Informational & Position Statements

Early Onset Scoliosis Consensus Statement

SRS Growing Spine Committee, June 2014

Early Onset Scoliosis (EOS) refers to spine deformity which is present before 8 – 10 years of age. EOS is further organized to reflect etiology as applicable:

Diagnostic Categories of EOS:

Idiopathic:

Curves for which there is no apparent cause or related underlying etiology

• Infantile idiopathic- a subgroup of idiopathic curves which develop in infants and children less than 3

Congenital:

A particular type of EOS in which the vertebrae develop incorrectly in utero.

• Congenital scoliosis is sometimes associated with cardiac and renal abnormalities. Evaluation may include studies of heart and kidneys.

Thoracogenic:

A particular type of EOS that may be encountered in the following settings:

• Multiple congenital rib fusions as seen in spondylocostal or spondylothoracic dysostosis, which may have congenital vertebral anomalies as well and may also be considered congenital scoliosis.
• Changes in the chest wall following thoracic surgery which may function as a tether which promotes change in the shape of the spine.

Neuromuscular:

Scoliosis which may develop in children with neuromuscular disorders including spinal muscular atrophy, cerebral palsy, spina bifida and brain or spinal cord injury.

Syndromic:

Certain syndromes, such as Marfans, Ehlers-Danlos and other connective tissue disorders, as well as neurofibromatosis, Prader-Willi, and many bone dysplasias may be associated with EOS.

Prognosis of EOS:

• EOS, depending on the severity, may be associated with compromised pulmonary function in childhood which may also become increasingly problematic in adult years.
• When untreated, severe EOS may be associated with an increased risk of early death due to pulmonary compromise.
• The term Thoracic Insufficiency Syndrome (TIS) is commonly used to describe the potential combined spine and pulmonary problems in EOS. TIS is defined as "the inability of the thorax to support normal respiration or lung growth".
• Idiopathic EOS with a Cobb angle of >35 degrees is likely to progress.
• In many children <2 years old with infantile idiopathic curves <35 degrees, scoliosis may resolve without treatment.
• Prognosis will also depend on any underlying disorders or comorbidities.

Evaluation of EOS:

• Plain X-rays are sufficient to make the diagnosis of EOS.
• MRI may be indicated for curves that are larger than 20 degrees or progressive, or if there are signs or symptoms of neurologic problems and in persistent or progressive infantile idiopathic scoliosis. Intra-spinal abnormalities are commonly associated with EOS, particularly congenital scoliosis.
• CT best helps visualize bone anatomy in congenital scoliosis, and is often useful for surgical planning, but must be weighed against risk of radiation to young child.

Treatment options in EOS may include:

Observation:

The behavior of the curve may be monitored via repeated exam and radiographic evaluations at various time-points during development to look for worsening or progression of the scoliosis. Should the curve progress, or if the curve is larger, treatment may be appropriate:

Bracing or casting:

Bracing or casting programs may help by allowing growth while minimizing curve progression. The need for surgery may be delayed and, in some instances such as infantile idiopathic scoliosis, surgery may be avoided. Anesthesia is usually required for casting children. Bracing or casting congenital scoliosis is rarely effective, but some believe bracing or casting a compensatory curve may be helpful.

Surgery:

• Various growth-friendly surgeries are designed to follow the principles of EOS treatment outlined above, allowing the spine and chest to grow while controlling spine and chest deformity. Surgery is generally recommended if brace or cast treatment should fail to control progression, or if curve pattern does not appear amenable to brace or cast treatment.
• Extensive thoracic spinal fusion in the very young child is associated with pulmonary compromise, and is rarely the best option.

Exercise:

Manipulation, physical therapy and/or exercise has not been shown to influence spinal deformity in EOS

Neuromonitoring Information Statement

SRS Information Statement, 2019

July 2019

To: SRS Colleagues

The attached information statement on Intraoperative Neurophysiological Monitoring of Spinal Cord Function During Spinal Deformity Surgery was developed to provide updated information to the membership. The information expresses the opinion that intraoperative neurophysiological spinal cord monitoring is no longer investigational (as was stated in the previous 2009 SRS Neuromonitoring Information Statement), but is instead a standard modality that is a nearly universally used adjunct to improve safety of surgical deformity correction procedures when the spinal cord is at risk. It has been conclusively demonstrated that intraoperative spinal cord monitoring facilitates detection of impending spinal cord deficit and facilitates early interventions that are likely to preserve spinal cord function.

Neurophysiological Monitoring of Spinal Cord Function During Spinal Deformity Surgery

Innovation in surgical technique and spinal implants has allowed surgeons to correct increasingly complex spinal deformities. However, large corrective forces applied to spinal deformities risks potential neurological deficits including loss of motor and sensory function in the lower extremities, and bowel and bladder incontinence. Reports from the SRS Morbidity and Mortality Committee and independent investigators have documented this rare (0.14-0.79%) but potentially devastating risk.  (Schmitt, 1981; MacEwen, 1975; Wilber, 1984 Diab, 2007; Burton, 2016; Bartley 2017). While all spine deformity correction surgery is inherently dangerous, patients with kyphosis, congenital scoliosis, and/or preexisting neurological abnormalities are at increased risk (1.3-3.6%). Furthermore, the use of pedicle subtraction osteotomy and three-column resection techniques independently increases this risk (adj. odds ratio 3.06 [1.14-8.19]) (Boachie-Adjei, 2015). Mechanisms of injury include direct stretching or compression of the spinal cord, direct injury to the cord from instruments/implants and/or interference with cord blood flow (Nuwer, 1988, Drummond, 2003). 

Prior to the development of intraoperative neuromonitoring (IONM), the only available method to detect a perioperative neurologic disfunction was the Stagnara wake-up test (Vauzelle, 1973). The test entails waking the patient intra-operatively sufficiently to follow commands and then asking for movement in all four extremities. However, the wake-up test has obvious limitations with regard to the timely ability to detect neurological changes and to localize cord compromise. (Stephen, 1996; Schwartz, 1997; Padberg, 1999; Strike, 2017). Another limitation is an inability of some patients to cooperate with the wake-up test because of age or mental status. On the other hand, the Stagnara wake-up test is a useful adjunctive modality for those cases where IONM is not possible, including patients with severe preexisting myelopathy (Master, 2008). Finally, a properly performed wake-up test is still considered the gold-standard for the detection of neurologic deficits and can be used to confirm a deficit when the results of intraoperative neuromonitoring are under question (Ferguson, 2014).

Somatosensory evoked potentials

In the late 1970s, the monitoring of somatosensory evoked potentials (SSEPs) was developed to help identify injury to the spinal cord as it was occurring, so that early interventions could be performed (such as reducing the correction). This modality monitors the integrity of the dorsal columns of the spinal cord through which pass signals for vibration and proprioception; it does not evaluate the integrity of the anterior column (motor pathways). Subsequent research demonstrated that SSEPs have good specificity (99-100%) with respect to predicting spinal cord injury (Nuwer, 1988; Dinner, 1986; Bieber, 1988; Brown, 1984, Thirumala, 2014). Furthermore, it was demonstrated that responding with corrective procedures to a SSEP alert was protective of cord function and integrity (Jones, 1983; Bieber, 1988). Despite this success, further evaluation of the technique demonstrated that SSEPs alone have an unacceptably low level of sensitivity (25-43%) (Ginsberg, 1985; Bridwell , 1998; Schwartz, 2007), i.e., spinal cord injuries can be missed.

Motor-evoked potential monitoring

Improvements in IONM continued with the development of transcranial motor-evoked potential monitoring (TcMEP) which evaluates the spinal cord motor tracts located in the anterior spinal cord. The safety and efficacy of this modality has been demonstrated repeatedly by a number of investigators (DiCindio, 2003; Hillbrand, 2004 Schwartz, 2007; Langeloo, 2003; Acharya, 2017). The main benefit of including TcMEP is the very high sensitivity (100%) of the modality and the resultant impressive negative predictive value seen in most studies; there exist very few cases in the literature describing a false negative TcMEP (Neira, 2016). However, it may not be possible to appropriately monitor all patients with TcMEP due to a variety of reasons including seizure disorders, raised intracranial pressure, cortical lesions and skull-based metal implants, amongst other contraindications (MacDonald, 2002).

