Where Are We Now?
Most children with spinal deformity will be diagnosed with idiopathic scoliosis. However, only a few will progress to the point that treatment is recommended [12]. Observation alone suffices for most patients. Brace treatment should be considered for those with moderate scoliosis (25° to 40° Cobb angle of the major curve) and remaining growth potential. Even when left untreated, about half of the children with scoliosis in the treatment range will not progress to the point that surgery is indicated [11].
Factors that might be associated with the risk of curve progression include chronological age, menstrual status, skeletal age, pubertal status, height velocity (growth spurt), and curve size. The remaining growth potential and risk of curve progression is best assessed in the spine, but because it is difficult to assess the growth plates there, other sites are used. The calcification, or capping, of the iliac crest (the Risser sign) can be used to determine the remaining growth potential [8] of a patient, but calcification generally occurs after the peak height velocity. Therefore, physicians should consider using other methods besides the Risser sign to determine growth potential [2]. Hand and wrist radiographs are commonly used to determine skeletal age and remaining growth potential, where ossification and closure of epiphyses are evaluated according to the Greulich and Pyle [5], or Tanner and Whitehouse classifications [10]. Physicians also use simplified derivatives, such as the Sanders simplified skeletal maturity system, the thumb ossification composite index, and the distal radius and ulna classifications [3, 6, 9].
In the current study, Cheung and colleagues link skeletal age measurements determined from the distal radius and ulna classification with growth patterns in children with idiopathic scoliosis [4]. The authors found that curve progression peaks sometime after peak height velocity. Cheung and colleagues included males in their study even though idiopathic scoliosis is seen more often in females. When determining the risk of curve progression in males, physicians have to rely more on skeletal age than in females, in which information on menarcheal status also is important [7]. By determining the curve progression in both males and females (which behaved similarly in this report), Cheung and colleagues added to our knowledge base.
Where Do We Need To Go?
Based on the results of the current study, we know that physicians should closely monitor brace treatment soon after peak height velocity. But ultimately, the goal is to avoid unnecessary followups and radiographs for those individuals who will not benefit from treatment, so we still need a better knowledge of patterns and rates of curve progression in patients with scoliosis.
Future studies should examine whether finding the continued curve progression after peak height velocity is important when treating children with idiopathic scoliosis. Will this new knowledge on curve progression help physicians to more exactly determine when it is time to treat with a brace? For those children treated with a brace, could this help us determine when use of the brace can be safely discontinued? We would also like to know whether this finding is similar across different ethnic groups. Is there any specific universal maturity index that is better correlated to rate of curve progression than others across races and ethnicities?
How Do We Get There?
A tool that predicts risk, rate, and time of curve progression with a very high degree of certainty would be ideal, and additional development of data extracted from hand radiographs seem possible. Future studies should validate the currently described measurements in different longitudinal cohorts with and without brace treatment, while also determining whether this approach—identifying children with high risk of curve progression—translates into less surgery or fewer children treated with a brace.
Further, we need observational studies that compare the various approaches to assessment of skeletal maturity to see which one correlates most closely related with curve progression; I expect more such studies to be published [1]. Secondary analyses of controlled clinical trials may be used to determine whether a certain skeletal maturation grade corresponds to risk for progression in the untreated and treated patient. These types of studies may also yield new and improved algorithms to guide treatment in idiopathic scoliosis.
Footnotes
This CORR Insights® is a commentary on the article “Curve Progression in Adolescent Idiopathic Scoliosis Does Not Match Skeletal Growth” by Cheung and colleagues available at: DOI: 10.1007/s11999.0000000000000027.
The author certifies that neither he, nor any members of his immediate family, have any commercial associations (such as consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article.
All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request.
The opinions expressed are those of the writers, and do not reflect the opinion or policy of CORR® or The Association of Bone and Joint Surgeons®.
This CORR Insights® comment refers to the article available at DOI: 10.1007/s11999.0000000000000027.
References
- 1.Busscher I, Wapstra FH, Veldhuizen AG. Predicting growth and curve progression in the individual patient with adolescent idiopathic scoliosis: design of a prospective longitudinal cohort study. BMC musculoskeletal disorders. 2010;11:93. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Charles YP, Canavese F, Dimeglio A. Curve progression risk in a mixed series of braced and nonbraced patients with idiopathic scoliosis related to skeletal maturity assessment on the olecranon. J Pediatr Orthop. Part B 2017;26:240–244. [DOI] [PubMed] [Google Scholar]
- 3.Cheung JP, Cheung PW, Samartzis D, Cheung KM, Luk KD. The use of the distal radius and ulna classification for the prediction of growth: peak growth spurt and growth cessation. Bone Joint J. 2016;98-B:1689–1696. [DOI] [PubMed] [Google Scholar]
- 4.Cheung JPY, Cheung PWH, Samartzis D, Luk KD. Curve progression in adolescent idiopathic acoliosis does not match skeletal growth. Clin Orthop Relat Res. [Published online ahead of print]. DOI: 10.1007/s11999.0000000000000027. [DOI] [PMC free article] [PubMed]
- 5.Greulich WW, Pyle SI. Radiographic Atlas of Skeletal Development of the Hand and Wrist. 2nd ed. Stanford, CA: Stanford University Press; 1959. [Google Scholar]
- 6.Hung ALH, Chau WW, Shi B, Chow SK, Yu FYP, Lam TP, Ng BKW, Qiu Y, Cheng JCY. Thumb ossification composite index (TOCI) for predicting peripubertal skeletal maturity and peak height velocity in idiopathic scoliosis: A validation study of premenarchal girls with adolescent idiopathic scoliosis followed longitudinally until skeletal maturity. J Bone Joint Surg Am. 2017;99:1438–1446. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Richards BS, Bernstein RM, D'Amato CR, Thompson GH. Standardization of criteria for adolescent idiopathic scoliosis brace studies: SRS committee on bracing and nonoperative management. Spine (Phila Pa 1976). 2005;30:2068–2075. [DOI] [PubMed] [Google Scholar]
- 8.Risser JC. The Iliac apophysis; an invaluable sign in the management of scoliosis. Clin Orthop. 1958;11:111–119. [PubMed] [Google Scholar]
- 9.Sanders JO, Browne RH, McConnell SJ, Margraf SA, Cooney TE, Finegold DN. Maturity assessment and curve progression in girls with idiopathic scoliosis. J Bone Joint Surg Am. 2007;89:64–73. [DOI] [PubMed] [Google Scholar]
- 10.Tanner JM, Healy MJR, Goldstein H, Cameron N. Assessment of Skeletal Maturity and Prediction of Adult Height (TW3 Method). 3rd ed London, UK: Saunders; 2001. [Google Scholar]
- 11.Weinstein SL, Dolan LA, Wright JG, Dobbs MB. Effects of bracing in adolescents with idiopathic scoliosis. N Engl J Med. 2013;369:1512–1521. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Willner S, Uden A. A prospective prevalence study of scoliosis in Southern Sweden. Acta Orthop Scand. 1982;53:233–237. [DOI] [PubMed] [Google Scholar]