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Skeletally Immature Patients With Adolescent Idiopathic Scoliosis Curves 15°–24° Are at High Risk for Progression
Spine Deformity 7 (2019) 870e874 www.spine-deformity.org
Skeletally Immature Patients With Adolescent Idiopathic Scoliosis Curves 15e24 Are at High Risk for Progression Karina A. Zapata, PT, DPT, PhDa,*, Daniel J. Sucato, MD, MSa, Mark C. Lee, MDb, Chan-Hee Jo, PhDa a
Texas Scottish Rite Hospital for Children, 2222 Welborn Street, Dallas, TX 75219, USA Connecticut Children’s Specialty Group, 85 Seymour Street, Hartford, CT 06106, USA Received 26 November 2018; revised 11 February 2019; accepted 27 February 2019
b
Abstract Study Design: Retrospective review. Objectives: To evaluate the incidence of adolescent idiopathic scoliosis (AIS) curve progression and brace prescription in skeletally immature patients (Risser 0 to Risser 1) with curves 15 e24 . Summary of Background Data: Many skeletally immature patients with mild AIS ask about the likelihood of curve progression. No studies have answered these questions. Methods: The charts and radiographs of 302 consecutive patients with curves 15 e24 at initial visit, Risser 0 to Risser 1, were reviewed until skeletal maturity (>Risser 4) or surgery. Curves averaged 19.1 2.9 at initial visit. The Risser grade was 0 in 247 patients (82%) and 1 in 55 patients (18%). Patients who were Risser 0 were compared with those who were Risser 1, curves 15 e19 were compared with curves 20 e24 . Results: The majority of patients demonstrated curve progression >5 (65%). Patients who were Risser 0 did not progress significantly more than patients who were Risser 1 (10 vs. 8 ) (p 5 .22). Patients with curves 20 e24 did not progress significantly more than patients with curves 15 e19 (10 vs. 9 ) (p 5 .65). Conclusions: Curve progression for small curves (15 e19 ) is similar to curves between 20 and 24 . Close observation or perhaps early intervention for these patients is necessary. These data may suggest a paradigm shift to earlier brace initiation and call for early treatment in small curves. Level of Evidence: Level II. Ó 2019 Scoliosis Research Society. All rights reserved. Keywords: Spine deformity; Adolescent idiopathic scoliosis; Mild curves; Early treatment
Introduction Skeletally immature patients with adolescent idiopathic scoliosis (AIS) whose major curves are less than 25 present a particularly challenging clinical dilemma. Patients Author disclosures: KAZ (none), DJS (a patent Globus with royalties paid), MCL (grants from Scoliosis Research Society, other from JBJS Classroom, outside the submitted work), CHJ (none). IRB approval: Institutional review board approval was received from Texas Scottish Rite Hospital for Children and University of Texas Southwestern. No funding was received from this work. *Corresponding author. Texas Scottish Rite Hospital for Children, 2222 Welborn Street, Dallas, TX 75219, USA. Tel.: (214) 559-7790; fax: (214) 224-3801. E-mail address: [email protected] (K.A. Zapata).
with significant residual spinal growth are at risk of curve progression and brace prescription, and a small number of progressive curves will eventually require surgical treatment [1-3]. Identifying patients with progressive small magnitude curves at presentation lies at the crux of clinical management, because medical interventions to halt curve progression may be warranted. The clinical determination of patients at risk for progression remains difficult despite a clear association between residual spinal growth and curve progression. Physicians assess spinal growth potential by using radiographic and clinical indicators of skeletal maturity and, from this information, estimate the risk of progression [1,4-8]. Skeletal maturity indices such as the Risser sign and triradiate cartilage closure are clinically
2212-134X/$ - see front matter Ó 2019 Scoliosis Research Society. All rights reserved. https://doi.org/10.1016/j.jspd.2019.02.012
K.A. Zapata et al. / Spine Deformity 7 (2019) 870e874
useful, because they can be evaluated on the same radiograph that was taken to measure curve magnitude [9]. However, skeletal maturity indices that have an established correlation with curve progression have questionable accuracy. In particular, numerous authors have noted an inexact correlation of radiographic Risser sign with skeletal maturity and residual spinal growth [10,11]. In a sample of 727 JIS and AIS patients with curves from 5 to 29 , Lonstein and Carlson (1984) reported that 68% of patients who were Risser 0 and Risser 1 with curves measuring 20 e29 demonstrated curve progression >5 , whereas only 23% of patients who were Risser 2 to Risser 4 with similar curve magnitudes progressed [1]. Older studies would conclude that patients who are Risser 0 and Risser 1 have a similar risk of curve progression for a given curve magnitude and were managed similarly [12]. However, today it is more commonly recognized that patients who are Risser 0 and Risser 1 do not share similar risk for curve progression, because the greatest spinal growth phase is during Risser 0 [7]. Recent research has also indicated that patients who are Risser 0 have worse brace treatment outcomes than patients who are Risser 1 [13,14]. It can be postulated that small curves below 25 may progress when significant growth remains [1-3]. Previous studies have suggested between 22% and 44% of patients who are Risser 0 or Risser 1 with curves less than 20 demonstrate curve progression greater than 10 [1,2]. Lonstein’s work demonstrated a progression risk of 38% for patients who are Risser 0 with curves between 5 and 29 . Despite the available data, no study has compared the progression risk of patients with small curves who are Risser 0 to patients who are Risser 1. Also, no study has compared subgroups of skeletally immature patients with small curves to determine if a patient with a 15 curve has the same progression risk as a patient with a 20 curve, information that could potentially guide the need for earlier intervention. The following case-control study examines the risk of curve progression in adolescents with idiopathic scoliosis who are Risser 0 and Risser 1 with curves presenting between 15 and 24 . We compared the progression risk of patients who are Risser 0 versus Risser 1, and 15 e19 versus 20 e24 .
