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Scoliosis Progression After the Nuss Procedure for Pectus Excavatum: A Case Report
Spine Deformity 7 (2019) 1003e1009 www.spine-deformity.org
Scoliosis Progression After the Nuss Procedure for Pectus Excavatum: A Case Report Lorena V. Floccari, MD*, Daniel J. Sucato, MD, MS, Brandon A. Ramo, MD Texas Scottish Rite Hospital for Children, 2222 Welborn St., Dallas, TX, 75219, USA Received 10 July 2018; revised 10 January 2019; accepted 12 January 2019
Abstract Introduction: Pectus excavatum and scoliosis are associated conditions with a high rate of coincidence. However, there are no reports to guide surgeons on the management of adolescents with moderate scoliosis and pectus excavatum, because there are conflicting conclusions in the literature regarding how the Nuss procedure with substernal bar affects scoliosis. Cases: In 2017, we encountered two patients with moderate scoliosis treated with a spinal orthosis. After undergoing the Nuss procedure for pectus excavatum, their scoliosis acutely progressed into surgical magnitude requiring posterior instrumented spinal fusion. The first patient progressed 26 despite the pre-Nuss radiographs showing him to be Risser 4/5, while the second patient also progressed 26 from the Nuss procedure. Both patients acknowledged noncompliance with brace wear because of discomfort after the Nuss procedure. However, their progression rate still doubles the rate of reported rapid accelerators, indicating that a significant component of curve progression is directly attributed to forces on the spine from the corrective maneuver with substernal bar. Conclusion: The purpose of this case report is to describe the features of these two patients to help with clinical decision-making in patients with moderate scoliosis (curves O25 ) who are contemplating the Nuss procedure for correction of pectus excavatum. We caution patients and providers that spinal deformity could worsen with surgical intervention of the pectus excavatum via the Nuss procedure and necessitate scoliosis surgery. Keywords: Scoliosis; Pectus excavatum; Nuss procedure
Introduction Pectus excavatum and scoliosis are associated conditions, as the anterior chest wall and sternum are directly linked to the vertebral column through the rib cage. When surgical treatment for the pectus excavatum is deemed necessary with elevated Haller indices [1], the incidence of scoliosis in these patients is 10% to 28% [2-6]. The Nuss procedure has been popularized as a minimally invasive technique for correction of the pectus excavatum deformity, using a curved bar inserted under the sternum through small thoracic incisions. The bar convexity is then flipped anteriorly, thereby correcting the sternal deformity [7]. Despite the high coincidence of these conditions, there are limited reports of how the Nuss procedure affects the Author disclosures: LVF (none), DJS (none), BAR (none). IRB approval: Not required. Funding: None. *Corresponding author. Texas Scottish Rite Hospital for Children, 2222 Welborn St., Dallas, TX, 75219, USA. Tel.: (214) 559-8430; fax: (214) 559-7570. E-mail address: [email protected] (L.V. Floccari). 2212-134X/$ - see front matter https://doi.org/10.1016/j.jspd.2019.01.009
progression of scoliosis. Niedbala et al. reported two cases of spinal asymmetry progression after a Nuss bar procedure to scoliosis measuring 16 and 14 , both of which reportedly resolved with physical therapy [8]. Conversely, Ghionzoli et al. found that the Nuss procedure had a favorable effect on adolescent idiopathic scoliosis (AIS), with a mean improvement of 1.5 in the Cobb angle [9]. Chung et al. reported that patients with Cobb angles 10 e15 had curvature improvement (e2.9 ), whereas patients with Cobb angle O15 had slight progression by 3.9 [10]. In these studies, age (chronologic or skeletal) was not reported, nor was the Risser sign, status of the triradiate cartilage, or other markers of skeletal maturity, making it uncertain whether slight curve progression was directly attributed to the Nuss procedure, to the natural progression of a scoliosis during adolescent growth, or simply measurement error given the small overall Cobb changes. Clearly, there are conflicting conclusions in the literature, and to our knowledge there are no reports to guide surgeons on the management of adolescents with moderate scoliosis (curves O25 ) and pectus excavatum. In 2017, we encountered two patients with scoliosis treated with a thoracolumbosacral orthosis (TLSO). After
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undergoing the Nuss procedure for pectus excavatum, their scoliosis rapidly progressed into a surgical magnitude deformity requiring posterior instrumented spinal fusion (PSF). This has not been previously reported in the literature. The purpose of this report is to describe the features of these patients to help with clinical decision making in patients with moderate scoliosis who may undergo a Nuss procedure for correction of pectus excavatum.
Case 1 The first patient presented as a 14-year-8-month-old boy with a right thoracic curve measuring 25 , Risser 0, with open triradiates (Fig. 1A, B). He had a body mass index of 15.9 with height in the 10th percentile. He was otherwise healthy, but was noted to have a large pectus excavatum. To prevent scoliosis curvature progression in the setting of
Fig. 1. Posteroanterior and lateral radiographs of Patient 1 on initial presentation (A, B), at which time orthosis was recommended. Before the Nuss procedure, the patient was nearly skeletally mature (C). Preoperative Haller index of 11.4 (D).
