Impact of Stem Collar-Calcar Gap Distance on Postoperative Bone Remodeling in Fully Hydroxyapatite-coated Stem

Impact of Stem Collar-Calcar Gap Distance on Postoperative Bone Remodeling in Fully Hydroxyapatite-coated Stem | 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 Article Impact of Stem Collar-Calcar Gap Distance on Postoperative Bone Remodeling in Fully Hydroxyapatite-coated Stem Yoshihisa Ohashi, Kensuke Fukushima, Yuto Osaki, Maho Tsuchiya, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4883665/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 24 May, 2025 Read the published version in Scientific Reports → Version 1 posted 13 You are reading this latest preprint version Abstract The collar of a cementless stem in total hip arthroplasty (THA) improves fixation and stability by connecting with the femoral calcar. Proper attachment is essential for reducing micromotion and preventing periprosthetic fractures of the femur. However, gaps between the femoral calcar and stem collar can occur during surgery, and it is unclear what degree of gap can be tolerated. This study evaluated 156 patients who received primary THA with the CORAIL stem. Medial and lateral gap distance were measured by frontal X-ray of the hip joint at 1 week and 1, 3, 6, 12, 24, and 36 months after THA. Clinical outcomes were assessed using Japanese Orthopaedic Association hip scores, and radiographic assessments included femoral morphology and stem alignment. Gaps were initially observed in 55 patients, with 42 showing complete gap disappearance within 36 months. On logistic regression analysis, lateral gap distance was shown to significantly influence gap disappearance, with an optimal cut-off of 5.5 mm by receiver operating characteristic curve analysis. A smaller lateral gap was correlated with quicker closure. When the gap between the collar and femoral calcar is within 5.5 mm, gap disappearance can be expected due to postoperative bone remodeling. Physical sciences/Materials science Physical sciences/Materials science/Techniques and instrumentation Health sciences/Diseases/Rheumatic diseases Health sciences/Diseases/Rheumatic diseases/Osteoarthritis Total hip arthroplasty Stem collar Fully hydroxyapatite-coated stem Bone remodeling Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction The cementless stem collar design provides better outcomes in total hip arthroplasty (THA). Attaching the stem collar directly to the cut calcar neck offers improved fixation, protection against subsidence, positive dispersion of vertical force into the calcar and resistance to stem rotation in relation to the femoral canal [ 1 – 4 ]. Both basic and clinical research indicate that the implementation of collared stems is associated with decreased risk of periprosthetic fracture of the femur [ 4 – 6 ]. In practical surgical scenarios, however, inability to properly attach the stem collar to the cut calcar neck occasionally occurs. A recent study using finite element analysis indicated that micromotion in the contact model between the stem collar and cut calcar neck was notably reduced compared to non-contact models under both flat-surface walking and stair climbing conditions [ 7 ]. In such cases, the stem collar may not fulfill its essential role. Thus, precise placement of the stem collar is important to optimizing outcomes in THA. A number of types of fully hydroxyapatite (HA)-coated stem with collar is available [ 8 – 10 ]. Several studies have reported the occurrence of bone remodeling in the calcar region when the stem collar is not in contact in the region of the femoral calcar [ 8 , 10 ]. This suggest that even if a gap occurs intraoperatively, post-operative bone remodeling can eliminate it and allow the collar to fulfil its role. However, the maximally acceptable gap distance between the collar of a fully HA-coated stem and the femoral calcar is unclear. Accordingly, an understanding of the distance of bone remodeling after THA will provide valuable intraoperative guidance for surgeons. In this study, we investigated the relationship between the gap distance occurring between the calcar and collar during fully HA-coated stem insertion and subsequent bone remodeling after primary THA. Materials and Methods Participants We enrolled 156 consecutive patients (156 hips) who underwent primary THA with a G7® cup (Zimmer Biomet, Warsaw, IN) and CORAIL® stem (DePuy Synthes, Warsaw, IN, USA) at a single center. All operations were performed using a minimally invasive antero-lateral supine approach. The CORAIL stem is a forged titanium stem with a double-tapered geometry that is plasma-coated with 155 µm of HA. HA is also coated on the back of the stem collar. Collar length increases with stem size, namely 6 mm with sizes 8 to 11, 7 mm with sizes 12 to 15, and 9 mm with sizes 16 and above. Collar thickness is 3.5 mm for all sizes. Patients in this study all received stems sizes 8 to 12. For inclusion, all patients were required to available for follow-up for 36 months after surgery, and to be ambulatory with advanced or end-stage hip osteoarthritis (HOA) or idiopathic osteonecrosis of the femoral head (ION). We excluded patients with no evidence of a gap on frontal X-ray of the hip joint one week after surgery. We also excluded patients with a history of hip surgery ipsilateral to the THA, intraoperative periprosthetic femoral fracture, subsidence of the stem by more than 2 mm, or reoperation due to aseptic loosening. Ethical approval for this retrospective observational study was obtained from our Institutional Review Board. The study was conducted in accordance with the Declaration of Helsinki, and all patients gave informed consent to participation. Clinical assessment Clinical outcomes were evaluated in accordance with the Japanese Orthopaedic Association (JOA) hip scores at 1 month before and 36 months after surgery. This scoring system consists of four elements, namely pain (0–40 points), range of motion (0–20 points), gait ability (0–20 points), and performance in activities of daily living (0–20 points), and is widely used to investigate hip joint conditions in Japan [ 11 ]. A higher score indicates a better condition of the post-operative hip joint. Radiographic assessment We assessed the gap between the femoral calcar and collar of the stem using postoperative frontal X-ray of the hip joint. X-rays were assessed at 1 week and 1, 3, 6, 12, 24, and 36 months after THA. To assess gap distance between the femoral calcar and collar, medial and lateral gap distances were investigated with a 1-mm pitch at all time points (Fig. 1 ). Measurement of gap distance relied on an X-ray taken one week post-surgery, which served as the initial reference point. We then assessed bone remodeling-induced disappearance of the gap over 36 months post-surgery, and determined the time until complete disappearance. Cases in which the gap disappeared within 36 months were classified as the contact group, and those in which the gap did not disappear as the non-contact group. A flowchart of the study is presented in Fig. 2 . We also evaluated the proximal femoral morphology using the Dorr classification [ 12 ] by measuring the calcaneal width at the mid-level of the lesser trochanter and the canal width at 10 cm below the lesser trochanter, and then calculating the calcaneal-to-canal ratio to determine bone type. As described elsewhere, femurs with a ratio of 0–0.5 were classified as Type A, 0.51–0.75 as Type B, and 0.76–1 as Type C, [ 13 , 14 ]. Stem alignment angle was investigated using the postoperative radiographs one week after THA and evaluated to assess stem insertion in varus and valgus, as differentiated by deviation of stem axis from the femoral axis, in which valgus alignment was defined as positive. We investigated whether the medial and lateral gap distances between the femoral calcar and stem collar influenced gap disappearance within 36 months post-surgery. We also calculated the cut-off values for medial and lateral gap distances at which gap disappearance due to bone remodeling could be expected, and the relationship between medial and lateral gap distances and time to gap disappearance. Statistical analyses The results are reported as mean ± standard error unless noted otherwise. To compare patient characteristics between the Contact and Non-contact groups, we used Pearson's chi-square test for categorical variables, parametric t-tests for continuous variables with a normal distribution, and the Mann-Whitney U-test for variables not following a normal distribution. Logistic regression analysis was conducted to investigate the impact of medial and lateral gap distances on disappearance within 36 months post-surgery. Independent variables included age, gender, BMI, Dorr type, stem alignment angle, and