Material and Methods Approval was obtained from the hospital and university institutional review boards. A consecutive series of AIS patients treated at a single institution between 1990 and 2005 were retrospectively evaluated. The charts and radiographs of 302 patients with curves at initial visit 15 e24 , Risser 0 to Risser 1, were reviewed until skeletal maturity (at least Risser 4) or surgery.
871
A strict bracing protocol was not employed by our facility during the study period, although the general consensus among providers was that bracing should be offered to skeletally immature patients with curves progressing greater than 25 . In addition, patients with confounding diagnoses such as skeletal dysplasia, leg length discrepancy, spondylolysis, and/or spondylolisthesis were excluded from the analysis. Additional exclusion criteria included fewer than three clinic visits with radiographs. Standard posteroanterior scoliosis radiographs were examined from the initial visit, before the start of bracing or planned surgery and, for patients observed or treated with bracing, at skeletal maturity. All radiographic measurements were performed by individuals with at least one year of training in the clinical and radiographic evaluation of patients with scoliosis. Radiographic measures included the Risser sign, Cobb angle, and triradiate cartilage closure. Curve patterns were classified according to a modified Lenke system, where the curve with the largest Cobb measure was considered structural and the other curves were considered structural only if measuring greater than 15 [15]. An alphabetical lumbar modifier was assigned to each radiograph, as described by Lenke, but no supine bending films were used. If more than one structural curve existed, the largest Cobb angle measured was used for comparison. Clinical data obtained from a review of the corresponding charts included gender and age. Statistical methods Statistical analyses were performed using SAS/STAT (version 9.4). A chi-square test was used to compare categorical variables, and for the small sample size a Fisher exact test was used. Continuous variables were first examined for normality of data distribution, and then a nonparametric test such as Mann-Whitney was executed for two groups of patients. A p value of !.05 was defined as statistical significance. Results The average age was 12.6 years at initial visit, and average curve at initial presentation was 19.1 (Table 1). The majority of the curves were modified Lenke 1 and 5, corresponding to single lumbar, thoracolumbar, or thoracic curves (Table 1). Females and patients who were Risser 0 were more than 80% of the cohort (Table 1). The triradiate cartilage was visualized in 262 of the 302 patients. The triradiate cartilage was open in 118 patients (45%) and closed in 144 patients (55%). Curves progressed an average of 9.1 9.8 (Table 1). Patients who were Risser 0 progressed an average of 10 10 compared with Risser 1 curve progression of 8 8 (p 5 .22)
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Table 1 Cohort demographics.
Table 3 Characteristics of patients whose curves progressed >45 (n524).
