Disturbingly high fracture rate of STRATOS bars in pectus corrections

Disturbingly high fracture rate of STRATOS bars in pectus corrections Abstract OBJECTIVES Several procedures have been described to correct pectus excavatum and carinatum. We have used a modified Ravitch procedure (STRATOS titanium bars) for patients who were unsuitable for the minimally invasive Nuss procedure. The operation produced excellent cosmetic results, but we have noted several fractures and displacements of the STRATOS bars. METHODS We reviewed all our STRATOS patients since first use in 2009 until 2014. We collated the following data of each patient: diagnosis, severity of pectus deformity, comorbidity, previous operations for pectus, age at bar implantation, the number of bars implanted and duration of implantation. Patients with severe comorbidity were excluded. RESULTS Between 2009 and 2014, 39 patients were treated for pectus deformities using the STRATOS bars. Twelve of 39 patients (31%) were identified as having bar(s) broken before removal. There were no significant differences between patients with fractured bars and those without, except for the number of bars implanted (P = 0.016) CONCLUSIONS This incidence of bar fracture is unexpectedly high, although the literature on this topic is sparse. The high fracture rate is alarming, because of its unpredictability and lack of clear aetiological factors. The operation is done (largely) for psychosocial and cosmetic reasons, and therefore, we must have complete confidence in the quality of the bars used in teenage pectus patients. We raise the issue to warn other units and encourage them to report bar fracture rates. Pectus , Paediatric , Chest wall , Patient safety , Surgical equipment INTRODUCTION Several procedures have been described for the correction of pectus excavatum (PE) and pectus carinatum (PC). Among them are various versions of the Ravitch procedure [1], of which the most recent is the STRATOS procedure using the Strasbourg Thorax Osteosyntheses System equipment from MedXpert GmbH, Heitersheim, Germany [2]. This equipment has the advantage of being very simple to use and supports the reconstructed anterior chest wall with 1 or 2 titanium bars clamped to the ribs by special adaptors. We have employed this technique since 2009 in patients we considered unsuitable for the more usual minimally invasive Nuss procedure, as per the unit policy. Therefore, the majority of the patients who undergo the STRATOS procedure are diagnosed with PC. In our centre, the open correction of chest wall deformities is done through a bilateral submammary skin incision and elevation of the pectoralis major, followed by resection of the cartilages accordingly to the modified Ravitch procedure. The STRATOS equipment is implanted by passing the titanium bar(s) behind (in case of PE) or in front (in case of PC) of the sternum, attaching to fixing clips on the rib(s) bilaterally. The operation has produced excellent cosmetic results and high patient satisfaction, but recently we have noted several fractures and displacements of the titanium bars used in the STRATOS system, and we report these in this article. Asymptomatic bar fractures were noted occasionally, but by mid-2014, our perception was that the incidence seemed rather high, and a few patients presented with symptoms, thus we decided retrospectively to review all our patients since we started implanting the STRATOS bars in 2009. MATERIALS AND METHODS This retrospective review was approved by the clinical governance and safety team of the Great Ormond Street Hospital for Children (GOSH). Patient records of all patients who had the STRATOS bar(s) implanted between January 2009 and December 2014 were used for examining clinical notes, operation records and X-rays. We collated the following data from each patient: diagnosis, severity of pectus deformity, comorbidity, previous operations for pectus, age at bar implantation, the number of bars implanted, duration of implantation (defined as the time from the implantation operation until the removal operation or until the time of diagnosis of bar fracture based on the X-ray) and any relevant symptoms. In addition to pectus patients, the STRATOS procedure is applied in our centre for the treatment of patients with Jeune syndrome. These patients were excluded from our study, as the bars are used to prolong the ribs instead of stabilizing the sternum. Pectus patients with comorbidity were included, and their additional diagnosis is listed in Table 1. As the true incidence of bar fracture became clear, we shared the data with the UK Medicines and Healthcare Products Regulatory Agency (London) and the manufacturer (see above). Also, after that moment, all broken bars were photographed and sent back to the manufacturer for analysis. Table 1: List of comorbidity patients with their diagnosis Patient number Diagnosis 1 Pectus excavatum and Treacher Collins syndrome 5 Pectus carinatum, LEOPARD syndrome, Von Willebrand disease and VSD 13 Pectus excavatum and recurrent clavicular subluxation 20 Pectus excavatum, extrinsic left main bronchus and oesophagus compression 22 Pectus carinatum and Charcot-Marie-Tooth disease 25 Pectus excavatum, aortic regurgitation, neurofibromatosis Type 1 and mild aortic root dilatation 26 Airway compression (complex pectus anomaly), thoracic-mediastinal abnormality and Kniest Syndrome 30 Pectus excavatum and aortic root replacement 32 Pectus excavatum and coagulation Factor VII deficiency 33 Pectus excavatum and subluxation of right sternoclavicular joint Patient number Diagnosis 1 Pectus excavatum and Treacher Collins syndrome 5 Pectus carinatum, LEOPARD syndrome, Von Willebrand disease and VSD 13 Pectus excavatum and recurrent clavicular subluxation 20 Pectus excavatum, extrinsic left main bronchus and oesophagus compression 22 Pectus carinatum and Charcot-Marie-Tooth disease 25 Pectus excavatum, aortic