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skeletal immaturity, he was started in a custom TLSO with instructions to wear his brace 18e20 hours/day. This patient was followed on a regular basis for three years. A compliance monitor in his TLSO brace recorded satisfactory brace wear compliance. He was noted to have some curvature progression during his adolescent growth spurt with a Lenke 2A right thoracic curve measuring 49 and left proximal thoracic curve measuring 40 at Risser 4/5 with closed triradiates (Fig. 1C). We recommended
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continued full-time TLSO brace wear for six additional months, as he was nearing skeletal maturity and hoped to avoid spinal fusion. At this point, he was referred to general surgery for concerns regarding his pectus excavatum. He was noted to have severe pectus with right sternal concavity and a Haller index of 11.4 (Fig. 1D). He underwent the Nuss procedure without complication, but postoperatively he noticed subjectively a worsened scoliosis appearance. He presented to
Fig. 2. Significant curvature progression was noted after the Nuss procedure on radiographs (A, B), and on clinical appearance (C-F).
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our clinic three months after the Nuss procedure, with a rapid curve progression from 49 to 75 (þ26 ) in a sixmonth time period (4.3 /mo) (Fig. 2A-F), despite preNuss radiographs showing him to be a Risser 4/5. He had had no change in his overall height during that six-month time interval. He did acknowledge that he had not worn his TLSO brace in the three months after the Nuss procedure because of chest wall discomfort and change in chest wall contour. Given his rapid curvature progression to surgical magnitude, posterior instrumented spinal fusion was recommended.
Case 2 The second patient initially presented as a 13-year-9month-old boy with a Lenke 2A curve with a 39 right thoracic curve, 44 left proximal thoracic curve, and 50 T5eT12 thoracic kyphosis. He was otherwise healthy, but was noted to have a significant pectus excavatum that had not been previously evaluated. His triradiates were nearly closed and he was Risser 0 (Fig. 3A, B), so he was started in a custom TLSO to be worn 18e20 hours per day. In-brace radiographs and an MRI obtained two months after initial visit were satisfactory.
Fig. 3. Posteroanterior and lateral radiographs (A, B) and clinical photographs (C, D) of Patient 2 on initial presentation. Significant curvature progression was noted after the Nuss procedure (E, F).
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Given that he was in the 93rd percentile for height (body mass index 22.4), with kyphoscoliosis and pectus excavatum (Fig. 3C, D), he underwent workup for Marfan syndrome, which ultimately was negative for criteria. He was seen by a general surgeon, and it was noted that his pectus excavatum deformity had Haller index of 6.7. The Nuss procedure was performed without complication. Postoperatively, he was seen by the orthotics team for adjustments to the custom TLSO to accommodate the change in chest contour. He returned to orthopedics clinic 3 months after the Nuss procedure. In the 7.5 months between initial presentation and the post-Nuss evaluation, his height had only increased by 0.9 cm, but his right thoracic curve had progressed by þ26 (3.5 /mo) to a surgical magnitude of 65. His triradiates were closed and he was Risser 4 (Fig. 3E, F). He did acknowledge that he had been noncompliant with brace wear owing to chest discomfort after the Nuss surgery. Given the curve progression, surgery with posterior instrumented spinal fusion was recommended and performed three months after this subsequent visit. Discussion In this case report, we present two patients who had rapid progression of scoliosis deformity after undergoing a Nuss procedure for their pectus excavatum. Sanders et al. has previously evaluated peak curve acceleration, and classified patients into low, moderate, or rapid acceleration groups at 0.3 , 0.8 , and 1.6 /mo, respectively [11]. In this series, Patient 1 progressed at a rate of 4.3 /mo, despite pre-Nuss radiographs showing Risser 4/5. Patient 2 also progressed more rapidly than expected at 3.5 /mo. As these rates both are more than double the rate of Sanders’ rapid acceleration group, we believe the rapid Cobb angle progression seen in these two patients can be attributed to the Nuss procedure. Curve progression is likely from direct forces placed on the thoracic spine during pectus deformity correction, and also indirectly from TLSO intolerance after the Nuss procedure due to chest wall discomfort and change in chest wall contour, despite brace accommodative modifications. This progression from moderate to severe scoliosis after Nuss procedure prompting scoliosis surgery has not been previously reported in the literature, but is an important finding in this population and will alter our clinical recommendations to patients with moderate scoliosis. Pectus excavatum is an anterior chest wall deformity with an incidence between 1:400 and 1:1,000 live births, with increased familial incidence, and association with connective tissue disorders such as Marfan and Ehlers Danlos syndromes [12]. In patients who are treated surgically for pectus excavatum, prior studies have reported 10% to 28% incidence of scoliosis [2-6]. Waters et al. theorized that the anterior chest wall deformity and rib cage alters the developing vertebral column, with asymmetric paraspinal muscles and intrathoracic pressures contributing to spinal deformity [2].