medial and lateral gap distance, while the dependent variable was disappearance of the gap within 36 months. We applied receiver operating characteristic (ROC) curve analysis to determine cut-off values for the medial and lateral gaps, aiming to predict gap disappearance within the specified post-surgery timeframe. Additionally, we used Spearman's rank correlation coefficient to assess correlations between gap distance and time to gap disappearance. Two observers independently analysed all radiographic images and resolved any disagreements through consensus. All statistical analyses were conducted with SPSS software (v.26.0; IBM, NY, USA), with statistical significance set at p < 0.05. Results Classification of Contact and Non-contact Groups In this study, gaps between the femoral calcar and collar of the stem were observed in the baseline X-rays of 55 cases. Among these, gaps disappeared within 36 months post-surgery in 42 cases (76.4%). Consequently, 42 cases were classified into the Contact group and 13 cases into the Non-contact group. The two groups did not significantly differ with regard to patient characteristics, including age, gender, BMI, clinical diagnosis, or Dorr type. Additionally, they did not differ with regard to clinical data, including stem alignment angle, and pre- and postoperative JOA hip scores. Details of patient characteristic and clinical data comparisons are shown in Table 1 . Table 1 Comparison of patient characteristics and clinical data Contact group Non-contact group p value Total patients, N 42 13 Sex, male/female, N 13/ 29 3/ 10 0.585 Age, years 60.62 ± 1.44 57.31 ± 3.70 0.319 Height, cm 158.11 ± 1.30 156.37 ± 2.30 0.357 Weight, kg 61.96 ± 1.64 64.41 ± 5.98 0.586 Body mass index, kg/m 2 24.75 ± 0.55 26.03 ± 1.97 0.714 Diagnoses, N HOA/ION 36/ 6 10/ 3 0.677 Dorr classification, N A/B/C 6/ 36/ 0 2/ 11/ 0 0.922 Stem alignment, ° -0.75 ± 0.26 0.12 ± 0.44 0.106 JOA hip scores One month before surgery Pain 14.64 ± 1.41 16.54 ± 2.85 0.754 Range of motion 13.76 ± 0.52 15.85 ± 0.81 0.051 Gait 15.29 ± 0.43 16.39 ± 0.83 0.076 Actives of daily living 13.29 ± 0.49 15.23 ± 0.92 0.093 36 months after surgery Pain 39.29 ± 0.27 39.62 ± 0.39 0.548 Range of motion 17.52 ± 0.23 17.62 ± 0.42 0.941 Gait 19.52 ± 0.25 19.85 ± 0.15 0.537 Actives of daily living 19.48 ± 0.31 19.85 ± 0.15 0.812 Abbreviations: HOA, hip osteoarthritis; ION, idiopathic osteonecrosis of the femoral head; JOA, the Japanese Orthopaedic Association Factors Influencing Gap Disappearance The only factor influencing disappearance of the gap within 36 months post-surgery was lateral gap distance (p = 0.02, Odds ratio = 2.79). There were no significant differences in other independent variables, including age, gender, BMI, Dorr type, stem alignment angle, or medial gap distance (Table 2 ). Table 2 Logistic regression analysis of the impact of medial and lateral gap distance between the femoral calcar and stem collar on disappearance within 36 months post-surgery Predictor Estimate SE p value Odds ratio 95% Confidence interval Lateral gap 1.02 0.44 0.020* 2.79 1.18–6.60 Medial gap -0.29 0.43 0.492 0.74 0.32–1.73 BMI -0.01 0.09 0.943 0.99 0.83–1.18 Sex -0.43 1.03 0.675 0.65 0.09–4.85 Age 0.02 0.05 0.741 1.02 0.92–1.13 Diagnosis (HOA or ION) 1.17 1.42 0.410 3.22 0.20–52.0 Dorr type (A or B) -0.28 1.08 0.796 0.76 0.09–6.31 Stem alignment 0.53 0.30 0.079 1.70 0.94–3.06 Abbreviations: SE, standard error; BMI, body mass index; Cl, confidence interval; *, p<0.05; HOA, hip osteoarthritis; ION, idiopathic osteonecrosis of the femoral head ROC Curve Analyses for Gap Disappearance Prediction ROC curve analyses were conducted to determine cut-off values for the medial and lateral gap distances in predicting gap disappearance within 36 months post-surgery (Fig. 3 ). AUC for the lateral gap distance was found to be 0.90, indicating good predictive accuracy. Optimal cut-off value for lateral gap distance was 5.5 mm, with a sensitivity of 0.85 and specificity of 0.86. For medial gap distance, the AUC was 0.74, suggesting moderate predictive accuracy, and the optimal cut-off value was 2.5 mm, with a sensitivity of 0.69 and specificity of 0.71. Correlation between Gap Distance and Time until Gap Disappearance We analyzed correlations between medial and lateral gap distances and time until gap disappearance in patients with the Contact group (Fig. 4 ). The results indicated a statistically significant correlation with the lateral gap distance (ρ = 0.315, p = 0.042), suggesting that a shorter duration until gap disappearance was associated with a smaller lateral gap distance between the femoral calcar and stem collar. In contrast, there was no significant correlation between medial gap distance and time until gap disappearance. Discussion In this retrospective observational study, we evaluated patients who received primary THA with the CORAIL stem, focusing on the impact of gap distance between the femoral calcar and collar on gap disappearance within 36 months after surgery. Radiographic assessments at multiple post-surgery intervals revealed gaps in 55 cases, of which 42 gaps disappeared and 13 did not. Lateral gap distance was the primary factor influencing gap disappearance, with an optimal cut-off value of 5.5 mm showing high predictive accuracy, whereas medial gap distance with a cut-off value of 2.5 mm showed moderate accuracy. A significant correlation was found between a smaller lateral gap and quicker gap disappearance, underscoring the importance of precise stem collar placement for successful bone remodeling and gap closure. We found no difference in JOA hip score at 36 months after surgery between the two groups. Further, no participant experienced periprosthetic femoral fracture or aseptic loosening of the stem after surgery. Recent evidence also indicated that the presence or absence of contact between the collar of a fully hydroxyapatite-coated stem and the femoral neck did not affect clinical outcomes during the first postoperative year [ 15 ]. However, several previous studies have indicated that use of a collared stem decreases risk of periprosthetic femur fractures [ 5 , 6 , 16 ]. In their recent multivariate logistic analysis with adjustment for age, sex, and BMI, Rodriguez et al. reported that non-collared cementless stems were associated with an approximately threefold increased risk of periprosthetic femoral fracture compared to fully HA coated and collared cementless stems in patients aged over 65 years who underwent primary THA [ 6 ]. Considering that the absence of contact between the collar and femoral calcar is equivalent to the use of a collarless stem, these findings emphasize the importance of precise placement of the stem collar in optimizing outcomes in THA. Although several studies have suggested the occurrence of bone remodeling between femoral calcar and stem collar, details have remained unclear. Vidalain reported the occurrence of bone remodeling in the calcar region with the CORAIL stem, and that on multivariate analysis femoral remodeling was not influenced to any significant extent by either patient- or prosthesis-related factors [ 8 ]. Our results are consistent with the findings of these studies. We revealed that disappearance of the gap due to bone remodeling was not influenced by age, gender, BMI, Dorr type, or stem alignment angle; rather, lateral gap distance was the only significant factor. These results indicate that the HA applied to the back of the stem collar may induce osteoinduction in the calcar region of the stem. Previous studies on bone remodeling in the stem collar and calcar gap did not considered gap distance [ 8 , 10 , 17 ]. In the present study, we found that the optimal cut-off value for lateral gap distance between the calcar and stem collar for gap disappearance was 5.5 mm (2.5mm for medial gap distance). Additionally, we identified a positive correlation between lateral gap distance and time to gap disappearance. These results suggest that achieving contact between the calcar and collar during the postoperative course requires a lateral gap distance during stem placement within 5.5 mm, and that the smaller the lateral gap distance, the earlier the calcar and collar will be in contact. Two basic studies have investigated risks associated with the femoral calcar-collar gap [ 7 , 18 ]. Watanabe et al. indicated that micromotion in the collar contact model was notably reduced compared to the non-contact model under both flat walking and stair climbing conditions [ 7 ]. In their study of the use of a composite femur in the CORAIL stem, Lamb et al. suggested that fracture torque and torsional stiffness were greater in the calcar-collar contact group than in the non-contact group [ 18 ]. They also reported that odds ratio for not achieving collar contact increased 