Parameters
MeanSD or n (%)
Range
Parameters
MeanSD or n (%)
Range
Initial chronologic age (years) Age at final visit (years) Gender Female Male Cobb angle of major curve ( ) Initial visit Final visit Curve progression Risser Grade 0 1 Initial modified Lenke curve type 1 2 3 4 5 6
12.6 1.1
10.1 to 16.4
12.21.1
10.2e14.0
16.0 1.6
12.5 to 21.8
Initial chronologic age (years) Gender Female Premenarchal Male Cobb angle of major curve ( ) Initial visit Final visit Risser Grade 0 1 Triradiate cartilage Open Closed Not visualized Initial modified Lenke curve type 1 2 3 5 6
254 (84) 48 (16)
19.1 2.9 28.2 10.5 9.1 9.8
15 to 24 8 to 75 e8 to 53
247 (82) 55 (18)
90 22 55 1 120 14
(30) (7) (18) (0) (40) (5)
(Table 2). Curves 20 e24 progressed an average of 10 11 compared with curves 15 e19 which progressed an average of 9 9 (p 5 .65). Surgery was performed in 6 (2%) patients (Table 2). However, 24 patients had a final curve magnitude of >45 , a general indication for surgical treatment (Table 3). The majority of patients with curves 15 e24 who were Risser 0 or Risser 1, demonstrated curve progression >5 (65%). Curves progressed less than 5 in 105 patients (35%), 5 e9 in 71 patients (24%), and progressed at least 10 in 126 patients (42%). Curves in 9 patients (3%) improved at least 5 at the final visit compared with initial film, averaging 19.1 3.7 at initial visit. Only one of these patients had been braced. See Table 4 for the incidence of curve progression >5 based on curve magnitude and Risser grade.
17 (71) 17 (100) 7 (29) 20.92.2 52.58.0
17e24 45e75
22 (92) 2 (8) 19 (79) 3 (13) 2 (8)
14 2 6 1 1
(58) (8) (25) (4) (4)
Table 4 Incidence of curve progression >5 based on curve magnitude and Risser grade. Risser Grade
Curves 15 e19 , % (n)
Curves 20 e24 , % (n)
p value
0 (n5247) 1 (n555)
66 (86) 63 (20)
67 (78) 57 (13)
.39
Discussion Medical/interventional treatment decisions in patients with mild AIS curves are dependent on the ability to determine the risk of curve progression. Parents almost always ask about the likelihood of curve progression. This study offers more information to better answer these clinical questions.
Table 2 Comparisons between Risser 0 (n 5 247) and Risser 1 (n 5 55) groups. Parameters
Risser 0
Risser 1
p value
Chronologic age (years), mean SD Gender, n (%) Female Male Initial visit, mean SD Final visit, mean SD Curve progression, mean SD Surgery, n (%) No Yes
12.5 1.1
13.2 0.9
!.01 .05
203 (83) 44 (17) 19.2 2.9 28.8 10.8 9.5 10.1
51 (93) 4 (7) 18.4 2.9 26.0 8.8 7.5 8.2
242 (98) 5 (2)
54 (98) 1 (2)
.06 .08 .22 .92
K.A. Zapata et al. / Spine Deformity 7 (2019) 870e874
This study demonstrates a high incidence of curve progression of skeletally immature patients (Risser 0 and Risser 1) with mild curves (15 e24 ). The majority of these patients progressed regardless of Risser status and curve magnitude at initial visit. That is, patients who were Risser 0 did not progress significantly more than patients who were Risser 1, and patients with curves 20 e24 did not progress significantly more than curves 15 e19 . This finding differs from a recent study evaluating the effect of Risser sign in curve progression in braced patients with AIS [13]. Although Karol found that braced patients who were Risser 0 were significantly more likely to progress to surgery, our study’s smaller curve magnitude and Risser sign inclusion criteria before brace initiation may have contributed to these different findings. Only 6 patients out of the 24 patients with final curve magnitudes of >45 required surgical treatment. Patients (n 5 18) did not have surgery as a result of either physician recommendationdas our institution more commonly uses a curve magnitude of O50 to recommend surgerydor patient choice. The majority of curve types with final curve magnitudes of >45 were Lenke 1 (58%), which is twice the percentage of the total cohort (30%). Although the majority of patients with mild curves demonstrated curve progression, some patients’ curve magnitude spontaneously improved (3%). Careful reevaluation of these radiographs was performed, and the measures were found to be accurate. The finding is not unique and was noted by Lonstein and Carlson (1984) in their original series [1]. A future study could evaluate factors that suggest a curve will improve without treatment in this subgroup of patients. Our results correlate well overall with that of Lonstein and Carlson (1984) who reported a 68% incidence of curve progression >5 in patients with curves 20 e29 who were Risser 0 and Risser 1. We found a 62% incidence of curve progression >5 in patients with curves 20 e24 who were Risser 0 and Risser 1. Although our study included a lower curve magnitude cut-off (24 ) than Lonstein and Carlson (29 ), we also included patients who were braced, because that is the standard of care today. Our study is limited first by its retrospective nature and the reliance on