The combined monitoring of sensory evoked potentials and motor evoked potentials during spine surgery decreases the false-negative rates of reporting (Iwasaki, et al. 2003, Leppanen, et al. 2005; Hilibrand, et al. 2004, Schwartz, et al. 2007; Tsirikos, 2019; Thirumala, 2016). It has been conclusively demonstrated that intraoperative spinal cord monitoring facilitates detection of impending spinal cord deficit and facilitates early interventions that are likely to preserve spinal cord function (Lyon, et al. 2004; Schwartz, et al., 2007, Pastorelli, 2011). A survey recently completed by the SRS Safety & Value Committee found that approximately 80% of survey respondents use both SSEPs and TcMEPs during spinal deformity surgery. Furthermore, the use of both modalities assures some level of monitoring should circumstances preclude or suspend the use of one or the other modality.

It is typical to perform monitoring of the upper extremities, in addition to the lower extremities, during deformity surgery. This serves two main purposes: 1. Global changes in monitoring, affecting both the upper and lower extremities, may indicate a technical issue or anesthetic cause for lost signals rather than thoracic spinal cord injury. 2. Isolated signal losses in the upper extremity may indicate an upper extremity injury due to direct compression or inappropriate positioning of the arms during surgery. (Polly, 2016)

EMG options

Besides SSEP and MEP, free-run EMG response is a passive modality that provides immediate actionable information, especially in the lumbar spine, for specific muscles and nerve roots by monitoring spontaneous muscle electrical activity (Chung, 2011). It has a high negative predictive value (98%) but also has significant potential limitations including low specificity and sensitivity with muscle-relaxing anesthetics (Larrata, 2018). It is considered a useful adjunct, especially with respect surgical treatment of high-grade spondylolisthesis, to combined and active monitoring by SSEPs and TcMEPs, but should not be used as the only IONM modality.

Triggered EMG screw stimulation is predictive of the lack of nerve root injury or irritation. It is an active modality that helps to evaluate whether the pedicle screw breaches the cortex and impinges on the spinal canal and/or nerve root. This is performed by active electrical stimulation of the pedicle screw and measuring the threshold at which the adjacent nerve root and corresponding muscle group respond, mostly in the lower extremities, and therefore relevant for the lumbar spine; a lower threshold may indicate a cortical breach prompting repositioning of the screw. While there are no accepted standards with respect to threshold levels in the lumbar spine, there are some guidelines that suggest successful screw placement with a resistance greater than 10mA (Glassman, 1995; Lee, 2015). For thoracic screw placement, a lower threshold of 6mA has been proposed (Raynor, 2002), but interpretation of thoracic screw thresholds is challenging and perhaps falsely reassuring (Samdani, 2011); on the other hand, the use of intercostal EMGs may improve their utility (Rodriguez-Olaverri, 2008; Shi, 2003).

An abnormal EMG response to pedicle screw triggered EMG during a spine procedure may or may not be associated with a clinical deficit (Leppanen, 2005), while on the contrary, normal EMG responses do not insure against lateral breeches. If used, triggered EMG screw stimulation should be considered an adjunct to careful pedicle tract palpation and radiographic evaluation rather than as a standalone evaluation of screw position. 40% of the respondents to the 2019 SRS IONM survey typically use one or both of the above adjunct EMG modalities during deformity surgeries.

Team approach

Neuromonitoring services should be provided in a collaborative team-based intraoperative process that is centered on patient safety. Frequently, intraoperative data is acquired by technologists then relayed to the surgeon, anesthesiologist, neurologist, PhD neurophysiologist, and/or another professional for interpretation; in some settings a neurophysiologist, neurologist or the surgeon obtains and evaluates the IONM data. Technologists require a graded level of supervision depending on their level of education, experience, and credentials.  Interpretation may be made in-person in the operating room or by remote consultation in a continuous or intermittent, yet timely, basis. At the interpretative level, there are a number of board certifications that directly apply to IONM. In the United States, The American Board of Neurophysiologic Monitoring requires the provider to have a doctoral degree and significant clinical experience, and the American Board of Clinical Neurophysiology is open to board-certified physicians in neurology, neurosurgery, or psychiatry who have done fellowship training in clinical neurophysiology.  Outside the United States, relevant certification is recommended according to community norms for acceptable practice in each country. The development of specific IONM credentials, where none presently exist, may be a consideration, and the above described certification pathways may provide potentially useful models (MacDonald, 2013; Gertsch, 2019).    

From a spinal deformity surgical team perspective, it is critical for IONM to be performed by practitioners skilled at both the technical and interpretative aspects of monitoring so that quick responses to changes can be made and conveyed in real time to the operating team.  Efforts should be directed at creating the most direct and expeditious flow of information between all intraoperative team members to ensure quality of patient care and safety.  Furthermore, the activities of the monitoring team should integrate well with those of the surgical and anesthesia teams, and should involve joint quality assurance and improvement activities (Skinner, 2019).

Anesthesia

Regarding anesthesia, different types of agents can have substantial effects on the utility of the various IONM modalities. Inhalational anesthetics can impact both SSEPs and TcMEPs (Diener, 2010). Total intravenous anesthesia (TIVA) techniques, avoiding volatile agents and nitrous oxide while relying more on intravenous agents, such as Propofol and remifentanil, have been developed to address these concerns such that both SSEPs and TcMEPs can be used successfully and concurrently. Muscle relaxants can also be used with TIVA, although only to a limited potency as they too have an adverse effect on TcMEP and EMG recordings (Owen, 1999). Once again, it is important to emphasize good communication and planning with the anesthesia team for each spinal deformity case in order to optimize the utility of IONM.

As in many other areas of medical intervention, checklists are an important decision aid in navigating the complex algorithm of potential responses when confronted with the loss of neuromonitoring signals and potential neurological injury.  Several investigators have attempted to standardize the interpretation of IONM changes and the subsequent response. (Stecker, 2012; Kim SS, 2012).  Most recently, in an effort jointly supported by the SRS and POSNA, Vitale et al developed a checklist for response to intraoperative neuromonitoring signal loss using a Delphi-driven consensus-based process which included environmental considerations, anesthetic/systemic factors, technical/neurophysiological variables and surgical details in the potential response. An important part of this checklist is the consideration of consultation with another spine surgeon if possible prior to continuing with the case when confronted with significant intraoperative neuromonitoring change (Vitale, 2014).

In conclusion:

• A substantial body of research has demonstrated that neurophysiologic monitoring can assist in the early detection of complications and often can stimulate / initiate an intervention that can possibly prevent permanent post-operative neurologic injury in patients undergoing spinal deformity operations on the spine (Fehlings, 2010).
• There is a consensus statement (Vitale, 2014) that the utility of neurophysiologic monitoring can be further enhanced by the use of a standardized protocol or checklist when an intraoperative alert occurs. Most surgeons use some type of checklist in the event of an intraoperative neuromonitoring change (SRS survey on IONM, 2019).
• An appropriate response to a neurophysiologic monitoring alert requires a rapid and direct flow of information amongst and between the monitoring, anesthesia and surgical teams such that all potential variables can be optimized efficiently and potential inciting maneuvers and/or implants can be identified and reversed.
• A 2019 survey amongst Scoliosis Research Society members found that the use of neurophysiologic monitoring (TcMEP and SSEP), is nearly universal during operative correction for pediatric and adult spinal deformity (SRS survey on IONM, 2019). The same survey found that EMG modalities are used adjunctively by 40% of respondents for the same type of cases.
• The Stagnara wake-up test remains a useful adjunctive tool for the detection of neurologic spinal cord deficits associated with spinal deformity correction, especially when IONM is not available or if there is a question about the validity of the results of a monitored patient. It has limited utility in the face of cognitive limitations.