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Ravitch described the traditional open technique of subperichondral resection of anomalous costal cartilage [13], whereas Nuss popularized a more minimally invasive technique using a curved bar inserted under the sternum using small thoracic incisions. After the bar is inserted with the convexity facing posteriorly, it is flipped anteriorly, correcting the sternal deformity [7]. Modifications of this procedure have been described, including thoracoscopic assistance, and various types of bars for stabilization [14]. Reported complications include bleeding, pneumothorax, atelectasis, wound infection, pleural effusion, and hemothorax, with potential for major but rare complications including cardiac perforation or other visceral injury, diaphragm injury, and thoracic outlet syndrome [15]. Other late complications include slipped substernal bar, skin and/ or sternal erosion, over-/undercorrection, recurrence, pericardial effusion, and pericarditis [15-21]. Correction of pectus excavatum primarily affects the sternum and anterior thorax, which are linked to the rib cage and spine; thus, it is intuitive that pectus excavatum correction can affect spinal alignment. However, there are limited reports on the relationship between pectus excavatum, surgical correction, and the impact on scoliosis. Niedbala et al. reported two cases in which spinal asymmetry progressed to scoliosis measuring 16 and 14 after a Nuss bar procedure, with both patients reportedly having resolution of the scoliosis with physical therapy. They theorized that the curvature progression was secondary to acute asymmetric thoracic pressures following the Nuss procedure [8]. Conversely, Ghionzoli et al. found that the Nuss procedure had a favorable effect on AIS, with a mean improvement of 1.5 in the Cobb angle. This group concluded that correction of the pectus should be offered during puberty as a timely option for treating pectus excavatum while stabilizing mild/moderate scoliosis [9]. In 2017, Chung et al. retrospectively analyzed 779 pectus excavatum patients who underwent surgical intervention with a Nuss bar, and found 63 patients (8%) with scoliosis [10]. At 34 months after bar removal, 65% of patients had improved Cobb angle, whereas 35% had worsened Cobb angle. The preoperative Cobb angle was the only factor that correlated with curve progression, as patients with Cobb angles 10 e15 had improvement (e2.9 ), whereas patients with Cobb angle O15 had slight curvature progression (þ3.9 ). Other factors did not correlate with curve progression, including age, sex, direction of curve, chest wall asymmetry, use of multiple bars, and bar duration. Additionally, no correlation was noted between pectus correction with improvements in Haller index and sternal tilt to the change in scoliosis Cobb angle postoperatively [10]. However, the chronologic and skeletal ages, and other markers of skeletal maturity such as Risser sign were not reported in that series, making it uncertain whether the curve progression was directly attributed to the pectus excavatum correction or just to the natural progression of scoliosis during adolescent growth.
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Prior biomechanical studies have also looked at the relationship between the Nuss procedure and spinal deformity. Chang et al. designed a finite element analysis and demonstrated that the Nuss procedure increases strain at both the anterior and posterior thirdeseventh ribs, including at the attachment to the vertebral column, which could influence chest and spine development [22]. This finding was also supported by Neves et al., who found increased stresses on the posterior fourthesixth ribs, supporting the hypothesis of induced scoliosis after correction of pectus deformity [23]. Furthermore, Nagasao et al. used CT scan data to produce finite element models to simulate the Nuss procedure and study force transmission. Correction of pectus excavatum with the Nuss procedure can either exacerbate or improve scoliosis, depending on the direction of the forces in relation to the direction of the thoracic curve. The spine deviates from the side with anterior thoracic concavity to the contralateral side; thus, a concave left pectus would exacerbate right thoracic scoliosis [24]. In this case series, Patient 1 had clear, rapid scoliosis progression after the Nuss procedure despite relative skeletal maturity. Although the patient acknowledges he did not wear his TLSO brace for 3 months postoperatively, he was Risser 4/5 and had not grown in height, and we attribute his þ26 curvature progression (4.3 /mo) directly to his Nuss procedure. Our second patient progressed þ26 after a Nuss procedure, while maturing from Risser 0 to Risser 4 despite only growing 0.9 cm in 7 months. However, his progression rate of 3.5 /mo is still more than double the rate in Sanders’ rapid accelerator group progressing at 1.6 / mo [11]. We attribute the curve progression directly to forces on the spine from the corrective maneuver with substernal bar, and also indirectly, as discomfort from the Nuss procedure and changed chest wall contour prohibited these patients from wearing their TLSO braces despite accommodative modifications. This report has several limitations inherent to its nature as a retrospective case report. Our institution has begun to use the Sanders staging method more routinely as a maturity parameter to predict spinal growth, as this method has been shown to be more accurate than the Risser stage [25], but we do not have hand radiographs available for these patients, given the retrospective nature of this case report. Although we are unable to perform Sanders scoring in these two patients, both of these patients’ curve progression rates are more than double the rate of the rapid acceleration group described by Sanders [11], indicating that their curve progression is not simply from the natural history of curvature progression. Furthermore, the primary goal for development of skeletal maturity indices is to identify where adolescents are at the time of their clinical visit relative to peak height velocity (PHV), as PHV correlates with curve progression. This is true for the Risser and Sanders staging systems. Fortunately, we do have direct data of these patients’ growth, which is informative with respect to where they are relative
