The number of bars in the Nuss procedure: treatment outcomes and complications. A large single-center Propensity Score Matched cohort study. 

The number of bars in the Nuss procedure: treatment outcomes and complications. 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A large single-center Propensity Score Matched cohort study. Piotr Jerzy Skrzypczak, Monika Rozmiarek, Tomasz Dobiecki, Magdalena Sielewicz, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4577876/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 16 Nov, 2024 Read the published version in Scientific Reports → Version 1 posted 10 You are reading this latest preprint version Abstract The Nuss procedure is the most common corrective surgery for pectus excavatum. We analyzed treatment outcomes and complication rates in 1,247 patients treated with the Nuss procedure from 2002 to 2021, focusing on the number of corrective bars used. Using Propensity Score Matching based on age, sex, BMI, pre-operative FEV1, and the Haller index, we created two groups: 546 patients with a single bar and 546 with two bars. Both groups achieved similar correction effects (Haller index: single bar = 2.58 vs. two bars = 2.56; p = 0.65). In the univariate analysis, in the two-bar group, the postoperative complications were observed more often (28.6% vs. 15.4%, p < 0.001), including pneumothorax (11.2% vs. 6.2%, p < 0.001), hemothorax (3.7% vs. 0.7%, p < 0.001), additional drainage (13.7% vs. 5.3%, p < 0.001), the need for thoracentesis (8.6% vs. 2.9%, p < 0.001), bar displacement (3.8% vs. 0.7%, p < 0.001), pleural effusion (10.6% vs 3.1%, p < 0.001), and fever (6.6% vs 3.8%, p < 0.041). In the logistic regression, two bars significantly increased the risk of postoperative complications (p = 0.019), including hematoma (p = 0.036), pleural effusion (p = 0.002), and the need for thoracentesis (p = 0.013). Using two corrective bars during the Nuss procedure is associated with a higher rate of postoperative complications but similar corrective results. Health sciences/Diseases Health sciences/Health care Health sciences/Medical research Health sciences/Risk factors Health sciences/Signs and symptoms Nuss procedure Pectus Excavatum corrective bars Haller Index bar rotation Figures Figure 1 INTRODUCTION Pectus excavatum (PE) is the most common congenital chest wall deformity in humans (1,2) . PE affects 0.1% of all live births and usually manifests during the neonatal period (1–3) . Despite being prevalent, the exact cause of PE remains unclear. Several hypotheses have been proposed, including developmental disorders, overgrowth of costal cartilage, and genetic predispositions (1) . PE decreases patients' quality of life in both their mental and physical well-being (4) . While some PE patients may be asymptomatic, others could complain of physical disorders (dyspnea, chest pain, and palpitations) or psychosocial symptoms (body image concerns and depression) (4–6) . Both cosmetic and functional impairments are indications for surgical correction (4–6) . In the treatment of PE, depending on the patient's age and the advancement of the deformation, conservative or surgical methods can be utilized (7–10) . Non-surgical interventions, such as the vacuum bell or silicone/polyethylene implants, are available options for less advanced deformities in younger patients (7,8) . However, surgery remains the primary intervention for older patients (6,10) . Since its introduction in 1998, the method proposed by Donald Nuss (10) has become increasingly prevalent and is now one of the most widely practiced operative treatments for PE globally (10) . The Nuss procedure involves minimally invasive insertion of one or more appropriately adjusted metal bars behind the sternum to correct the depressed chest wall (11,12) . Advantages of the Nuss procedure include minimal invasiveness, reduced surgical trauma, and fewer PE recurrences after bar removal (13) , distinguishing it from the Ravitch method (14) . The most common postoperative complications after the Nuss procedure include bar displacement, pneumothorax, wound infection, pleural effusion, or chronic pain. (15,16) The number of bars used during the Nuss procedure has not been precisely determined. Many surgeons consider it dependent on the severity of the defect or the patient's characteristics, such as age, weight, or height (17–19) . Furthermore, the issue of precise indications of when a patient should receive multiple bar treatment is also rarely discussed in the literature. The aim of the study was to analyze the treatment outcomes and the frequency of complications in patients with a PE treated with the Nuss procedure, depending on the number of corrective bars used. METHODS This retrospective cohort study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). The Bioethics Committee of the Poznan University of Medical Sciences waived the need to obtain informed consent for the collection and analysis of the anonymized data and for the publication of the results of this single-center, retrospective, cohort study. The study included 1,247 patients with PE who underwent surgery between 2002 and 2021 using the Nuss procedure. The patients were preoperatively examined and were qualified for the operation on an outpatient basis. The size of the PE was evaluated using the Haller index, which was based on two chest X-ray projections: postero-anterior and right lateral. According to Khanna et al. [ 20 ] and Rattan et al. (21) , the Haller index based on radiography correlates well with that calculated on computed tomography (CT). Routine preoperative thoracic CT scans were not performed due to their potential malignancy and cumulative lifetime radiation exposure (21–23) . Chest CT scans were limited to cases of advanced symmetrical or significantly asymmetrical deformities. The main indications for surgical treatment were cosmetic concerns, dyspnea on exertion, or a Haller index ≥ 3.5. The surgical procedure was performed under general anesthesia and the modified Nuss method initially described in 1998 (10) . All patients received additional analgesia using an epidural infusion of 0.25% bupivacaine. Correction of the deformity involved the insertion of one or two appropriately bent correctional steel bars (BBH Mikromed, Dąbrowa Górnicza, Poland). Videothoracoscopy was utilized during each operation, and the bars were inserted retrosternally. An additional stabilizing bar was introduced to prevent implant displacement, typically following the insertion of the first bar, and secured to the adjacent ribs using absorbable sutures. The basic characteristics are presented in Table 1 . Table 1 Basic characteristics of the studied group. Single-bar group (n = 692) Two- bars group (n = 546) Age (years, median, Q3-Q1) 16 (20 − 15) 18 (23 − 15) Sex, n (%) - male , - female , − 562 (81.2%), − 130 (18.8%), 422 (77.3%), 124 (22.8%), BMI (kg/m2, median) 19,8 (20.5–17.9) 19,8 (24.3–20.1) FEV1% (median) 89 (93.1 − 78.8) 89 (90 − 80) pre-operative Haller index (median) 3.4 (4.3-3) 3.7 (4.4-3) Statistical analysis The analyzed data were expressed as mean ± standard deviation, median, minimum, maximum values, interquartile range (Q1 lower quartile, Q3 upper quartile), or percentage, as appropriate. The relationship between variables was analyzed using Spearman’s rank correlation coefficient. The normality of distribution was tested using the Shapiro–Wilk test, and equality of variances was checked using Levene’s test. A comparison of two unpaired groups was performed using the unpaired t-test for data that followed a normal distribution and had homogeneity of variances or the Mann–Whitney U-test. Categorical data were analyzed using the χ2 test when the sample size was larger than 40, and all expected values were greater than ten; for other situations, the exact test of Fisher or χ2 test with Yate’s correction was used. All results were considered significant at p < 0.05. To create two comparable groups, we used the Propensity Score Matching analysis. To calculate the predicted probability, the following variables were used: age, sex, BMI, pre-operative FEV1, and the Haller index based on the closest value of the predicted probability. The most appropriately matched pairs were selected using a “nearest neighbor” matching algorithm without replacement with a caliper of 0.01. Data manipulation and all calculations were performed in IBM® SPSS® Statistics version 27th (PS Imago Pro 8). RESULTS Using the propensity score matching analysis, we obtained two groups that are similar in terms of basic characteristics (Table 2 ). The process of performing the Propensity Score Matching analysis is illustrated in Fig. 1 . A similar correction effect assessed with the Haller index was achieved (single-bar group = 2.58 vs. two-bars group = 2.56; p = 0.65). The basic characteristics of the groups after Propensity Score Matching are presented in the Table 2 . Table 2 The basics characteristics of the studied groups after propensity score matching and the results of the comparison in terms of the complications rates and the effects of the correction. Single-bar group (n = 546) Two- bars group (n = 546) p-value Age (years, median, Q3-Q1) 16 (20 − 14) 18 (23 − 15) 0.08 Sex, n (%) - male , - female , − 446 (81.6%), − 100 (18.4%), 422 (77.3%), 124 (22.8%), P = 0.1 BMI (kg/m2, median) 19,6 (21.5–18.0) 19.8 (21.9–18.1) 0.440 FEV1% (median) 91.1 (101 − 82.1) 91 (100.5–82.5) 0.562 pre-operative Haller index (median) 3.6 (4.0-2.9) 3.8 (4.4-3) 0.07 post-operative Haller Index 2.6 (2.8–2.2) 2.6 (2.9–2.2) 0.650 Complications total numer of