3.8-fold for each mm of separation in the regression model [ 18 ]. Many fully HA-coated stems now have the collared option [ 19 ]. The angle and size of the stem collar varies from model to model. Surgeons therefore need to be more attentive to the angle and length in femoral neck osteotomy and in the placement of collared stems. There are a number of potential limitations to this study. First, only one stem product was used, and other stem models may give different results. Second, due to the relatively small sample size and limited number of follow-up time points, no differences between the two groups were observed in clinical outcome. Despite these limitations, we hope our results will serve as an important intraoperative indicator for surgeons using this stem. Conclusion This retrospective observational study evaluated the impact of gap distance between the femoral calcar and stem collar on gap disappearance within 36 months post-surgery in patients undergoing primary THA with the CORAIL stem. Our findings indicate that lateral gap distance is a significant factor influencing gap disappearance, with an optimal cut-off value of 5.5 mm. A smaller lateral gap is associated with more rapid gap closure, emphasizing the importance of precise stem collar placement to successful bone remodeling. Our results provide valuable intraoperative guidance for surgeons. When the gap between the collar and femoral calcar is within 5.5 mm, gap disappearance due to postoperative bone remodeling can be expected. Declarations Acknowledgements We would like to thank Dmed for English language editing. Author contributions All authors contributed to the literature search, critical review, data analysis, and manuscript preparation. All authors read and approved the final manuscript. Data availability The datasets supporting the conclusions of this article are included within the article. The raw data can be requested from the corresponding author, YO. Competing Interests The authors have no relevant financial or non-financial interests to disclose. Funding The authors declare that no funds, grants, or other support were received during the preparation of this manuscript. Ethics Approval Approval was granted by the Institutional Review Board of Kitasato University Hospital (Number: B22-089). References Demey, G., Fary, C., Lustig, S., Neyret, P. & si Selmi, T. Does a collar improve the immediate stability of uncemented femoral hip stems in total hip arthroplasty? A bilateral comparative cadaver study. J Arthroplasty 26, 1549–1555, doi: 10.1016/j.arth.2011.03.030 (2011). Panichkul, P., Bavonratanavech, S., Arirachakaran, A. & Kongtharvonskul, J. Comparative outcomes between collared versus collarless and short versus long stem of direct anterior approach total hip arthroplasty: a systematic review and indirect meta-analysis. Eur J Orthop Surg Traumatol 29, 1693–1704, doi: 10.1007/s00590-019-02516-1 (2019). Cidambi, K. R. et al. Impact of Femoral Stem Design on Failure After Anterior Approach Total Hip Arthroplasty. J Arthroplasty 33, 800–804, doi: 10.1016/j.arth.2017.10.023 (2018). Johnson, A. J. et al. A Calcar Collar Is Protective Against Early Torsional/Spiral Periprosthetic Femoral Fracture: A Paired Cadaveric Biomechanical Analysis. J Bone Joint Surg Am 102, 1427–1433, doi: 10.2106/JBJS.19.01125 (2020). Lamb, J. N. et al. A calcar collar is protective against early periprosthetic femoral fracture around cementless femoral components in primary total hip arthroplasty: a registry study with biomechanical validation. Bone Joint J 101-B, 779–786, doi: 10.1302/0301-620X.101B7.BJJ-2018-1422.R1 (2019). Rodriguez, S. et al. How Much Protection Does a Collar Provide? Assessing Risk of Early Periprosthetic Femur Fractures Following Total Hip Arthroplasty in Elderly Patients. J Arthroplasty 39, 997–1000.e1, doi: 10.1016/j.arth.2023.10.020 (2024). Watanabe, R., Mishima, H., Totsuka, S., Nishino, T. & Yamazaki, M. Primary Stability of Collared and Collarless Cementless Femoral Stems - A Finite Element Analysis Study. Arthroplast Today 21, 101140, doi: 10.1016/j.artd.2023.101140 (2023). Vidalain, J. P. Twenty-year results of the cementless Corail stem. Int Orthop 35, 189–194, doi: 10.1007/s00264-010-1117-2 (2011). Ohashi, Y. et al. Influence of broach surface design of a fully hydroxyapatite coated, double tapered stem on periprosthetic bone mineral density after total hip arthroplasty: a study based on the morphology of the proximal femur. Arch Orthop Trauma Surg, doi: 10.1007/s00402-024-05430-2 (2024). Hayashi, S. et al. Hydroxyapatite-coated compaction short stem represents a characteristic pattern of peri-prosthetic bone remodelling after total hip arthroplasty. Arch Orthop Trauma Surg 142, 2903–2910. doi: 10.1007/s00402-021-04140-3 (2022). Kuribayashi, M. et al. Reliability and validity of the Japanese Orthopaedic Association hip score. J Orthop Sci 15, 452–458. doi: 10.1007/s00776-010-1490-0 (2010). Dorr, L.D. et al. Structural and cellular assessment of bone quality of proximal femur. Bone. 14, 231–242. doi: 10.1016/8756-3282(93)90146-2 (1993). Issa, K., Stroh, A. D., Mont, M. A. & Bonutti, P.M.. Effect of bone type on clinical and radiographic outcomes of a proximally-coated cementless stem in primary total hip arthroplasties. J Orthop Res 32, 1214–1220. doi: 10.1002/jor.22648 . (2014). Park, C.W. et al. Femoral Stem Survivorship in Dorr Type A Femurs After Total Hip Arthroplasty Using a Cementless Tapered Wedge Stem: A Matched Comparative Study With Type B Femurs. J Arthroplasty 34, 527–533. doi: 10.1016/j.arth.2018.11.004 (2019). Iwakiri, K. et al. No Impact of Contact Between the Medial Collar of a Hydroxyapatite-Coated Triple-Tapered Stem and the Femoral Neck on Periprosthetic Bone Mineral Density. J Arthroplasty 39, 2082–2087. doi: 10.1016/j.arth.2024.02.011 (2024). Konow, T., Baetz, J., Melsheimer, O., Grimberg, A. & Morlock, M. Factors influencing periprosthetic femoral fracture risk. Bone Joint J 103-B, 650–658. doi: 10.1302/0301-620X.103B4.BJJ-2020-1046.R2 (2021). Jacquot, L. et al. Clinical and Radiographic Outcomes at 25–30 Years of a Hip Stem Fully Coated With Hydroxylapatite. J Arthroplasty 33, 482–490. doi: 10.1016/j.arth.2017.09.040 (2018). Lamb, J. N., Coltart, O., Adekanmbi, I., Pandit, H. G. & Stewart, T. Calcar-collar contact during simulated periprosthetic femoral fractures increases resistance to fracture and depends on the initial separation on implantation: A composite femur in vitro study. Clin Biomech (Bristol, Avon). 87, 105411. doi: 10.1016/j.clinbiomech.2021.105411 (2021). Radaelli, M., Buchalter, D. B., Mont, M.A., Schwarzkopf, R. & Hepinstall, M. S. A New Classification System for Cementless Femoral Stems in Total Hip Arthroplasty. J Arthroplasty 38, 502–510. doi: 10.1016/j.arth.2022.09.014 (2023). Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 24 May, 2025 Read the published version in Scientific Reports → Version 1 posted Editorial decision: Revision requested 30 Sep, 2024 Reviews received at journal 29 Sep, 2024 Reviewers agreed at journal 17 Sep, 2024 Reviews received at journal 10 Sep, 2024 Reviewers agreed at journal 10 Sep, 2024 Reviews received at journal 09 Sep, 2024 Reviewers agreed at journal 06 Sep, 2024 Reviewers agreed at journal 05 Sep, 2024 Reviewers invited by journal 22 Aug, 2024 Editor assigned by journal 22 Aug, 2024 Editor invited by journal 13 Aug, 2024 Submission checks completed at journal 09 Aug, 2024 First submitted to journal 08 Aug, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-4883665","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":346025551,"identity":"4606df7c-6a32-4249-a5dc-1edc2fd2c008","order_by":0,"name":"Yoshihisa Ohashi","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABKElEQVRIie3QsUrEMBjA8e846JSza0q19RFaAqXg4KtUDnpLQcX9qBTqJK6Vewl9g8gH7VK4TQLncCLo4lAXcShiroLcYSyOgvlDStrwo0kAdLq/mSEHJ6Z8UuB0c83rI1b6SVZmkP6GgMc7AptElceH5fKtvdtmt3gjoA6n5gU+LRtAMM84nBypiDHxz/NHEizicQiCUipi/7SQhNYRsEJFSEBHKUqSBBQaeRYBfjZ6R5ATYERNrLZFwmaHrx1x59VLRuRf3B5iEwOJZycGXW3M44nfEe8HYqER2zs5ErqIWRjV1LoWyfFlARPi1wep6ixbVVZazy3um7PxvWjKqenMq6umgT3HqbBkihvbxfW3aG0utzTI2XcBbqr4+NXwoW9Vp9Pp/ksfPKFm2SBVAZ4AAAAASUVORK5CYII=","orcid":"","institution":"Kitasato University School of Medicine","correspondingAuthor":true,"prefix":"","firstName":"Yoshihisa","middleName":"","lastName":"Ohashi","suffix":""},{"id":346025552,"identity":"55ff0a69-621b-431e-90ba-b7ea04daccc7","order_by":1,"name":"Kensuke Fukushima","email":"","orcid":"","institution":"Kitasato University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Kensuke","middleName":"","lastName":"Fukushima","suffix":""},{"id":346025553,"identity":"f3080b38-56dc-4c15-8295-9ac8c0bb03ca","order_by":2,"name":"Yuto Osaki","email":"","orcid":"","institution":"Kitasato