Tag Archive | adolescent idiopathic scoliosis
June 29, 2021  

Journal Club Resident Spotlight: Jui-Yo Hsu

JBJS is pleased to highlight the orthopaedic residents who help implement the Robert Bucholz Resident Journal Club Grants at their institutions. The grant program promotes career-long skills in evaluating the orthopaedic literature. Click here for more information.

Name: Jui-Yo Hsu

Affiliation: National Taiwan University Hospital

What was the topic of the most “dynamic” journal club meeting you have had so far this year?

In March 2021, we hosted a spine journal club focusing on adolescent idiopathic scoliosis (AIS). It was our pleasure to have Prof. Andrew J. Schoenfeld, deputy editor of JBJS, join our discussion. His remarkable advice and unique insight inspired in-depth discussion. Our advisor and moderator, Prof. Shu-Hua Yang (楊曙華), chairperson of Taiwan Spine Society, who is also a pioneer in the field of AIS research, also provided great support to our journal club. The paper we presented was “Selecting the ‘Touched Vertebra’ as the Lowest Instrumented Vertebra in Patients with Lenke Type-1 and 2 Curves” (J Bone Joint Surg Am. 2020 Nov 18;102(22):1966-1973.) by Beauchamp, et al. All the faculty and residents were highly involved in the discussion. Due to the high relevance of this topic to clinical decision making in surgical correction of AIS, both Prof. Schoenfeld and Prof. Yang shared their viewpoints and precious clinical and surgical experiences with the audience.

What are the top 3 characteristics of an engaging, enlightening journal club presentation?

First, it’s important to keep the journal club intriguing to the participants. Therefore, choosing a good topic plays a key role. Residents will be more involved if the topic is clinically important, related to a familiar surgery, or connects to their own ongoing research. Second, because knowledge of the topic may vary between senior and junior residents, we assign one of our senior residents to provide background knowledge before the discussion. Reading the article and preparing in advance are required for every participant, and we also encourage everyone to come up with several questions before the journal club. Finally, support and participation from the faculty are crucial to the journal club. They can provide clinical experiences to residents and provoke further discussion. It is even more beneficial if the participants discuss their own cases with both colleagues and instructors.

How has the COVID-19 pandemic affected your journal-club activities?

In Taiwan, fortunately we were able to maintain normal lives and all residents and staff were able to participate in the journal club in person, despite the global pandemic. However, due to a local outbreak in Taiwan in early May 2021, restrictions were imposed on indoor gatherings. We therefore decided to host our journal club online. In fact, residents were more engaged in online journal club. Using the chatroom feature, residents were able to ask question at any time without interrupting the speaker, and supplementary materials could be shared by anyone at any time. I believe online meetings may become mainstream in the post COVID-19 era.

Aside from orthopaedic content, what have you been reading lately?

I have been reading Cribsheet: A Data-Driven Guide to Better, More Relaxed Parenting, from Birth to Preschool, by Emily Oster. It is a remarkable and useful book for first-time parents. I just welcomed my first child in April 2021, and this book provides practical advice in parenting with enormous medical references. Surprisingly, it was written by an economist. I feel more relieved and confident in parenting my son after reading this book.

How has free access to JBJS Clinical Classroom benefitted you and your journal club?

JBJS Clinical Classroom is very helpful in terms of learning orthopaedic knowledge for both junior and senior residents. Its innovative design makes it very easy and efficient to review previously learned concepts. The content is also very neat but with wide coverage across different specialties, which is also very helpful for orthopaedic board exam preparation.

June 28, 2021  

What’s New in Spine Surgery 2021 

Every month, JBJS publishes a review of the most pertinent and impactful studies reported in the orthopaedic literature during the previous year in 14 subspecialties. Click here for a collection of all such OrthoBuzz specialty-update summaries. 

This month, co-author Jacob M. Buchowski, MD, MS summarizes the 5 most compelling findings from the studies highlighted in the recently published “What’s New in Spine Surgery.” 

Degenerative Cervical Myelopathy

–In a multicenter, double-blinded, placebo-controlled, randomized phase-3 trial, investigators found no additional benefit from riluzole use with regard to functional outcome scores among patients who underwent decompression and fusion for cervical myelopathy1. The primary outcome of interest was the change in the modified Japanese Orthopaedic Association (mJOA) score at 6 months. 