the complications 84 (15.4) 156 (28.6) < .001 pneumothorax 34 (6.2) 61 (11.2) 0.004 hematoma 4 (0.7) 20 (3.7) < .001 pleural effusion 17 (3.1) 58 (10.6) < .001 additional drainage 29 (5.3) 75 (13.7) < .001 thoracocenthesis 16 (2.9) 47 (8.6) < .001 bar displacement 4 (0.7) 21 (3.8) < .001 wound infection 3 (0.5) 2 (0.4) 0.5 pain in the chest 5 (0.9) 11 (2.0) 0.131 fever 21 (3.8) 36 (6.6) 0.041 deformation reccurence 9 (1.6) 9 (1.6) 0.99 lack of corrections 3 (0.5) 4 (0.7) 0.5 re-hospitalization 23 (4.2) 45 (8.2) 0.06 reoperation 19 (3.5) 39 (7.2) 0.07 other complications 14 (2.6) 19 (3.5) 0.374 In the two-bars group, postoperative complications were observed significantly more often (28.6% vs. 15.4%, p < 0.001), including pneumothorax (11.2% vs. 6.2%, p < 0.001), hemothorax (3.7% vs. 0.7%, p < 0.001), additional drainage (13.7% vs. 5.3%, p < 0.001), thoracentesis (8.6% vs. 2.9%, p < 0.001), bar rotation (3.8% vs. 0.7%, p < 0.001), pleural effusion (10.6% vs 3.1%, p < 0.001), and fever (6.6% vs 3.8%, p < 0.041). In the logistic regression analysis, the following factors were analyzed: age, sex, preoperative Haller index, BMI, and the number of bars used. Implantation of two corrective bars significantly increased the risk of postoperative complications (p = 0.019), including hematoma (p = 0.036), effusion (p = 0.002), and the need for thoracentesis (p = 0.013). The results of the logistic regression are presented in Table 3 . Table 3 Results of the logistic regression. The influence of age, sex, BMI, pre-operative Haller index, and number of bars used on the occurrence of post-operative complications. Type of the complication p-value OR (95% CI) Total number of the post-operative complications. age 0.793 0.99 (0.916–1.069) sex 0.911 1.057(0.4-2.792) BMI 0.608 0.958 (0.814–1.128) pre-operative Haller index 0.606 1.094 (0.777–1.542) number of bars used 0.019 2.636 (1.172–5.929) Pneumothorax age 0.049 0.785 (0.617–0.999) sex 0.223 2,399 (0.588–9.794) BMI 0.274 0.862 (0.66–1.125) pre-operative Haller index 0.735 1.092 (0.655–1.821) number of bars used 0.305 2.014 (0.528–7.680) Hematoma age 0.405 1.051 (0.934–1.183) sex 0.949 0.942 (0.155–5.738) BMI 0.158 1.270 (0.911–1.771) pre-operative Haller index 0.026 1.954 (1.082–3.528) number of bars used 0.036 6.874 (1.129–41.844) Pleural effusion age 0.977 1.002 (0.9-1.115) sex 0.177 0.226 (0.026–1.960) BMI 0.235 1.172 (0.902–1.522) pre-operative Haller index 0.727 1.120 (0.592–2.119) number of bars used 0.002 8.914 (2.243–35.431) Additional drainage age 0.026 0.783 (0.631–0.971) sex 0.343 1.944 (0.492–7.681) BMI 0.92 0.988 (0.776–1.257) pre-operative Haller index 0.627 1.128 (0.695–1.831) number of bars used 0.085 2.887 (0.864–9.653) Thoracocentesis age 0.024 1.121 (1.015–1.238) sex 0.16 0.287 (0.05–1.635) BMI 0.822 0.971 (0.755–1.25) pre-operative Haller index 0.190 1.379 (0.853–2.228) number of bars used 0.013 4.42 (1.369–14.272) Bar displacement age 0.509 0.04 (-0.054-0.11) sex 0.723 0.04 (-0.067-0.096) BMI 0.661 0.043 (-0.103-0.07) pre-operative Haller index 0.306 0.026 (-0.08-0.025) number of bars used 0.048 0.043 (0.001–0.17) Fever age 0.049 0.842 (0.708–1.001) sex 0.699 0.728 (0.143–3.699) BMI 0.545 1.072 (0.854–1.346) pre-operative Haller index 0.127 0.54 (0.243–1.201) number of bars used 0.08 2.954 (0.872–10.009) DISCUSSION We found that patients who were operated on with one correction bar and those who received two correction bars achieved similar correction effects as measured by the Haller index. However, the use of two bars during the Nuss procedure was associated with a significantly higher incidence of complications, including hematoma, pleural effusion, and the necessity for thoracentesis. Preparing the intercostal space for the insertion of an additional corrective bar may lead to postoperative complications such as hematoma or pleural effusion. These complications often necessitate decompression and thoracocentesis, as evidenced in our results. Therefore, in our center, the standard practice is to introduce one correction bar if the advancement of the deformation, anatomical considerations, and the patient's age permit. An additional bar is frequently added in older, taller, and more severely deformed patients. Since the introduction of the Nuss procedure in the recent century (10) , the method has gained significant popularity and has undergone several modifications (6,24) . Initially, the method involved using a single bar for the majority of patients with PE. However, as the technique became more widespread, the surgical indications were broadened, particularly to encompass adult patients. In their case, multiple correction bars were often utilized (6,25) . Moreover, the advancement of thoracoscopy and its potential for routine usage during correction bar insertion ensures the safety of the procedure and reduces the occurrence of severe complications (26,27) . The procedure yields favorable corrective outcomes for PE. While it is minimally invasive, it remains a surgical intervention associated with the potential for serious complications. The risk of complications increases with patient age or when utilizing multiple correction bars (6,27–29) . Bar displacement remains one of the most severe complications following the Nuss procedure (30) . The incidence of this complication is estimated to range from 1.8–16.6% (10,31–33) , with reoperation required in 3.4–27% of cases (30) . Several surgical methods are employed to prevent common mechanisms of bar displacement, such as bar flipping, lateral sliding, or hinge point disruption (27) . Most techniques facilitate the solid attachment of the bar to the ribs: stabilizers, bar fixation with stainless-steel wire or a shorter bar (34–36) . Other common complications include postoperative pneumothorax, pleural effusion, pericardial effusion, hemothorax, and infectious complications (6,27,29) . The number of bars used remains a topic of discussion, with some centers considering the insertion of two correction bars as a standard practice. Stanfill et al. emphasized in their study the efficacy of the Nuss procedure employing two corrective bars to mitigate bar rotation and enhance bar stability (30) . However, they involved relatively small sample sizes of 58 and 27 patients, which were also unequal in size. In our propensity score-matched analysis, we observed a statistically significant higher incidence of bar rotation in the two-bars group. A similar finding was reported by Uemura et al., who used two bars with lateral stabilizing in high-risk patients (37) . Conversely, achieving satisfactory correction of deep sternal depression in PE often requires the use of two corrective bars. Chen et al. noted more infections in patients who underwent insertion of two corrective bars (17) . Furthermore, they emphasized the importance of lower weight and the value of the Haller index as essential risk factors that elevate the likelihood of severe infections. They suggested a cut-off point of 50 kilograms as the target group of patients who can be safely and effectively undergo surgery with two correction bars (17) . An important challenge in corrective PE surgery is the issue of operating on adult patients. It is recommended to perform surgery on younger individuals, particularly adolescents aged 12–16 (18,19) , as they tend to experience better cosmetic outcomes and fewer serious complications. This is attributed to the constitution of the skeletal system and anatomical factors, which contribute to a higher frequency of post-operative complications in adults (6,27) . However, experienced centers also operate on adult patients, using two corrective bars as a standard and only sporadically using two-bars in adolescents (38) . Ben et al. (39) reviewed the effect of treatment on 153 patients with significantly asymmetric PE who underwent multiple-bar Nuss operations. However, their study exhibits a notable disparity in the size of the compared groups: 151 patients received treatment with two bars, while only 2 cases were treated with three bars. The authors obtained favorable results: displacement of a bar only in one case, bar exposure in seven cases, and high scores in post-operative satisfaction questionnaires. The authors of the study recommend the multiple-bar Nuss operation for patients with significantly deformed PE as a safe and effective method that yields optimal cosmetic results (39) . Although the authors acknowledge that one bar may suffice in many cases, they emphasize the superiority of employing two bars to achieve better cosmetic outcomes in both the lying and standing positions (39) . In their compelling study, Nagaso et al. (40) conducted a detailed analysis of postoperative pain in patients undergoing the Nuss procedure with the implantation of one or two corrective bars. They used a patient-controlled anesthetic system to assess the requirement for painkillers in both groups and observed more severe pain in the single-bar group. Furthermore, they performed a biomechanical analysis, revealing that utilizing double bars reduces stress on the thoraces. The authors recommend double-bar application for patients with advanced PE and difficult correction conditions. Such treatment ensures more effective cosmetic results, reduces postoperative pain, and improves the biomechanical correction conditions. However, their study involved very small groups of 14 vs. 10 patients. According to Nagaso's study (40) , more favorable biomechanics of correction using double-bar correction causes pressure dispersion. According to the authors, it minimizes the possibility of displacement