In view of the accumulated research and clinical experience demonstrating the effectiveness of neurophysiologic monitoring, and based on the results of a 2019 member survey, the Scoliosis Research Society concludes that the use of intraoperative spinal cord neurophysiological monitoring during operative procedures that aim to correct spinal deformities is considered optimal care when the spinal cord is at risk, and is strongly recommended unless contra-indicated. The Scoliosis Research Society considers intraoperative real-time neurophysiological monitoring, specifically TcMEP and SSEP, with or without EMG modalities, the standard method for early detection of an evolving or impending spinal cord deficit during surgical deformity correction of the spine, that will allow timely intervention before permanent neurologic injury occurs. The SRS recommends that intra-operative neuromonitoring is adopted worldwide.

References

1. Acharya S, Palukuri N, Gupta P, Kohli M. Transcranial Motor Evoked Potentials during Spinal Deformity Corrections-Safety, Efficacy, Limitations, and the Role of a Checklist. Front Surg. 2017 Feb 13;4:8. Doi: 10.3389/fsurg.2017.00008. eCollection 2017.
2. Bartley CE, Yaszay B, Bastrom TP, et al. Perioperative and Delayed Major Complications Following Surgical Treatment of Adolescent Idiopathic Scoliosis. J Bone Joint Sug Am. 2017 Jul 19;99(14):1206-1212. Doi: 10.2106/JBJS.16.01331.
3. Bieber E, Tolo V, Uematsu S. Spinal cord monitoring during posterior spinal instrumentation and fusion. J Clinical Ortho and Rel Research 229:121-124, 1988.
4. Boachie-Adjei O, Yagi M, Nemani VM, et al. Incidence and Risk Factors for Major Surgical Complications in Patients With Complex Spinal Deformity: A Report From an SRS GOP Site. Spine Deform. 2015 Jan;3(1):57-64. Doi: 10.1016/j.jspd.2014.06.008. Epub 2014 Dec 18.
5. Bridwell KH, Lenke LG, Baldus C, Blanke K. Major intraoperative neurologic deficits in pediatric and adult spinal deformity patients: Incidence and etiology at one institution. Spine 23(3): 324-331, 1998.
6. Brown RH, Nash CL, Berilla JA, Amaddio MD. Cortical evoked potential monitoring: A system for intraoperative monitoring of spinal cord function. J Spine 9(3):256-261, 1984.
7. Burton DC, Carlson BB, Place HM, et al. Results of the Scoliosis Research Society Morbidity and Mortality Database 2009-2012: A Report From the Morbidity and Mortality Committee. Spine Deform. 2016 Sep;4(5):338-343. Doi: 10.1016/j.jspd.2016.05.003. Epub 2016 Aug 21.
8. Chung I, Grigorian AA. EMG and evoked potentials in the operating room during spinal surgery. In: Schwartz M, ed. EMG Methods for Evaluating Muscle and Nerve Function. InTech; 2011:325-340.
9. Deiner S. Highlights of anesthetic considerations for intraoperative neuromonitoring. Semin Cardiothorac Vasc Anesth. 2010;14:51-53
10. Diab M, Smith AR, Kuklo TR. Neural Complications in the Surgical Treatment of Adolescent Idiopathic Scoliosis. Spine 32(24):2759-63, 2007
11. DiCindio S, Theroux M, Shah S, et al.  Multimodality monitoring of transcranial electric motor and somatosensory evoked potentials during surgical correction of spinal deformity in patients with cerebral palsy and other neuromuscular disorders.  Spine 28(16):1851-1856, 2003.
12. Dinner DS, Luders H, Lesser RP, et al. Intraoperative spinal somatosensory evoked potential monitoring. J Neurosurg 65:807-814, 1986.
13. Drummond D, Schwartz D, Johnston D, and Farmer J.  Neurological Injury Complicating Surgery.  In: Dewald, R. (ed.) Spinal Deformities: The Comprehensive Text. Thieme Medical Publishers, Inc., NY pp. 615-625, 2003.
14. Fehlings MG, Brodke DS, Norvell DC, Dettori JR. The evidence for intraoperative neurophysiological monitoring in spine surgery: does it make a difference? Spine (Phila Pa 1976). 2010 Apr 20;35(9 Suppl):S37-46.
15. Ferguson J, Hwang SW, Tataryn Z, Samdani AF. Neuromonitoring changes in pediatric spinal deformity surgery: A single-institution experience. J Neurosurg Pediatrics 13:247-254, 2014.
16. Gertsch, J.H., Moreira, J.J., Lee, G.R. et al. J Clin Monit Comput (2019) 33: 175. https://doi.org/10.1007/s10877-018-0201-9
17. Ginsburg HH, Shetter AG, Raudzens PA. Postoperative paraplegia with preserved intraoperative somatosensory evoked potentials. J Neurosurg 63:296-300, 1985
18. Glassman SD, Dimar JR, Puno RM, et al. A prospective analysis of intraoperative electromyographic monitoring of pedicle screw placement with computed tomographic scan confirmation. Spine 1995; 20: 1375-9.
19. Hilibrand A, Schwartz D, Sethuraman V, Vaccaro A, Albert T. Comparison of transcranial electric motor and somatosensory evoked potential monitoring during cervical spine surgery.  J Bone Joint Surg Am. Vol. 86, 1248-1253, 2004
20. Iwasaki H, Tamaki T, Yoshida M, et al. Efficacy and limitations of current methods of intraoperative spinal cord monitoring. J. Orthop. Sci. 8:635-42, 2003
21. Jones SJ, Edgar MA, Ransford AO, Thomas NP. A system for the electrophysiological monitoring of the spinal cord during operations for scoliosis. J Bone Joint 65-B(2):134-139, 1983.
22. Kim SS, Cho BC, Kim JH, et al. Complications of perterior vertebral resection for spinal deformity. Asian Spine J. 2012;6:257-265.
23. Langeloo DD, Journee HL, Polak B, de Kleuver MA.  A new application of TCE-MEP:  spinal cord monitoring in patients with severe neuromuscular weakness undergoing corrective spine surgery.  J Spinal Disord 2001, 14: 445-448.
24. Laratta JL, Ha A, Shillingford JN, et al. Neuromonitoring in Sinal Deformity Surgery: A Multimodality Approach. Global Spine J 8(1):68-77, 2018.
25. Lee CH, Kim HW, Kim HR, Lee CY, Kim JH, Sala F. Can triggered electromyography thresholds assure accurate pedicle screw placements? A systematic review and meta-analysis of diagnostic test accuracy. Clin Neurophysiol. 2015 Oct;126(10):2019-25. doi: 10.1016/j.clinph.2014.11.026. Epub 2014 Dec 15.
26. Leppanen RE, Abnm D. American Society of Neurophysiological Monitoring: J Clin Monit Cimput 19: 437-61, 2005.
27. Lyon R, Lieberman JA, Grabovac MT, Hu S. Strategies for managing decreased motor evoked potential signals while distracting the spine during correction of scoliosis. J. Neurosurg. Anesthesiol. 16:167-70, 2004
28. MacEwen GD, Bunnell WP, Sriram K. Acute neurological complications in the treatment of scoliosis: A report of the Scoliosis Research Society. J Bone Joint Surg 57A:404-408, 1975.
29. MacDonald DB. Safety of intraoperative transcranial electrical stimulation motor evoked potential monitoring. J Clin Neurophysiol. 2002 Oct;19(5):416-29.
30. Malhotra NR, Shaffrey CI. Intraoperative electrophysiological monitoring in spine surgery. Spine. 2010;35:2167-2179.
31. Master DL, Thompson GH, Poe-Kochert C, Biro C. Spinal cord monitoring for scoliosis surgery in Rett syndrome: can these patients be accurately monitored? J Pediatr Orthop. 2008 Apr-May;28(3):342-6. Doi: 10.1097/BPO.0b013e318168d194.
32. NeiraVM, Ghaffari K, Bulusu S, Moroz PJ, Jarvis JG, Barrowman N, Splinter W. Diagnostic accuracy of neuromonitoring for identification of new neurologic deficits in pediatric spinal fusion surgery.  Anesth Analg 123(6):1556-66, 2016.
33. Nuwer M. Spinal Cord Monitoring, Chapter 3 in Evoked potential monitoring in the operating room. Raven Press, New York, 49-101, 1988.
34. Owen JH. The application of intraoperative monitoring during surgery for spinal deformity. Spine. 1999;24:2649-2662.
35. Padberg AM, Bridwell KH. Spinal cord monitoring: current state of the art. Orthop Clin North Am 30: 407-33, 1999.
36. Pastorelli F, Di Silvestre M, Plasmati R, et al. The prevention of neural complications in the surgical treatment of scoliosis: the role of the neurophysiological intraoperative monitoring. Eur Spine J. 2011 May;20 Suppl 1:S105-14. Doi: 10.1007/s00586-011-1756-z. Epub 2011 Mar 18.
37. Polly DW Jr, Rice K, Tamkus A. What Is the Frequency of Intraoperative Alerts During Pediatric Spinal Deformity Surgery Using Current Neuromonitoring Methodology? A Retrospective Study of 218 Surgical Procedures. Neurodiagn J. 2016 Mar;56(1):17-31.
38. Raynor BL, Lenke LG, Kim Y, Hanson DS, Wilson-Holden TJ, Bridwell KH, et al.: Can triggered electromyograph thresholds predict safe thoracic pedicle screw placement? Spine 27:2030-2035, 2002
39. Rodriguez-Olaverri JC, Mimick NC, Merola A, et al. Using triggered electromyographic threshold in the intercostal muscles to evaluate the accuracy of upper thoracic pedicle screw placement (T3-T6). Spine (Phila pa 1976). 2008;33:E194-197.
40. Samdani AF, Tantorski M, Cahill PJ, Ranade A, Koch S, Clements DH, Betz RR, Asghar J. Triggered electromyography for placement of thoracic pedicle screws: is it reliable? Eur Spine J. 2011 Jun;20(6):869-74.
41. Schmitt EW. Neurological complications in the treatment of scoliosis. A sequential report of the Scoliosis Research Society 1971-1979. Reported at the 17th annual meeting of the Scoliosis Research Society, Denver, CO, 1981.
42. Schwartz D, Drummond D, Schwartz J, et al. Neurophysiological monitoring during scoliosis surgery: A multimodality approach.  Seminars in Spine Surgery Vol. 9, No. 2, 97-111, 1997.
43. Schwartz DM, Auerbach JD, Dormans JP, et al. Neurophysiological detection of impending spinal cord injury during scoliosis surgery. J Bone Joint Surg 89A:2440-9, 2007
44. Schwartz D, Dormans JP, Drummond DS, et al. Transcranial Electric Motor Evoked Potential Monitoring During Spine Surgery:  Is It Safe?  Presented at the 42nd Annual Meeting of the Scoliosis Research Society.  Edinburg, Scotland, September 6, 2007.
45. Shi YB, Binette M, Marting WH, et al. Electrical stimulation for intraoperative evaluation of thoracic pedicle screw placement. Spine. 2003;28:595-601
46. Skinner SA, Aydinlar EI, Borges LF, et al. Is the new ASNM intraoperative neuromonitoring supervision “guideline” a trustworthy guideline? A commentary. J Clin Monit Comput. 2019; 33(2): 185–190. Published online 2019 Jan 5. doi: 10.1007/s10877-018-00242-3
47. Stecker MM. A review of intraoperative monitoring for spinal surgery. Surg Neurol Int. 2012;3(suppl 3):S174-S187. Doi:10.4103/2152-7806.98579
48. Stephen JP, Sullivan MR, Hicks RG, et al: Cotrel-Dubousset instrumentation in children using simultaneous motor and somatosensory evoked potential monitoring. Spine 21: 2450-7, 1996.
49. Strike SA, Hassanzadeh H, Jain A, et al. Intraoperative Neuromonitoring in Pediatric and Adult Spine Deformity Surgery. Clin Spine Surg 30(9):E1174-E1181, 2017.
50. Thirumala PD, Bodily L, Tint D, et al. Somatosensory-evoked potential monitoring during instrumented scoliosis corrective procedures: validity revisited. Spine J. 2014 Aug 1;14(8):1572-80. Doi: 10.1016/j.spinee.2013.09.035. Epub 2013 Oct 19.
51. Tsirikos A, Duckworth A, Henderson L, Michaelson C. Multi-Modal Intra-Operative Spinal Cord Monitoring (IOM) During Spinal Deformity Surgery: Efficacy, Diagnostic Characteristics and Algorithm Development Med Princ Pract. 2019 Jun 4. Doi: 10.1159/000501256. [Epub ahead of print]
52. Vauzelle C, Stagnara P, Jouvinroux P: Functional monitoring of spinal cord activity during spinal surgery. Clin Orthop 93:173-178, 1973.
53. Vitale MG, Skaggs DL, Pace GI, et al. Best practices in intraoperative neuromonitoring in spine deformity surgery: Development of an intraoperative checklist to optimize response. Spine Deformity. 2014;2:333-339.
54. Wilber RG, Thompson GH, Shaffer JW, et al: Post-operative neurological deficits in segmental spinal instrumentation. J Bone Joint Surg 66A:1178-1187, 1984.

