr.2015.11.001\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIorio R, Healy WL, Warren PD, Appleby D. Lateral trochanteric pain following primary total hip arthroplasty. J Arthroplasty. 2006;21:233\u0026ndash;6. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.arth.2005.03.041\u003c/span\u003e\u003cspan address=\"10.1016/j.arth.2005.03.041\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eInnmann MM, Maier MW, Streit MR, Grammatopoulos G, Bruckner T, Gotterbarm T, et al. Additive influence of hip offset and leg length reconstruction on postoperative improvement in clinical outcome after total hip arthroplasty. J Arthroplasty. 2018;33:156\u0026ndash;61. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.arth.2017.08.007\u003c/span\u003e\u003cspan address=\"10.1016/j.arth.2017.08.007\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSayed-Noor AS, Sjoden GO. Greater trochanteric pain after total hip arthroplasty: the incidence, clinical outcome and associated factors. Hip Int. 2006;16:202\u0026ndash;6. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.5301/hip.2008.4186\u003c/span\u003e\u003cspan address=\"10.5301/hip.2008.4186\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJameson SS, Lees D, James P, Serrano-Pedraza I, Partington PF, Muller SD, et al. Lower rates of dislocation with increased femoral head size after primary total hip replacement: a five-year analysis of NHS patients in England. J Bone Joint Surg Br. 2011;93:876\u0026ndash;80. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1302/0301-620X.93B7.26657\u003c/span\u003e\u003cspan address=\"10.1302/0301-620X.93B7.26657\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLittle NJ, Busch CA, Gallagher JA, Rorabeck CH, Bourne RB. Acetabular polyethylene wear and acetabular inclination and femoral offset. Clin Orthop Relat Res. 2009;467:2895\u0026ndash;900. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s11999-009-0845-3\u003c/span\u003e\u003cspan address=\"10.1007/s11999-009-0845-3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJingushi S, Ohfuji S, Sofue M, Hirota Y, Itoman M, Matsumoto T, et al. Multiinstitutional epidemiological study regarding osteoarthritis of the hip in Japan. J Orthop Sci. 2010;15:626\u0026ndash;31. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00776-010-1507-8\u003c/span\u003e\u003cspan address=\"10.1007/s00776-010-1507-8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003cdiv class=\"gridtable\"\u003e\n \u003ctable border=\"1\" id=\"Tab1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003ePatient demographics\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eCharacteristic\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eValue\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eNumber of patients (hips/cases)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e283/256\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eGender (hips/cases)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e68/58\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e215/198\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eAge at THA\u003csup\u003e*\u003c/sup\u003e (years)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e63.3\u0026thinsp;\u0026plusmn;\u0026thinsp;11.1 (33\u0026ndash;85)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eBMI (kg/m\u003csup\u003e2\u003c/sup\u003e) \u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e24.5\u0026thinsp;\u0026plusmn;\u0026thinsp;4.4 (15.8\u0026ndash;39.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eDiagnosis (hips/cases)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOA\u003c/p\u003e\n \u003cp\u003eONFH\u003c/p\u003e\n \u003cp\u003eFNF\u003c/p\u003e\n \u003cp\u003eRA\u003c/p\u003e\n \u003cp\u003eRDC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e216/196\u003c/p\u003e\n \u003cp\u003e51/44\u003c/p\u003e\n \u003cp\u003e8/8\u003c/p\u003e\n \u003cp\u003e3/3\u003c/p\u003e\n \u003cp\u003e5/5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"3\"\u003e\u003csup\u003e*\u003c/sup\u003e Values are presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (range)\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"3\"\u003e\u003cem\u003eBMI\u003c/em\u003e, body mass index; \u003cem\u003eOA\u003c/em\u003e, osteoarthritis; \u003cem\u003eONFH\u003c/em\u003e, osteonecrosis of the femoral head; FNF, femoral neck fracture; \u003cem\u003eRA\u003c/em\u003e, rheumatoid arthritis; \u003cem\u003eRDC\u003c/em\u003e, rapidly destructive coxopathy; \u003cem\u003eTHA\u003c/em\u003e, total hip arthroplasty\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable border=\"1\" id=\"Tab2\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eResults of the univariate analysis of factors for dislocation after total hip arthroplasty\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\" style=\"width: 24.1913%;\"\u003e\n \u003cp\u003eVariable\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.3624%;\"\u003e\n \u003cp\u003eDislocation (+)\u003c/p\u003e\n \u003cp\u003en\u0026thinsp;=\u0026thinsp;9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.4212%;\"\u003e\n \u003cp\u003eDislocation (-)\u003c/p\u003e\n \u003cp\u003en\u0026thinsp;=\u0026thinsp;274\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 6.2391%;\"\u003e\n \u003cp\u003e\u003cem\u003ep-\u003c/em\u003evalue\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\" style=\"width: 24.1913%;\"\u003e\n \u003cp\u003eAge at THA\u003csup\u003e*\u003c/sup\u003e (years)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.3624%;\"\u003e\n \u003cp\u003e61.7\u0026thinsp;\u0026plusmn;\u0026thinsp;14.2 (40\u0026ndash;79)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.4212%;\"\u003e\n \u003cp\u003e63.4\u0026thinsp;\u0026plusmn;\u0026thinsp;11 (33\u0026ndash;85)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 6.2391%;\"\u003e\n \u003cp\u003e\u003cem\u003e0.652\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"2\" style=\"width: 15.6567%;\"\u003e\n \u003cp\u003eSex (hips/cases)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 8.5347%;\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.3624%;\"\u003e\n \u003cp\u003e2/2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.4212%;\"\u003e\n \u003cp\u003e66/56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"2\" style=\"width: 6.2391%;\"\u003e\n \u003cp\u003e\u003cem\u003e1.000\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 8.5347%;\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.3624%;\"\u003e\n \u003cp\u003e7/7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.4212%;\"\u003e\n \u003cp\u003e208/191\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\" style=\"width: 24.1913%;\"\u003e\n \u003cp\u003eBMI (kg/m\u003csup\u003e2\u003c/sup\u003e) \u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.3624%;\"\u003e\n \u003cp\u003e25\u0026thinsp;\u0026plusmn;\u0026thinsp;5.5 (17.2\u0026ndash;36.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.4212%;\"\u003e\n \u003cp\u003e24.5\u0026thinsp;\u0026plusmn;\u0026thinsp;4.4 (15.8\u0026ndash;39.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 6.2391%;\"\u003e\n \u003cp\u003e\u003cem\u003e0.722\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"2\" style=\"width: 15.6567%;\"\u003e\n \u003cp\u003eMean CA\u003csup\u003e*\u003c/sup\u003e (degree)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 8.5347%;\"\u003e\n \u003cp\u003eWidmer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.3624%;\"\u003e\n \u003cp\u003e30.4\u0026thinsp;\u0026plusmn;\u0026thinsp;8.5 (15.1\u0026ndash;41.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.4212%;\"\u003e\n \u003cp\u003e37.1\u0026thinsp;\u0026plusmn;\u0026thinsp;5.9 (19.8\u0026ndash;62.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 6.2391%;\"\u003e\n \u003cp\u003e\u003cem\u003e0.001\u003c/em\u003e\u003csup\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 8.5347%;\"\u003e\n \u003cp\u003eYoshimine\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.3624%;\"\u003e\n \u003cp\u003e81.3\u0026thinsp;\u0026plusmn;\u0026thinsp;12 (60\u0026ndash;95)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.4212%;\"\u003e\n \u003cp\u003e90.6\u0026thinsp;\u0026plusmn;\u0026thinsp;7.4 (66.7\u0026ndash;118.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 6.2391%;\"\u003e\n \u003cp\u003e\u003cem\u003e\u0026lt;\u0026thinsp;0.001\u003c/em\u003e\u003csup\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"2\" style=\"width: 15.6567%;\"\u003e\n \u003cp\u003eWidmer CA (hips)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 8.5347%;\"\u003e\n \u003cp\u003eGood\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.3624%;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.4212%;\"\u003e\n \u003cp\u003e156\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"2\" style=\"width: 6.2391%;\"\u003e\n \u003cp\u003e\u003cem\u003e0.0469\u003c/em\u003e\u003csup\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 8.5347%;\"\u003e\n \u003cp\u003ePoor\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.3624%;\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.4212%;\"\u003e\n \u003cp\u003e118\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"2\" style=\"width: 15.6567%;\"\u003e\n \u003cp\u003eYoshimine CA (hips)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 8.5347%;\"\u003e\n \u003cp\u003eGood\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.3624%;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.4212%;\"\u003e\n \u003cp\u003e229\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"2\" style=\"width: 6.2391%;\"\u003e\n \u003cp\u003e\u003cem\u003e0.01\u003c/em\u003e\u003csup\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 8.5347%;\"\u003e\n \u003cp\u003ePoor\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.3624%;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.4212%;\"\u003e\n \u003cp\u003e45\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"2\" style=\"width: 15.6567%;\"\u003e\n \u003cp\u003eTotal offset (hips)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 8.5347%;\"\u003e\n \u003cp\u003eIncrease (+)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.3624%;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.4212%;\"\u003e\n \u003cp\u003e168\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"2\" style=\"width: 6.2391%;\"\u003e\n \u003cp\u003e\u003cem\u003e0.004\u003c/em\u003e\u003csup\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 8.5347%;\"\u003e\n \u003cp\u003eDecrease (-)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.3624%;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.4212%;\"\u003e\n \u003cp\u003e106\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"2\" style=\"width: 15.6567%;\"\u003e\n \u003cp\u003eAcetabular offset (hips)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 8.5347%;\"\u003e\n \u003cp\u003eIncrease (+)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.3624%;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.4212%;\"\u003e\n \u003cp\u003e62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"2\" style=\"width: 6.2391%;\"\u003e\n \u003cp\u003e\u003cem\u003e1.000\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 8.5347%;\"\u003e\n \u003cp\u003eDecrease (-)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.3624%;\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.4212%;\"\u003e\n \u003cp\u003e212\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"2\" style=\"width: 15.6567%;\"\u003e\n \u003cp\u003eFemoral offset (hips)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 8.5347%;\"\u003e\n \u003cp\u003eIncrease (+)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.3624%;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.4212%;\"\u003e\n \u003cp\u003e217\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"2\" style=\"width: 6.2391%;\"\u003e\n \u003cp\u003e\u003cem\u003e0.406\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 8.5347%;\"\u003e\n \u003cp\u003eDecrease (-)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.3624%;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.4212%;\"\u003e\n \u003cp\u003e57\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\" style=\"width: 24.1913%;\"\u003e\n \u003cp\u003eTotal offset D \u003csup\u003e*\u003c/sup\u003e (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.3624%;\"\u003e\n \u003cp\u003e-3.5\u0026thinsp;\u0026plusmn;\u0026thinsp;8.0(-15.9〜12.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.4212%;\"\u003e\n \u003cp\u003e1.1\u0026thinsp;\u0026plusmn;\u0026thinsp;8.9 (-31.7〜43.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 6.2391%;\"\u003e\n \u003cp\u003e\u003cem\u003e0.124\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\" style=\"width: 24.1913%;\"\u003e\n \u003cp\u003eAcetabular offset D \u003csup\u003e*\u003c/sup\u003e (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.3624%;\"\u003e\n \u003cp\u003e-6.1\u0026thinsp;\u0026plusmn;\u0026thinsp;8.0 (-22.3〜3.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.4212%;\"\u003e\n \u003cp\u003e-5.1\u0026thinsp;\u0026plusmn;\u0026thinsp;6.6 (-30.8〜26)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 6.2391%;\"\u003e\n \u003cp\u003e\u003cem\u003e0.67\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\" style=\"width: 24.1913%;\"\u003e\n \u003cp\u003eFemoral offset D \u003csup\u003e*\u003c/sup\u003e (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.3624%;\"\u003e\n \u003cp\u003e1.6\u0026thinsp;\u0026plusmn;\u0026thinsp;5.4 (-4.7〜12.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.4212%;\"\u003e\n \u003cp\u003e5.3\u0026thinsp;\u0026plusmn;\u0026thinsp;7.0 (-14.1〜29.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 6.2391%;\"\u003e\n \u003cp\u003e\u003cem\u003e0.103\u003c/em\u003e\u003csup\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"5\" style=\"width: 62.0381%;\"\u003e\u003csup\u003e*\u003c/sup\u003e Values are presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (range)\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"5\" style=\"width: 62.0381%;\"\u003e\u003csup\u003ea\u003c/sup\u003e Statically significant \u003cem\u003ep\u003c/em\u003e-value\u0026thinsp;\u0026lt;\u0026thinsp;0.05\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"5\" style=\"width: 62.0381%;\"\u003e\u003cem\u003eBMI\u003c/em\u003e, body mass index; \u003cem\u003eCA\u003c/em\u003e, combined anteversion: \u003cem\u003eD\u003c/em\u003e, the value obtained by subtracting the preoperative value from the postoperative value for each offset; \u003cem\u003eTHA\u003c/em\u003e, total hip arthroplasty\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cdiv class=\"gridtable\"\u003e\u003cbr\u003e\u003c/div\u003e\n\u003cp\u003e\u003cspan lang=\"\"\u003eTable 3 Dislocation rate of each group of combined anteversion and total offset (dislocated cases/total cases)\u003c/span\u003e\u003c/p\u003e\n\u003cp\u003e3-\u003cspan lang=\"\"\u003eA Widmer\u003c/span\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellpadding=\"0\" cellspacing=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"39.21568627450981%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cspan lang=\"\"\u003eWidmer\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"31.65266106442577%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cspan lang=\"\"\u003eTO decrease\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"29.131652661064425%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cspan lang=\"\"\u003eTO increase\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"39.21568627450981%\"\u003e\n \u003cp\u003e\u003cspan lang=\"\"\u003eCA good\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"31.65266106442577%\"\u003e\n \u003cp\u003e\u003cspan lang=\"\"\u003e3.2% (2/62)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"29.131652661064425%\"\u003e\n \u003cp\u003e\u003cspan lang=\"\"\u003e0% (0/96)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"39.21568627450981%\"\u003e\n \u003cp\u003e\u003cspan lang=\"\"\u003eCA poor\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"31.65266106442577%\"\u003e\n \u003cp\u003e\u003cspan lang=\"\"\u003e11.5% (6/52)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"29.131652661064425%\"\u003e\n \u003cp\u003e\u003cspan lang=\"\"\u003e1.4% (1/73)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cspan lang=\"\"\u003e3-B