of the bar. In our study on a very large group of patients, it is difficult for us to agree - we found that in the case of double-bar correction, rotation of one of the bars occurred more often. Lo et al. analyzed a cohort comprising nearly 300 patients, with a majority undergoing the use of two or even three correction bars. By employing bilateral thoracoscopy for precise assessment of intraoperative deformation, they achieved an overall complication rate of 6.8%. Notably, they found that the postoperative complications rate was significantly related only to the Haller index (24) . Bar displacement necessitating reoperation emerged as the most common complication reported in their study. Early complications included pneumonia, delayed pleural effusion, and postoperative wound infections, while late complications involved chronic postoperative pain. Although patients with three bars experienced longer hospital stays, the difference was not statistically significant (24) . The authors acknowledge several limitations of the study. Firstly, our study has the character of a retrospective cohort study. Our study has no precise indications for using one or two corrective bars in patients. For the most part, the decision was based on the surgeon's experience as well as the patient's pre-operative imaging and physical examination. Consequently, there exists a possibility of selective bias. The surgeries were performed in a high-volume center by an experienced team of 2–3 thoracic surgeons. To enhance the reliability of the data analysis, Propensity Score Matching was employed, incorporating key confounders mentioned in the literature to calculate predictive probabilities. Additionally, the study included one of the largest cohorts available, comprising over 1,000 patients operated on in a single center. While this is a single-center study, it draws upon multi-years of experience, thereby enriching the depth of the findings. CONCLUSIONS The utilization of two correction bars during the Nuss procedure is associated with a higher rate of severe postoperative complications. The correction effects assessed by the Haller index demonstrated similarity across both patient groups, irrespective of the number of correction bars employed. If the anatomical conditions are sufficient to achieve optimal correction, employing a single correction bar should be considered the standard approach. Declarations Disclosures The work presented in this publication was conducted with the participation of the Greater Poland Center of Digital Medicine. The Center is funded by the Medical Research Agency (S. Moniuszki 1A, 00–014 Warsaw, Poland) grant number 2023/ABM/02/00007 − 00, financed from the state budget (29 999 256,00 PLN). Author Contribution Conceptualization, P.S. and K.P.; Data curation, M.R, T.D., M.Su. and M.S.; Formal analysis, P.S. and M.R.; Investigation, P.S., M.R. and M.Su.; Methodology, P.S and K.P.; Project administration, C.P.; Resources, M.R.; Software, P.S.; Supervision, K.P. and C.P.; Visualization, P.S.; Writing—original draft, P.S. and K.P.; Writing—review and editing, C.P., M.S., M.Su., K.P., M.R. and T.D. All authors have read and agreed to the published version of the manuscript. Data Availability The datasets used and/or analysed during the current study available from the corresponding author on reasonable request. References Brochhausen C, Turial S, Müller FKP, et al. Pectus excavatum: history, hypotheses and treatment options. Interact Cardiovasc Thorac Surg 2012;14:801–6. McHam B, Winkler L. Pectus Carinatum (Pigeon Chest). StatPearls, Treasure Island (FL): StatPearls Publishing; 2019. Fokin AA, Steuerwald NM, Ahrens WA, Allen KE. 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Hebra A, Swoveland B, Egbert M, et al. Outcome analysis of minimally invasive repair of pectus excavatum: review of 251 cases. J Pediatr Surg 2000;35:252–7; discussion 257–258. Park HJ, Lee SY, Lee CS, Youm W, Lee KR. The Nuss procedure for pectus excavatum: evolution of techniques and early results on 322 patients. Ann Thorac Surg 2004;77:289–95. Pilegaard HK, Licht PB. Early results following the Nuss operation for pectus excavatum–a single-institution experience of 383 patients. Interact Cardiovasc Thorac Surg 2008;7:54–7. Park HJ, Chung W-J, Lee IS, Kim KT. Mechanism of bar displacement and corresponding bar fixation techniques in minimally invasive repair of pectus excavatum. J Pediatr Surg 2008;43:74–8. Hebra A, Gauderer MW, Tagge EP, Adamson WT, Othersen HB. A simple technique for preventing bar displacement with the Nuss repair of pectus excavatum. J Pediatr Surg 2001;36:1266–8. Nuss D, Croitoru DP, Kelly RE, Goretsky MJ, Nuss KJ, Gustin TS. Review and discussion of the complications of minimally invasive pectus excavatum repair. Eur J Pediatr Surg Off J Austrian Assoc Pediatr Surg Al Z Kinderchir 2002;12:230–4. Uemura S, Nakagawa Y, Yoshida A, Choda Y. Experience in 100 cases with the Nuss procedure using a technique for stabilization of the pectus bar. Pediatr Surg Int 2003;19:186–9. Kim DH, Hwang JJ, Lee MK, Lee DY, Paik HC. Analysis of the Nuss Procedure for Pectus Excavatum in Different Age Groups. Ann Thorac Surg 2005;80:1073–7. Ben XS, Deng C, Tian D, et al. Multiple-bar Nuss operation: an individualized treatment scheme for patients with significantly asymmetric pectus excavatum. J Thorac Dis Nagaso T, Miyamoto J, Kokaji K, et al. Double-bar application decreases postoperative pain after the Nuss procedure. J Thorac Cardiovasc Surg 2010;140:39–44.e2. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 16 Nov, 2024 Read the published version in Scientific Reports → Version 1 posted Editorial decision: Revision requested 08 Aug, 2024 Reviews received at journal 06 Aug, 2024 Reviews received at journal 03 Aug, 2024 Reviewers agreed at journal 29 Jul, 2024 Reviewers agreed at journal 28 Jul, 2024 Reviewers invited by journal 18 Jul, 2024 Editor assigned by journal 25 Jun, 2024 Editor invited by journal 18 Jun, 2024 Submission checks completed at journal 17 Jun, 2024 First submitted to journal 13 Jun, 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. 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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-4577876","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":320722591,"identity":"745db50f-bf66-4550-afbb-be54b3da4226","order_by":0,"name":"Piotr Jerzy Skrzypczak","email":"data:image/png;base64,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","orcid":"","institution":"Poznan University of Medical Sciences","correspondingAuthor":true,"prefix":"","firstName":"Piotr","middleName":"Jerzy","lastName":"Skrzypczak","suffix":""},{"id":320722592,"identity":"99c93c09-4d49-4cd7-902b-6f4770294bf5","order_by":1,"name":"Monika Rozmiarek","email":"","orcid":"","institution":"Poznan University of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Monika","middleName":"","lastName":"Rozmiarek","suffix":""},{"id":320722593,"identity":"9d7bfd00-06fb-466b-a117-6d6749da0997","order_by":2,"name":"Tomasz Dobiecki","email":"","orcid":"","institution":"Poznan University of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Tomasz","middleName":"","lastName":"Dobiecki","suffix":""},{"id":320722594,"identity":"495b172a-da8b-4732-9f02-92239b4e6ab0","order_by":3,"name":"Magdalena Sielewicz","email":"","orcid":"","institution":"Poznan University of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Magdalena","middleName":"","lastName":"Sielewicz","suffix":""},{"id":320722595,"identity":"cffbab3e-c6c4-43ca-8e76-66e4ffecf308","order_by":4,"name":"Michał Suchodolski","email":"","orcid":"","institution":"Poznan University of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Michał","middleName":"","lastName":"Suchodolski","suffix":""},{"id":320722596,"identity":"22f3d15e-1a37-4823-b08b-abf5e84a11e1","order_by":5,"name":"Magdalena Roszak","email":"","orcid":"","institution":"Poznan University of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Magdalena","middleName":"","lastName":"Roszak","suffix":""},{"id":320722597,"identity":"b5f6dc57-d587-4960-8a1b-edaf1f6e0f8f","order_by":6,"name":"Cezary Piwkowski","email":"","orcid":"","institution":"Poznan University of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Cezary","middleName":"","lastName":"Piwkowski","suffix":""},{"id":320722598,"identity":"14b550fd-b32a-4af9-91a5-3dcb89684f8f","order_by":7,"name":"Krystian Pawlak","email":"","orcid":"","institution":"Poznan University of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Krystian","middleName":"","lastName":"Pawlak","suffix":""}],"badges":[],"createdAt":"2024-06-13 18:15:16","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4577876/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4577876/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41598-024-79562-1","type":"published","date":"2024-11-16T15:56:51+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":60341231,"identity":"a92fc2c9-7474-4827-8425-db8f137f6a4c","added_by":"auto","created_at":"2024-07-15 18:42:02","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":30093,"visible":true,"origin":"","legend":"\u003cp\u003eThe flow diagram summarizing the subsequent stages of Propensity Score Matching analysis.\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-4577876/v1/a273e2a8cf82e333e2124e21.png"},{"id":69274495,"identity":"b9d01023-111e-4608-9d42-4e40c638ea0e","added_by":"auto","created_at":"2024-11-18 16:00:55","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":715363,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4577876/v1/d88489ad-5a2d-46f2-aff4-216d07754e92.