University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Yuto","middleName":"","lastName":"Osaki","suffix":""},{"id":346025558,"identity":"7d5e2ace-7265-456d-8924-a1a6c3be4051","order_by":3,"name":"Maho Tsuchiya","email":"","orcid":"","institution":"Kitasato University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Maho","middleName":"","lastName":"Tsuchiya","suffix":""},{"id":346025559,"identity":"3af50371-56ff-4bda-ba55-97c9805dc329","order_by":4,"name":"Hiroki Saito","email":"","orcid":"","institution":"Kitasato University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Hiroki","middleName":"","lastName":"Saito","suffix":""},{"id":346025560,"identity":"2cbe6d44-0daa-4020-91d1-11facd68f8aa","order_by":5,"name":"Kentaro Uchida","email":"","orcid":"","institution":"Kitasato University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Kentaro","middleName":"","lastName":"Uchida","suffix":""},{"id":346025561,"identity":"d2c2df13-a768-4324-98b2-5f77dd2346d9","order_by":6,"name":"Katsufumi Uchiyama","email":"","orcid":"","institution":"Kitasato University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Katsufumi","middleName":"","lastName":"Uchiyama","suffix":""},{"id":346025562,"identity":"d98dcce6-1331-494e-8b66-f982785775c5","order_by":7,"name":"Naonobu Takahira","email":"","orcid":"","institution":"Kitasato University School of Allied Health Sciences","correspondingAuthor":false,"prefix":"","firstName":"Naonobu","middleName":"","lastName":"Takahira","suffix":""},{"id":346025563,"identity":"27b59a24-dfaf-431b-98e1-e1bd03526c8d","order_by":8,"name":"Masashi Takaso","email":"","orcid":"","institution":"Kitasato University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Masashi","middleName":"","lastName":"Takaso","suffix":""}],"badges":[],"createdAt":"2024-08-09 01:39:37","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4883665/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4883665/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41598-025-02970-4","type":"published","date":"2025-05-24T15:57:42+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":66075691,"identity":"50e25496-a486-4cdf-9932-3b28e4f74b40","added_by":"auto","created_at":"2024-10-07 12:57:33","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":355725,"visible":true,"origin":"","legend":"\u003cp\u003eAssessment of medial and lateral gap distance between the femoral calcar and stem collar using postoperative frontal X-ray of the hip joint. The medial and lateral gap distances were examined at a pitch of 1 mm at all points.\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4883665/v1/f16269ead1863ad951656833.jpeg"},{"id":66075694,"identity":"fc4c84a0-e21a-4be3-96b1-d6c06be9ffa1","added_by":"auto","created_at":"2024-10-07 12:57:33","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":420391,"visible":true,"origin":"","legend":"\u003cp\u003eFlowchart of this study.\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4883665/v1/d212252fae681ef5fb713bea.jpeg"},{"id":66075693,"identity":"7423a393-63d3-4591-bb79-071a9e7fa946","added_by":"auto","created_at":"2024-10-07 12:57:33","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":213166,"visible":true,"origin":"","legend":"\u003cp\u003eReceiver operating characteristics curve for medial and lateral gap distance at one week post-operatively in predicting gap disappearance within 36 months post-surgery.\u003c/p\u003e\n\u003cp\u003eCut-off value of the lateral gap distance for gap disappearance was 5.5 mm, with asensitivity of 0.85 and specificity of 0.86 (red line). Cut-off value of medial gap distance for gap disappearance was 2.5 mm, with sensitivity of 0.69 and specificity of 0.71 (blue line).\u003c/p\u003e","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4883665/v1/20fba3333fb30de6412f9e63.jpeg"},{"id":66075692,"identity":"5484f918-fa6f-49d5-bb1d-96a8eba50163","added_by":"auto","created_at":"2024-10-07 12:57:33","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":202307,"visible":true,"origin":"","legend":"\u003cp\u003eCorrelation between lateral (A) and medial (B) distance at one week post-operatively and duration of gap disappearance within 36 months post-surgery. Correlation coefficient is represented by ρ.\u003c/p\u003e","description":"","filename":"floatimage4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4883665/v1/fb6a8cd8c3dc793e3e8a08d6.jpeg"},{"id":83460036,"identity":"3dd8e739-0091-4e06-90ec-076d749a9826","added_by":"auto","created_at":"2025-05-26 16:09:19","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1894736,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4883665/v1/64b29cc6-8de1-4a92-81b9-d7723f2ad3cf.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Impact of Stem Collar-Calcar Gap Distance on Postoperative Bone Remodeling in Fully Hydroxyapatite-coated Stem","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe cementless stem collar design provides better outcomes in total hip arthroplasty (THA). Attaching the stem collar directly to the cut calcar neck offers improved fixation, protection against subsidence, positive dispersion of vertical force into the calcar and resistance to stem rotation in relation to the femoral canal [\u003cspan additionalcitationids=\"CR2 CR3\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Both basic and clinical research indicate that the implementation of collared stems is associated with decreased risk of periprosthetic fracture of the femur [\u003cspan additionalcitationids=\"CR5\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn practical surgical scenarios, however, inability to properly attach the stem collar to the cut calcar neck occasionally occurs. A recent study using finite element analysis indicated that micromotion in the contact model between the stem collar and cut calcar neck was notably reduced compared to non-contact models under both flat-surface walking and stair climbing conditions [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. In such cases, the stem collar may not fulfill its essential role. Thus, precise placement of the stem collar is important to optimizing outcomes in THA.\u003c/p\u003e \u003cp\u003eA number of types of fully hydroxyapatite (HA)-coated stem with collar is available [\u003cspan additionalcitationids=\"CR9\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Several studies have reported the occurrence of bone remodeling in the calcar region when the stem collar is not in contact in the region of the femoral calcar [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. This suggest that even if a gap occurs intraoperatively, post-operative bone remodeling can eliminate it and allow the collar to fulfil its role. However, the maximally acceptable gap distance between the collar of a fully HA-coated stem and the femoral calcar is unclear. Accordingly, an understanding of the distance of bone remodeling after THA will provide valuable intraoperative guidance for surgeons.\u003c/p\u003e \u003cp\u003eIn this study, we investigated the relationship between the gap distance occurring between the calcar and collar during fully HA-coated stem insertion and subsequent bone remodeling after primary THA.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eParticipants\u003c/h2\u003e \u003cp\u003eWe enrolled 156 consecutive patients (156 hips) who underwent primary THA with a G7\u0026reg; cup (Zimmer Biomet, Warsaw, IN) and CORAIL\u0026reg; stem (DePuy Synthes, Warsaw, IN, USA) at a single center. All operations were performed using a minimally invasive antero-lateral supine approach. The CORAIL stem is a forged titanium stem with a double-tapered geometry that is plasma-coated with 155 \u0026micro;m of HA. HA is also coated on the back of the stem collar. Collar length increases with stem size, namely 6 mm with sizes 8 to 11, 7 mm with sizes 12 to 15, and 9 mm with sizes 16 and above. Collar thickness is 3.5 mm for all sizes. Patients in this study all received stems sizes 8 to 12.\u003c/p\u003e \u003cp\u003eFor inclusion, all patients were required to available for follow-up for 36 months after surgery, and to be ambulatory with advanced or end-stage hip osteoarthritis (HOA) or idiopathic osteonecrosis of the femoral head (ION). We excluded patients with no evidence of a gap on frontal X-ray of the hip joint one week after surgery. We also excluded patients with a history of hip surgery ipsilateral to the THA, intraoperative periprosthetic femoral fracture, subsidence of the stem by more than 2 mm, or reoperation due to aseptic loosening.\u003c/p\u003e \u003cp\u003e Ethical approval for this retrospective observational study was obtained from our Institutional Review Board. The study was conducted in accordance with the Declaration of Helsinki, and all patients gave informed consent to participation.