regurgitation, neurofibromatosis Type 1 and mild aortic root dilatation 26 Airway compression (complex pectus anomaly), thoracic-mediastinal abnormality and Kniest Syndrome 30 Pectus excavatum and aortic root replacement 32 Pectus excavatum and coagulation Factor VII deficiency 33 Pectus excavatum and subluxation of right sternoclavicular joint The patients with fractured bars are indicated in italics. VSD: ventricular septal defect. Table 1: List of comorbidity patients with their diagnosis Patient number Diagnosis 1 Pectus excavatum and Treacher Collins syndrome 5 Pectus carinatum, LEOPARD syndrome, Von Willebrand disease and VSD 13 Pectus excavatum and recurrent clavicular subluxation 20 Pectus excavatum, extrinsic left main bronchus and oesophagus compression 22 Pectus carinatum and Charcot-Marie-Tooth disease 25 Pectus excavatum, aortic regurgitation, neurofibromatosis Type 1 and mild aortic root dilatation 26 Airway compression (complex pectus anomaly), thoracic-mediastinal abnormality and Kniest Syndrome 30 Pectus excavatum and aortic root replacement 32 Pectus excavatum and coagulation Factor VII deficiency 33 Pectus excavatum and subluxation of right sternoclavicular joint Patient number Diagnosis 1 Pectus excavatum and Treacher Collins syndrome 5 Pectus carinatum, LEOPARD syndrome, Von Willebrand disease and VSD 13 Pectus excavatum and recurrent clavicular subluxation 20 Pectus excavatum, extrinsic left main bronchus and oesophagus compression 22 Pectus carinatum and Charcot-Marie-Tooth disease 25 Pectus excavatum, aortic regurgitation, neurofibromatosis Type 1 and mild aortic root dilatation 26 Airway compression (complex pectus anomaly), thoracic-mediastinal abnormality and Kniest Syndrome 30 Pectus excavatum and aortic root replacement 32 Pectus excavatum and coagulation Factor VII deficiency 33 Pectus excavatum and subluxation of right sternoclavicular joint The patients with fractured bars are indicated in italics. VSD: ventricular septal defect. RESULTS Between 2009 and 2014, 39 patients were treated for chest wall deformities with the implantation of the STRATOS bars. Table 2 summarizes the characteristics of all the patients. Twelve of the 39 patients (31%) treated with STRATOS for their pectus were identified as having bar(s) broken before removal. In 6 of these 12 patients, the broken bar was noticed only during a routine chest X-ray as part of the pre-bar removal protocol. Another 6 patients returned to our clinic early with the following symptoms: chest pain (3 patients), increased breathlessness (2), movement of the bar in the chest (2) and slight recurrence of chest wall deformity (1). The most common place of fracture was in the middle of the bar (42%), 29% of the fractures occurred at the connection between the bar and clip and 29% was identified at the angle of the clips. Table 2: Characteristics of patients treated using the STRATOS procedure Patient number Gender Comorbidity Diagnosis (PE/PC) Age at operation (years) Previous Nuss operation Number of bars Duration of implantation (months) Broken bar 1 Male Yes PE 21.5 Yes 2 71 2 Male No PE 18.0 Yes 1 62 3 Female No PE 18.1 Yes 2 39 4 Male No PC 15.0 No 2 49 5 Male Yes PC 17.2 No 2 44 6 Male No PC 15.0 No 2 15 Yes 7 Male No PE 16.5 Yes 2 33 8 Male No PC 16.8 No 1 41 9 Male No PC 18.5 No 2 25 Yes 10 Male No PC 16.3 No 2 36 11 Male No PC 18.8 No 2 23 12 Male No PC 14.7 No 2 38 Yes 13 Male Yes PE 15.5 No 2 38 14 Male No PC 18.0 No 2 36 15 Male No PC 16.7 No 2 32 16 Male No PC 15.5 No 2 24 Yes 17 Male No PE 15.1 Yes 1 27 18 Male No PC 14.1 No 1 28 Yes 19 Male No PC 18.0 No 1 27 Yes 20 Male Yes PE 4.3 No 1 28 Yes 21 Male No PC 16.3 No 2 29 22 Male Yes PC 16.3 No 1 28 23 Male No PC 17.6 No 1 27 24 Male No PC 15.0 No 1 26 25 Male Yes PE 16.3 No 1 25 26 Male Yes PC 12.8 No 1 11 27 Male No PC 15.6 No 1 23 28 Male No PE 15.8 Yes 1 18 Yes 29 Male No PE 15.6 No 1 14 30 Male Yes PE 4.8 No 1 19 Yes 31 Male No PC 16.3 No 1 17 32 Male Yes PE 17.9 Yes 1 16 Yes 33 Male Yes PE 16.6 No 1 17 34 Male No PE 16.1 No 1 0 35 Male No PE 19.8 No 1 4 Yes 36 Male No PC 17.6 No 1 5 37 Female No PC 15.3 Yes 1 4 Yes 38 Female No PC 14.9 No 2 2 39 Male No PC 19.1 No 1 2 Patient number Gender Comorbidity Diagnosis (PE/PC) Age at operation (years) Previous Nuss operation Number of bars Duration of implantation (months) Broken bar 1 Male Yes PE 21.5 Yes 2 71 2 Male No PE 18.0 Yes 1 62 3 Female No PE 18.1 Yes 2 39 4 Male No PC 15.0 No 2 49 5 Male Yes PC 17.2 No 2 44 6 Male No PC 15.0 No 2 15 Yes 7 Male No PE 16.5 Yes 2 33 8 Male No PC 16.8 No 1 41 9 Male No PC 18.5 No 2 25 Yes 10 Male No PC 16.3 No 2 36 11 Male No PC 18.8 No 2 23 12 Male No PC 14.7 No 2 38 Yes 13 Male Yes PE 15.5 No 2 38 14 Male No PC 18.0 No 2 36 15 Male No PC 16.7 No 2 32 16 Male No PC 15.5 No 2 24 Yes 17 Male No PE 15.1 Yes 1 27 18 Male No PC 14.1 No 1 28 Yes 19 Male No PC 18.0 No 1 27 Yes 20 Male Yes PE 4.3 No 1 28 Yes 21 Male No PC 16.3 No 2 29 22 Male Yes PC 16.3 No 1 28 23 Male No PC 17.6 No 1 27 24 Male No PC 15.0 No 1 26 25 Male Yes PE 16.3 No 1 25 26 Male Yes PC 12.8 No 1 11 27 Male No PC 15.6 No 1 23 28 Male No PE 15.8 Yes 1 18 Yes 29 Male No PE 15.6 No 1 14 30 Male Yes PE 4.8 No 1 19 Yes 31 Male No PC 16.3 No 1 17 32 Male Yes PE 17.9 Yes 1 16 Yes 33 Male Yes PE 16.6 No 1 17 34 Male No PE 16.1 No 1 0 35 Male No PE 19.8 No 1 4 Yes 36 Male No PC 17.6 No 1 5 37 Female No PC 15.3 Yes 1 4 Yes 38 Female No PC 14.9 No 2 2 39 Male No PC 19.1 No 1 2 PC: pectus carinatum; PE: pectus excavatum. Table 2: Characteristics of patients treated using the STRATOS procedure Patient number Gender Comorbidity Diagnosis (PE/PC) Age at operation (years) Previous Nuss operation Number of bars Duration of implantation (months) Broken bar 1 Male Yes PE 21.5 Yes 2 71 2 Male No PE 18.0 Yes 1 62 3 Female No PE 18.1 Yes 2 39 4 Male No PC 15.0 No 2 49 5 Male Yes PC 17.2 No 2 44 6 Male No PC 15.0 No 2 15 Yes 7 Male No PE 16.5 Yes 2 33 8 Male No PC 16.8 No 1 41 9 Male No PC 18.5 