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"The number of bars in the Nuss procedure: treatment outcomes and complications. A large single-center Propensity Score Matched cohort study. ","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003ePectus excavatum (PE) is the most common congenital chest wall deformity in humans \u003csup\u003e(1,2)\u003c/sup\u003e. PE affects 0.1% of all live births and usually manifests during the neonatal period \u003csup\u003e(1\u0026ndash;3)\u003c/sup\u003e. Despite being prevalent, the exact cause of PE remains unclear. Several hypotheses have been proposed, including developmental disorders, overgrowth of costal cartilage, and genetic predispositions \u003csup\u003e(1)\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003ePE decreases patients' quality of life in both their mental and physical well-being \u003csup\u003e(4)\u003c/sup\u003e. While some PE patients may be asymptomatic, others could complain of physical disorders (dyspnea, chest pain, and palpitations) or psychosocial symptoms (body image concerns and depression) \u003csup\u003e(4\u0026ndash;6)\u003c/sup\u003e. Both cosmetic and functional impairments are indications for surgical correction \u003csup\u003e(4\u0026ndash;6)\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eIn the treatment of PE, depending on the patient's age and the advancement of the deformation, conservative or surgical methods can be utilized \u003csup\u003e(7\u0026ndash;10)\u003c/sup\u003e. Non-surgical interventions, such as the vacuum bell or silicone/polyethylene implants, are available options for less advanced deformities in younger patients \u003csup\u003e(7,8)\u003c/sup\u003e. However, surgery remains the primary intervention for older patients \u003csup\u003e(6,10)\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eSince its introduction in 1998, the method proposed by Donald Nuss \u003csup\u003e(10)\u003c/sup\u003e has become increasingly prevalent and is now one of the most widely practiced operative treatments for PE globally \u003csup\u003e(10)\u003c/sup\u003e. The Nuss procedure involves minimally invasive insertion of one or more appropriately adjusted metal bars behind the sternum to correct the depressed chest wall \u003csup\u003e(11,12)\u003c/sup\u003e. Advantages of the Nuss procedure include minimal invasiveness, reduced surgical trauma, and fewer PE recurrences after bar removal \u003csup\u003e(13)\u003c/sup\u003e, distinguishing it from the Ravitch method \u003csup\u003e(14)\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe most common postoperative complications after the Nuss procedure include bar displacement, pneumothorax, wound infection, pleural effusion, or chronic pain. \u003csup\u003e(15,16)\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eThe number of bars used during the Nuss procedure has not been precisely determined. Many surgeons consider it dependent on the severity of the defect or the patient's characteristics, such as age, weight, or height \u003csup\u003e(17\u0026ndash;19)\u003c/sup\u003e. Furthermore, the issue of precise indications of when a patient should receive multiple bar treatment is also rarely discussed in the literature.\u003c/p\u003e \u003cp\u003eThe aim of the study was to analyze the treatment outcomes and the frequency of complications in patients with a PE treated with the Nuss procedure, depending on the number of corrective bars used.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cp\u003e This retrospective cohort study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). The Bioethics Committee of the Poznan University of Medical Sciences waived the need to obtain informed consent for the collection and analysis of the anonymized data and for the publication of the results of this single-center, retrospective, cohort study. The study included 1,247 patients with PE who underwent surgery between 2002 and 2021 using the Nuss procedure.\u003c/p\u003e \u003cp\u003eThe patients were preoperatively examined and were qualified for the operation on an outpatient basis. The size of the PE was evaluated using the Haller index, which was based on two chest X-ray projections: postero-anterior and right lateral. According to Khanna et al. [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] and Rattan et al. \u003csup\u003e(21)\u003c/sup\u003e, the Haller index based on radiography correlates well with that calculated on computed tomography (CT). Routine preoperative thoracic CT scans were not performed due to their potential malignancy and cumulative lifetime radiation exposure \u003csup\u003e(21\u0026ndash;23)\u003c/sup\u003e. Chest CT scans were limited to cases of advanced symmetrical or significantly asymmetrical deformities.\u003c/p\u003e \u003cp\u003eThe main indications for surgical treatment were cosmetic concerns, dyspnea on exertion, or a Haller index\u0026thinsp;\u0026ge;\u0026thinsp;3.5. The surgical procedure was performed under general anesthesia and the modified Nuss method initially described in 1998 \u003csup\u003e(10)\u003c/sup\u003e. All patients received additional analgesia using an epidural infusion of 0.25% bupivacaine. Correction of the deformity involved the insertion of one or two appropriately bent correctional steel bars (BBH Mikromed, Dąbrowa G\u0026oacute;rnicza, Poland). Videothoracoscopy was utilized during each operation, and the bars were inserted retrosternally. An additional stabilizing bar was introduced to prevent implant displacement, typically following the insertion of the first bar, and secured to the adjacent ribs using absorbable sutures.\u003c/p\u003e \u003cp\u003eThe basic characteristics are presented 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\u003eBasic characteristics of the studied group.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSingle-bar group (n\u0026thinsp;=\u0026thinsp;692)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTwo- bars group (n\u0026thinsp;=\u0026thinsp;546)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAge (years, median, Q3-Q1)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e16 (20\u0026thinsp;\u0026minus;\u0026thinsp;15)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18 (23\u0026thinsp;\u0026minus;\u0026thinsp;15)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSex, n (%)\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e- male\u003c/b\u003e,\u003c/p\u003e \u003cp\u003e\u003cb\u003e- female\u003c/b\u003e,\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026minus;\u0026thinsp;562\u0026nbsp;(81.2%),\u003c/p\u003e \u003cp\u003e\u0026minus;\u0026thinsp;130 (18.8%),\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e422 (77.3%),\u003c/p\u003e \u003cp\u003e124 (22.8%),\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eBMI (kg/m2, median)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e19,8 (20.5\u0026ndash;17.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e19,8\u0026nbsp;(24.3\u0026ndash;20.1)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFEV1% (median)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e89 (93.1 \u0026minus;\u0026thinsp;78.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e89 (90\u0026thinsp;\u0026minus;\u0026thinsp;80)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003epre-operative Haller index (median)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.4 (4.3-3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.7 (4.4-3)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eThe analyzed data were expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation, median, minimum, maximum values, interquartile range (Q1 lower quartile, Q3 upper quartile), or percentage, as appropriate. The relationship between variables was analyzed using Spearman\u0026rsquo;s rank correlation coefficient. The normality of distribution was tested using the Shapiro\u0026ndash;Wilk test, and equality of variances was checked using Levene\u0026rsquo;s test. A comparison of two unpaired groups was performed using the unpaired t-test for data that followed a normal distribution and had homogeneity of variances or the Mann\u0026ndash;Whitney U-test. Categorical data were analyzed using the χ2 test when the sample size was larger than 40, and all expected values were greater than ten; for other situations, the exact test of Fisher or χ2 test with Yate\u0026rsquo;s correction was used. All results were considered significant at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003cp\u003eTo create two comparable groups, we used the Propensity Score Matching analysis. To calculate the predicted probability, the following variables were used: age, sex, BMI, pre-operative FEV1, and the Haller index based on the closest value of the predicted probability. The most appropriately matched pairs were selected using a \u0026ldquo;nearest neighbor\u0026rdquo; matching algorithm without replacement with a caliper of 0.01. Data manipulation and all calculations were performed in IBM\u0026reg; SPSS\u0026reg; Statistics version 27th (PS Imago Pro 8).\u003c/p\u003e \u003c/div\u003e"},{"header":"RESULTS","content":"\u003cp\u003eUsing the propensity score matching analysis, we obtained two groups that are similar in terms of basic characteristics (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The process of performing the Propensity Score Matching analysis is illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. A similar correction effect assessed with the Haller index was achieved (single-bar group\u0026thinsp;=\u0026thinsp;2.58 vs. two-bars group\u0026thinsp;=\u0026thinsp;2.56; p\u0026thinsp;=\u0026thinsp;0.65). The basic characteristics of the groups after Propensity Score Matching are presented in the 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\u003eThe basics characteristics of the studied groups after propensity score matching and the results of the comparison in terms of the complications rates and the effects of the correction.