\u003c/p\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eClinical assessment\u003c/h3\u003e\n\u003cp\u003eClinical outcomes were evaluated in accordance with the Japanese Orthopaedic Association (JOA) hip scores at 1 month before and 36 months after surgery. This scoring system consists of four elements, namely pain (0\u0026ndash;40 points), range of motion (0\u0026ndash;20 points), gait ability (0\u0026ndash;20 points), and performance in activities of daily living (0\u0026ndash;20 points), and is widely used to investigate hip joint conditions in Japan [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. A higher score indicates a better condition of the post-operative hip joint.\u003c/p\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eRadiographic assessment\u003c/h2\u003e \u003cp\u003eWe assessed the gap between the femoral calcar and collar of the stem using postoperative frontal X-ray of the hip joint. X-rays were assessed at 1 week and 1, 3, 6, 12, 24, and 36 months after THA. To assess gap distance between the femoral calcar and collar, medial and lateral gap distances were investigated with a 1-mm pitch at all time points (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Measurement of gap distance relied on an X-ray taken one week post-surgery, which served as the initial reference point. We then assessed bone remodeling-induced disappearance of the gap over 36 months post-surgery, and determined the time until complete disappearance. Cases in which the gap disappeared within 36 months were classified as the contact group, and those in which the gap did not disappear as the non-contact group. A flowchart of the study is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eWe also evaluated the proximal femoral morphology using the Dorr classification [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] by measuring the calcaneal width at the mid-level of the lesser trochanter and the canal width at 10 cm below the lesser trochanter, and then calculating the calcaneal-to-canal ratio to determine bone type. As described elsewhere, femurs with a ratio of 0\u0026ndash;0.5 were classified as Type A, 0.51\u0026ndash;0.75 as Type B, and 0.76\u0026ndash;1 as Type C, [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Stem alignment angle was investigated using the postoperative radiographs one week after THA and evaluated to assess stem insertion in varus and valgus, as differentiated by deviation of stem axis from the femoral axis, in which valgus alignment was defined as positive.\u003c/p\u003e \u003cp\u003eWe investigated whether the medial and lateral gap distances between the femoral calcar and stem collar influenced gap disappearance within 36 months post-surgery. We also calculated the cut-off values for medial and lateral gap distances at which gap disappearance due to bone remodeling could be expected, and the relationship between medial and lateral gap distances and time to gap disappearance.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analyses\u003c/h2\u003e \u003cp\u003eThe results are reported as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard error unless noted otherwise. To compare patient characteristics between the Contact and Non-contact groups, we used Pearson's chi-square test for categorical variables, parametric t-tests for continuous variables with a normal distribution, and the Mann-Whitney U-test for variables not following a normal distribution. Logistic regression analysis was conducted to investigate the impact of medial and lateral gap distances on disappearance within 36 months post-surgery. Independent variables included age, gender, BMI, Dorr type, stem alignment angle, and medial and lateral gap distance, while the dependent variable was disappearance of the gap within 36 months. We applied receiver operating characteristic (ROC) curve analysis to determine cut-off values for the medial and lateral gaps, aiming to predict gap disappearance within the specified post-surgery timeframe. Additionally, we used Spearman's rank correlation coefficient to assess correlations between gap distance and time to gap disappearance. Two observers independently analysed all radiographic images and resolved any disagreements through consensus. All statistical analyses were conducted with SPSS software (v.26.0; IBM, NY, USA), with statistical significance set at \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eClassification of Contact and Non-contact Groups\u003c/h2\u003e \u003cp\u003eIn this study, gaps between the femoral calcar and collar of the stem were observed in the baseline X-rays of 55 cases. Among these, gaps disappeared within 36 months post-surgery in 42 cases (76.4%). Consequently, 42 cases were classified into the Contact group and 13 cases into the Non-contact group. The two groups did not significantly differ with regard to patient characteristics, including age, gender, BMI, clinical diagnosis, or Dorr type. Additionally, they did not differ with regard to clinical data, including stem alignment angle, and pre- and postoperative JOA hip scores. Details of patient characteristic and clinical data comparisons are shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of patient characteristics and clinical data\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eContact group\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNon-contact group\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal patients, N\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex, male/female, N\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13/ 29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3/ 10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.585\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge, years\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e60.62\u0026thinsp;\u0026plusmn;\u0026thinsp;1.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e57.31\u0026thinsp;\u0026plusmn;\u0026thinsp;3.70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.319\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHeight, cm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e158.11\u0026thinsp;\u0026plusmn;\u0026thinsp;1.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e156.37\u0026thinsp;\u0026plusmn;\u0026thinsp;2.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.357\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWeight, kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e61.96\u0026thinsp;\u0026plusmn;\u0026thinsp;1.64\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e64.41\u0026thinsp;\u0026plusmn;\u0026thinsp;5.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.586\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBody mass index, kg/m\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e24.75\u0026thinsp;\u0026plusmn;\u0026thinsp;0.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e26.03\u0026thinsp;\u0026plusmn;\u0026thinsp;1.97\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.714\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDiagnoses, N\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHOA/ION\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e36/ 6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10/ 3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.677\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDorr classification, N\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA/B/C\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6/ 36/ 0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2/ 11/ 0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.922\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStem alignment, \u0026deg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0.75\u0026thinsp;\u0026plusmn;\u0026thinsp;0.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.12\u0026thinsp;\u0026plusmn;\u0026thinsp;0.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.106\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eJOA hip scores\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOne month before surgery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePain\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14.64\u0026thinsp;\u0026plusmn;\u0026thinsp;1.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e16.54\u0026thinsp;\u0026plusmn;\u0026thinsp;2.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.754\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRange of motion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13.76\u0026thinsp;\u0026plusmn;\u0026thinsp;0.52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15.85\u0026thinsp;\u0026plusmn;\u0026thinsp;0.81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.051\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGait\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e16.39\u0026thinsp;\u0026plusmn;\u0026thinsp;0.