Screening for the Early Detection for Idiopathic Scoliosis in Adolescents - September 2015

SRS/POSNA/AAOS /AAP Position Statement

M. Timothy Hresko, MD; Vishwas R. Talwalkar, MD; Richard M. Schwend, MD

9/2/2015 v2

The Scoliosis Research Society (SRS), American Academy of Orthopedic Surgeons (AAOS), Pediatric Orthopedic Society of North America (POSNA) and American Academy of Pediatrics (AAP) believe that there has been additional useful research in the early detection and management of adolescent idiopathic scoliosis (AIS) since the review performed by the United States Preventive Services Task Force (USPSTF) in 2004.  This information should be available for use by patients, treating health care providers, and policy makers in assessing the relative risks and benefits of the early identification and management of AIS. 

The AAOS, SRS, POSNA, and AAP believe that there are documented benefits of earlier detection and non-surgical management of AIS, earlier identification of severe deformities that are surgically treated, and of incorporating screening of children for AIS by knowledgeable health care providers as a part of their care.  

Introduction

Scoliosis is a three-dimensional spine deformity characterized by lateral and rotational curvature of the spine. The most common form is idiopathic scoliosis, which usually becomes evident in the early adolescent years in approximately three percent of children under age 16 and has a genetic tendency although the specifics of the genetic influence have not been completely determined. Curve progression is related to the age of the child and the magnitude of the deformity.  The majority of children do not display progressive curves, though a subset of children with adolescent idiopathic scoliosis may exhibit rapid progression. Weinstein, et al reported in the New England Journal of Medicine that there were more than 3600 hospital discharges related to AIS surgery in the year 2009 based on the HCUP KIDS data base (1).This spinal disorder can have a significant impact on the physical and psychosocial health of affected individuals.  Scoliosis may also be the initial presenting sign of underlying conditions such as heritable collagen diseases, neurologic conditions, or skeletal dysplasia which may have been undetected until adolescence.