\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=\"left\" 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\u003eSingle-bar group (n\u0026thinsp;=\u0026thinsp;546)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTwo- bars group (n\u0026thinsp;=\u0026thinsp;546)\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\u003e\u003cb\u003eAge (years, median, Q3-Q1)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e16 (20\u0026thinsp;\u0026minus;\u0026thinsp;14)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18 (23\u0026thinsp;\u0026minus;\u0026thinsp;15)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.08\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSex, n (%)\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e- male\u003c/b\u003e,\u003c/p\u003e \u003cp\u003e\u003cb\u003e- female\u003c/b\u003e,\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026minus;\u0026thinsp;446\u0026nbsp;(81.6%),\u003c/p\u003e \u003cp\u003e\u0026minus;\u0026thinsp;100 (18.4%),\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e422 (77.3%),\u003c/p\u003e \u003cp\u003e124 (22.8%),\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP\u0026thinsp;=\u0026thinsp;0.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eBMI (kg/m2, median)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e19,6 (21.5\u0026ndash;18.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e19.8\u0026nbsp;(21.9\u0026ndash;18.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.440\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFEV1% (median)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e91.1 (101 \u0026minus;\u0026thinsp;82.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e91 (100.5\u0026ndash;82.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.562\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003epre-operative Haller index (median)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.6 (4.0-2.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.8 (4.4-3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.07\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003epost-operative Haller Index\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.6 (2.8\u0026ndash;2.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.6 (2.9\u0026ndash;2.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.650\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eComplications\u003c/b\u003e\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\u003etotal numer of the complications\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e84 (15.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e156 (28.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epneumothorax\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e34 (6.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e61 (11.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e0.004\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ehematoma\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4 (0.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e20 (3.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epleural effusion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e17 (3.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e58 (10.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eadditional drainage\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e29 (5.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e75 (13.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ethoracocenthesis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e16 (2.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e47 (8.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ebar displacement\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4 (0.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e21 (3.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ewound infection\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3 (0.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2 (0.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epain in the chest\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5 (0.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11 (2.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.131\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003efever\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e21 (3.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e36 (6.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e0.041\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003edeformation reccurence\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9 (1.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9 (1.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.99\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003elack of corrections\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3 (0.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4 (0.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ere-hospitalization\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e23 (4.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e45 (8.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e0.06\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ereoperation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e19 (3.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e39 (7.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e0.07\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eother complications\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14 (2.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e19 (3.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.374\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\u003e \u003c/p\u003e \u003cp\u003eIn the two-bars group, postoperative complications were observed significantly more often (28.6% vs. 15.4%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), including pneumothorax (11.2% vs. 6.2%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), hemothorax (3.7% vs. 0.7%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), additional drainage (13.7% vs. 5.3%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), thoracentesis (8.6% vs. 2.9%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), bar rotation (3.8% vs. 0.7%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), pleural effusion (10.6% vs 3.1%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), and fever (6.6% vs 3.8%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.041).\u003c/p\u003e \u003cp\u003eIn the logistic regression analysis, the following factors were analyzed: age, sex, preoperative Haller index, BMI, and the number of bars used. Implantation of two corrective bars significantly increased the risk of postoperative complications (p\u0026thinsp;=\u0026thinsp;0.019), including hematoma (p\u0026thinsp;=\u0026thinsp;0.036), effusion (p\u0026thinsp;=\u0026thinsp;0.002), and the need for thoracentesis (p\u0026thinsp;=\u0026thinsp;0.013). The results of the logistic regression are presented in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eResults of the logistic regression. The influence of age, sex, BMI, pre-operative Haller index, and number of bars used on the occurrence of post-operative complications.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\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=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eType of the complication\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eOR (95% CI)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal number of the post-operative complications.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\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\u003e0.793\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.99 (0.916\u0026ndash;1.069)\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\u003e0.911\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.057(0.4-2.792)\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\u003e0.608\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.958 (0.814\u0026ndash;1.128)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epre-operative Haller index\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.606\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.094 (0.777\u0026ndash;1.542)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003enumber of bars used\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e0.019\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003e2.636 (1.172\u0026ndash;5.929)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePneumothorax\u003c/b\u003e\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 \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\u003e\u003cb\u003e0.049\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003e0.785 (0.617\u0026ndash;0.999)\u003c/b\u003e\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\u003e0.223\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2,399 (0.588\u0026ndash;9.794)\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\u003e0.274\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.862 (0.66\u0026ndash;1.125)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epre-operative