to PHV. Although total height is not an exact surrogate for spinal growth, given potential inaccuracies imposed by coronally and sagittally directed growth, the lack of change in height does reflect lack of lower extremity growth as well, indicating these patients were beyond PHV at the time of curvature progression. Another potential limitation is that an MRI was not obtained for patient 1, as this was an idiopathic curve by all criteria, including apical lordosis at the apex of the coronal curve [26]. In accordance with multiple published reports [27-29], our institution does not regularly obtain MRIs for idiopathic curves. Finally, we are limited in analysis as these are the only two patients we identified at our institution who were treated with the Nuss procedure while undergoing bracing for moderate scoliosis. All Nuss procedures are performed by pediatric general surgeons at a partner institution in our community, which has a ‘‘chest wall’’ center of excellence to which we refer our patients with pectus excavatum. We unfortunately do not have access to the medical records at that institution to understand their denominators. The literature on the association of pectus deformities and scoliosis generally has included a known coincidence of these two conditions of approximately 10% to 28%, with most patients having mild scoliosis rarely requiring treatment of any kind. We present two patients with moderate scoliosis who progressed rapidly into surgical magnitude curvature immediately after the Nuss procedures. This has not been previously reported. We caution patients and providers with moderate scoliosis that spinal deformity could worsen with surgical intervention of the pectus excavatum via the Nuss procedure and necessitate scoliosis surgery. References [1] Haller Jr JA, Kramer SS, Lietman SA. Use of CT scans in selection of patients for pectus excavatum surgery: a preliminary report. J Pediatr Surg 1987;22:904e6. [2] Waters P, Welch K, Micheli LJ, et al. Scoliosis in children with pectus excavatum and pectus carinatum. J Pediatr Orthop 1989;9:551e6. [3] Hong JY, Suh SW, Park HJ, et al. Correlations of adolescent idiopathic scoliosis and pectus excavatum. J Pediatr Orthop 2011;31:870e4. [4] Kelly 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;252:1072e81. [5] Park HJ, Kim JJ, Park JK, et al. Effects of Nuss procedure on thoracic scoliosis in patients with pectus excavatum. J Thorac Dis 2017;9: 3810e6. [6] Wang Y, Chen G, Xie L, et al. Mechanical factors play an important role in pectus excavatum with thoracic scoliosis. J Cardiothorac Surg 2012;7:118. [7] Nuss D, Kelly Jr RE, Croitoru DP, et al. A 10-year review of a minimally invasive technique for the correction of pectus excavatum. J Pediatr Surg 1998;33:545e52. [8] Niedbala A, Adams M, Boswell WC, et al. Acquired thoracic scoliosis following minimally invasive repair of pectus excavatum. Am Surg 2003;69:530e3. [9] Ghionzoli M, Martin A, Bongini M, et al. Scoliosis and pectus excavatum in adolescents: does the Nuss procedure affect the scoliotic curvature? J Laparoendosc Adv Surg Tech A 2016;26:734e9.
L.V. Floccari et al. / Spine Deformity 7 (2019) 1003e1009 [10] Chung JH, Park HJ, Kim KT. Scoliosis after pectus excavatum correction: does it improve or worsen? Eur J Cardiothorac Surg 2017;52:76e82. [11] Sanders JO, Browne RH, McConnell SJ, et al. Maturity assessment and curve progression in girls with idiopathic scoliosis. J Bone Joint Surg Am 2007;89:64e73. [12] Creswick HA, Stacey MW, Kelly Jr RE, et al. Family study of the inheritance of pectus excavatum. J Pediatr Surg 2006;41: 1699e703. [13] Ravitch MM. The operative treatment of pectus excavatum. Ann Surg 1949;129:429e44. [14] Hebra A. Minimally invasive pectus surgery. Chest Surg Clin N Am 2000;10:329e39. vii. [15] Moss RL, Albanese CT, Reynolds M. Major complications after minimally invasive repair of pectus excavatum: case reports. J Pediatr Surg 2001;36:155e8. [16] Hebra A, Kelly RE, Ferro MM, et al. Life-threatening complications and mortality of minimally invasive pectus surgery. J Pediatr Surg 2018;53:728e32. [17] Haller Jr JA. Complications of surgery for pectus excavatum. Chest Surg Clin N Am 2000;10:415e26. ix. [18] Nuss D, Croitoru DP, Kelly Jr RE, et al. Review and discussion of the complications of minimally invasive pectus excavatum repair. Eur J Pediatr Surg 2002;12:230e4. [19] Hoel TN, Rein KA, Svennevig JL. A life-threatening complication of the Nuss procedure for pectus excavatum. Ann Thorac Surg 2006;81: 370e2. [20] Jeong JY, Suh JH, Yoon JS, et al. Delayed-onset hypovolemic shock after the Nuss procedure for pectus excavatum. J Cardiothorac Surg 2014;9:15.
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[21] Yang MH, Cheng YL, Tsai CS, et al. Delayed cardiac tamponade after the Nuss procedure for pectus excavatum: a case report and simple management. Heart Surg Forum 2008;11:E129e31. [22] Chang PY, Hsu ZY, Chen DP, et al. Preliminary analysis of the forces on the thoracic cage of patients with pectus excavatum after the Nuss procedure. Clin Biomech (Bristol, Avon) 2008;23:881e5. [23] Neves SC, Pinho AC, Fonseca JC, et al. Finite element analysis of pectus carinatum surgical correction via a minimally invasive approach. Comput Methods Biomech Biomed Engin 2015;18:711e20. [24] Nagasao T, Noguchi M, Miyamoto J, et al. Dynamic effects of the Nuss procedure on the spine in asymmetric pectus excavatum. J Thorac Cardiovasc Surg 2010;140:1294e1299.e1. [25] Minkara A, Bainton N, Tanaka M, et al. High risk of mismatch between Sanders and Risser staging in adolescent idiopathic scoliosis: are we guiding treatment using the wrong classification. J Pediatr Orthop 2018. https: //doi.org/10.1097/BPO.0000000000001135 [Epub ahead of print]. [26] Ouellet JA, LaPlaza J, Erickson MA, et al. Sagittal plane deformity in the thoracic spine: a clue to the presence of syringomyelia as a cause of scoliosis. Spine (Phila Pa 1976) 2003;28:2147e51. [27] Winter RB, Lonstein JE, Heithoff KB, et al. Magnetic resonance imaging evaluation of the adolescent patient with idiopathic scoliosis before spinal instrumentation and fusion: a prospective, doubleblinded study of 140 patients. Spine (Phila Pa 1976) 1997;22:855e8. [28] Do T, Fras C, Burke S, et al. Clinical value of routine preoperative magnetic resonance imaging in adolescent idiopathic scoliosis: a prospective study of three hundred and twenty-seven patients. J Bone Joint Surg Am 2001;83:577e9. [29] Diab M, Landman Z, Lubicky J, et al. Use and outcome of MRI in the surgical treatment of adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 2011;36:667e71.