No 2 25 Yes 10 Male No PC 16.3 No 2 36 11 Male No PC 18.8 No 2 23 12 Male No PC 14.7 No 2 38 Yes 13 Male Yes PE 15.5 No 2 38 14 Male No PC 18.0 No 2 36 15 Male No PC 16.7 No 2 32 16 Male No PC 15.5 No 2 24 Yes 17 Male No PE 15.1 Yes 1 27 18 Male No PC 14.1 No 1 28 Yes 19 Male No PC 18.0 No 1 27 Yes 20 Male Yes PE 4.3 No 1 28 Yes 21 Male No PC 16.3 No 2 29 22 Male Yes PC 16.3 No 1 28 23 Male No PC 17.6 No 1 27 24 Male No PC 15.0 No 1 26 25 Male Yes PE 16.3 No 1 25 26 Male Yes PC 12.8 No 1 11 27 Male No PC 15.6 No 1 23 28 Male No PE 15.8 Yes 1 18 Yes 29 Male No PE 15.6 No 1 14 30 Male Yes PE 4.8 No 1 19 Yes 31 Male No PC 16.3 No 1 17 32 Male Yes PE 17.9 Yes 1 16 Yes 33 Male Yes PE 16.6 No 1 17 34 Male No PE 16.1 No 1 0 35 Male No PE 19.8 No 1 4 Yes 36 Male No PC 17.6 No 1 5 37 Female No PC 15.3 Yes 1 4 Yes 38 Female No PC 14.9 No 2 2 39 Male No PC 19.1 No 1 2 Patient number Gender Comorbidity Diagnosis (PE/PC) Age at operation (years) Previous Nuss operation Number of bars Duration of implantation (months) Broken bar 1 Male Yes PE 21.5 Yes 2 71 2 Male No PE 18.0 Yes 1 62 3 Female No PE 18.1 Yes 2 39 4 Male No PC 15.0 No 2 49 5 Male Yes PC 17.2 No 2 44 6 Male No PC 15.0 No 2 15 Yes 7 Male No PE 16.5 Yes 2 33 8 Male No PC 16.8 No 1 41 9 Male No PC 18.5 No 2 25 Yes 10 Male No PC 16.3 No 2 36 11 Male No PC 18.8 No 2 23 12 Male No PC 14.7 No 2 38 Yes 13 Male Yes PE 15.5 No 2 38 14 Male No PC 18.0 No 2 36 15 Male No PC 16.7 No 2 32 16 Male No PC 15.5 No 2 24 Yes 17 Male No PE 15.1 Yes 1 27 18 Male No PC 14.1 No 1 28 Yes 19 Male No PC 18.0 No 1 27 Yes 20 Male Yes PE 4.3 No 1 28 Yes 21 Male No PC 16.3 No 2 29 22 Male Yes PC 16.3 No 1 28 23 Male No PC 17.6 No 1 27 24 Male No PC 15.0 No 1 26 25 Male Yes PE 16.3 No 1 25 26 Male Yes PC 12.8 No 1 11 27 Male No PC 15.6 No 1 23 28 Male No PE 15.8 Yes 1 18 Yes 29 Male No PE 15.6 No 1 14 30 Male Yes PE 4.8 No 1 19 Yes 31 Male No PC 16.3 No 1 17 32 Male Yes PE 17.9 Yes 1 16 Yes 33 Male Yes PE 16.6 No 1 17 34 Male No PE 16.1 No 1 0 35 Male No PE 19.8 No 1 4 Yes 36 Male No PC 17.6 No 1 5 37 Female No PC 15.3 Yes 1 4 Yes 38 Female No PC 14.9 No 2 2 39 Male No PC 19.1 No 1 2 PC: pectus carinatum; PE: pectus excavatum. The median age of the patients was 16.3 years (range 4.3–21.5 years). For patients with intact bars, the median age (range) was 15.4 years (4.3–19.8 years) compared to patients with broken bars 16.3 years (12.8–21.5 years). There was no significant difference between groups (P = 0.17). There was no significant difference in the incidence of bar fracture between patients with PC or PE as well (P = 0.72). There is no evidence that the bar fractures are related to comorbidity as only 3 of 10 patients with comorbidity had a broken bar (33% vs 31% without comorbidity). Twenty-nine patients had the STRATOS procedure as their first correction of chest wall deformity, 8 patients had a previous correction with the Nuss bar and 2 patients had a previous open correction without bars. There was no significance in bar failures between the patients with failed Nuss procedure attempts and other patients (P = 0.60). There was no significant difference in incidence of bar fractures in relation to the duration of implantation between fractured and intact bars (P = 0.12). For patients with intact bars, the median duration of implantation was 27 months (0–71 months), as compared to patients with broken bars where the median duration was 22 months (4–38 months). The number of fractures in patients with 1 bar was twice as high as seen in 8 of 19 (42%) as against those with more than 1 bar [4/20 (20%) fractures], and this was statistically significant (P = 0.02). DISCUSSION The STRATOS bars were first described by Wihlm et al. [2] in 2007 for the use in chest wall deformities, severe chest traumas and reconstructive surgery following chest wall tumours. The bar is made of pure titanium and is hold in place by metal clips which are placed on the ribs. There have been 3 previous reports, in which the STRATOS bars were broken during follow-up [3–5], a total of 3 patients altogether. Stefani et al. described a 20-year old man treated for PE; his bar broke on the left angle. The possible explanation they offered was that the pressure the sternum applied over the bar finally caused the rupture, favoured by the manoeuvre of angulation of the joint [3]. Berthet et al. [4] reported 2 patients who had fractured bars, and they underwent chest wall reconstruction after non-small-cell lung cancer removal. Both patients experienced a delayed rupture of the titanium bar (STRATOS) at the joint. In the first study with the STRATOS bars by Wihlm et al. [2], there were no fractures in any of the 14 patients. One possible explanation is that they implanted 2 bars in each patient, but as we have seen in our patient group, this is not a guarantee that the bars will not break. Another explanation is that they published only the short-term results. In 2015, Berthet et al. reported deformations (anteroposterior bending) of the STRATOS implants in 17 of the 20 patients treated for chest wall deformities. In total, they found 13 fractures in 47 patients (28%), and this included patients for chest wall reconstruction after tumour removal as well [5]. Various explanations can be offered as to why a bar might break, ranging from excessive sternal pressure (Stefani et al.), poor insertion technique, the use of too few bars (Whilm et al. used 2 bars in the patients he described in 2007) or failure of the equipment itself. Any of the combined tensile or compressive and torsional force could result in excessive force, leading to rubbing and loosening at the site, which may subsequently release large quantities of titanium into the surrounding tissues [6]. In our series, we were unable to identify a clear individual cause in any of the patients. The only significant difference in fracture rates was related to the number of bars used. However, even implanting 2 bars does