Dysphagia After Multilevel ACDF

–A Level-I double-blinded randomized controlled trial demonstrated a significant decrease in the severity of dysphagia after multilevel anterior cervical discectomy and fusion (ACDF) among patients who received local intraoperative corticosteroids (56 in the treatment group vs 53 in the control group)2. 

Preop. Epidural Steroid Injection and Postop. Infection 

–A retrospective study of patients who underwent lumbar spine surgical procedures for radiculopathy and/or spinal stenosis3 found that: 

  • In the decompression group, there was no significant difference in the postoperative infection rate between those who had a preoperative epidural steroid injection (2,957 of 9,903) and those who did not.  
  • Among those who underwent fusion, there was a significantly higher rate of infection (2.68%) for those who had preoperative epidural steroid injection (1,383 of 5,108) vs those who did not (1.69%).  
  • In the fusion group, there was a significantly higher rate of infection for those who had a steroid injection within 30 days or >90 days preoperatively, but patients with injection between 30 and 90 days preoperatively had no increased risk of postoperative infection. 

Adolescent Idiopathic Scoliosis (AIS)

–In a Level-IV study, investigators examined the relationship between thoracic morphology and pulmonary function in patients with AIS (mean age, 15.6 years)4. They found a strong positive correlation between the costophrenic angle distance and forced vital capacity, FEV1, vital capacity, and total lung capacity, suggesting that the costophrenic angle distance can be used to assess pulmonary function outcome. Their findings also suggest that an apical vertebral deviation ratio of >0.2 is associated with moderate to severe impairment of lung function. 

Early-Onset Scoliosis (EOS) 

–In a cross-sectional study of prospectively enrolled patients across multiple centers, investigators examined the influence of the classification of EOS etiology, radiographic parameters, and medical comorbidities on the Early Onset Scoliosis Questionnaire (EOSQ), a measure of health-related quality of life. Scores were lower in many EOSQ domains for patients with neuromuscular and syndromic etiologies. The total and subdomain scores were similar between patients with congenital and idiopathic EOS.  

References 

  1. Fehlings MG, Badhiwala JH, Ahn H, Farhadi HF, Shaffrey CI, Nassr A, Mummaneni P, Arnold PM, Jacobs WB, Riew KD, Kelly M, Brodke DS, Vaccaro AR, Hilibrand AS, Wilson J, Harrop JS, Yoon ST, Kim KD, Fourney DR, Santaguida C, Massicotte EM, Kopjar B. Safety and efficacy of riluzole in patients undergoing decompressive surgery for degenerative cervical myelopathy (CSM-Protect): a multicentre, double-blind, placebo-controlled, randomised, phase 3 trial. Lancet Neurol. 2021 Feb;20(2):98-106. Epub 2020 Dec 22. 
  2. Kim HJ, Alluri R, Stein D, Lebl D, Huang R, Lafage R, Bennett T, Lafage V, Albert T. Effect of topical steroid on swallowing following ACDF: results of a prospective double-blind randomized control trial. Spine (Phila Pa 1976). 2021 Apr 1;46(7):413-20.  
  3. Kreitz TM, Mangan J, Schroeder GD, Kepler CK, Kurd MF, Radcliff KE, Woods BI, Rihn JA, Anderson DG, Vaccaro AR, Hilibrand AS. Do preoperative epidural steroid injections increase the risk of infection after lumbar spine surgery? Spine (Phila Pa 1976). 2021 Feb 1;46(3):E197-202. 
  4. Deng Z, Luo M, Zhou Q, Yang X, Liu L, Song Y. Relationship between pulmonary function and thoracic morphology in adolescent idiopathic scoliosis: a new index, the “apical vertebra deviation ratio”, as a predictive factor for pulmonary function impairment. Spine (Phila Pa 1976). 2021 Jan 15;46(2):87-94. 

 

February 17, 2021  

What’s New in Pediatric Orthopaedics 2021

Every month, JBJS publishes a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in 14 specialty areas. Click here for a collection of all such OrthoBuzz Guest Editorial summaries.

This month, co-author Lindsay M. Andras, MD summarizes the 5 most compelling findings from the >80 studies highlighted in the most recent “What’s New in Pediatric Orthopaedics.”