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.076\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eActives of daily living\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.49\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15.23\u0026thinsp;\u0026plusmn;\u0026thinsp;0.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.093\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e36 months after surgery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePain\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e39.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e39.62\u0026thinsp;\u0026plusmn;\u0026thinsp;0.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.548\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRange of motion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e17.52\u0026thinsp;\u0026plusmn;\u0026thinsp;0.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e17.62\u0026thinsp;\u0026plusmn;\u0026thinsp;0.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.941\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGait\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e19.52\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e19.85\u0026thinsp;\u0026plusmn;\u0026thinsp;0.15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.537\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eActives of daily living\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e19.48\u0026thinsp;\u0026plusmn;\u0026thinsp;0.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e19.85\u0026thinsp;\u0026plusmn;\u0026thinsp;0.15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.812\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\u003cp\u003eAbbreviations: HOA, hip osteoarthritis; ION, idiopathic osteonecrosis of the femoral head; JOA, the Japanese Orthopaedic Association\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eFactors Influencing Gap Disappearance\u003c/h2\u003e \u003cp\u003eThe only factor influencing disappearance of the gap within 36 months post-surgery was lateral gap distance (p\u0026thinsp;=\u0026thinsp;0.02, Odds ratio\u0026thinsp;=\u0026thinsp;2.79). There were no significant differences in other independent variables, including age, gender, BMI, Dorr type, stem alignment angle, or medial gap distance (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eLogistic regression analysis of the impact of medial and lateral gap distance between the femoral calcar and stem collar on disappearance within 36 months post-surgery\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePredictor\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eEstimate\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSE\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eOdds ratio\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e95% Confidence interval\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLateral gap\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.020*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.18\u0026ndash;6.60\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMedial gap\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-0.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.492\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.32\u0026ndash;1.73\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.943\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.99\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.83\u0026ndash;1.18\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-0.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.675\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.09\u0026ndash;4.85\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.741\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.92\u0026ndash;1.13\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDiagnosis (HOA or ION)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.410\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e3.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.20\u0026ndash;52.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDorr type (A or B)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-0.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.796\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.76\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.09\u0026ndash;6.31\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStem alignment\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.079\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.94\u0026ndash;3.06\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003eAbbreviations: SE, standard error; BMI, body mass index; Cl, confidence interval; *, p\u0026lt;0.05; HOA, hip osteoarthritis; ION, idiopathic osteonecrosis of the femoral head\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eROC Curve Analyses for Gap Disappearance Prediction\u003c/h2\u003e \u003cp\u003eROC curve analyses were conducted to determine cut-off values for the medial and lateral gap distances in predicting gap disappearance within 36 months post-surgery (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). AUC for the lateral gap distance was found to be 0.90, indicating good predictive accuracy. Optimal cut-off value for lateral gap distance was 5.5 mm, with a sensitivity of 0.85 and specificity of 0.86. For medial gap distance, the AUC was 0.74, suggesting moderate predictive accuracy, and the optimal cut-off value was 2.5 mm, with a sensitivity of 0.69 and specificity of 0.71.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eCorrelation between Gap Distance and Time until Gap Disappearance\u003c/h2\u003e \u003cp\u003eWe analyzed correlations between medial and lateral gap distances and time until gap disappearance in patients with the Contact group (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). The results indicated a statistically significant correlation with the lateral gap distance (ρ\u0026thinsp;=\u0026thinsp;0.315, p\u0026thinsp;=\u0026thinsp;0.042), suggesting that a shorter duration until gap disappearance was associated with a smaller lateral gap distance between the femoral calcar and stem collar. In contrast, there was no significant correlation between medial gap distance and time until gap disappearance.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn this retrospective observational study, we evaluated patients who received primary THA with the CORAIL stem, focusing on the impact of gap distance between the femoral calcar and collar on gap disappearance within 36 months after surgery. Radiographic assessments at multiple post-surgery intervals revealed gaps in 55 cases, of which 42 gaps disappeared and 13 did not. Lateral gap distance was the primary factor influencing gap disappearance, with an optimal cut-off value of 5.5 mm showing high predictive accuracy, whereas medial gap distance with a cut-off value of 2.5 mm showed moderate accuracy. A significant correlation was found between a smaller lateral gap and quicker gap disappearance, underscoring the importance of precise stem collar placement for successful bone remodeling and gap closure.\u003c/p\u003e \u003cp\u003eWe found no difference in JOA hip score at 36 months after surgery between the two groups. Further, no participant experienced periprosthetic femoral fracture or aseptic loosening of the stem after surgery. Recent evidence also indicated that the presence or absence of contact between the collar of a fully hydroxyapatite-coated stem and the femoral neck did not affect clinical outcomes during the first postoperative year [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. However, several previous studies have indicated that use of a collared stem decreases risk of periprosthetic femur fractures [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. In their recent multivariate logistic analysis with adjustment for age, sex, and BMI, Rodriguez et al. reported that non-collared cementless stems were associated with an approximately threefold increased risk of periprosthetic femoral fracture compared to fully HA coated and collared cementless stems in patients aged over 65 years who underwent primary THA [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Considering that the absence of contact between the collar and femoral calcar is equivalent to the use of a collarless stem, these findings emphasize the importance of precise placement of the stem collar in optimizing outcomes in THA.