not guarantee success as 20% of our patients with 2 bars had at least 1 broken bar. It could potentially be that we used a poor technique for inserting the bars—manipulating the bar and the fixing clips too much during implantation caused it to lose strength over time and eventually break. An argument can be made for this hypothesis as 4 of the 14 fractures (29%) occurred in the angle of the fixing clips, and this part is frequently adjusted during implantation to position the bar correctly. However, the high rate of fractures (42%) in the middle of the bar challenges this hypothesis (Fig. 1). While the angles of the clip are often manipulated during surgery and thus could be weakened, the middle of the bar is barely handled during the procedure. The remaining 29% of the fractures was identified at the connection between the bar and the fixing clips. This part is secured with an implant crimping pliers, although this requires very limited force to attach. Figure 1: View largeDownload slide Overview of STRATOS bar fractures (with permission from MedXpert). Figure 1: View largeDownload slide Overview of STRATOS bar fractures (with permission from MedXpert). None of the patients reported trauma or an occasion where their chest became exposed to a force of high magnitude. One patient described that he felt his bar break when he took a morning stretch and another patient while rowing—the only record of severe exercise being related to bar fracture. We advise our patients to stay away from contact sport for the duration of the bar in situ for the initial 6 months, but expect them to function normally after 6 months. Because of the lack of evidence on acute injury causing the fractures, we considered the possibility that the fractures were caused by constant force of the displaced chest wall on the bars and clips. There was no significant difference in the incidence rate of bar fractures between the PE and PC patients, thus the hypothesis of constant chest wall pressure causing the fractures is questionable. By the end of 2014, we had implanted the STRATOS bars in 39 patients and removed again in 21 patients, and in 14 patients, this was done as routinely planned. The other 7 patients had their bar removed at an earlier stage than initially planned due to complications; in 6 of these patients, this was due to the fractured bar(s). Except for 1 patient (104 days), the duration between the discovery on X-ray and the removal of the fractured bar was less than 1 month (1–27 days). None of the patients with fractured bar(s) required emergency surgery because of complications, and none of the patients reported significant recurrence that required a new operation. Besides the bar fractures, we had another major complication requiring reoperation 1 month after implantation. This was due to a pneumothorax caused by a non-fractured loose bar, and during the reoperation, we replaced the bar and the new bar has not been removed as of December 31, 2014. Although the follow-up period is still short, we have had no patients requesting new surgery after the removal of the bar, as recurrence was none or minimal. The high fracture rate is very alarming, especially because of their unpredictability and lack of clear aetiological factors. The operation is done (largely) for psychosocial and cosmetic reasons, and therefore, we must have complete confidence in the quality of the bars used in teenage pectus patients. In our series, 6 of the 12 patients with fractured bar(s) had no symptoms on discovery of the fractured bar on X-ray, and the other 6 patients reported only mild symptoms as chest pain, breathlessness and movement in the chest. Although these symptoms were relatively mild, a fractured metal bar can result in sharp metal edges, which have the potential to perforate internal organs such as the lung or even the heart [7], and the proximity to both intercostal and internal mammary vessels is also important. As a result of this review, we have placed a moratorium on the use of this equipment until more data become available. ACKNOWLEDGEMENTS We thank MedXpert GmbH for their cooperation. Conflict of interest: none declared. REFERENCES 1 Ravitch M. The operative treatment of pectus excavatum . Ann Surg 1949 ; 129 : 429 – 44 . Google Scholar CrossRef Search ADS PubMed 2 Wihlm JM , Grosdidier G , Chapelier A. Thoracic osteosyntheses for chest wall malformations, traumas and tumors using the STRATOS titanium system: initial experience . Interact CardioVasc Thorac Surg 2007 ; 6 : 273 . 3 Stefani A , Nesci J , Morandi U. STRATOS™ system for the repair of pectus excavatum . Interact CardioVasc Thorac Surg 2013 ; 17 : 1056 – 8 . Google Scholar CrossRef Search ADS PubMed 4 Berthet JP , Canaud L , D’Annoville T , Alric P , Marty-Ane CH. Titanium plates and Dual-Mesh: a modern combination for reconstructing very large chest wall defects . Ann Thorac Surg 2011 ; 91 : 1709 – 16 . Google Scholar CrossRef Search ADS PubMed 5 Berthet JP , Gomez Caro AG , Solovei L , Gilbert M , Bommart S , Gaudard P et al. Titanium implant failure after chest wall osteosynthesis . Ann Thorac Surg 2015 ; 99 : 1945 – 52 . Google Scholar CrossRef Search ADS PubMed 6 Sharma PK , Willems TP , Touw DJ , Woudstra W , Erasmus ME , Ebels T. Implant failure: STRATOS system for pectus repair . Ann Thorac Surg 2017 ; 103 : 1536 – 43 . Google Scholar CrossRef Search ADS PubMed 7 Zhang R , Hagl C , Bobylev D , Breymann T , Schmitto JD , Haverich A et al. Intrapericardial migration of dislodged sternal struts as late complication of open pectus excavatum repairs . J Cardiothorac Surg 2011 ; 6 : 40. Google Scholar CrossRef Search ADS PubMed © The Author(s) 2018. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png European Journal of Cardio-Thoracic Surgery Oxford University Press

Disturbingly high fracture rate of STRATOS bars in pectus corrections

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Oxford University Press