Anterior Vertebral Body Tethering vs Spinal Fusion

–Motion-sparing approaches to scoliosis treatment are attracting increased interest. An informative retrospective study compared 2 to 5-year outcomes of anterior vertebral body tethering (AVBT, 23 patients) and posterior spinal fusion (26 patients) in the treatment of adolescent idiopathic scoliosis. Curve correction was significantly better in the posterior fusion group (mean curve magnitude of 16° vs 33° in the AVBT group). Posterior fusion also demonstrated a revision rate of 0%, while a revision rate of 39% was found for AVBT (9 of 23), with 12 patients (52%) showing evidence of tether breakage.

Antibiotic Regimens for Osteoarticular Infection

–While osteomyelitis is often treated with a 4 to 6-week course of intravenous (IV) antibiotics, intriguing results were reported in a study examining the data of 74 patients before and after the initiation of early transition to oral antibiotics for osteoarticular infection1. In the early transition group, which received IV antibiotics for a median of 7 days, no return ED visits or readmissions were reported. Of note, this approach also appeared to stave off complications related to the peripherally inserted central catheters, which necessitated a return to the ED for 16% of the patients who received the longer course of IV antibiotics.

Developmental Dysplasia of the Hips

–What is the long-term likelihood of total hip arthroplasty (THA) when closed reduction or open reduction and Salter innominate osteotomy is used for the treatment of developmental dysplasia of the hips (DDH) in children after walking age? A comparative analysis of hip survival at 45 years showed that both open and closed reduction “provided substantial benefit relative to the natural history of DDH,” but THA is the expected outcome in middle adulthood, particularly for bilateral hips managed with closed reduction after the age of 18 months.

Legg-Calvé-Perthes Disease

–A case-series report noted “predictable radiographic healing and marked clinical improvement” after open reduction and surgical fixation (ORIF) of symptomatic osteochondritis dissecans lesions seen as sequelae to Legg-Calvé-Perthes disease2. Mean follow-up was 4.6 years.

Pediatric Syndactyly Reconstruction

–Synthetic dermal substitute shows merit as an alternative to skin grafting in syndactyly reconstruction, as found in a recent study3. Of 21 webs, normal vascularity was noted in 20, normal pigmentation in 17, normal skin pliability in 13, and flat scar height in 15, with no complications observed. Of note, a small sheet of synthetic dermal substitute costs approximately $350.

References

  1. Islam S, Biary N, Wrotniak B. Favorable outcomes with early transition to oral antibiotics for pediatric osteoarticular infections. Clin Pediatr (Phila). 2019 Jun;58(6):696-9. Epub 2019 Feb 8.
  2. Lamplot JD, Schoenecker PL, Pascual-Garrido C, Nepple JJ, Clohisy JC. Open reduction and internal fixation for the treatment of symptomatic osteochondritis dissecans of the femoral head in patients with sequelae of Legg-Calvé-Perthes disease. J Pediatr Orthop. 2020 Mar;40(3):120-8.
  3. Wall LB, Velicki K, Roberts S, Goldfarb CA. Outcomes of pediatric syndactyly repair using synthetic dermal substitute. J Hand Surg Am. 2020 Aug;45(8):773.e1-6. Epub 2020 Feb 13.
October 26, 2020  

Postop Dexamethasone Cuts Opioid Use after AIS Surgery

OrthoBuzz occasionally receives posts from guest bloggers. This guest post comes from Impact Science, in response to a recent article in JBJS.

Pain management is an important aspect of postoperative care after posterior spinal fusion for the treatment of adolescent idiopathic scoliosis (AIS). Opioid medications, while highly effective and commonly used for postoperative analgesia, have many well-documented adverse effects. Several recent studies have suggested that dexamethasone, a glucocorticoid, is an effective adjunct for postoperative pain management after many adult orthopaedic procedures, but its use after AIS surgery has not been well studied.

Beginning in 2017, doctors at Children’s Healthcare of Atlanta added dexamethasone to their postoperative pain control pathway for adolescent spinal-fusion patients. In the October 21, 2020 issue of The Journal of Bone & Joint Surgery, Fletcher et al. report findings from a cohort study that investigated the postoperative outcomes of 113 patients (median age of 14 years) who underwent posterior spinal fusion between 2015 and 2018. The main outcome of interest—opioid consumption while hospitalized—was determined by converting all postoperative opioids given into morphine milligram equivalents (MME).