Prevention of severe scoliosis is a major commitment of physicians caring for spinal deformities. Beginning in 1984, the American Academy of Orthopaedic Surgeons (AAOS) and the Scoliosis Research Society (SRS) formally endorsed the early detection of scoliosis in children whose deformities may have gone unnoticed. In 2007 AAOS, SRS, POSNA, and AAP endorsed an informational statement that explained the pertinent aspects of the issue of screening for scoliosis (2).  This statement disagreed with the recommendations of the U.S. Preventive Services Task Force (USPSTF) which in 2004 recommended against the routine screening of asymptomatic adolescents for idiopathic scoliosis, citing a low predictive value of screening, a relatively small percentage of children who progress, and the possibility of unnecessary treatment including brace use (3). Although AAOS, SRS, POSNA, and AAP recognized that support for scoliosis screening has limitations, the informational statement claimed that potential benefits that patients with idiopathic scoliosis receive from early treatment of their deformities can be substantial. The joint statement concluded that “…if scoliosis screening is undertaken, the AAOS, SRS, POSNA, and AAP agree that females should be screened twice, at 10 and 12… and boys once, at age 13 or 14 ….”

In addition, the AAOS, SRS, POSNA, and AAP statement expressed the importance of educating screening personnel to minimize unnecessary referrals and to optimize the appropriate use of spine radiographs, as not all children referred as a result of screening require radiographs. If radiographs were needed, physicians were advised to take necessary precautions to limit the patient's exposure to radiation.

This updated position paper will provide further information to support the continued evaluation of adolescents for scoliosis. In addition, we urge the USPSTF to reconsider their 2004 recommendation regarding screening for scoliosis.

Screening for Scoliosis – The Current Evidence

Routine clinical screening for scoliosis continues to be controversial. Previous studies have both supported (4, 5) and discouraged routine screening (6, 7, 8). To date, no prospective, randomized, controlled studies have been performed on population screening for scoliosis.  We believe that such a study is unlikely to be performed at the current time. This concern was recognized in the 1996 U.S. Preventive Services Task Force (USPSTF) report which concluded that there was insufficient evidence to make a recommendation for, or against, screening programs for AIS(9).  However, in 2004, the USPSTF changed their earlier opinion and recommended against routine screening of asymptomatic adolescents for scoliosis largely based on a change in methodology without new evidence to indicate that screening was not effective (10).

There have been several publications on screening for scoliosis since 2007 that include a systematic review of the literature and large retrospective studies. In 2013, Labelle et al. published a consensus statement developed by an international task force of the SRS regarding screening for AIS (11).  The task force performed a systematic review of the literature through 2012 and used a modified Delphi process following the framework of the World Health Organization to reach consensus on the validity of a screening program. The panel reached consensus on the five domains studied, with four of the domains – technical efficacy, clinical, program and treatment effectiveness – supportive of screening, but there was insufficient evidence to make a statement with respect to cost effectiveness. 

Screening examinations for spine deformity vary in different locations, from a purely visual examination to a physical examination, scoliometer reading, and surface topographic measures during an annual health services examination. The clinical examination of chest and trunk for asymmetry is considered a proxy for spine deformity. The forward bend Adams test with the use of a scoliometer (a specialized inclinometer) was agreed upon by the SRS task force as an effective quantitative measure with five to seven degrees of deformity as a threshold for positive screening. The task force did not reach agreement on the need for topographic measurement. Since females reach puberty about two years before males and are afflicted with a magnitude of scoliosis requiring treatment three to four times more frequently than males, the task force recommended that screening be performed twice for females at age 10 and 12 years in order to capture variation in maturity.  Males could be screened once at age 13 to 14 years.

AAOS, SRS, POSNA, and AAP believe that screening examinations for spine deformity should be part of the medical home preventative services visit for females at age 10 and 12 years, and males once at age 13 or 14 years. 

The clinical effectiveness of screening for the detection of curves greater than 20 degrees was supported in a large retrospective study by Luk, et al of 115,190 adolescents followed until the age of 19 years (12). 2.8 percent of adolescents were referred for a radiograph. At final follow-up, the positive predictive value for spinal curvature greater than 20 degrees was 43.8 percent and 9.8 percent for treatment. Sensitivity was near 90 percent for both diagnosis and treatment. Conversely, Yawn, et al reported on a population-based school screening program in Rochester, Minnesota (13). In this retrospective cohort study, 4.1 percent (68/2242) of children screened positively and were referred for evaluation. The positive predictive value was low (.05) and they concluded that roughly 450 children would need to be screened for every child who subsequently received treatment as a result of screening. The discrepancy in these studies points out the need for effective screening systems as inappropriate false positive screening may lead to unnecessary referrals and radiographs with higher population cost. Although well done population screening may be an effective means to capture all children at risk, many communities may not have sufficient resources to carry out these programs.  In all communities, primary care providers serve as an important source for screening. Education of primary care providers in the clinical examination for early detection of scoliosis and the use of a decision algorithm has been shown to be effective in the reduction of referrals to specialty care (14). Documentation of the screening and discussion of a positive screening result with a parent/guardian is important.  After a child has an abnormal scoliosis screening evaluation, a clinician should confirm a possible diagnosis of spinal deformity and consider obtaining a spine radiograph if indicated. There are no peer-reviewed reports comparing rates of early and late detection of scoliosis in communities with and without population screening or community provider based screening programs. 

AAOS, SRS, POSNA and AAP believe that effective screening programs must have well trained screening personnel who can utilize forward bending tests and scoliometer measurements to correctly identify and appropriately refer individuals with AIS for further investigation. 

The cost of population based screening programs has been raised as a concern. In 2000, Yawn et al published a study that examined issues related to charges of population screening program, including the primary care visit, orthopedist visit, and radiographs. The total costs were estimated to be $34.40 per child screened, $4,198.67 per case identified and $15,115.20 per child treated (15). Lee, et al used the data from the Hong Kong program to give a more detailed estimate of cost (2005 US dollars) for each segment of the screening and subsequent care (16). The cost per student for screening was $17.94 and for screening plus diagnostic tests was $20.02. In addition, they calculated the cost of brace treatment until age 19 to be $8,018 while the cost of surgery and care to age 19 was at least $27,538, as this estimate did not take into account any subsequent revision surgery which is reported to occur in 5-10 percent of patients (17,18). There are no similar studies that establish the cost of screening in the medical home model.

Concerns have previously been raised about radiation exposure in children who screen positive and receive a radiograph, but are not found to have scoliosis (19).  All studies of screening programs show that there is a significant rate of false positives that are further referred for evaluation and possible spinal imaging.  Current techniques of shielding, patient positioning, use of special films, the institution of digital radiography, and newer low dose imaging systems using slit scanning have significantly reduced the radiation exposure. Luo et al noted that current imaging techniques have reduced radiation exposure to radiosensitive breast tissue to 1/100^th of that used in patients report by Doody, et al in the US Scoliosis Cohort study. (20) 

AAOS, SRS, POSNA and AAP believe that the principles of ALARA (as low as reasonably allowable) should be applied in the diagnostic imaging of children to decrease radiation exposure from spinal imaging for AIS (21).

Treatment for those detected from scoliosis screening

Effective treatment of patients referred from scoliosis screening should be able to reduce the risk of a curve progressing to a point where surgery is indicated or, for severe curves, to be able to identify patients who would benefit from surgery before the deformity progresses to a degree that increases the risks associated with surgery.  

Brace treatment for scoliosis has been the most prescribed non-operative method of treatment over the past 40 years. In recent years, refinements have been made in identifying which patients with idiopathic scoliosis may benefit most from this treatment (22). 

The two most common parameters used to assess the effectiveness of non-operative treatment of scoliosis have been defined as the ability to prevent curve progression to the point of surgery or to show a difference in the likelihood of curve progression of greater than five degrees by the time a patient has finished growth.  Katz et al demonstrated the efficacy of bracing in a non-controlled population where 82 percent of patients who wore a brace for greater than 12 hours per day had less than five degrees of curve progression compared to only 31 percent of those who wore the brace for less than seven hours per day (23).  An important feature of this study was that brace wear compliance was monitored by a temperature sensitive data recorder imbedded in the spinal orthosis.  