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© The Author(s) 2018. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
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Abstract

Abstract OBJECTIVES Several procedures have been described to correct pectus excavatum and carinatum. We have used a modified Ravitch procedure (STRATOS titanium bars) for patients who were unsuitable for the minimally invasive Nuss procedure. The operation produced excellent cosmetic results, but we have noted several fractures and displacements of the STRATOS bars. METHODS We reviewed all our STRATOS patients since first use in 2009 until 2014. We collated the following data of each patient: diagnosis, severity of pectus deformity, comorbidity, previous operations for pectus, age at bar implantation, the number of bars implanted and duration of implantation. Patients with severe comorbidity were excluded. RESULTS Between 2009 and 2014, 39 patients were treated for pectus deformities using the STRATOS bars. Twelve of 39 patients (31%) were identified as having bar(s) broken before removal. There were no significant differences between patients with fractured bars and those without, except for the number of bars implanted (P = 0.016) CONCLUSIONS This incidence of bar fracture is unexpectedly high, although the literature on this topic is sparse. The high fracture rate is alarming, because of its unpredictability and lack of clear aetiological factors. The operation is done (largely) for psychosocial and cosmetic reasons, and therefore, we must have complete confidence in the quality of the bars used in teenage pectus patients. We raise the issue to warn other units and encourage them to report bar fracture rates. Pectus , Paediatric , Chest wall , Patient safety , Surgical equipment INTRODUCTION Several procedures have been described for the correction of pectus excavatum (PE) and pectus carinatum (PC). Among them are various versions of the Ravitch procedure [1], of which the most recent is the STRATOS procedure using the Strasbourg Thorax Osteosyntheses System equipment from MedXpert GmbH, Heitersheim, Germany [2]. This equipment has the advantage of being very simple to use and supports the reconstructed anterior chest wall with 1 or 2 titanium bars clamped to the ribs by special adaptors. We have employed this technique since 2009 in patients we considered unsuitable for the more usual minimally invasive Nuss procedure, as per the unit policy. Therefore, the majority of the patients who undergo the STRATOS procedure are diagnosed with PC. In our centre, the open correction of chest wall deformities is done through a bilateral submammary skin incision and elevation of the pectoralis major, followed by resection of the cartilages accordingly to the modified Ravitch procedure. The STRATOS equipment is implanted by passing the titanium bar(s) behind (in case of PE) or in front (in case of PC) of the sternum, attaching to fixing clips on the rib(s) bilaterally. The operation has produced excellent cosmetic results and high patient satisfaction, but recently we have noted several fractures and displacements of the titanium bars used in the STRATOS system, and we report these in this article. Asymptomatic bar fractures were noted occasionally, but by mid-2014, our perception was that the incidence seemed rather high, and a few patients presented with symptoms, thus we decided retrospectively to review all our patients since we started implanting the STRATOS bars in 2009. MATERIALS AND METHODS This retrospective review was approved by the clinical governance and safety team of the Great Ormond Street Hospital for Children (GOSH). Patient records of all patients who had the STRATOS bar(s) implanted between January 2009 and December 2014 were used for examining clinical notes, operation records and X-rays. We collated the following data from each patient: diagnosis, severity of pectus deformity, comorbidity, previous operations for pectus, age at bar implantation, the number of bars implanted, duration of implantation (defined as the time from the implantation operation until the removal operation or until the time of diagnosis of bar fracture based on the X-ray) and any relevant symptoms. In addition to pectus patients, the STRATOS procedure is applied in our centre for the treatment of patients with Jeune syndrome. These patients were excluded from our study, as the bars are used to prolong the ribs instead of stabilizing the sternum. Pectus patients with comorbidity were included, and their additional diagnosis is listed in Table 1. As the true incidence of bar fracture became clear, we shared the data with the UK Medicines and Healthcare Products Regulatory Agency (London) and the manufacturer (see above). Also, after that moment, all broken bars were photographed and sent back to the manufacturer for analysis. Table 1: List of comorbidity patients with their diagnosis Patient number Diagnosis 1 Pectus excavatum and Treacher Collins syndrome 5 Pectus carinatum, LEOPARD syndrome, Von Willebrand disease and VSD 13 Pectus excavatum and recurrent clavicular subluxation 20 Pectus excavatum, extrinsic left main bronchus and oesophagus compression 22 Pectus carinatum and Charcot-Marie-Tooth disease 25 Pectus excavatum, aortic regurgitation, neurofibromatosis Type 1 and mild aortic root dilatation 26 Airway compression (complex pectus anomaly), thoracic-mediastinal abnormality and Kniest Syndrome 30 Pectus excavatum and aortic root replacement 32 Pectus excavatum and coagulation Factor VII deficiency 33 Pectus excavatum and subluxation of right sternoclavicular joint Patient number Diagnosis 1 Pectus excavatum and Treacher Collins syndrome 5 Pectus carinatum, LEOPARD syndrome, Von Willebrand disease and VSD 13 Pectus excavatum and recurrent clavicular subluxation 20 Pectus excavatum, extrinsic left main bronchus and oesophagus compression 22 Pectus carinatum and