Because dexamethasone entered their institution’s standardized pathway for this operation in 2017, it was easy for the authors to divide these patients into two groups; 65 of the study patients did not receive postoperative steroids, while 48 patients were managed with 3 doses of steroids postoperatively. Relative to the former group, the latter group showed a 39.6% decrease in total MME used and a 29.5% decrease in weight-based MME. Patients who received postoperative dexamethasone were also more likely to walk at the time of initial physical therapy evaluation. Notably, the authors found no differences between the groups with regard to wound dihescence or 90-day infection rates—2 complications that have been associated with chronic use of perioperative steroids.

In commenting on these findings, Amy L. McIntosh, MD from Texas Scottish Rite Hospital for Children writes that she was so impressed that she plans “on adding dexamethasone to our institution’s standardized AIS care pathway.”

Impact Science is a team of highly specialized subject-area experts (Life Sciences, Physical Sciences, Medicine & Humanities), who collaborate with authors, societies, libraries, universities, and various other stakeholders for services to enhance research impact. Through research engagement and science communication, Impact Science aims at democratizing science by making research-backed content accessible to the world.

May 7, 2020  

Is the Tethering Juice Worth the Squeeze in AIS?

The tried-and-true treatment for progressive adolescent idiopathic scoliosis (AIS) is a posterior spinal fusion (PSF). However, for skeletally immature patients, there is increasing interest in motion-sparing growth modulation, specifically anterior vertebral body tethering (AVBT). Early reports on tethering looked promising, but the long-term prognosis remains fuzzy.

Newton et al. clarify this somewhat in the May 6, 2020 issue of JBJS. They retrospectively compared outcomes among a cohort of 23 AVBT patients followed for a mean of 3.4 years with those among a matched cohort of 26 PSF patients followed for a mean of 3.6 years. The groups were well-matched in terms of demographics and preoperative curve measurements, but the AVBT group was slightly less skeletally mature based on triradiate cartilage status and Sanders classification.

The authors found that both groups experienced significant postoperative curve correction, but the PSF group had significantly greater immediate correction of the main thoracic curve (78%) than the AVBT group (36%). Smaller immediate correction is to be expected in a growth-modulation procedure, which allows the spine to “grow straighter” over time with the tether. But at the final follow-up, the AVBT group had only a 43% curve correction versus 69% final follow-up correction in the PSF group. In addition, 9 revision procedures occurred in the AVBT group, versus none in the PSF group. Twelve patients (52%) in the AVBT group had evidence of broken tethers, with 3 of those patients undergoing revision surgery due to curve progression linked to tether breakage.

Overall, 12 of 23 patients in the AVBT group (52%) were deemed a “clinical success” at the end of the study (defined as a thoracic curve <35° without a need for a secondary fusion) while all 26 patients in the PSF group were deemed a clinical success. Anterior vertebral body tethering may have a role in the treatment of scoliosis in the growing spine, but the results to date, including these from Newton et al., lead me to question whether the tethering “juice” in its current form is worth the “squeeze.”

Matthew R. Schmitz, MD
JBJS Deputy Editor for Social Media

February 21, 2020  

What’s New in Pediatric Orthopaedic Surgery 2020

Every month, JBJS publishes a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in 13 subspecialties. Click here for a collection of OrthoBuzz summaries of these “What’s New” articles. This month, co-author Kelly Vanderhave, MD selected the 5 most clinically compelling findings from the more than 50 studies summarized in the February 19, 2020 “What’s New in Pediatric Orthopaedic Surgery.”

ACL Reconstruction
—ACL reconstruction in pediatric patients continues to receive research attention. A recent review of >560 cases showed that soft-tissue grafts used in this population were twice as likely to fail (13%) as patellar tendon grafts (6%) (p <0.001).1

Septic Arthritis of the Hip
—A multicenter study identified the following independent risk factors for a repeat surgical procedure after initial arthrotomy for septic arthritis of the hip: presenting CRP of >10 mg/dL and ESR of >40 mm/hr, and the presence of osteomyelitis and MRSA.2

Adolescent Idiopathic Scoliosis
—A minimum 20-year follow-up of a cohort study evaluating 180 patients after observation, bracing, or surgical management of adolescent idiopathic scoliosis found the following:

  • In the observation cohort, 5 of 36 patients underwent a scoliosis surgical procedure as an adult.
  • In the bracing cohort, only 1 of 41 patients required an additional spinal surgical procedure.
  • In the surgical cohort, 7 of 103 patients required a revision surgical procedure.