Scoliosis Progression After the Nuss Procedure for Pectus Excavatum: A Case Report Lorena V. Floccari, MD*, Daniel J. Sucato, MD, MS, Brandon A. Ramo, MD Texas Scottish Rite Hospital for Children, 2222 Welborn St., Dallas, TX, 75219, USA Received 10 July 2018; revised 10 January 2019; accepted 12 January 2019
Abstract Introduction: Pectus excavatum and scoliosis are associated conditions with a high rate of coincidence. However, there are no reports to guide surgeons on the management of adolescents with moderate scoliosis and pectus excavatum, because there are conflicting conclusions in the literature regarding how the Nuss procedure with substernal bar affects scoliosis. Cases: In 2017, we encountered two patients with moderate scoliosis treated with a spinal orthosis. After undergoing the Nuss procedure for pectus excavatum, their scoliosis acutely progressed into surgical magnitude requiring posterior instrumented spinal fusion. The first patient progressed 26 despite the pre-Nuss radiographs showing him to be Risser 4/5, while the second patient also progressed 26 from the Nuss procedure. Both patients acknowledged noncompliance with brace wear because of discomfort after the Nuss procedure. However, their progression rate still doubles the rate of reported rapid accelerators, indicating that a significant component of curve progression is directly attributed to forces on the spine from the corrective maneuver with substernal bar. Conclusion: The purpose of this case report is to describe the features of these two patients to help with clinical decision-making in patients with moderate scoliosis (curves O25 ) who are contemplating the Nuss procedure for correction of pectus excavatum. We caution patients and providers that spinal deformity could worsen with surgical intervention of the pectus excavatum via the Nuss procedure and necessitate scoliosis surgery. Keywords: Scoliosis; Pectus excavatum; Nuss procedure
Introduction Pectus excavatum and scoliosis are associated conditions, as the anterior chest wall and sternum are directly linked to the vertebral column through the rib cage. When surgical treatment for the pectus excavatum is deemed necessary with elevated Haller indices [1], the incidence of scoliosis in these patients is 10% to 28% [2-6]. The Nuss procedure has been popularized as a minimally invasive technique for correction of the pectus excavatum deformity, using a curved bar inserted under the sternum through small thoracic incisions. The bar convexity is then flipped anteriorly, thereby correcting the sternal deformity [7]. Despite the high coincidence of these conditions, there are limited reports of how the Nuss procedure affects the Author disclosures: LVF (none), DJS (none), BAR (none). IRB approval: Not required. Funding: None. *Corresponding author. Texas Scottish Rite Hospital for Children, 2222 Welborn St., Dallas, TX, 75219, USA. Tel.: (214) 559-8430; fax: (214) 559-7570. E-mail address: [email protected] (L.V. Floccari). 2212-134X/$ - see front matter https://doi.org/10.1016/j.jspd.2019.01.009
progression of scoliosis. Niedbala et al. reported two cases of spinal asymmetry progression after a Nuss bar procedure to scoliosis measuring 16 and 14 , both of which reportedly resolved with physical therapy [8]. Conversely, Ghionzoli et al. found that the Nuss procedure had a favorable effect on adolescent idiopathic scoliosis (AIS), with a mean improvement of 1.5 in the Cobb angle [9]. Chung et al. reported that patients with Cobb angles 10 e15 had curvature improvement (e2.9 ), whereas patients with Cobb angle O15 had slight progression by 3.9 [10]. In these studies, age (chronologic or skeletal) was not reported, nor was the Risser sign, status of the triradiate cartilage, or other markers of skeletal maturity, making it uncertain whether slight curve progression was directly attributed to the Nuss procedure, to the natural progression of a scoliosis during adolescent growth, or simply measurement error given the small overall Cobb changes. Clearly, there are conflicting conclusions in the literature, and to our knowledge there are no reports to guide surgeons on the management of adolescents with moderate scoliosis (curves O25 ) and pectus excavatum. In 2017, we encountered two patients with scoliosis treated with a thoracolumbosacral orthosis (TLSO). After
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undergoing the Nuss procedure for pectus excavatum, their scoliosis rapidly progressed into a surgical magnitude deformity requiring posterior instrumented spinal fusion (PSF). This has not been previously reported in the literature. The purpose of this report is to describe the features of these patients to help with clinical decision making in patients with moderate scoliosis who may undergo a Nuss procedure for correction of pectus excavatum.