medical records and radiographs. Although curve progression has always been quantified radiographically, several factors that motivate clinicians to treat irrespective of Cobb measurements, such as the severity of the axial rotation, could not be examined. The current data cannot distinguish who will and will not progress to brace wear or surgery. It only offers guidance as to who may require more aggressive medical/interventional treatment. For example, physiotherapeutic scoliosis-specific exercises may prevent the need for brace wear [16-18] and may be a treatment option in committed families concerned about curve progression and in families averse to brace wear. Because brace wear can reduce curve progression and may prevent the need
873
for a possible future surgery [19], initiating brace wear in patients who are Risser 0 with curves smaller than 25 may be warranted, especially in patients with open triradiate cartilages who are at higher risk of progression to surgery [13]. Patients at highest risk of progression (Lenke 1, Risser 0, premenarchal females, open triradiate cartilage) should initially be monitored every four to six months, depending on the curve severity. For example, a patient at highest risk of progression with a 15 curve should be monitored in six months compared with a 19 curve in four months. If curves progress >5 at followup, but are still !25 , consider early treatment. In patients who are Risser 0, premenarchal females, and have open triradiate cartilages, we commonly prescribe nighttime brace wear for thoracolumbar or lumbar curves at least 20 and occasionally full-time brace wear for thoracic curves at least 20 . We prescribe nighttime brace wear more readily than full-time brace wear for 20 curves, because it is considered less burdensome. We consider initiating brace wear in patients with even smaller curves (>15 ) at highest risk of progression and a strong family history of severe scoliosis. We need other predictive signs in addition to the Cobb angle, because waiting for curve progression leads directly to delayed initiation of treatment. Recent work suggests that dedicated hand or elbow radiographs may be more accurate in determining the risk of progression in the skeletally immature patient with AIS [20,21]. However, we did not evaluate additional radiographs. We have recently started obtaining hand radiographs to determine a simplified Tanner Whitehouse III skeletal maturity assessment to better understand progression risk [21]. Future research can compare the accuracy and efficacy of different methods in determining the risk of curve progression. Our study identified information from standard scoliosis radiographs that can be used to gauge the risk of progression. Overall, such information may have the most clinical relevance for the practitioner who routinely interprets standard scoliosis films in deciding patient treatment. Conclusions Curve progression for small curves (!20 ) is similar to curves between 20 and 24 in patients with AIS who are Risser 0 or Risser 1. Close observation or perhaps early intervention for these patients is necessary. These data suggest a paradigm shift and call for early treatment in small curves. Key points Most patients (65%) with AIS who are Risser 0 to 1 with curves 15 e24 will progress >5 . Curve progression for AIS may require closer observation or early treatment.
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Acknowledgment The authors acknowledge Jeffrey Hopkins, Anna McClung, Amy McIntosh, Bryan Tompkins, Joshua Meier, Dinesh Tawrani, and Jack Dale for performing radiographic measurements.
References [1] Lonstein JE, Carlson JM. The prediction of curve progression in untreated idiopathic scoliosis during growth. J Bone Joint Surg Am 1984;66:1061e71. [2] Bunnell WP. The natural history of idiopathic scoliosis. Clin Orthop Relat Res 1988;229:20e5. [3] Weinstein SL, Ponseti IV. Curve progression in idiopathic scoliosis. J Bone Joint Surg Am 1983;65:447e55. [4] Ylikoski M. Growth and progression of adolescent idiopathic scoliosis in girls. J Pediatr Orthop B 2005;14:320e4. [5] Peterson LE, Nachemson AL. Prediction of progression of the curve in girls who have adolescent idiopathic scoliosis of moderate severity. Logistic regression analysis based on data from the brace study of the scoliosis research society. J Bone Joint Surg Am 1995;77:823e7. [6] Little DG, Song KM, Katz D, et al. Relationship of peak height velocity to other maturity indicators in idiopathic scoliosis in girls. J Bone Joint Surg Am 2000;82:685e93. [7] 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. [8] Sanders JO, Herring JA, Browne RH. Posterior arthrodesis and instrumentation in the immature (Risser-grade-0) spine in idiopathic scoliosis. J Bone Joint Surg Am 1995;77:39e45. [9] Risser JC. The iliac apophysis: an invaluable sign in the management of scoliosis. Clin Orthop 1958;11:111e9.