Haller index\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.735\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.092 (0.655\u0026ndash;1.821)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003enumber of bars used\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.305\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.014 (0.528\u0026ndash;7.680)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHematoma\u003c/b\u003e\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 \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\u003e0.405\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.051 (0.934\u0026ndash;1.183)\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\u003e0.949\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.942 (0.155\u0026ndash;5.738)\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\u003e0.158\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.270 (0.911\u0026ndash;1.771)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epre-operative Haller index\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e0.026\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003e1.954 (1.082\u0026ndash;3.528)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003enumber of bars used\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e0.036\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003e6.874 (1.129\u0026ndash;41.844)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePleural effusion\u003c/b\u003e\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 \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\u003e0.977\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.002 (0.9-1.115)\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\u003e0.177\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.226 (0.026\u0026ndash;1.960)\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\u003e0.235\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.172 (0.902\u0026ndash;1.522)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epre-operative Haller index\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.727\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.120 (0.592\u0026ndash;2.119)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003enumber of bars used\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e0.002\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003e8.914 (2.243\u0026ndash;35.431)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAdditional drainage\u003c/b\u003e\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 \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\u003e\u003cb\u003e0.026\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003e0.783 (0.631\u0026ndash;0.971)\u003c/b\u003e\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\u003e0.343\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.944 (0.492\u0026ndash;7.681)\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\u003e0.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.988 (0.776\u0026ndash;1.257)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epre-operative Haller index\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.627\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.128 (0.695\u0026ndash;1.831)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003enumber of bars used\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.085\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.887 (0.864\u0026ndash;9.653)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eThoracocentesis\u003c/b\u003e\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 \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\u003e\u003cb\u003e0.024\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003e1.121 (1.015\u0026ndash;1.238)\u003c/b\u003e\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\u003e0.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.287 (0.05\u0026ndash;1.635)\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\u003e0.822\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.971 (0.755\u0026ndash;1.25)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epre-operative Haller index\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.190\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.379 (0.853\u0026ndash;2.228)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003enumber of bars used\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e0.013\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003e4.42 (1.369\u0026ndash;14.272)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eBar displacement\u003c/b\u003e\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 \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\u003e0.509\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.04 (-0.054-0.11)\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\u003e0.723\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.04 (-0.067-0.096)\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\u003e0.661\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.043 (-0.103-0.07)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epre-operative Haller index\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.306\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.026 (-0.08-0.025)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003enumber of bars used\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e0.048\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003e0.043 (0.001\u0026ndash;0.17)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFever\u003c/b\u003e\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 \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\u003e\u003cb\u003e0.049\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003e0.842 (0.708\u0026ndash;1.001)\u003c/b\u003e\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\u003e0.699\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.728 (0.143\u0026ndash;3.699)\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\u003e0.545\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.072 (0.854\u0026ndash;1.346)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epre-operative Haller index\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.127\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.54 (0.243\u0026ndash;1.201)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003enumber of bars used\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.954 (0.872\u0026ndash;10.009)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eWe found that patients who were operated on with one correction bar and those who received two correction bars achieved similar correction effects as measured by the Haller index. However, the use of two bars during the Nuss procedure was associated with a significantly higher incidence of complications, including hematoma, pleural effusion, and the necessity for thoracentesis.\u003c/p\u003e \u003cp\u003ePreparing the intercostal space for the insertion of an additional corrective bar may lead to postoperative complications such as hematoma or pleural effusion. These complications often necessitate decompression and thoracocentesis, as evidenced in our results. Therefore, in our center, the standard practice is to introduce one correction bar if the advancement of the deformation, anatomical considerations, and the patient's age permit. An additional bar is frequently added in older, taller, and more severely deformed patients.\u003c/p\u003e \u003cp\u003eSince the introduction of the Nuss procedure in the recent century \u003csup\u003e(10)\u003c/sup\u003e, the method has gained significant popularity and has undergone several modifications \u003csup\u003e(6,24)\u003c/sup\u003e. Initially, the method involved using a single bar for the majority of patients with PE. However, as the technique became more widespread, the surgical indications were broadened, particularly to encompass adult patients. In their case, multiple correction bars were often utilized \u003csup\u003e(6,25)\u003c/sup\u003e .\u003c/p\u003e \u003cp\u003eMoreover, the advancement of thoracoscopy and its potential for routine usage during correction bar insertion ensures the safety of the procedure and reduces the occurrence of severe complications \u003csup\u003e(26,27)\u003c/sup\u003e. The procedure yields favorable corrective outcomes for PE. While it is minimally invasive, it remains a surgical intervention associated with the potential for serious complications. The risk of complications increases with patient age or when utilizing multiple correction bars \u003csup\u003e(6,27\u0026ndash;29)\u003c/sup\u003e .\u003c/p\u003e \u003cp\u003eBar displacement remains one of the most severe complications following the Nuss procedure \u003csup\u003e(30)\u003c/sup\u003e. The incidence of this complication is estimated to range from 1.8\u0026ndash;16.6% \u003csup\u003e(10,31\u0026ndash;33)\u003c/sup\u003e, with reoperation required in 3.4\u0026ndash;27% of cases \u003csup\u003e(30)\u003c/sup\u003e. Several surgical methods are employed to prevent common mechanisms of bar displacement, such as bar flipping, lateral sliding, or hinge point disruption \u003csup\u003e(27)\u003c/sup\u003e. Most techniques facilitate the solid attachment of the bar to the ribs: stabilizers, bar fixation with stainless-steel wire or a shorter bar \u003csup\u003e(34\u0026ndash;36)\u003c/sup\u003e. Other common complications include postoperative pneumothorax, pleural effusion, pericardial effusion, hemothorax, and infectious complications \u003csup\u003e(6,27,29)\u003c/sup\u003e .