Charcot-Marie-Tooth disease 25 Pectus excavatum, aortic regurgitation, neurofibromatosis Type 1 and mild aortic root dilatation 26 Airway compression (complex pectus anomaly), thoracic-mediastinal abnormality and Kniest Syndrome 30 Pectus excavatum and aortic root replacement 32 Pectus excavatum and coagulation Factor VII deficiency 33 Pectus excavatum and subluxation of right sternoclavicular joint The patients with fractured bars are indicated in italics. VSD: ventricular septal defect. Table 1: List of comorbidity patients with their diagnosis Patient number Diagnosis 1 Pectus excavatum and Treacher Collins syndrome 5 Pectus carinatum, LEOPARD syndrome, Von Willebrand disease and VSD 13 Pectus excavatum and recurrent clavicular subluxation 20 Pectus excavatum, extrinsic left main bronchus and oesophagus compression 22 Pectus carinatum and Charcot-Marie-Tooth disease 25 Pectus excavatum, aortic regurgitation, neurofibromatosis Type 1 and mild aortic root dilatation 26 Airway compression (complex pectus anomaly), thoracic-mediastinal abnormality and Kniest Syndrome 30 Pectus excavatum and aortic root replacement 32 Pectus excavatum and coagulation Factor VII deficiency 33 Pectus excavatum and subluxation of right sternoclavicular joint Patient number Diagnosis 1 Pectus excavatum and Treacher Collins syndrome 5 Pectus carinatum, LEOPARD syndrome, Von Willebrand disease and VSD 13 Pectus excavatum and recurrent clavicular subluxation 20 Pectus excavatum, extrinsic left main bronchus and oesophagus compression 22 Pectus carinatum and Charcot-Marie-Tooth disease 25 Pectus excavatum, aortic regurgitation, neurofibromatosis Type 1 and mild aortic root dilatation 26 Airway compression (complex pectus anomaly), thoracic-mediastinal abnormality and Kniest Syndrome 30 Pectus excavatum and aortic root replacement 32 Pectus excavatum and coagulation Factor VII deficiency 33 Pectus excavatum and subluxation of right sternoclavicular joint The patients with fractured bars are indicated in italics. VSD: ventricular septal defect. RESULTS Between 2009 and 2014, 39 patients were treated for chest wall deformities with the implantation of the STRATOS bars. Table 2 summarizes the characteristics of all the patients. Twelve of the 39 patients (31%) treated with STRATOS for their pectus were identified as having bar(s) broken before removal. In 6 of these 12 patients, the broken bar was noticed only during a routine chest X-ray as part of the pre-bar removal protocol. Another 6 patients returned to our clinic early with the following symptoms: chest pain (3 patients), increased breathlessness (2), movement of the bar in the chest (2) and slight recurrence of chest wall deformity (1). The most common place of fracture was in the middle of the bar (42%), 29% of the fractures occurred at the connection between the bar and clip and 29% was identified at the angle of the clips. Table 2: Characteristics of patients treated using the STRATOS procedure Patient number Gender Comorbidity Diagnosis (PE/PC) Age at operation (years) Previous Nuss operation Number of bars Duration of implantation (months) Broken bar 1 Male Yes PE 21.5 Yes 2 71 2 Male No PE 18.0 Yes 1 62 3 Female No PE 18.1 Yes 2 39 4 Male No PC 15.0 No 2 49 5 Male Yes PC 17.2 No 2 44 6 Male No PC 15.0 No 2 15 Yes 7 Male No PE 16.5 Yes 2 33 8 Male No PC 16.8 No 1 41 9 Male No PC 18.5 No 2 25 Yes 10 Male No PC 16.3 No 2 36 11 Male No PC 18.8 No 2 23 12 Male No PC 14.7 No 2 38 Yes 13 Male Yes PE 15.5 No 2 38 14 Male No PC 18.0 No 2 36 15 Male No PC 16.7 No 2 32 16 Male No PC 15.5 No 2 24 Yes 17 Male No PE 15.1 Yes 1 27 18 Male No PC 14.1 No 1 28 Yes 19 Male No PC 18.0 No 1 27 Yes 20 Male Yes PE 4.3 No 1 28 Yes 21 Male No PC 16.3 No 2 29 22 Male Yes PC 16.3 No 1 28 23 Male No PC 17.6 No 1 27 24 Male No PC 15.0 No 1 26 25 Male Yes PE 16.3 No 1 25 26 Male Yes PC 12.8 No 1 11 27 Male No PC 15.6 No 1 23 28 Male No PE 15.8 Yes 1 18 Yes 29 Male No PE 15.6 No 1 14 30 Male Yes PE 4.8 No 1 19 Yes 31 Male No PC 16.3 No 1 17 32 Male Yes PE 17.9 Yes 1 16 Yes 33 Male Yes PE 16.6 No 1 17 34 Male No PE 16.1 No 1 0 35 Male No PE 19.8 No 1 4 Yes 36 Male No PC 17.6 No 1 5 37 Female No PC 15.3 Yes 1 4 Yes 38 Female No PC 14.9 No 2 2 39 Male No PC 19.1 No 1 2 Patient number Gender Comorbidity Diagnosis (PE/PC) Age at operation (years) Previous Nuss operation Number of bars Duration of implantation (months) Broken bar 1 Male Yes PE 21.5 Yes 2 71 2 Male No PE 18.0 Yes 1 62 3 Female No PE 18.1 Yes 2 39 4 Male No PC 15.0 No 2 49 5 Male Yes PC 17.2 No 2 44 6 Male No PC 15.0 No 2 15 Yes 7 Male No PE 16.5 Yes 2 33 8 Male No PC 16.8 No 1 41 9 Male No PC 18.5 No 2 25 Yes 10 Male No PC 16.3 No 2 36 11 Male No PC 18.8 No 2 23 12 Male No PC 14.7 No 2 38 Yes 13 Male Yes PE 15.5 No 2 38 14 Male No PC 18.0 No 2 36 15 Male No PC 16.7 No 2 32 16 Male No PC 15.5 No 2 24 Yes 17 Male No PE 15.1 Yes 1 27 18 Male No PC 14.1 No 1 28 Yes 19 Male No PC 18.0 No 1 27 Yes 20 Male Yes PE 4.3 No 1 28 Yes 21 Male No PC 16.3 No 2 29 22 Male Yes PC 16.3 No 1 28 23 Male No PC 17.6 No 1 27 24 Male No PC 15.0 No 1 26 25 Male Yes PE 16.3 No 1 25 26 Male Yes PC 12.8 No 1 11 27 Male No PC 15.6 No 1 23 28 Male No PE 15.8 Yes 1 18 Yes 29 Male No PE 15.6 No 1 14 30 Male Yes PE 4.8 No 1 19 Yes 31 Male No PC 16.3 No 1 17 32 Male Yes PE 17.9 Yes 1 16 Yes 33 Male Yes PE 16.6 No 1 17 34 Male No PE 16.1 No 1 0 35 Male No PE 19.8 No 1 4 Yes 36 Male No PC 17.6 No 1 5 37 Female No PC 15.3 Yes 1 4 Yes 38 Female No PC 14.9 No 2 2 39 Male No PC 19.1 No 1 2 PC: pectus carinatum; PE: pectus excavatum. Table 2: Characteristics of patients treated using the STRATOS procedure Patient number Gender Comorbidity Diagnosis (PE/PC) Age at operation (years) Previous Nuss operation Number of bars Duration of implantation (months) Broken bar 1 Male Yes PE 21.5 Yes 2 71 2 Male No PE 18.0 Yes 1 62 3 Female No PE 18.1 Yes 2 39 4 Male No PC 15.0 No 2 49 5 Male Yes PC 17.2 No 2 44 6 Male No PC 15.0 No 2 15 Yes 7 Male No PE 