Yoshimine\u003c/span\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellpadding=\"0\" cellspacing=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"39.21568627450981%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cspan lang=\"\"\u003eYoshimine\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"31.65266106442577%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cspan lang=\"\"\u003eTO decrease\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"29.131652661064425%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cspan lang=\"\"\u003eTO increase\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"39.21568627450981%\"\u003e\n \u003cp\u003e\u003cspan lang=\"\"\u003eCA good\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"31.65266106442577%\"\u003e\n \u003cp\u003e\u003cspan lang=\"\"\u003e4.8% (4/84)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"29.131652661064425%\"\u003e\n \u003cp\u003e\u003cspan lang=\"\"\u003e0% (0/126)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"39.21568627450981%\"\u003e\n \u003cp\u003e\u003cspan lang=\"\"\u003eCA poor\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"31.65266106442577%\"\u003e\n \u003cp\u003e\u003cspan lang=\"\"\u003e20% (4/20)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"29.131652661064425%\"\u003e\n \u003cp\u003e\u003cspan lang=\"\"\u003e3.6% (1/28)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cem\u003e\u003cspan lang=\"\"\u003eCA,\u0026nbsp;\u003c/span\u003e\u003c/em\u003e\u003cspan lang=\"\"\u003ecombined anteversion: \u003cem\u003eTO,\u0026nbsp;\u003c/em\u003etotal offset\u003c/span\u003e\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003ctable border=\"1\" id=\"Tab4\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eNumber of dislocations by femoral head size\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eDislocation (+)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eDislocation (-)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ep-\u003c/em\u003evalue\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eFemoral head size\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026ge;\u0026thinsp;32 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e220\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cem\u003e0.392\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;32mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e54\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Total hip arthroplasty, Dislocation, Combined anteversion, Offset ","lastPublishedDoi":"10.21203/rs.3.rs-1863433/v2","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-1863433/v2","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eImplant impingement and soft tissue tension are factors involved in dislocation after total hip arthroplasty (THA). Combined anteversion (CA) has been used as an indicator for implant placement; however, placing implants optimally remains challenging. Moreover, the effect of changes in offset on dislocation remains unclear. We aimed to clarify the effects of postoperative CA and pre- and postoperative changes in offset on dislocation.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eWe included patients who underwent primary cementless THA performed between 2013 and 2020. The mean values of CA and offset in the dislocation and non-dislocation groups were compared. The CA values within \u0026plusmn;\u0026thinsp;10% of the recommended values were defined as good CA, and those outside the range were defined as poor CA. The dislocation rates in the good and poor CA groups and in the groups with and without increased offset were compared.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eA total of 283 hips were included. The mean values of CA in the dislocation and non-dislocation groups were significantly different (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). The dislocation rate was significantly lower in the good CA group (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). The dislocation rates in the groups with and without increased total offset were 0.5% and 4.3%, respectively (p\u0026thinsp;=\u0026thinsp;0.004). There were no dislocations in patients with good CA and increased offset.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eThe dislocation rate was significantly lower when implants were placed within \u0026plusmn;\u0026thinsp;10% of the recommended CA value. Our results suggest that dislocation can be avoided by placing the implant in the good CA range and considering the increase in total offset on the operative side.\u003c/p\u003e","manuscriptTitle":"Clinical effects of combined anteversion and offset on postoperative dislocation in total hip arthroplasty","msid":"","msnumber":"","nonDraftVersions":[{"code":2,"date":"2022-11-22 15:44:13","doi":"10.21203/rs.3.rs-1863433/v2","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}},{"code":1,"date":"2022-07-26 17:53:13","doi":"10.21203/rs.3.rs-1863433/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"d798e87c-3ae5-4ce1-a659-793ea4565fae","owner":[],"postedDate":"November 22nd, 2022","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2023-02-03T18:59:19+00:00","versionOfRecord":[],"versionCreatedAt":"2022-11-22 15:44:13","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v2","identity":"rs-1863433","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-1863433","identity":"rs-1863433","version":["v2"]},"buildId":"7rjqhiLT3MXkJMwkYKINL","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}