\u003c/p\u003e \u003cp\u003eThe number of bars used remains a topic of discussion, with some centers considering the insertion of two correction bars as a standard practice. Stanfill et al. emphasized in their study the efficacy of the Nuss procedure employing two corrective bars to mitigate bar rotation and enhance bar stability \u003csup\u003e(30)\u003c/sup\u003e. However, they involved relatively small sample sizes of 58 and 27 patients, which were also unequal in size. In our propensity score-matched analysis, we observed a statistically significant higher incidence of bar rotation in the two-bars group. A similar finding was reported by Uemura et al., who used two bars with lateral stabilizing in high-risk patients \u003csup\u003e(37)\u003c/sup\u003e .\u003c/p\u003e \u003cp\u003eConversely, achieving satisfactory correction of deep sternal depression in PE often requires the use of two corrective bars. Chen et al. noted more infections in patients who underwent insertion of two corrective bars \u003csup\u003e(17)\u003c/sup\u003e. Furthermore, they emphasized the importance of lower weight and the value of the Haller index as essential risk factors that elevate the likelihood of severe infections. They suggested a cut-off point of 50 kilograms as the target group of patients who can be safely and effectively undergo surgery with two correction bars \u003csup\u003e(17)\u003c/sup\u003e .\u003c/p\u003e \u003cp\u003eAn important challenge in corrective PE surgery is the issue of operating on adult patients. It is recommended to perform surgery on younger individuals, particularly adolescents aged 12\u0026ndash;16 \u003csup\u003e(18,19)\u003c/sup\u003e, as they tend to experience better cosmetic outcomes and fewer serious complications. This is attributed to the constitution of the skeletal system and anatomical factors, which contribute to a higher frequency of post-operative complications in adults \u003csup\u003e(6,27)\u003c/sup\u003e. However, experienced centers also operate on adult patients, using two corrective bars as a standard and only sporadically using two-bars in adolescents \u003csup\u003e(38)\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eBen et al. \u003csup\u003e(39)\u003c/sup\u003e reviewed the effect of treatment on 153 patients with significantly asymmetric PE who underwent multiple-bar Nuss operations. However, their study exhibits a notable disparity in the size of the compared groups: 151 patients received treatment with two bars, while only 2 cases were treated with three bars. The authors obtained favorable results: displacement of a bar only in one case, bar exposure in seven cases, and high scores in post-operative satisfaction questionnaires. The authors of the study recommend the multiple-bar Nuss operation for patients with significantly deformed PE as a safe and effective method that yields optimal cosmetic results \u003csup\u003e(39)\u003c/sup\u003e. Although the authors acknowledge that one bar may suffice in many cases, they emphasize the superiority of employing two bars to achieve better cosmetic outcomes in both the lying and standing positions \u003csup\u003e(39)\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eIn their compelling study, Nagaso et al. \u003csup\u003e(40)\u003c/sup\u003e conducted a detailed analysis of postoperative pain in patients undergoing the Nuss procedure with the implantation of one or two corrective bars. They used a patient-controlled anesthetic system to assess the requirement for painkillers in both groups and observed more severe pain in the single-bar group. Furthermore, they performed a biomechanical analysis, revealing that utilizing double bars reduces stress on the thoraces. The authors recommend double-bar application for patients with advanced PE and difficult correction conditions. Such treatment ensures more effective cosmetic results, reduces postoperative pain, and improves the biomechanical correction conditions. However, their study involved very small groups of 14 vs. 10 patients. According to Nagaso's study \u003csup\u003e(40)\u003c/sup\u003e, more favorable biomechanics of correction using double-bar correction causes pressure dispersion. According to the authors, it minimizes the possibility of displacement of the bar. In our study on a very large group of patients, it is difficult for us to agree - we found that in the case of double-bar correction, rotation of one of the bars occurred more often.\u003c/p\u003e \u003cp\u003eLo et al. analyzed a cohort comprising nearly 300 patients, with a majority undergoing the use of two or even three correction bars. By employing bilateral thoracoscopy for precise assessment of intraoperative deformation, they achieved an overall complication rate of 6.8%. Notably, they found that the postoperative complications rate was significantly related only to the Haller index \u003csup\u003e(24)\u003c/sup\u003e. Bar displacement necessitating reoperation emerged as the most common complication reported in their study. Early complications included pneumonia, delayed pleural effusion, and postoperative wound infections, while late complications involved chronic postoperative pain. Although patients with three bars experienced longer hospital stays, the difference was not statistically significant \u003csup\u003e(24)\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe authors acknowledge several limitations of the study. Firstly, our study has the character of a retrospective cohort study. Our study has no precise indications for using one or two corrective bars in patients. For the most part, the decision was based on the surgeon's experience as well as the patient's pre-operative imaging and physical examination. Consequently, there exists a possibility of selective bias. The surgeries were performed in a high-volume center by an experienced team of 2\u0026ndash;3 thoracic surgeons. To enhance the reliability of the data analysis, Propensity Score Matching was employed, incorporating key confounders mentioned in the literature to calculate predictive probabilities. Additionally, the study included one of the largest cohorts available, comprising over 1,000 patients operated on in a single center. While this is a single-center study, it draws upon multi-years of experience, thereby enriching the depth of the findings.\u003c/p\u003e"},{"header":"CONCLUSIONS","content":"\u003cp\u003e \u003col\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eThe utilization of two correction bars during the Nuss procedure is associated with a higher rate of severe postoperative complications.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eThe correction effects assessed by the Haller index demonstrated similarity across both patient groups, irrespective of the number of correction bars employed.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eIf the anatomical conditions are sufficient to achieve optimal correction, employing a single correction bar should be considered the standard approach.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003c/ol\u003e \u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eDisclosures\u003c/h2\u003e \u003cp\u003eThe work presented in this publication was conducted with the participation of the Greater Poland Center of Digital Medicine. The Center is funded by the Medical Research Agency (S. Moniuszki 1A, 00\u0026ndash;014 Warsaw, Poland) grant number 2023/ABM/02/00007\u0026thinsp;\u0026minus;\u0026thinsp;00, financed from the state budget (29 999 256,00 PLN).\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eConceptualization, P.S. and K.P.; Data curation, M.R, T.D., M.Su. and M.S.; Formal analysis, P.S. and M.R.; Investigation, P.S., M.R. and M.Su.; Methodology, P.S and K.P.; Project administration, C.P.; Resources, M.R.; Software, P.S.; Supervision, K.P. and C.P.; Visualization, P.S.; Writing\u0026mdash;original draft, P.S. and K.P.; Writing\u0026mdash;review and editing, C.P., M.S., M.Su., K.P., M.R. and T.D. All authors have read and agreed to the published version of the manuscript.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe datasets used and/or analysed during the current study available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eBrochhausen C, Turial S, M\u0026uuml;ller FKP, et al. Pectus excavatum: history, hypotheses and treatment options. Interact Cardiovasc Thorac Surg 2012;14:801\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMcHam B, Winkler L. Pectus Carinatum (Pigeon Chest). StatPearls, Treasure Island (FL): StatPearls Publishing; 2019.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFokin AA, Steuerwald NM, Ahrens WA, Allen KE. Anatomical, histologic, and genetic characteristics of congenital chest wall deformities. 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Ann Thorac Surg 2016;102:1711\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSnel BJ, Spronk CA, Werker PMN, van der Lei B. Pectus excavatum reconstruction with silicone implants: long-term results and a review of the english-language literature. Ann Plast Surg 2009;62:205\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHaecker F-M, Sesia SB. Intraoperative use of the vacuum bell for elevating the sternum during the Nuss procedure. J Laparoendosc Adv Surg Tech A 2012;22:934\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHaecker F-M. The vacuum bell for conservative treatment of pectus excavatum: the Basle experience. Pediatr Surg Int 2011;27:623\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNuss D, Kelly RE, Croitoru DP, Katz ME. A 10-year review of a minimally invasive technique for the correction of pectus excavatum. J Pediatr Surg 1998;33:545\u0026ndash;52.