Case 1 The first patient presented as a 14-year-8-month-old boy with a right thoracic curve measuring 25 , Risser 0, with open triradiates (Fig. 1A, B). He had a body mass index of 15.9 with height in the 10th percentile. He was otherwise healthy, but was noted to have a large pectus excavatum. To prevent scoliosis curvature progression in the setting of
Fig. 1. Posteroanterior and lateral radiographs of Patient 1 on initial presentation (A, B), at which time orthosis was recommended. Before the Nuss procedure, the patient was nearly skeletally mature (C). Preoperative Haller index of 11.4 (D).
L.V. Floccari et al. / Spine Deformity 7 (2019) 1003e1009
skeletal immaturity, he was started in a custom TLSO with instructions to wear his brace 18e20 hours/day. This patient was followed on a regular basis for three years. A compliance monitor in his TLSO brace recorded satisfactory brace wear compliance. He was noted to have some curvature progression during his adolescent growth spurt with a Lenke 2A right thoracic curve measuring 49 and left proximal thoracic curve measuring 40 at Risser 4/5 with closed triradiates (Fig. 1C). We recommended
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continued full-time TLSO brace wear for six additional months, as he was nearing skeletal maturity and hoped to avoid spinal fusion. At this point, he was referred to general surgery for concerns regarding his pectus excavatum. He was noted to have severe pectus with right sternal concavity and a Haller index of 11.4 (Fig. 1D). He underwent the Nuss procedure without complication, but postoperatively he noticed subjectively a worsened scoliosis appearance. He presented to
Fig. 2. Significant curvature progression was noted after the Nuss procedure on radiographs (A, B), and on clinical appearance (C-F).
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our clinic three months after the Nuss procedure, with a rapid curve progression from 49 to 75 (þ26 ) in a sixmonth time period (4.3 /mo) (Fig. 2A-F), despite preNuss radiographs showing him to be a Risser 4/5. He had had no change in his overall height during that six-month time interval. He did acknowledge that he had not worn his TLSO brace in the three months after the Nuss procedure because of chest wall discomfort and change in chest wall contour. Given his rapid curvature progression to surgical magnitude, posterior instrumented spinal fusion was recommended.
Case 2 The second patient initially presented as a 13-year-9month-old boy with a Lenke 2A curve with a 39 right thoracic curve, 44 left proximal thoracic curve, and 50 T5eT12 thoracic kyphosis. He was otherwise healthy, but was noted to have a significant pectus excavatum that had not been previously evaluated. His triradiates were nearly closed and he was Risser 0 (Fig. 3A, B), so he was started in a custom TLSO to be worn 18e20 hours per day. In-brace radiographs and an MRI obtained two months after initial visit were satisfactory.
Fig. 3. Posteroanterior and lateral radiographs (A, B) and clinical photographs (C, D) of Patient 2 on initial presentation. Significant curvature progression was noted after the Nuss procedure (E, F).
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Given that he was in the 93rd percentile for height (body mass index 22.4), with kyphoscoliosis and pectus excavatum (Fig. 3C, D), he underwent workup for Marfan syndrome, which ultimately was negative for criteria. He was seen by a general surgeon, and it was noted that his pectus excavatum deformity had Haller index of 6.7. The Nuss procedure was performed without complication. Postoperatively, he was seen by the orthotics team for adjustments to the custom TLSO to accommodate the change in chest contour. He returned to orthopedics clinic 3 months after the Nuss procedure. In the 7.5 months between initial presentation and the post-Nuss evaluation, his height had only increased by 0.9 cm, but his right thoracic curve had progressed by þ26 (3.5 /mo) to a surgical magnitude of 65. His triradiates were closed and he was Risser 4 (Fig. 3E, F). He did acknowledge that he had been noncompliant with brace wear owing to chest discomfort after the Nuss surgery. Given the curve progression, surgery with posterior instrumented spinal fusion was recommended and performed three months after this subsequent visit. Discussion In this case report, we present two patients who had rapid progression of scoliosis deformity after undergoing a Nuss procedure for their pectus excavatum. Sanders et al. has previously evaluated peak curve acceleration, and classified patients into low, moderate, or rapid acceleration groups at 0.3 , 0.8 , and 1.6 /mo, respectively [11]. In this series, Patient 1 progressed at a rate of 4.3 /mo, despite pre-Nuss radiographs showing Risser 4/5. Patient 2 also progressed more rapidly than expected at 3.5 /mo. As these rates both are more than double the rate of Sanders’ rapid acceleration group, we believe the rapid Cobb angle progression seen in these two patients can be attributed to the Nuss procedure. Curve progression is likely from direct forces placed on the thoracic spine during pectus deformity correction, and also indirectly from TLSO intolerance after the Nuss procedure due to chest wall discomfort and change in chest wall contour, despite brace accommodative modifications. This progression from moderate to severe scoliosis after Nuss procedure prompting scoliosis surgery has not been previously reported in the literature, but is an important finding in this population and will alter our clinical recommendations to patients with moderate scoliosis. Pectus excavatum is an anterior chest wall deformity with an incidence between 1:400 and 1:1,000 live births, with increased familial incidence, and association with connective tissue disorders such as Marfan and Ehlers Danlos syndromes [12]. In patients who are treated surgically for pectus excavatum, prior studies have reported 10% to 28% incidence of scoliosis [2-6]. Waters et al. theorized that the anterior chest wall deformity and rib cage alters the developing vertebral column, with asymmetric paraspinal muscles and intrathoracic pressures contributing to spinal deformity [2].