\u003c/p\u003e \u003cp\u003eAlthough several studies have suggested the occurrence of bone remodeling between femoral calcar and stem collar, details have remained unclear. Vidalain reported the occurrence of bone remodeling in the calcar region with the CORAIL stem, and that on multivariate analysis femoral remodeling was not influenced to any significant extent by either patient- or prosthesis-related factors [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Our results are consistent with the findings of these studies. We revealed that disappearance of the gap due to bone remodeling was not influenced by age, gender, BMI, Dorr type, or stem alignment angle; rather, lateral gap distance was the only significant factor. These results indicate that the HA applied to the back of the stem collar may induce osteoinduction in the calcar region of the stem.\u003c/p\u003e \u003cp\u003ePrevious studies on bone remodeling in the stem collar and calcar gap did not considered gap distance [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. In the present study, we found that the optimal cut-off value for lateral gap distance between the calcar and stem collar for gap disappearance was 5.5 mm (2.5mm for medial gap distance). Additionally, we identified a positive correlation between lateral gap distance and time to gap disappearance. These results suggest that achieving contact between the calcar and collar during the postoperative course requires a lateral gap distance during stem placement within 5.5 mm, and that the smaller the lateral gap distance, the earlier the calcar and collar will be in contact. Two basic studies have investigated risks associated with the femoral calcar-collar gap [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Watanabe et al. indicated that micromotion in the collar contact model was notably reduced compared to the non-contact model under both flat walking and stair climbing conditions [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. In their study of the use of a composite femur in the CORAIL stem, Lamb et al. suggested that fracture torque and torsional stiffness were greater in the calcar-collar contact group than in the non-contact group [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. They also reported that odds ratio for not achieving collar contact increased 3.8-fold for each mm of separation in the regression model [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Many fully HA-coated stems now have the collared option [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. The angle and size of the stem collar varies from model to model. Surgeons therefore need to be more attentive to the angle and length in femoral neck osteotomy and in the placement of collared stems.\u003c/p\u003e \u003cp\u003eThere are a number of potential limitations to this study. First, only one stem product was used, and other stem models may give different results. Second, due to the relatively small sample size and limited number of follow-up time points, no differences between the two groups were observed in clinical outcome. Despite these limitations, we hope our results will serve as an important intraoperative indicator for surgeons using this stem.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis retrospective observational study evaluated the impact of gap distance between the femoral calcar and stem collar on gap disappearance within 36 months post-surgery in patients undergoing primary THA with the CORAIL stem. Our findings indicate that lateral gap distance is a significant factor influencing gap disappearance, with an optimal cut-off value of 5.5 mm. A smaller lateral gap is associated with more rapid gap closure, emphasizing the importance of precise stem collar placement to successful bone remodeling. Our results provide valuable intraoperative guidance for surgeons. When the gap between the collar and femoral calcar is within 5.5 mm, gap disappearance due to postoperative bone remodeling can be expected.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe would like to thank Dmed for English language editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors contributed to the literature search, critical review, data analysis, and manuscript preparation. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets supporting the conclusions of this article are included within the article. The raw data can be requested from the corresponding author, YO.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors have no relevant financial or non-financial interests to disclose.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that no funds, grants, or other support were received during the preparation of this manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics Approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eApproval was granted by the Institutional Review Board of Kitasato University Hospital (Number: B22-089).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eDemey, G., Fary, C., Lustig, S., Neyret, P. \u0026amp; si Selmi, T. Does a collar improve the immediate stability of uncemented femoral hip stems in total hip arthroplasty? A bilateral comparative cadaver study. J Arthroplasty 26, 1549\u0026ndash;1555, doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.arth.2011.03.030\u003c/span\u003e\u003cspan address=\"10.1016/j.arth.2011.03.030\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2011).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePanichkul, P., Bavonratanavech, S., Arirachakaran, A. \u0026amp; Kongtharvonskul, J. Comparative outcomes between collared versus collarless and short versus long stem of direct anterior approach total hip arthroplasty: a systematic review and indirect meta-analysis. Eur J Orthop Surg Traumatol 29, 1693\u0026ndash;1704, doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00590-019-02516-1\u003c/span\u003e\u003cspan address=\"10.1007/s00590-019-02516-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2019).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCidambi, K. R. \u003cem\u003eet al.\u003c/em\u003e Impact of Femoral Stem Design on Failure After Anterior Approach Total Hip Arthroplasty. J Arthroplasty 33, 800\u0026ndash;804, doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.arth.2017.10.023\u003c/span\u003e\u003cspan address=\"10.1016/j.arth.2017.10.023\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2018).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJohnson, A. J. \u003cem\u003eet al.\u003c/em\u003e A Calcar Collar Is Protective Against Early Torsional/Spiral Periprosthetic Femoral Fracture: A Paired Cadaveric Biomechanical Analysis. J Bone Joint Surg Am 102, 1427\u0026ndash;1433, doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.2106/JBJS.19.01125\u003c/span\u003e\u003cspan address=\"10.2106/JBJS.19.01125\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2020).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLamb, J. N. \u003cem\u003eet al.\u003c/em\u003e A calcar collar is protective against early periprosthetic femoral fracture around cementless femoral components in primary total hip arthroplasty: a registry study with biomechanical validation. Bone Joint J 101-B, 779\u0026ndash;786, doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1302/0301-620X.101B7.BJJ-2018-1422.R1\u003c/span\u003e\u003cspan address=\"10.1302/0301-620X.101B7.BJJ-2018-1422.R1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2019).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRodriguez, S. \u003cem\u003eet al.\u003c/em\u003e How Much Protection Does a Collar Provide? Assessing Risk of Early Periprosthetic Femur Fractures Following Total Hip Arthroplasty in Elderly Patients. J Arthroplasty 39, 997\u0026ndash;1000.e1, doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.arth.2023.10.020\u003c/span\u003e\u003cspan address=\"10.1016/j.arth.2023.10.020\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2024).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWatanabe, R., Mishima, H., Totsuka, S., Nishino, T. \u0026amp; Yamazaki, M. Primary Stability of Collared and Collarless Cementless Femoral Stems - A Finite Element Analysis Study. Arthroplast Today 21, 101140, doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.artd.2023.101140\u003c/span\u003e\u003cspan address=\"10.1016/j.artd.2023.101140\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2023).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVidalain, J. P. Twenty-year results of the cementless Corail stem. Int Orthop 35, 189\u0026ndash;194, doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00264-010-1117-2\u003c/span\u003e\u003cspan address=\"10.1007/s00264-010-1117-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2011).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOhashi, Y. et al. Influence of broach surface design of a fully hydroxyapatite coated, double tapered stem on periprosthetic bone mineral density after total hip arthroplasty: a study based on the morphology of the proximal femur. Arch Orthop Trauma Surg, doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00402-024-05430-2\u003c/span\u003e\u003cspan address=\"10.1007/s00402-024-05430-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2024).