16.5 Yes 2 33 8 Male No PC 16.8 No 1 41 9 Male No PC 18.5 No 2 25 Yes 10 Male No PC 16.3 No 2 36 11 Male No PC 18.8 No 2 23 12 Male No PC 14.7 No 2 38 Yes 13 Male Yes PE 15.5 No 2 38 14 Male No PC 18.0 No 2 36 15 Male No PC 16.7 No 2 32 16 Male No PC 15.5 No 2 24 Yes 17 Male No PE 15.1 Yes 1 27 18 Male No PC 14.1 No 1 28 Yes 19 Male No PC 18.0 No 1 27 Yes 20 Male Yes PE 4.3 No 1 28 Yes 21 Male No PC 16.3 No 2 29 22 Male Yes PC 16.3 No 1 28 23 Male No PC 17.6 No 1 27 24 Male No PC 15.0 No 1 26 25 Male Yes PE 16.3 No 1 25 26 Male Yes PC 12.8 No 1 11 27 Male No PC 15.6 No 1 23 28 Male No PE 15.8 Yes 1 18 Yes 29 Male No PE 15.6 No 1 14 30 Male Yes PE 4.8 No 1 19 Yes 31 Male No PC 16.3 No 1 17 32 Male Yes PE 17.9 Yes 1 16 Yes 33 Male Yes PE 16.6 No 1 17 34 Male No PE 16.1 No 1 0 35 Male No PE 19.8 No 1 4 Yes 36 Male No PC 17.6 No 1 5 37 Female No PC 15.3 Yes 1 4 Yes 38 Female No PC 14.9 No 2 2 39 Male No PC 19.1 No 1 2 Patient number Gender Comorbidity Diagnosis (PE/PC) Age at operation (years) Previous Nuss operation Number of bars Duration of implantation (months) Broken bar 1 Male Yes PE 21.5 Yes 2 71 2 Male No PE 18.0 Yes 1 62 3 Female No PE 18.1 Yes 2 39 4 Male No PC 15.0 No 2 49 5 Male Yes PC 17.2 No 2 44 6 Male No PC 15.0 No 2 15 Yes 7 Male No PE 16.5 Yes 2 33 8 Male No PC 16.8 No 1 41 9 Male No PC 18.5 No 2 25 Yes 10 Male No PC 16.3 No 2 36 11 Male No PC 18.8 No 2 23 12 Male No PC 14.7 No 2 38 Yes 13 Male Yes PE 15.5 No 2 38 14 Male No PC 18.0 No 2 36 15 Male No PC 16.7 No 2 32 16 Male No PC 15.5 No 2 24 Yes 17 Male No PE 15.1 Yes 1 27 18 Male No PC 14.1 No 1 28 Yes 19 Male No PC 18.0 No 1 27 Yes 20 Male Yes PE 4.3 No 1 28 Yes 21 Male No PC 16.3 No 2 29 22 Male Yes PC 16.3 No 1 28 23 Male No PC 17.6 No 1 27 24 Male No PC 15.0 No 1 26 25 Male Yes PE 16.3 No 1 25 26 Male Yes PC 12.8 No 1 11 27 Male No PC 15.6 No 1 23 28 Male No PE 15.8 Yes 1 18 Yes 29 Male No PE 15.6 No 1 14 30 Male Yes PE 4.8 No 1 19 Yes 31 Male No PC 16.3 No 1 17 32 Male Yes PE 17.9 Yes 1 16 Yes 33 Male Yes PE 16.6 No 1 17 34 Male No PE 16.1 No 1 0 35 Male No PE 19.8 No 1 4 Yes 36 Male No PC 17.6 No 1 5 37 Female No PC 15.3 Yes 1 4 Yes 38 Female No PC 14.9 No 2 2 39 Male No PC 19.1 No 1 2 PC: pectus carinatum; PE: pectus excavatum. The median age of the patients was 16.3 years (range 4.3–21.5 years). For patients with intact bars, the median age (range) was 15.4 years (4.3–19.8 years) compared to patients with broken bars 16.3 years (12.8–21.5 years). There was no significant difference between groups (P = 0.17). There was no significant difference in the incidence of bar fracture between patients with PC or PE as well (P = 0.72). There is no evidence that the bar fractures are related to comorbidity as only 3 of 10 patients with comorbidity had a broken bar (33% vs 31% without comorbidity). Twenty-nine patients had the STRATOS procedure as their first correction of chest wall deformity, 8 patients had a previous correction with the Nuss bar and 2 patients had a previous open correction without bars. There was no significance in bar failures between the patients with failed Nuss procedure attempts and other patients (P = 0.60). There was no significant difference in incidence of bar fractures in relation to the duration of implantation between fractured and intact bars (P = 0.12). For patients with intact bars, the median duration of implantation was 27 months (0–71 months), as compared to patients with broken bars where the median duration was 22 months (4–38 months). The number of fractures in patients with 1 bar was twice as high as seen in 8 of 19 (42%) as against those with more than 1 bar [4/20 (20%) fractures], and this was statistically significant (P = 0.02). DISCUSSION The STRATOS bars were first described by Wihlm et al. [2] in 2007 for the use in chest wall deformities, severe chest traumas and reconstructive surgery following chest wall tumours. The bar is made of pure titanium and is hold in place by metal clips which are placed on the ribs. There have been 3 previous reports, in which the STRATOS bars were broken during follow-up [3–5], a total of 3 patients altogether. Stefani et al. described a 20-year old man treated for PE; his bar broke on the left angle. The possible explanation they offered was that the pressure the sternum applied over the bar finally caused the rupture, favoured by the manoeuvre of angulation of the joint [3]. Berthet et al. [4] reported 2 patients who had fractured bars, and they underwent chest wall reconstruction after non-small-cell lung cancer removal. Both patients experienced a delayed rupture of the titanium bar (STRATOS) at the joint. In the first study with the STRATOS bars by Wihlm et al. [2], there were no fractures in any of the 14 patients. One possible explanation is that they implanted 2 bars in each patient, but as we have seen in our patient group, this is not a guarantee that the bars will not break. Another explanation is that they published only the short-term results. In 2015, Berthet et al. reported deformations (anteroposterior bending) of the STRATOS implants in 17 of the 20 patients treated for chest wall deformities. In total, they found 13 fractures in 47 patients (28%), and this included patients for chest wall reconstruction after tumour removal as well [5]. Various explanations can be offered as to why a bar might break, ranging from excessive sternal pressure (Stefani et al.), poor insertion technique, the use of too few bars (Whilm et al. used 2 bars in the patients he described in 2007) or failure of the equipment itself. Any of the combined tensile or compressive and torsional force could result in excessive force, leading to rubbing and loosening at the site, which may subsequently release large quantities of titanium into the surrounding tissues [6]. In our series, we were unable to identify a clear individual cause in any of the patients. The only significant difference in fracture rates was related to the