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNuss D. Recent experiences with minimally invasive pectus excavatum repair \u0026ldquo;Nuss procedure.\u0026rdquo; Jpn J Thorac Cardiovasc Surg Off Publ Jpn Assoc Thorac Surg Nihon Kyobu Geka Gakkai Zasshi 2005;53:338\u0026ndash;44.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNuss D. Minimally invasive surgical repair of pectus excavatum. Semin Pediatr Surg 2008;17:209\u0026ndash;17.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMolik KA, Engum SA, Rescorla FJ, West KW, Scherer LR, Grosfeld JL. Pectus excavatum repair: experience with standard and minimal invasive techniques. J Pediatr Surg 2001;36:324\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRavitch MM. The Operative Treatment of Pectus Excavatum. Ann Surg 1949;129:429\u0026ndash;44.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAkhtar M, Razick DI, Saeed A, et al. Complications and Outcomes of the Nuss Procedure in Adult Patients: A Systematic Review. Cureus n.d.;15:e35204.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGarzi A, Prestipino M, Rubino MS, Di Crescenzo RM, Calabr\u0026ograve; E. Complications of the \u0026ldquo;Nuss Procedure\u0026rdquo; In Pectus Excavatum. Transl Med UniSa 2020;22:24\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen HYM, Cheng WYR, Chan H, Ng WS. Associated risk factors for patients undergoing a unique or double Nuss bar placement for pectus excavatum. Asian Cardiovasc Thorac Ann 2023;31:221\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKelly RE, Goretsky MJ, Obermeyer R, et al. Twenty-one years of experience with minimally invasive repair of pectus excavatum by the Nuss procedure in 1215 patients. Ann Surg 2010;252:1072\u0026ndash;81.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFrantz FW. Indications and guidelines for pectus excavatum repair. Curr Opin Pediatr 2011;23:486\u0026ndash;91.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKhanna G, Jaju A, Don S, Keys T, Hildebolt CF. Comparison of Haller index values calculated with chest radiographs versus CT for pectus excavatum evaluation. Pediatr Radiol 2010;40:1763\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRattan AS, Laor T, Ryckman FC, Brody AS. Pectus excavatum imaging: enough but not too much. Pediatr Radiol 2010;40:168\u0026ndash;72.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMueller C, Saint-Vil D, Bouchard S. Chest x-ray as a primary modality for preoperative imaging of pectus excavatum. J Pediatr Surg 2008;43:71\u0026ndash;3.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRice HE, Frush DP, Farmer D, Waldhausen JH, APSA Education Committee. Review of radiation risks from computed tomography: essentials for the pediatric surgeon. J Pediatr Surg 2007;42:603\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLo P-C, Tzeng I-S, Hsieh M-S, Yang M-C, Wei B-C, Cheng Y-L. The Nuss procedure for pectus excavatum: An effective and safe approach using bilateral thoracoscopy and a selective approach to use multiple bars in 296 adolescent and adult patients. PLoS ONE 2020;15:e0233547.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJaroszewski DE, Ewais MM, Chao C-J, et al. Success of Minimally Invasive Pectus Excavatum Procedures (Modified Nuss) in Adult Patients (\u0026ge;\u0026thinsp;30 Years). Ann Thorac Surg 2016;102:993\u0026ndash;1003.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHanna WC, Ko MA, Blitz M, Shargall Y, Compeau CG. Thoracoscopic Nuss procedure for young adults with pectus excavatum: excellent midterm results and patient satisfaction. Ann Thorac Surg 2013;96:1033\u0026ndash;6; discussion 1037\u0026ndash;1038.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCheng Y-L, Lee S-C, Huang T-W, Wu C-T. Efficacy and safety of modified bilateral thoracoscopy-assisted Nuss procedure in adult patients with pectus excavatum. Eur J Cardio-Thorac Surg Off J Eur Assoc Cardio-Thorac Surg 2008;34:1057\u0026ndash;61.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eErşen E, Demirkaya A, Kılı\u0026ccedil; B, et al. Minimally invasive repair of pectus excavatum (MIRPE) in adults: is it a proper choice? Wideochirurgia Inne Tech Maloinwazyjne Videosurgery Miniinvasive Tech 2016;11:98\u0026ndash;104.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang D-K, Tang J-M, Ben X-S, et al. Surgical correction of 639 pectus excavatum cases via the Nuss procedure. J Thorac Dis 2015;7:1595\u0026ndash;605.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStanfill AB, DiSomma N, Henriques SM, Wallace LJ, Vegunta RK, Pearl RH. Nuss procedure: decrease in bar movement requiring reoperation with primary placement of two bars. J Laparoendosc Adv Surg Tech A 2012;22:412\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHebra A, Swoveland B, Egbert M, et al. Outcome analysis of minimally invasive repair of pectus excavatum: review of 251 cases. J Pediatr Surg 2000;35:252\u0026ndash;7; discussion 257\u0026ndash;258.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePark HJ, Lee SY, Lee CS, Youm W, Lee KR. The Nuss procedure for pectus excavatum: evolution of techniques and early results on 322 patients. Ann Thorac Surg 2004;77:289\u0026ndash;95.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePilegaard HK, Licht PB. Early results following the Nuss operation for pectus excavatum\u0026ndash;a single-institution experience of 383 patients. Interact Cardiovasc Thorac Surg 2008;7:54\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePark HJ, Chung W-J, Lee IS, Kim KT. Mechanism of bar displacement and corresponding bar fixation techniques in minimally invasive repair of pectus excavatum. J Pediatr Surg 2008;43:74\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHebra A, Gauderer MW, Tagge EP, Adamson WT, Othersen HB. A simple technique for preventing bar displacement with the Nuss repair of pectus excavatum. J Pediatr Surg 2001;36:1266\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNuss D, Croitoru DP, Kelly RE, Goretsky MJ, Nuss KJ, Gustin TS. Review and discussion of the complications of minimally invasive pectus excavatum repair. Eur J Pediatr Surg Off J Austrian Assoc Pediatr Surg Al Z Kinderchir 2002;12:230\u0026ndash;4.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eUemura S, Nakagawa Y, Yoshida A, Choda Y. Experience in 100 cases with the Nuss procedure using a technique for stabilization of the pectus bar. Pediatr Surg Int 2003;19:186\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKim DH, Hwang JJ, Lee MK, Lee DY, Paik HC. Analysis of the Nuss Procedure for Pectus Excavatum in Different Age Groups. Ann Thorac Surg 2005;80:1073\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBen XS, Deng C, Tian D, et al. Multiple-bar Nuss operation: an individualized treatment scheme for patients with significantly asymmetric pectus excavatum. J Thorac Dis\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNagaso T, Miyamoto J, Kokaji K, et al. Double-bar application decreases postoperative pain after the Nuss procedure. J Thorac Cardiovasc Surg 2010;140:39\u0026ndash;44.e2.\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":"Nuss procedure, Pectus Excavatum, corrective bars, Haller Index, bar rotation","lastPublishedDoi":"10.21203/rs.3.rs-4577876/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4577876/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe Nuss procedure is the most common corrective surgery for pectus excavatum. We analyzed treatment outcomes and complication rates in 1,247 patients treated with the Nuss procedure from 2002 to 2021, focusing on the number of corrective bars used.\u003c/p\u003e \u003cp\u003eUsing Propensity Score Matching based on age, sex, BMI, pre-operative FEV1, and the Haller index, we created two groups: 546 patients with a single bar and 546 with two bars.\u003c/p\u003e \u003cp\u003eBoth groups achieved similar correction effects (Haller index: single bar =\u0026thinsp;2.58 vs. two bars\u0026thinsp;=\u0026thinsp;2.56; p\u0026thinsp;=\u0026thinsp;0.65). In the univariate analysis, in the two-bar group, the postoperative complications were observed more often (28.6% vs. 15.4%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), including pneumothorax (11.2% vs. 6.2%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), hemothorax (3.7% vs. 0.7%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), additional drainage (13.7% vs. 5.3%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), the need for thoracentesis (8.6% vs. 2.9%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), bar displacement (3.8% vs. 0.7%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), pleural effusion (10.6% vs 3.1%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), and fever (6.6% vs 3.8%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.041). In the logistic regression, two bars significantly increased the risk of postoperative complications (p\u0026thinsp;=\u0026thinsp;0.019), including hematoma (p\u0026thinsp;=\u0026thinsp;0.036), pleural effusion (p\u0026thinsp;=\u0026thinsp;0.002), and the need for thoracentesis (p\u0026thinsp;=\u0026thinsp;0.013).\u003c/p\u003e \u003cp\u003eUsing two corrective bars during the Nuss procedure is associated with a higher rate of postoperative complications but similar corrective results.\u003c/p\u003e","manuscriptTitle":"The number of bars in the Nuss procedure: treatment outcomes and complications. A large single-center Propensity Score Matched cohort study. 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