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHayashi, S. \u003cem\u003eet al.\u003c/em\u003e Hydroxyapatite-coated compaction short stem represents a characteristic pattern of peri-prosthetic bone remodelling after total hip arthroplasty. Arch Orthop Trauma Surg 142, 2903\u0026ndash;2910. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00402-021-04140-3\u003c/span\u003e\u003cspan address=\"10.1007/s00402-021-04140-3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2022).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKuribayashi, M. \u003cem\u003eet al.\u003c/em\u003e Reliability and validity of the Japanese Orthopaedic Association hip score. J Orthop Sci 15, 452\u0026ndash;458. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00776-010-1490-0\u003c/span\u003e\u003cspan address=\"10.1007/s00776-010-1490-0\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2010).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDorr, L.D. \u003cem\u003eet al.\u003c/em\u003e Structural and cellular assessment of bone quality of proximal femur. Bone. 14, 231\u0026ndash;242. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/8756-3282(93)90146-2\u003c/span\u003e\u003cspan address=\"10.1016/8756-3282(93)90146-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (1993).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIssa, K., Stroh, A. D., Mont, M. A. \u0026amp; Bonutti, P.M.. Effect of bone type on clinical and radiographic outcomes of a proximally-coated cementless stem in primary total hip arthroplasties. J Orthop Res 32, 1214\u0026ndash;1220. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1002/jor.22648\u003c/span\u003e\u003cspan address=\"10.1002/jor.22648\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. (2014).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePark, C.W. \u003cem\u003eet al.\u003c/em\u003e Femoral Stem Survivorship in Dorr Type A Femurs After Total Hip Arthroplasty Using a Cementless Tapered Wedge Stem: A Matched Comparative Study With Type B Femurs. J Arthroplasty 34, 527\u0026ndash;533. doi: 10.1016/j.arth.2018.11.004 (2019).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIwakiri, K. \u003cem\u003eet al.\u003c/em\u003e No Impact of Contact Between the Medial Collar of a Hydroxyapatite-Coated Triple-Tapered Stem and the Femoral Neck on Periprosthetic Bone Mineral Density. J Arthroplasty 39, 2082\u0026ndash;2087. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.arth.2024.02.011\u003c/span\u003e\u003cspan address=\"10.1016/j.arth.2024.02.011\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2024).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKonow, T., Baetz, J., Melsheimer, O., Grimberg, A. \u0026amp; Morlock, M. Factors influencing periprosthetic femoral fracture risk. Bone Joint J 103-B, 650\u0026ndash;658. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1302/0301-620X.103B4.BJJ-2020-1046.R2\u003c/span\u003e\u003cspan address=\"10.1302/0301-620X.103B4.BJJ-2020-1046.R2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2021).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJacquot, L. \u003cem\u003eet al.\u003c/em\u003e Clinical and Radiographic Outcomes at 25\u0026ndash;30 Years of a Hip Stem Fully Coated With Hydroxylapatite. J Arthroplasty 33, 482\u0026ndash;490. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.arth.2017.09.040\u003c/span\u003e\u003cspan address=\"10.1016/j.arth.2017.09.040\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2018).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLamb, J. N., Coltart, O., Adekanmbi, I., Pandit, H. G. \u0026amp; Stewart, T. Calcar-collar contact during simulated periprosthetic femoral fractures increases resistance to fracture and depends on the initial separation on implantation: A composite femur in vitro study. Clin Biomech (Bristol, Avon). 87, 105411. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.clinbiomech.2021.105411\u003c/span\u003e\u003cspan address=\"10.1016/j.clinbiomech.2021.105411\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2021).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRadaelli, M., Buchalter, D. B., Mont, M.A., Schwarzkopf, R. \u0026amp; Hepinstall, M. S. A New Classification System for Cementless Femoral Stems in Total Hip Arthroplasty. J Arthroplasty 38, 502\u0026ndash;510. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.arth.2022.09.014\u003c/span\u003e\u003cspan address=\"10.1016/j.arth.2022.09.014\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2023).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Total hip arthroplasty, Stem collar, Fully hydroxyapatite-coated stem, Bone remodeling","lastPublishedDoi":"10.21203/rs.3.rs-4883665/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4883665/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe collar of a cementless stem in total hip arthroplasty (THA) improves fixation and stability by connecting with the femoral calcar. Proper attachment is essential for reducing micromotion and preventing periprosthetic fractures of the femur. However, gaps between the femoral calcar and stem collar can occur during surgery, and it is unclear what degree of gap can be tolerated. This study evaluated 156 patients who received primary THA with the CORAIL stem. Medial and lateral gap distance were measured by frontal X-ray of the hip joint at 1 week and 1, 3, 6, 12, 24, and 36 months after THA. Clinical outcomes were assessed using Japanese Orthopaedic Association hip scores, and radiographic assessments included femoral morphology and stem alignment. Gaps were initially observed in 55 patients, with 42 showing complete gap disappearance within 36 months. On logistic regression analysis, lateral gap distance was shown to significantly influence gap disappearance, with an optimal cut-off of 5.5 mm by receiver operating characteristic curve analysis. A smaller lateral gap was correlated with quicker closure. When the gap between the collar and femoral calcar is within 5.5 mm, gap disappearance can be expected due to postoperative bone remodeling.\u003c/p\u003e","manuscriptTitle":"Impact of Stem Collar-Calcar Gap Distance on Postoperative Bone Remodeling in Fully Hydroxyapatite-coated Stem","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-10-07 12:57:28","doi":"10.21203/rs.3.rs-4883665/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-09-30T22:25:04+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-09-29T19:10:59+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"332498726925098240742611574334345879453","date":"2024-09-17T17:50:18+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-09-11T00:18:08+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"184622829805510891325201521331162109782","date":"2024-09-10T06:23:33+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-09-09T07:43:50+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"187384527373865445919747498794312485755","date":"2024-09-06T07:50:34+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"222790926081077257697856993172633561569","date":"2024-09-05T10:41:47+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-08-23T02:22:56+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-08-23T02:19:53+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2024-08-13T04:23:42+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-08-09T04:00:44+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2024-08-09T01:38:19+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"87d5a2df-3c89-471e-af94-a0a4ed17ee6e","owner":[],"postedDate":"October 7th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":36686797,"name":"Physical sciences/Materials science"},{"id":36686798,"name":"Physical sciences/Materials science/Techniques and instrumentation"},{"id":36686799,"name":"Health sciences/Diseases/Rheumatic diseases"},{"id":36686800,"name":"Health sciences/Diseases/Rheumatic diseases/Osteoarthritis"}],"tags":[],"updatedAt":"2025-05-26T16:01:39+00:00","versionOfRecord":{"articleIdentity":"rs-4883665","link":"https://doi.org/10.1038/s41598-025-02970-4","journal":{"identity":"scientific-reports","isVorOnly":false,"title":"Scientific Reports"},"publishedOn":"2025-05-24 15:57:42","publishedOnDateReadable":"May 24th, 2025"},"versionCreatedAt":"2024-10-07 12:57:28","video":"","vorDoi":"10.1038/s41598-025-02970-4","vorDoiUrl":"https://doi.org/10.1038/s41598-025-02970-4","workflowStages":[]},"version":"v1","identity":"rs-4883665","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4883665","identity":"rs-4883665","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}