At a mean follow-up of 30 years, there were no significant differences in patient-reported outcomes between the 3 cohorts.3

Infection after Spinal Deformity Surgery
—A retrospective study of >600 pediatric patients who underwent spinal deformity surgery identified 2 independent risk factors among 11 cases of deep surgical site infection that occurred >3 months after the procedure:

  • Nonidiopathic scoliosis (e.g., neuromuscular, congenital, and syndromic etiologies)
  • High volume of crystalloid administered during surgery (mean of 3.3 ±1.2 L in the group with surgical site infections vs 2.4 ±1.0 L in the infected group)

Redosing antibiotics intraoperatively after 3 hours did not significantly influence the risk of infection.4

Hip Dislocations in Infants with CP
—Among 11 patients (15 hips) with spastic cerebral palsy whose preoperative mean acetabular index was 29°, surgical hip reconstruction (a combination of open reduction, adductor tenotomy, femoral osteotomy, and/or pelvic osteotomy) yielded the following results at a mean follow-up of 40 months:

  • Mean migration index of 7%
  • Mean acetabular index of 22°
  • No instances of osteonecrosis
  • 90% achievement and maintenance of hip reduction in those who underwent open reduction with or without pelvic or femoral osteotomy.5

References

  1. Ho B, Edmonds EW, Chambers HG, Bastrom TP, Pennock AT. Risk factors for early ACL reconstruction failure in pediatric and adolescent patients: a review of 561 cases. J Pediatr Orthop. 2018 Aug;38(7):388-92.
  2. Murphy RF, Plumblee L, Barfield WB, Murphy JS, Fuerstenau N, Spence DD, Kelly DM, Dow MA, Mooney JF 3rd. Septic arthritis of the hip-risk factors associated with secondary surgery. J Am Acad Orthop Surg. 2019 May 1;27(9):321-6.
  3. Larson AN, Baky F, Ashraf A, Baghdadi YM, Treder V, Polly DW Jr, Yaszemski MJ. Minimum 20-year health-related quality of life and surgical rates after the treatment of adolescent idiopathic scoliosis. Spine Deform. 2019 May;7(3):417-27.
  4. Du JY, Poe-Kochert C, Thompson GH, Son-Hing JP, Hardesty CK, Mistovich RJ. Risk factors for early infection in pediatric spinal deformity surgery: a multivariate analysis. Spine Deform. 2019 May;7(3):410-6.
  5. Refakis CA, Baldwin KD, Spiegel DA, Sankar WN. Treatment of the dislocated hip in infants with spasticity. J Pediatr Orthop. 2018 Aug;38(7):345-9.
December 12, 2018  

Confirmed: TXA Works Well in Adolescent Scoliosis Surgery

The evidence favoring tranexamic acid (TXA) for reducing surgical blood loss is ample and growing, but until now robust data were sparse regarding its efficacy in the setting of adolescent idiopathic scoliosis surgery. In the December 5, 2018 issue of The Journal of Bone & Joint Surgery, Goobie et al. report on a randomized, blinded, placebo-controlled trial showing that, in that population, TXA reduced perioperative blood loss by 27%, compared with blood loss in a placebo group.

Even with recent advances in scoliosis surgical technique, blood transfusions are common. And, because transfusions are associated with significant morbidity and mortality, limiting operative blood loss and reducing the need for transfusion have become focal points for orthopaedic surgeons.

In this Level-I trial, >100 patients between the ages of 10 and 18 years undergoing elective posterior instrumented spinal fusion were randomized to receive either TXA (infusion of a 50-mg/kg loading dose and a 10-mg/kg/h maintenance dose) or normal saline (delivered in the same way and dose) during surgery. The TXA group demonstrated an overall 27% reduction in cumulative blood loss and a 2-fold reduction in the percentage of patients with clinically relevant blood loss (defined as >20 mL/kg).

The cumulative effect of reduced blood loss was enhanced over time, with the positive effect of TXA being most evident in procedures lasting >4 hours. None of the patients in the TXA group required a transfusion or developed side effects such as thromboembolism or seizures.