[10] Little DG, Sussman MD. The Risser sign: a critical analysis. J Pediatr Orthop 1994;14:569e75. [11] Biondi J, Weiner DS, Bethem D, et al. Correlation of Risser sign and bone age determination in adolescent idiopathic scoliosis. J Pediatr Orthop 1985;5:697e701. [12] Weinstein SL, Dolan LA, Cheng JC, et al. Adolescent idiopathic scoliosis. Lancet 2008;371:1527e37. [13] Karol LA, Virostek D, Felton K, et al. The effect of the Risser stage on bracing outcome in adolescent idiopathic scoliosis. J Bone Joint Surg Am 2016;98:1253e9. [14] Katz DE, Herring JA, Browne RH, et al. Brace wear control of curve progression in adolescent idiopathic scoliosis. J Bone Joint Surg Am 2010;92:1343e52. [15] Lenke LG, Edwards 2nd CC, Bridwell KH. The Lenke classification of adolescent idiopathic scoliosis: how it organizes curve patterns as a template to perform selective fusions of the spine. Spine (Phila Pa 1976) 2003;28:S199e207. [16] Monticone M, Ambrosini E, Cazzaniga D, et al. Active selfcorrection and task-oriented exercises reduce spinal deformity and improve quality of life in subjects with mild adolescent idiopathic scoliosis. Results of a randomised controlled trial. Eur Spine J 2014;23:1204e14. [17] Anwer S, Alghadir A, Shaphe A, et al. Effects of exercise on spinal deformities and quality of life in patients with adolescent idiopathic scoliosis. Biomed Res Int 2015;2015:123848. [18] Zapata K, Sucato D, Jo C. Physiotherapeutic scoliosis-specific exercises may reduce curve progression in mild adolescent idiopathic scoliosis curves. Ped Phys Ther 2019;31:280e5. [19] Weinstein SL, Dolan LA, Wright JG, et al. Effects of bracing in adolescents with idiopathic scoliosis. N Engl J Med 2013;369:1512e21. [20] Charles YP, Dimeglio A, Canavese F, et al. Skeletal age assessment from the olecranon for idiopathic scoliosis at Risser grade 0. J Bone Joint Surg Am 2007;89:2737e44. [21] Sanders JO, Khoury JG, Kishan S, et al. Predicting scoliosis progression from skeletal maturity: a simplified classification during adolescence. J Bone Joint Surg Am 2008;90:540e53.
Skeletally Immature Patients With Adolescent Idiopathic Scoliosis Curves 15e24 Are at High Risk for Progression Karina A. Zapata, PT, DPT, PhDa,*, Daniel J. Sucato, MD, MSa, Mark C. Lee, MDb, Chan-Hee Jo, PhDa a
Texas Scottish Rite Hospital for Children, 2222 Welborn Street, Dallas, TX 75219, USA Connecticut Children’s Specialty Group, 85 Seymour Street, Hartford, CT 06106, USA Received 26 November 2018; revised 11 February 2019; accepted 27 February 2019
b
Abstract Study Design: Retrospective review. Objectives: To evaluate the incidence of adolescent idiopathic scoliosis (AIS) curve progression and brace prescription in skeletally immature patients (Risser 0 to Risser 1) with curves 15 e24 . Summary of Background Data: Many skeletally immature patients with mild AIS ask about the likelihood of curve progression. No studies have answered these questions. Methods: The charts and radiographs of 302 consecutive patients with curves 15 e24 at initial visit, Risser 0 to Risser 1, were reviewed until skeletal maturity (>Risser 4) or surgery. Curves averaged 19.1 2.9 at initial visit. The Risser grade was 0 in 247 patients (82%) and 1 in 55 patients (18%). Patients who were Risser 0 were compared with those who were Risser 1, curves 15 e19 were compared with curves 20 e24 . Results: The majority of patients demonstrated curve progression >5 (65%). Patients who were Risser 0 did not progress significantly more than patients who were Risser 1 (10 vs. 8 ) (p 5 .22). Patients with curves 20 e24 did not progress significantly more than patients with curves 15 e19 (10 vs. 9 ) (p 5 .65). Conclusions: Curve progression for small curves (15 e19 ) is similar to curves between 20 and 24 . Close observation or perhaps early intervention for these patients is necessary. These data may suggest a paradigm shift to earlier brace initiation and call for early treatment in small curves. Level of Evidence: Level II. Ó 2019 Scoliosis Research Society. All rights reserved. Keywords: Spine deformity; Adolescent idiopathic scoliosis; Mild curves; Early treatment
Introduction Skeletally immature patients with adolescent idiopathic scoliosis (AIS) whose major curves are less than 25 present a particularly challenging clinical dilemma. Patients Author disclosures: KAZ (none), DJS (a patent Globus with royalties paid), MCL (grants from Scoliosis Research Society, other from JBJS Classroom, outside the submitted work), CHJ (none). IRB approval: Institutional review board approval was received from Texas Scottish Rite Hospital for Children and University of Texas Southwestern. No funding was received from this work. *Corresponding author. Texas Scottish Rite Hospital for Children, 2222 Welborn Street, Dallas, TX 75219, USA. Tel.: (214) 559-7790; fax: (214) 224-3801. E-mail address: [email protected] (K.A. Zapata).