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Ravitch described the traditional open technique of subperichondral resection of anomalous costal cartilage [13], whereas Nuss popularized a more minimally invasive technique using a curved bar inserted under the sternum using small thoracic incisions. After the bar is inserted with the convexity facing posteriorly, it is flipped anteriorly, correcting the sternal deformity [7]. Modifications of this procedure have been described, including thoracoscopic assistance, and various types of bars for stabilization [14]. Reported complications include bleeding, pneumothorax, atelectasis, wound infection, pleural effusion, and hemothorax, with potential for major but rare complications including cardiac perforation or other visceral injury, diaphragm injury, and thoracic outlet syndrome [15]. Other late complications include slipped substernal bar, skin and/ or sternal erosion, over-/undercorrection, recurrence, pericardial effusion, and pericarditis [15-21]. Correction of pectus excavatum primarily affects the sternum and anterior thorax, which are linked to the rib cage and spine; thus, it is intuitive that pectus excavatum correction can affect spinal alignment. However, there are limited reports on the relationship between pectus excavatum, surgical correction, and the impact on scoliosis. Niedbala et al. reported two cases in which spinal asymmetry progressed to scoliosis measuring 16 and 14 after a Nuss bar procedure, with both patients reportedly having resolution of the scoliosis with physical therapy. They theorized that the curvature progression was secondary to acute asymmetric thoracic pressures following the Nuss procedure [8]. Conversely, Ghionzoli et al. found that the Nuss procedure had a favorable effect on AIS, with a mean improvement of 1.5 in the Cobb angle. This group concluded that correction of the pectus should be offered during puberty as a timely option for treating pectus excavatum while stabilizing mild/moderate scoliosis [9]. In 2017, Chung et al. retrospectively analyzed 779 pectus excavatum patients who underwent surgical intervention with a Nuss bar, and found 63 patients (8%) with scoliosis [10]. At 34 months after bar removal, 65% of patients had improved Cobb angle, whereas 35% had worsened Cobb angle. The preoperative Cobb angle was the only factor that correlated with curve progression, as patients with Cobb angles 10 e15 had improvement (e2.9 ), whereas patients with Cobb angle O15 had slight curvature progression (þ3.9 ). Other factors did not correlate with curve progression, including age, sex, direction of curve, chest wall asymmetry, use of multiple bars, and bar duration. Additionally, no correlation was noted between pectus correction with improvements in Haller index and sternal tilt to the change in scoliosis Cobb angle postoperatively [10]. However, the chronologic and skeletal ages, and other markers of skeletal maturity such as Risser sign were not reported in that series, making it uncertain whether the curve progression was directly attributed to the pectus excavatum correction or just to the natural progression of scoliosis during adolescent growth.
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Prior biomechanical studies have also looked at the relationship between the Nuss procedure and spinal deformity. Chang et al. designed a finite element analysis and demonstrated that the Nuss procedure increases strain at both the anterior and posterior thirdeseventh ribs, including at the attachment to the vertebral column, which could influence chest and spine development [22]. This finding was also supported by Neves et al., who found increased stresses on the posterior fourthesixth ribs, supporting the hypothesis of induced scoliosis after correction of pectus deformity [23]. Furthermore, Nagasao et al. used CT scan data to produce finite element models to simulate the Nuss procedure and study force transmission. Correction of pectus excavatum with the Nuss procedure can either exacerbate or improve scoliosis, depending on the direction of the forces in relation to the direction of the thoracic curve. The spine deviates from the side with anterior thoracic concavity to the contralateral side; thus, a concave left pectus would exacerbate right thoracic scoliosis [24]. In this case series, Patient 1 had clear, rapid scoliosis progression after the Nuss procedure despite relative skeletal maturity. Although the patient acknowledges he did not wear his TLSO brace for 3 months postoperatively, he was Risser 4/5 and had not grown in height, and we attribute his þ26 curvature progression (4.3 /mo) directly to his Nuss procedure. Our second patient progressed þ26 after a Nuss procedure, while maturing from Risser 0 to Risser 4 despite only growing 0.9 cm in 7 months. However, his progression rate of 3.5 /mo is still more than double the rate in Sanders’ rapid accelerator group progressing at 1.6 / mo [11]. We attribute the curve progression directly to forces on the spine from the corrective maneuver with substernal bar, and also indirectly, as discomfort from the Nuss procedure and changed chest wall contour prohibited these patients from wearing their TLSO braces despite accommodative modifications. This report has several limitations inherent to its nature as a retrospective case report. Our institution has begun to use the Sanders staging method more routinely as a maturity parameter to predict spinal growth, as this method has been shown to be more accurate than the Risser stage [25], but we do not have hand radiographs available for these patients, given the retrospective nature of this case report. Although we are unable to perform Sanders scoring in these two patients, both of these patients’ curve progression rates are more than double the rate of the rapid acceleration group described by Sanders [11], indicating that their curve progression is not simply from the natural history of curvature progression. Furthermore, the primary goal for development of skeletal maturity indices is to identify where adolescents are at the time of their clinical visit relative to peak height velocity (PHV), as PHV correlates with curve progression. This is true for the Risser and Sanders staging systems. Fortunately, we do have direct data of these patients’ growth, which is informative with respect to where they are relative