In an interesting sidenote, the authors asked the participating orthopaedic surgeons, who were blinded to the randomization, to guess which group each patient had been assigned to by evaluating the relative ooziness of the surgical field. The surgeons guessed correctly 72% of the time.

Overall, these findings prompted the authors to conclude that “the use of TXA as part of a multimodal blood management strategy, as was employed in this study, should be considered the standard of care for patients undergoing surgery for adolescent idiopathic scoliosis.”

June 27, 2018  

What’s New in Spine Surgery 2018

Spine_Graphic for OBuzzEvery month, JBJS publishes a Specialty Update—a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in 13 subspecialties. Click here for a collection of all OrthoBuzz Specialty Update summaries.

This month, OrthoBuzz asked Chad Krueger, MD, JBJS Deputy Editor for Social Media, to select the five most clinically compelling findings from among the more than 25 studies cited in the June 20, 2018 Specialty Update on Spine Surgery.

Cervical Spine
—A Level-III retrospective analysis found that patients who received a preoperative cervical epidural steroid injection prior to an anterior cervical discectomy and fusion or a posterior cervical fusion had a significantly greater risk of postoperative infection than those who did not receive a preoperative steroid injection.1 Prospective studies are needed to further clarify the perioperative infection risk associated with cervical epidural steroid injections.

Lumbar Spine
—A Level-II randomized pilot trial comparing titanium-coated PEEK interbody spacers with non-coated PEEK spacers among 40 patients who underwent transforaminal lumbar interbody fusion found that patients in both groups had 92% fusion at 3 months, with no significant between-group differences in pain and disability outcomes.2

—A Level-II randomized study of 108 patients who underwent lumbar discectomy compared outcomes among those who experienced 2 weeks versus 6 weeks of postoperative activity restriction. At the 1-year follow-up there was a nonsignificant difference in recurrent herniation (11% in the 2-week group versus 7% in the 6-week group) and no significant between-group differences in pain or disability scores.3

RF Ablation for Chronic Low Back Pain
—A Level-II meta-analysis involving 454 patients with chronic low back pain found that those who underwent radiofrequency (RF) lumbar-facet denervation had significantly reduced VAS back pain compared to a group that underwent a sham procedure or epidural block. Those in the denervation group who benefited most were those who had responded favorably to an initial diagnostic facet block.4

Adolescent Idiopathic Scoliosis
—A Level-II study assessing the ability of surface topography to evaluate spinal deformity in children with adolescent idiopathic scoliosis followed 45 patients for 1 year. This method plus radiography allowed researchers to determine mild curves with strong negative predictive value and sensitivity. The authors estimated that surface topographic analyses could reduce patient exposure to ionizing radiation by eliminating 31% of surveillance radiographs in these patients.5

References

  1. Cancienne JM, Werner BC, Puvanesarajah V, Hassanzadeh H, Singla A, Shen FH, Shimer AL. Does the timing of preoperative epidural steroid injection affect infection risk after ACDF or posterior cervical fusion?Spine (Phila Pa 1976). 2017 Jan 15;42(2):71-7.
  2. Rickert M, Fleege C, Tarhan T, Schreiner S, Makowski MR, Rauschmann M, Arabmotlagh M. Transforaminal lumbar interbody fusion using polyetheretherketone oblique cages with and without a titanium coating: a randomised clinical pilot study. Bone Joint J.2017 Oct;99-B(10):1366-72.
  3. Bono CM, Leonard DA, Cha TD, Schwab JH, Wood KB, Harris MB, Schoenfeld AJ. The effect of short (2-weeks) versus long (6-weeks) post-operative restrictions following lumbar discectomy: a prospective randomized control trial. Eur Spine J.2017 Mar;26(3):905-12. Epub 2016 Nov 2.
  4. Lee CH, Chung CK, Kim CH. The efficacy of conventional radiofrequency denervation in patients with chronic low back pain originating from the facet joints: a meta-analysis of randomized controlled trials. Spine J.2017 Nov;17(11):1770-80. Epub 2017 May 30.
  5. Hong A, Jaswal N, Westover L, Parent EC, Moreau M, Hedden D, Adeeb S. Surface topography classification trees for assessing severity and monitoring progression in adolescent idiopathic scoliosis. Spine (Phila Pa 1976).2017 Jul 1;42(13):E781-7.