In 2013, the results of a multi-center NIH funded, randomized clinical trial of the effectiveness of bracing to prevent progression of scoliosis were published (1). The Bracing in Adolescent Idiopathic Scoliosis Trial (BRAiST) included patients randomized to brace wear or no brace wear and a patient preference cohort. The inclusion criteria were skeletal immaturity and a moderate scoliosis of 20-40 degrees. The primary outcome was curve progression to 50 degrees or more (treatment failure) or reaching skeletal maturity without curve progression to 50 degrees (treatment success). The study was concluded prior to full enrollment by the NIH Data Safety and Monitoring Board due to the interim analysis that showed that braced patients had a significantly better rate of treatment success than non-braced patients. In the randomly assigned group, 75 percent of braced patients versus 42 percent of observational patients successfully reached skeletal maturity with a curve magnitude of less than 50 degrees (surgical range). This was a 56 percent reduction in relative risk of progression to a surgical level of scoliosis. The success rate of bracing was highly correlated to the number of hours of brace wear, based on temperature data recorder compliance monitor.  The number of patients needed to treat (NNT) in order to prevent one surgery was three. No difference was found in patient reported quality of life or adverse effects in the braced or observational patients.  An independent study by Sanders et al supported the results of BRAiST with a similar NNT of 3 (24).

Other means for non-operative treatment of scoliosis have also been studied. Scoliosis specific exercises used to supplement brace wear or prevent progression in mild curves have been reported. A randomized clinical trial of patients with mild scoliosis of 10-20 degrees has shown that scoliosis specific exercises may prevent progression to the level of deformity that would result in brace treatment (25).

These high quality studies have established that non-operative treatment with bracing or scoliosis specific exercises may reduce the number of patients progressing to a surgical level.  To be effective, these treatments need to be applied to smaller curves prior to skeletal maturity.  This places emphasis on the need for earlier detection of scoliosis. Early detection by screening programs that identify adolescents at risk for progression will offer patients and families the opportunity to seek effective, non-operative treatments. The patient preference of non-operative brace treatment rather than observation was noted in the patient preference arm of BRAiST where there was a 2:1 ratio for selection of bracing over observation.  Non-operative therapies are most effective in curves of lesser magnitudes, thus supporting the value of early detection.

AAOS, SRS, POSNA and AAP believe that recent high quality studies demonstrate that non-operative interventions such as bracing and scoliosis specific exercises can decrease the likelihood of curve progression to the point of requiring surgical treatment. 

Educational resources are listed below that provide more specific instruction and guidelines for conducting screening examinations for scoliosis.

AAOS.org; SRS.org; POSNA.org; healthychildren.org

References

1. Weinstein SL, Dolan LA, Wright JG, Dobbs MB: Effects of bracing in adolescents with idiopathic scoliosis. N Engl J Med. 2013 Oct 17;369(16):1512-21.
2. Richards BS, Vitale MG: Statement: screening for idiopathic scoliosis in adolescents: an information statement. J Bone Joint Surg Am 2008, 90:195–198
3. Final Recommendation Statement: Idiopathic Scoliosis in Adolescents: Screening. U.S. Preventive Services Task Force. February 2014. Accessed 8/30/15 http://www.uspreventiveservicestaskforce.org/Page/Document/RecommendationStatementFinal/idiopathic-scoliosis-in-adolescents-screening
4. Ashworth MA, Hancock JA, Ashworth L, Tessier KA: Scoliosis screening: An approach to cost/benefit analysis. Spine 1988;13:1187-1188.
5. Montgomery F, Willner S: Screening for idiopathic scoliosis: Comparison of 90 cases shows less surgery by early diagnosis. Acta Orthop Scand 1993;64: 456-458)
6. Yawn BP, Yawn RA, Hodge D, et al: A population-based study of school scoliosis screening.  JAMA 1999;282:1427–1432.
7. Yawn BP, Yawn RA, Roy A: The estimated cost of school scoliosis screening. Spine 2000;25:2387-2391.
8. Morais T, Bernier M, Turcotte F: Age- and sex-specific prevalence of scoliosis and the value of school screening programs. Am J Public Health 1985;75:1377-1380)
9. U.S. Preventive Services Task Force. Guide to Clinical Preventive Services, 2nd ed. Washington, DC; Office of Disease Prevention and Health Promotion, 1996.
10. Final Evidence Review: Idiopathic Scoliosis in Adolescents: Screening. U.S. Preventive Services Task Force. February 2014. http://www.uspreventiveservicestaskforce.org/Page/Document/final-evidence-review61/idiopathic-scoliosis-in-adolescents-screening
11. Labelle H, Richards RB, De Kleuver M, et al. Screening for adolescent idiopathic scoliosis: an information statement by the Scoliosis Research Society international task force Scoliosis 2013, 8:17
12. Luk DK, Lee CF, Cheung KM, et al: Clinical effectiveness of school screening for adolescent idiopathic scoliosis: a large population-based retrospective cohort study. Spine 2010, 35:1607–1614
13. Yawn BP, Yawn RA, Hodge D, et al: A population-based study of school scoliosis screening. JAMA 1999;282:1427–1432
14. Vernacchio L, Trudell EK, Hresko MT, et al.  A quality improvement program to reduce unnecessary referrals for adolescent scoliosis. Pediatrics, 2013. 131(3): p. e912-20.
15. Yawn BP, Yawn RA, Roy A: The estimated cost of school scoliosis screening. Spine  2000;25:2387-2391
16. Lee CF, Fong DY, Cheung KM Costs of School Scoliosis Screening: A Large, Population-Based Study. SPINE Volume 35, Number 26, pp 2266–2272
17. Ramo BA, Richards SB: Repeat surgical interventions following “definitive” instrumentation and fusion for idiopathic scoliosis: five year update on a previously published cohort. Spine (Phila Pa 1976). 2012 Jun 15;37(14):1211-7
18. Campos M, Dolan L, Weinstein S:  Unanticipated revision surgery in adolescent idiopathic scoliosis. Spine 2012,37(12):1048-53. doi: 10.1097/BRS.0b013e31823ced6f.
19. Morais T, Bernier M, Turcotte F: Age- and sex-specific prevalence of scoliosis and the value of school screening programs. Am J Public Health 1985;75:1377-13806
20. Luo TD, Stans AA, Schueler BA, Larson N: Cumulative radiation exposure with EOS imaging compared with standard spine radiographs. J Spine Deformity 3( 2015) p144-150
21. The ALARA (as low as reasonably achievable) concept in pediatric CT intelligent dose reduction. Multidisciplinary conference organized by the Society of Pediatric Radiology. August 18-19, 2001.Pediatr Radiol. 2002 Apr;32(4):217-313. Epub 2002 Mar 6) 
22. Richards BS, Bernstein RM, D’Amato CR, et al: Standardization of criteria for adolescent idiopathic scoliosis brace studies: SRS Committee on bracing and non- operative management. Spine2005;30:2068-2075
23. Katz DE, Herring JA, Browne RH, Kelly DM, Birch JG: Brace wear control of curve progression in adolescent idiopathic scoliosis. J Bone Joint Surg Am. 2010;92:1343-52
24. Sanders JO, Newton PO, Browne RH, Katz DE, Birch JG, Herrring JA: Bracing for Idiopathic Scoliosis: How Many Patients Require Treatment to Prevent One Surgery?  J Bone Joint Surg Am. 2014;96:649-53
25. Monticone M, Ambrosini E, Cazzaniga D, Rocca B, Ferrante S: Active self-correction 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) 23:1204–1214

9/2/2015

Scoliosis Research Society Position Statement on Magnetic Controlled Growing Rods (MCGR )

June 2023

Charles E. Johnston, MD; Nicholas D. Fletcher, MD; Colin Nnadi, FRCS (Orth)