with significant residual spinal growth are at risk of curve progression and brace prescription, and a small number of progressive curves will eventually require surgical treatment [1-3]. Identifying patients with progressive small magnitude curves at presentation lies at the crux of clinical management, because medical interventions to halt curve progression may be warranted. The clinical determination of patients at risk for progression remains difficult despite a clear association between residual spinal growth and curve progression. Physicians assess spinal growth potential by using radiographic and clinical indicators of skeletal maturity and, from this information, estimate the risk of progression [1,4-8]. Skeletal maturity indices such as the Risser sign and triradiate cartilage closure are clinically
2212-134X/$ - see front matter Ó 2019 Scoliosis Research Society. All rights reserved. https://doi.org/10.1016/j.jspd.2019.02.012
K.A. Zapata et al. / Spine Deformity 7 (2019) 870e874
useful, because they can be evaluated on the same radiograph that was taken to measure curve magnitude [9]. However, skeletal maturity indices that have an established correlation with curve progression have questionable accuracy. In particular, numerous authors have noted an inexact correlation of radiographic Risser sign with skeletal maturity and residual spinal growth [10,11]. In a sample of 727 JIS and AIS patients with curves from 5 to 29 , Lonstein and Carlson (1984) reported that 68% of patients who were Risser 0 and Risser 1 with curves measuring 20 e29 demonstrated curve progression >5 , whereas only 23% of patients who were Risser 2 to Risser 4 with similar curve magnitudes progressed [1]. Older studies would conclude that patients who are Risser 0 and Risser 1 have a similar risk of curve progression for a given curve magnitude and were managed similarly [12]. However, today it is more commonly recognized that patients who are Risser 0 and Risser 1 do not share similar risk for curve progression, because the greatest spinal growth phase is during Risser 0 [7]. Recent research has also indicated that patients who are Risser 0 have worse brace treatment outcomes than patients who are Risser 1 [13,14]. It can be postulated that small curves below 25 may progress when significant growth remains [1-3]. Previous studies have suggested between 22% and 44% of patients who are Risser 0 or Risser 1 with curves less than 20 demonstrate curve progression greater than 10 [1,2]. Lonstein’s work demonstrated a progression risk of 38% for patients who are Risser 0 with curves between 5 and 29 . Despite the available data, no study has compared the progression risk of patients with small curves who are Risser 0 to patients who are Risser 1. Also, no study has compared subgroups of skeletally immature patients with small curves to determine if a patient with a 15 curve has the same progression risk as a patient with a 20 curve, information that could potentially guide the need for earlier intervention. The following case-control study examines the risk of curve progression in adolescents with idiopathic scoliosis who are Risser 0 and Risser 1 with curves presenting between 15 and 24 . We compared the progression risk of patients who are Risser 0 versus Risser 1, and 15 e19 versus 20 e24 .
Material and Methods Approval was obtained from the hospital and university institutional review boards. A consecutive series of AIS patients treated at a single institution between 1990 and 2005 were retrospectively evaluated. The charts and radiographs of 302 patients with curves at initial visit 15 e24 , Risser 0 to Risser 1, were reviewed until skeletal maturity (at least Risser 4) or surgery.