to PHV. Although total height is not an exact surrogate for spinal growth, given potential inaccuracies imposed by coronally and sagittally directed growth, the lack of change in height does reflect lack of lower extremity growth as well, indicating these patients were beyond PHV at the time of curvature progression. Another potential limitation is that an MRI was not obtained for patient 1, as this was an idiopathic curve by all criteria, including apical lordosis at the apex of the coronal curve [26]. In accordance with multiple published reports [27-29], our institution does not regularly obtain MRIs for idiopathic curves. Finally, we are limited in analysis as these are the only two patients we identified at our institution who were treated with the Nuss procedure while undergoing bracing for moderate scoliosis. All Nuss procedures are performed by pediatric general surgeons at a partner institution in our community, which has a ‘‘chest wall’’ center of excellence to which we refer our patients with pectus excavatum. We unfortunately do not have access to the medical records at that institution to understand their denominators. The literature on the association of pectus deformities and scoliosis generally has included a known coincidence of these two conditions of approximately 10% to 28%, with most patients having mild scoliosis rarely requiring treatment of any kind. We present two patients with moderate scoliosis who progressed rapidly into surgical magnitude curvature immediately after the Nuss procedures. This has not been previously reported. We caution patients and providers with moderate scoliosis that spinal deformity could worsen with surgical intervention of the pectus excavatum via the Nuss procedure and necessitate scoliosis surgery. References [1] Haller Jr JA, Kramer SS, Lietman SA. Use of CT scans in selection of patients for pectus excavatum surgery: a preliminary report. J Pediatr Surg 1987;22:904e6. [2] Waters P, Welch K, Micheli LJ, et al. Scoliosis in children with pectus excavatum and pectus carinatum. J Pediatr Orthop 1989;9:551e6. [3] Hong JY, Suh SW, Park HJ, et al. Correlations of adolescent idiopathic scoliosis and pectus excavatum. J Pediatr Orthop 2011;31:870e4. [4] Kelly 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;252:1072e81. [5] Park HJ, Kim JJ, Park JK, et al. Effects of Nuss procedure on thoracic scoliosis in patients with pectus excavatum. J Thorac Dis 2017;9: 3810e6. [6] Wang Y, Chen G, Xie L, et al. Mechanical factors play an important role in pectus excavatum with thoracic scoliosis. J Cardiothorac Surg 2012;7:118. [7] Nuss D, Kelly Jr RE, Croitoru DP, et al. A 10-year review of a minimally invasive technique for the correction of pectus excavatum. J Pediatr Surg 1998;33:545e52. [8] Niedbala A, Adams M, Boswell WC, et al. Acquired thoracic scoliosis following minimally invasive repair of pectus excavatum. Am Surg 2003;69:530e3. [9] Ghionzoli M, Martin A, Bongini M, et al. Scoliosis and pectus excavatum in adolescents: does the Nuss procedure affect the scoliotic curvature? J Laparoendosc Adv Surg Tech A 2016;26:734e9.
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[21] Yang MH, Cheng YL, Tsai CS, et al. Delayed cardiac tamponade after the Nuss procedure for pectus excavatum: a case report and simple management. Heart Surg Forum 2008;11:E129e31. [22] Chang PY, Hsu ZY, Chen DP, et al. Preliminary analysis of the forces on the thoracic cage of patients with pectus excavatum after the Nuss procedure. Clin Biomech (Bristol, Avon) 2008;23:881e5. [23] Neves SC, Pinho AC, Fonseca JC, et al. Finite element analysis of pectus carinatum surgical correction via a minimally invasive approach. Comput Methods Biomech Biomed Engin 2015;18:711e20. [24] Nagasao T, Noguchi M, Miyamoto J, et al. Dynamic effects of the Nuss procedure on the spine in asymmetric pectus excavatum. J Thorac Cardiovasc Surg 2010;140:1294e1299.e1. [25] Minkara A, Bainton N, Tanaka M, et al. High risk of mismatch between Sanders and Risser staging in adolescent idiopathic scoliosis: are we guiding treatment using the wrong classification. J Pediatr Orthop 2018. https: //doi.org/10.1097/BPO.0000000000001135 [Epub ahead of print]. [26] Ouellet JA, LaPlaza J, Erickson MA, et al. Sagittal plane deformity in the thoracic spine: a clue to the presence of syringomyelia as a cause of scoliosis. Spine (Phila Pa 1976) 2003;28:2147e51. [27] Winter RB, Lonstein JE, Heithoff KB, et al. Magnetic resonance imaging evaluation of the adolescent patient with idiopathic scoliosis before spinal instrumentation and fusion: a prospective, doubleblinded study of 140 patients. Spine (Phila Pa 1976) 1997;22:855e8. [28] Do T, Fras C, Burke S, et al. Clinical value of routine preoperative magnetic resonance imaging in adolescent idiopathic scoliosis: a prospective study of three hundred and twenty-seven patients. J Bone Joint Surg Am 2001;83:577e9. [29] Diab M, Landman Z, Lubicky J, et al. Use and outcome of MRI in the surgical treatment of adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 2011;36:667e71.