Magnetically-controlled growing rods (MCGR) have been developed as a growth-sparing implant for management of early-onset scoliosis (EOS), combining the ability to control/correct scoliosis deformity while permitting lengthening of the spine to avoid early growth-ending spinal fusion. MCGRs can be expanded externally by a hand-held actuator, thus obviating the need for surgical lengthening and sparing the patient the risks of repeated anesthetics and open surgical procedures. As the lengthening is performed in the outpatient setting, these rods appeared to be the ideal alternative to existing distraction-based implants that required surgical lengthening.¹ Following the 2014 release of the device in the US, MCGRs became the most commonly used implant for EOS index procedures and many surgeons chose to replace/convert “traditional”  implants already in place so that open surgical lengthening would hopefully become  unnecessary. ^{2 3}

While the MCGR technology clearly succeeds in decreasing the number of surgical procedures for an individual patient compared to a traditional distraction-based “growing” implant, experience has proven it to have its own set of technical and surgical challenges and limitations which make it less a panacea than was originally hoped. Although the surgical site infection rate for MCGR is significantly lower than the standard TGR/VEPTR implants, it has a similar incidence of rod breakage and anchor failure as both devices are anchored only at the upper and lower end of the spine allowing for more stress through the unfused segments.⁴ The incidence of unplanned revision in the operating room (UPROR) for MCGR is similar to that of TGR/VEPTR.^{5 6} Furthermore, a problem unique to MCGR is early stalling of the device’s expandability, representing a “law of diminishing returns” seen in other growing spine implants, partly due to diminishing distractive power as the rod lengthens. Studies have found that roughly 50% of MCGRs can no longer be lengthened after 24 months post-implantation and only 21% of implants ever reach full excursion. Failure of rods to lengthen often create treatment dilemmas for patients and providers when conversion to a definitive spinal fusion is a less appealing option  such as in younger patients^7-11. Additionally, one version of the device required recall by the manufacturer for a casing seal failure , and there is more recent concern over metallosis in tissues and elevated serum levels of possibly harmful metal ions (e.g. titanium) in children and female patients of child bearing age, although the actual toxicity of the local and systemic metallic levels remains unknown.^{12 13 14}

Surgeons and parents adopted MCGR due to the prospect of fewer surgeries, however  the anticipated psychosocial benefit and  improved health-related quality of life (HRQoL) due to MCGR non-invasive lengthening has been elusive in published studies^{15 16}. Compared to TGR, reduction in anxiety and depressive symptoms has not been observed, and quality of life, measured by the EOSQ-24, is only marginally, but not significantly, improved in MCGR patients. ¹⁷

Current indications for MCGR include  low demand patients with collapsing or progressive deformity who are not able to tolerate repeated anesthetics and children requiring additional spine length for respiratory function considerations who have failed or rejected non-operative treatment/delay tactics. Current expert consensus has identified some relative contraindications to MCGR use, although most are not quantified. ¹⁸For example, an elevated BMI is considered a contraindication due to inability to access the magnetic actuator and lengthen an implant which is covered by excessive soft tissue and is too “deep”.^{19 20} On the other hand, MCGRs should be avoided in patients with insufficient skin and soft tissue coverage (due to low BMI or scarring, for example). Hyperkyphotic deformities may be a relative contraindication because of contouring limitation imposed by the unbendable portion of the rod which contains the magnetic mechanism.²¹  Stiff deformities, as determined by some form of traction or bending radiographs preoperatively, are a relative contraindication, as is insufficient spinal length in a small patient to accommodate the implant. As with any growing implant, the complication profile has generated more attention to delay tactics in order to minimize the need for any growth-sparing methods.

In summary, despite these recognized limitations this is an innovative technology that has tried to bridge the value-based healthcare divide. In those cases where full completion of the MCGR program has been achieved with one implantation and one final fusion, cost-savings to the health economy are in plain sight.^{22 23} Financial and parental benefits from the diminished number of lost school/workdays, along with potential psychosocial and QOL benefits to young patients still under active treatment, are the current and future expected benefits the SRS anticipates from this technology.

References

1. Thompson W, Thakar C, Rolton DJ, et al. The use of magnetically-controlled growing rods to treat children with early-onset scoliosis: early radiological results in 19 children. Bone Joint J 2016;98-B(9):1240-7. doi: 10.1302/0301-620X.98B9.37545 [published Online First: 2016/09/03]
2. Cheung KM, Cheung JP, Samartzis D, et al. Magnetically controlled growing rods for severe spinal curvature in young children: a prospective case series. Lancet 2012;379(9830):1967-74. doi: 10.1016/S0140-6736(12)60112-3 [published Online First: 2012/04/24]
3. Cheung JP, Samartzis D, Cheung KM. A novel approach to gradual correction of severe spinal deformity in a pediatric patient using the magnetically-controlled growing rod. Spine J 2014;14(7):e7-13. doi: 10.1016/j.spinee.2014.01.046 [published Online First: 2014/02/06]
4. Thakar C, Kieser DC, Mardare M, et al. Systematic review of the complications associated with magnetically controlled growing rods for the treatment of early onset scoliosis. Eur Spine J 2018;27(9):2062-71. doi: 10.1007/s00586-018-5590-4 [published Online First: 2018/04/21]
5. Kwan KYH, Alanay A, Yazici M, et al. Unplanned Reoperations in Magnetically Controlled Growing Rod Surgery for Early Onset Scoliosis With a Minimum of Two-Year Follow-Up. Spine (Phila Pa 1976) 2017;42(24):E1410-E14. doi: 10.1097/BRS.0000000000002297 [published Online First: 2017/06/29]
6. Welborn MC, Bouton D. Outcomes of MCGR at > 3 year average follow-up in severe scoliosis: who undergoes elective revision vs UPROR? Spine Deform 2022;10(2):457-63. doi: 10.1007/s43390-021-00424-1 [published Online First: 2021/10/15]
7. Cheung JPY, Yiu KKL, Samartzis D, et al. Rod Lengthening With the Magnetically Controlled Growing Rod: Factors Influencing Rod Slippage and Reduced Gains During Distractions. Spine (Phila Pa 1976) 2018;43(7):E399-E405. doi: 10.1097/BRS.0000000000002358 [published Online First: 2017/08/03]
8. Cheung JPY, Zhang T, Bow C, et al. The Crooked Rod Sign: A New Radiological Sign to Detect Deformed Threads in the Distraction Mechanism of Magnetically Controlled Growing Rods and a Mode of Distraction Failure. Spine (Phila Pa 1976) 2020;45(6):E346-E51. doi: 10.1097/BRS.0000000000003268 [published Online First: 2019/10/02]
9. Cobanoglu M, Shah SA, Gabos P, et al. Comparison of Intended Lengthening of Magnetically Controlled Growing Rods: Ultrasound Versus X-Ray. J Pediatr Orthop 2019;39(2):e141-e46. doi: 10.1097/BPO.0000000000001072 [published Online First: 2017/10/11]
10. Gilday SE, Schwartz MS, Bylski-Austrow DI, et al. Observed Length Increases of Magnetically Controlled Growing Rods are Lower Than Programmed. J Pediatr Orthop 2018;38(3):e133-e37. doi: 10.1097/BPO.0000000000001119 [published Online First: 2018/01/11]
11. Poon S, Spencer HT, Fayssoux RS, et al. Maximal Force Generated by Magnetically Controlled Growing Rods Decreases With Rod Lengthening. Spine Deform 2018;6(6):787-90. doi: 10.1016/j.jspd.2018.03.009 [published Online First: 2018/10/24]
12. Teoh KH, von Ruhland C, Evans SL, et al. Metallosis following implantation of magnetically controlled growing rods in the treatment of scoliosis: a case series. Bone Joint J 2016;98-B(12):1662-67. doi: 10.1302/0301-620X.98B12.38061 [published Online First: 2016/12/03]
13. Li Y, Graham CK, Robbins C, et al. Elevated Serum Titanium Levels in Children With Early Onset Scoliosis Treated With Growth-friendly Instrumentation. J Pediatr Orthop 2020;40(6):e420-e23. doi: 10.1097/BPO.0000000000001463 [published Online First: 2020/06/06]
14. Zhang T, Sze KY, Peng ZW, et al. Systematic investigation of metallosis associated with magnetically controlled growing rod implantation for early-onset scoliosis. Bone Joint J 2020;102-B(10):1375-83. doi: 10.1302/0301-620X.102B10.BJJ-2020-0842.R1 [published Online First: 2020/10/01]
15. Bauer JM, Yorgova P, Neiss G, et al. Early Onset Scoliosis: Is there an Improvement in Quality of Life With Conversion From Traditional Growing Rods to Magnetically Controlled Growing Rods? J Pediatr Orthop 2019;39(4):e284-e88. doi: 10.1097/BPO.0000000000001299 [published Online First: 2018/11/13]
16. Cheung JPY, Yiu K, Kwan K, et al. Mean 6-Year Follow-up of Magnetically Controlled Growing Rod Patients With Early Onset Scoliosis: A Glimpse of What Happens to Graduates. Neurosurgery 2019;84(5):1112-23. doi: 10.1093/neuros/nyy270 [published Online First: 2018/08/14]
17. Doany ME, Olgun ZD, Kinikli GI, et al. Health-Related Quality of Life in Early-Onset Scoliosis Patients Treated Surgically: EOSQ Scores in Traditional Growing Rod Versus Magnetically Controlled Growing Rods. Spine (Phila Pa 1976) 2018;43(2):148-53. doi: 10.1097/BRS.0000000000002274 [published Online First: 2017/06/13]
18. Matsumoto H, Sinha R, Roye BD, et al. Contraindications to magnetically controlled growing rods: consensus among experts in treating early onset scoliosis. Spine Deform 2022;10(6):1289-97. doi: 10.1007/s43390-022-00543-3 [published Online First: 2022/07/04]
19. Seidel CP, Gilday SE, Jain VV, et al. How much does depth matter? Magnetically controlled growing rod distraction directly influenced by rod tissue depth. Spine Deform 2022;10(1):177-82. doi: 10.1007/s43390-021-00399-z [published Online First: 2021/09/28]
20. Hung CW, Vitale MG, Samdani A, et al. Outcomes of Primary and Conversion Magnetically Controlled Growth Rods Are Different at Two-Year Follow-up: Results of North American Release. Spine Deform 2019;7(5):829-35. doi: 10.1016/j.jspd.2019.01.002 [published Online First: 2019/09/10]
21. Pasha S, Sturm PF. Contouring the magnetically controlled growing rods: impact on expansion capacity and proximal junctional kyphosis. Eur J Orthop Surg Traumatol 2021;31(1):79-84. doi: 10.1007/s00590-020-02743-x [published Online First: 2020/07/28]
22. Luhmann SJ, McAughey EM, Ackerman SJ, et al. Cost analysis of a growth guidance system compared with traditional and magnetically controlled growing rods for early-onset scoliosis: a US-based integrated health care delivery system perspective. Clinicoecon Outcomes Res 2018;10:179-87. doi: 10.2147/CEOR.S152892 [published Online First: 2018/03/29]
23. Polly DW, Jr., Ackerman SJ, Schneider K, et al. Cost analysis of magnetically controlled growing rods compared with traditional growing rods for early-onset scoliosis in the US: an integrated health care delivery system perspective. Clinicoecon Outcomes Res 2016;8:457-65. doi: 10.2147/CEOR.S113633 [published Online First: 2016/10/04]