871
A strict bracing protocol was not employed by our facility during the study period, although the general consensus among providers was that bracing should be offered to skeletally immature patients with curves progressing greater than 25 . In addition, patients with confounding diagnoses such as skeletal dysplasia, leg length discrepancy, spondylolysis, and/or spondylolisthesis were excluded from the analysis. Additional exclusion criteria included fewer than three clinic visits with radiographs. Standard posteroanterior scoliosis radiographs were examined from the initial visit, before the start of bracing or planned surgery and, for patients observed or treated with bracing, at skeletal maturity. All radiographic measurements were performed by individuals with at least one year of training in the clinical and radiographic evaluation of patients with scoliosis. Radiographic measures included the Risser sign, Cobb angle, and triradiate cartilage closure. Curve patterns were classified according to a modified Lenke system, where the curve with the largest Cobb measure was considered structural and the other curves were considered structural only if measuring greater than 15 [15]. An alphabetical lumbar modifier was assigned to each radiograph, as described by Lenke, but no supine bending films were used. If more than one structural curve existed, the largest Cobb angle measured was used for comparison. Clinical data obtained from a review of the corresponding charts included gender and age. Statistical methods Statistical analyses were performed using SAS/STAT (version 9.4). A chi-square test was used to compare categorical variables, and for the small sample size a Fisher exact test was used. Continuous variables were first examined for normality of data distribution, and then a nonparametric test such as Mann-Whitney was executed for two groups of patients. A p value of !.05 was defined as statistical significance. Results The average age was 12.6 years at initial visit, and average curve at initial presentation was 19.1 (Table 1). The majority of the curves were modified Lenke 1 and 5, corresponding to single lumbar, thoracolumbar, or thoracic curves (Table 1). Females and patients who were Risser 0 were more than 80% of the cohort (Table 1). The triradiate cartilage was visualized in 262 of the 302 patients. The triradiate cartilage was open in 118 patients (45%) and closed in 144 patients (55%). Curves progressed an average of 9.1 9.8 (Table 1). Patients who were Risser 0 progressed an average of 10 10 compared with Risser 1 curve progression of 8 8 (p 5 .22)
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K.A. Zapata et al. / Spine Deformity 7 (2019) 870e874
Table 1 Cohort demographics.
Table 3 Characteristics of patients whose curves progressed >45 (n524).
Parameters
MeanSD or n (%)
Range
Parameters
MeanSD or n (%)
Range
Initial chronologic age (years) Age at final visit (years) Gender Female Male Cobb angle of major curve ( ) Initial visit Final visit Curve progression Risser Grade 0 1 Initial modified Lenke curve type 1 2 3 4 5 6
12.6 1.1
10.1 to 16.4
12.21.1
10.2e14.0
16.0 1.6
12.5 to 21.8
Initial chronologic age (years) Gender Female Premenarchal Male Cobb angle of major curve ( ) Initial visit Final visit Risser Grade 0 1 Triradiate cartilage Open Closed Not visualized Initial modified Lenke curve type 1 2 3 5 6
254 (84) 48 (16)
19.1 2.9 28.2 10.5 9.1 9.8
15 to 24 8 to 75 e8 to 53
247 (82) 55 (18)
90 22 55 1 120 14
(30) (7) (18) (0) (40) (5)
(Table 2). Curves 20 e24 progressed an average of 10 11 compared with curves 15 e19 which progressed an average of 9 9 (p 5 .65). Surgery was performed in 6 (2%) patients (Table 2). However, 24 patients had a final curve magnitude of >45 , a general indication for surgical treatment (Table 3). The majority of patients with curves 15 e24 who were Risser 0 or Risser 1, demonstrated curve progression >5 (65%). Curves progressed less than 5 in 105 patients (35%), 5 e9 in 71 patients (24%), and progressed at least 10 in 126 patients (42%). Curves in 9 patients (3%) improved at least 5 at the final visit compared with initial film, averaging 19.1 3.7 at initial visit. Only one of these patients had been braced. See Table 4 for the incidence of curve progression >5 based on curve magnitude and Risser grade.
17 (71) 17 (100) 7 (29) 20.92.2 52.58.0
17e24 45e75
22 (92) 2 (8) 19 (79) 3 (13) 2 (8)
14 2 6 1 1
(58) (8) (25) (4) (4)
Table 4 Incidence of curve progression >5 based on curve magnitude and Risser grade. Risser Grade
Curves 15 e19 , % (n)
Curves 20 e24 , % (n)
p value
0 (n5247) 1 (n555)
66 (86) 63 (20)
67 (78) 57 (13)
.39
Discussion Medical/interventional treatment decisions in patients with mild AIS curves are dependent on the ability to determine the risk of curve progression. Parents almost always ask about the likelihood of curve progression. This study offers more information to better answer these clinical questions.