number of bars used. However, even implanting 2 bars does not guarantee success as 20% of our patients with 2 bars had at least 1 broken bar. It could potentially be that we used a poor technique for inserting the bars—manipulating the bar and the fixing clips too much during implantation caused it to lose strength over time and eventually break. An argument can be made for this hypothesis as 4 of the 14 fractures (29%) occurred in the angle of the fixing clips, and this part is frequently adjusted during implantation to position the bar correctly. However, the high rate of fractures (42%) in the middle of the bar challenges this hypothesis (Fig. 1). While the angles of the clip are often manipulated during surgery and thus could be weakened, the middle of the bar is barely handled during the procedure. The remaining 29% of the fractures was identified at the connection between the bar and the fixing clips. This part is secured with an implant crimping pliers, although this requires very limited force to attach. Figure 1: View largeDownload slide Overview of STRATOS bar fractures (with permission from MedXpert). Figure 1: View largeDownload slide Overview of STRATOS bar fractures (with permission from MedXpert). None of the patients reported trauma or an occasion where their chest became exposed to a force of high magnitude. One patient described that he felt his bar break when he took a morning stretch and another patient while rowing—the only record of severe exercise being related to bar fracture. We advise our patients to stay away from contact sport for the duration of the bar in situ for the initial 6 months, but expect them to function normally after 6 months. Because of the lack of evidence on acute injury causing the fractures, we considered the possibility that the fractures were caused by constant force of the displaced chest wall on the bars and clips. There was no significant difference in the incidence rate of bar fractures between the PE and PC patients, thus the hypothesis of constant chest wall pressure causing the fractures is questionable. By the end of 2014, we had implanted the STRATOS bars in 39 patients and removed again in 21 patients, and in 14 patients, this was done as routinely planned. The other 7 patients had their bar removed at an earlier stage than initially planned due to complications; in 6 of these patients, this was due to the fractured bar(s). Except for 1 patient (104 days), the duration between the discovery on X-ray and the removal of the fractured bar was less than 1 month (1–27 days). None of the patients with fractured bar(s) required emergency surgery because of complications, and none of the patients reported significant recurrence that required a new operation. Besides the bar fractures, we had another major complication requiring reoperation 1 month after implantation. This was due to a pneumothorax caused by a non-fractured loose bar, and during the reoperation, we replaced the bar and the new bar has not been removed as of December 31, 2014. Although the follow-up period is still short, we have had no patients requesting new surgery after the removal of the bar, as recurrence was none or minimal. The high fracture rate is very alarming, especially because of their unpredictability and lack of clear aetiological factors. The operation is done (largely) for psychosocial and cosmetic reasons, and therefore, we must have complete confidence in the quality of the bars used in teenage pectus patients. In our series, 6 of the 12 patients with fractured bar(s) had no symptoms on discovery of the fractured bar on X-ray, and the other 6 patients reported only mild symptoms as chest pain, breathlessness and movement in the chest. Although these symptoms were relatively mild, a fractured metal bar can result in sharp metal edges, which have the potential to perforate internal organs such as the lung or even the heart [7], and the proximity to both intercostal and internal mammary vessels is also important. As a result of this review, we have placed a moratorium on the use of this equipment until more data become available. ACKNOWLEDGEMENTS We thank MedXpert GmbH for their cooperation. Conflict of interest: none declared. REFERENCES 1 Ravitch M. The operative treatment of pectus excavatum . Ann Surg 1949 ; 129 : 429 – 44 . Google Scholar CrossRef Search ADS PubMed 2 Wihlm JM , Grosdidier G , Chapelier A. Thoracic osteosyntheses for chest wall malformations, traumas and tumors using the STRATOS titanium system: initial experience . Interact CardioVasc Thorac Surg 2007 ; 6 : 273 . 3 Stefani A , Nesci J , Morandi U. STRATOS™ system for the repair of pectus excavatum . Interact CardioVasc Thorac Surg 2013 ; 17 : 1056 – 8 . Google Scholar CrossRef Search ADS PubMed 4 Berthet JP , Canaud L , D’Annoville T , Alric P , Marty-Ane CH. Titanium plates and Dual-Mesh: a modern combination for reconstructing very large chest wall defects . Ann Thorac Surg 2011 ; 91 : 1709 – 16 . Google Scholar CrossRef Search ADS PubMed 5 Berthet JP , Gomez Caro AG , Solovei L , Gilbert M , Bommart S , Gaudard P et al. Titanium implant failure after chest wall osteosynthesis . Ann Thorac Surg 2015 ; 99 : 1945 – 52 . Google Scholar CrossRef Search ADS PubMed 6 Sharma PK , Willems TP , Touw DJ , Woudstra W , Erasmus ME , Ebels T. Implant failure: STRATOS system for pectus repair . Ann Thorac Surg 2017 ; 103 : 1536 – 43 . Google Scholar CrossRef Search ADS PubMed 7 Zhang R , Hagl C , Bobylev D , Breymann T , Schmitto JD , Haverich A et al. Intrapericardial migration of dislodged sternal struts as late complication of open pectus excavatum repairs . J Cardiothorac Surg 2011 ; 6 : 40. Google Scholar CrossRef Search ADS PubMed © The Author(s) 2018. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices)

Journal

European Journal of Cardio-Thoracic SurgeryOxford University Press

Published: Jun 5, 2018

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