Table 2 Comparisons between Risser 0 (n 5 247) and Risser 1 (n 5 55) groups. Parameters
Risser 0
Risser 1
p value
Chronologic age (years), mean SD Gender, n (%) Female Male Initial visit, mean SD Final visit, mean SD Curve progression, mean SD Surgery, n (%) No Yes
12.5 1.1
13.2 0.9
!.01 .05
203 (83) 44 (17) 19.2 2.9 28.8 10.8 9.5 10.1
51 (93) 4 (7) 18.4 2.9 26.0 8.8 7.5 8.2
242 (98) 5 (2)
54 (98) 1 (2)
.06 .08 .22 .92
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This study demonstrates a high incidence of curve progression of skeletally immature patients (Risser 0 and Risser 1) with mild curves (15 e24 ). The majority of these patients progressed regardless of Risser status and curve magnitude at initial visit. That is, patients who were Risser 0 did not progress significantly more than patients who were Risser 1, and patients with curves 20 e24 did not progress significantly more than curves 15 e19 . This finding differs from a recent study evaluating the effect of Risser sign in curve progression in braced patients with AIS [13]. Although Karol found that braced patients who were Risser 0 were significantly more likely to progress to surgery, our study’s smaller curve magnitude and Risser sign inclusion criteria before brace initiation may have contributed to these different findings. Only 6 patients out of the 24 patients with final curve magnitudes of >45 required surgical treatment. Patients (n 5 18) did not have surgery as a result of either physician recommendationdas our institution more commonly uses a curve magnitude of O50 to recommend surgerydor patient choice. The majority of curve types with final curve magnitudes of >45 were Lenke 1 (58%), which is twice the percentage of the total cohort (30%). Although the majority of patients with mild curves demonstrated curve progression, some patients’ curve magnitude spontaneously improved (3%). Careful reevaluation of these radiographs was performed, and the measures were found to be accurate. The finding is not unique and was noted by Lonstein and Carlson (1984) in their original series [1]. A future study could evaluate factors that suggest a curve will improve without treatment in this subgroup of patients. Our results correlate well overall with that of Lonstein and Carlson (1984) who reported a 68% incidence of curve progression >5 in patients with curves 20 e29 who were Risser 0 and Risser 1. We found a 62% incidence of curve progression >5 in patients with curves 20 e24 who were Risser 0 and Risser 1. Although our study included a lower curve magnitude cut-off (24 ) than Lonstein and Carlson (29 ), we also included patients who were braced, because that is the standard of care today. Our study is limited first by its retrospective nature and the reliance on medical records and radiographs. Although curve progression has always been quantified radiographically, several factors that motivate clinicians to treat irrespective of Cobb measurements, such as the severity of the axial rotation, could not be examined. The current data cannot distinguish who will and will not progress to brace wear or surgery. It only offers guidance as to who may require more aggressive medical/interventional treatment. For example, physiotherapeutic scoliosis-specific exercises may prevent the need for brace wear [16-18] and may be a treatment option in committed families concerned about curve progression and in families averse to brace wear. Because brace wear can reduce curve progression and may prevent the need
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for a possible future surgery [19], initiating brace wear in patients who are Risser 0 with curves smaller than 25 may be warranted, especially in patients with open triradiate cartilages who are at higher risk of progression to surgery [13]. Patients at highest risk of progression (Lenke 1, Risser 0, premenarchal females, open triradiate cartilage) should initially be monitored every four to six months, depending on the curve severity. For example, a patient at highest risk of progression with a 15 curve should be monitored in six months compared with a 19 curve in four months. If curves progress >5 at followup, but are still !25 , consider early treatment. In patients who are Risser 0, premenarchal females, and have open triradiate cartilages, we commonly prescribe nighttime brace wear for thoracolumbar or lumbar curves at least 20 and occasionally full-time brace wear for thoracic curves at least 20 . We prescribe nighttime brace wear more readily than full-time brace wear for 20 curves, because it is considered less burdensome. We consider initiating brace wear in patients with even smaller curves (>15 ) at highest risk of progression and a strong family history of severe scoliosis. We need other predictive signs in addition to the Cobb angle, because waiting for curve progression leads directly to delayed initiation of treatment. Recent work suggests that dedicated hand or elbow radiographs may be more accurate in determining the risk of progression in the skeletally immature patient with AIS [20,21]. However, we did not evaluate additional radiographs. We have recently started obtaining hand radiographs to determine a simplified Tanner Whitehouse III skeletal maturity assessment to better understand progression risk [21]. Future research can compare the accuracy and efficacy of different methods in determining the risk of curve progression. Our study identified information from standard scoliosis radiographs that can be used to gauge the risk of progression. Overall, such information may have the most clinical relevance for the practitioner who routinely interprets standard scoliosis films in deciding patient treatment. Conclusions Curve progression for small curves (!20 ) is similar to curves between 20 and 24 in patients with AIS who are Risser 0 or Risser 1. Close observation or perhaps early intervention for these patients is necessary. These data suggest a paradigm shift and call for early treatment in small curves. Key points Most patients (65%) with AIS who are Risser 0 to 1 with curves 15 e24 will progress >5 . Curve progression for AIS may require closer observation or early treatment.
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Acknowledgment The authors acknowledge Jeffrey Hopkins, Anna McClung, Amy McIntosh, Bryan Tompkins, Joshua Meier, Dinesh Tawrani, and Jack Dale for performing radiographic measurements.
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