Vertebral body tethering (VBT) in idiopathic pediatric spinal deformity

May 2023: This statement is based on the literature as of May 2023. As an emerging technology, this statement will be reviewed and updated as appropriate by May 2024.

Benny T. Dahl, MD, PhD, DMSci; Nicholas D. Fletcher, MD; Joshua M. Pahys, MD

The primary surgical treatment for adolescent idiopathic scoliosis (AIS) has been posterior spinal fusion (PSF) for over four decades. In most studies the long-term results have been satisfactory with health-related quality of life comparable to the background population.
There is, however, an ongoing discussion about the long-term consequences of posterior instrumentation and fusion regarding the development of disc degeneration in the lumbar unfused segments of the spine. This has prompted an increasing interest in surgical treatment of AIS without fusion of the spine. One increasingly popular technique is vertebral body tethering (VBT).

The theory behind the use of VBT for the treatment of spinal deformities is to use a flexible cord to limit the growth of the convex side of the spine and correct the coronal deformity through modulation of spinal growth. A recent clinical study has demonstrated that VBT treatment is capable of restoring the symmetry of the apical vertebra and discs indicating an asymmetrical alteration of vertebral growth (Newton, Takahashi, et al., 2022).

Since the first publication in 2010, numerous experimental and clinical studies have investigated the mechanism of action and clinical outcomes after VBT treatment of AIS (Crawford & Lenke, 2010). Since then, one of the primary challenges with the technique has been reoperation rates which have been consistently higher than those reported with PSF. The need for additional surgery after VBT has been described in 18% to 41% of patients, with the primary indications for reoperation being overcorrection or breakage of the tether (Newton et al., 2018).

One of the largest series of patients comparing VBT with PSF was published by the Harms Study Group in 2022  using data from 9 centers. (Newton, Parent, et al., 2022). 38 out of 237 VBT patients underwent revision surgery corresponding to a reoperation rate of 16%. About half of these patients were converted to PSF and half had excessive correction requiring tether release or removal. In the PSF group the revision rate was 1.3%. In that study no specific inclusion criteria regarding skeletal maturity were applied, and all patients had a single thoracic curve tethered. Patients were matched by age, thoracic curve, sex, and maturity using the Risser score. Almost two thirds of patients in the VBT group were Risser 0 compared to 23% in the PSF group, reflective of an older PSF population.

Advocates for the use of VBT as an alternative to PSF note that VBT may be able to maintain more normal motion of the spine. This has been demonstrated in a clinical study by Pahys et al (Pahys et al., 2022). Based on a single-center comparison of patients treated with PSF or VBT using computerized 3D evaluation, it was demonstrated that the lumbar motion was significantly higher in the lumbar VBT group compared to the lumbar PSF group, but the SRS-22 scores were similar. It should also be noted that there was no appreciable difference in motion in the thoracic spine suggesting less benefit of thoracic VBT when compared to selective thoracic PSF.

Perioperative complications
Severe complications after VBT are rare. In a large series of almost 200 patients operated by one surgeon the overall 90-day complication rate was less than 7% including 2 hemothoracies and one superficial wound infection. Only one patient underwent early re-operation to replace a screw. No patients required allogenic blood transfusion (Meyers et al., 2021).

Growth potential
One essential aspect of VBT treatment is the assessment of skeletal maturity and growth potential. There is significant variation in the reporting of requirements for growth potential in the literature. Most studies, however, only include AIS patients with Cobb angles less than 65 degrees, Risser 0-1 and Sanders digital score < 5 (Pahys et al., 2022). Future studies will be needed to assess the utility of VBT in patients with larger curves, non-idiopathic etiologies, and skeletally mature patients. While VBT has been used in older teenagers and some adults, there is no published data to support this practice at this time.

Tether breakage
In most studies the criterion for tether breakage has been an angular change of two adjacent screws of more than 5 degrees (Newton et al., 2018). In a study on ten patients undergoing revision surgery after VBT this definition could only correctly diagnose 56% of breakages and many breakages did not result in loss of correction (Trobisch et al., 2022).

In conclusion, the Scoliosis Research Society recognizes that VBT may be an effective treatment modality in some pediatric patients with idiopathic scoliosis. The decision regarding choice of treatment should be made in close dialogue with patients and families, especially underlining that the current scientific results do not show a significant, clinically relevant difference in outcome compared to PSF, and an increased risk of revision surgery should be expected if VBT is chosen.  In the US The Tether by ZimVie (Westminster, CO) is HDE approved by the FDA for progressive idiopathic scoliosis in skeletally immature patients with a major Cobb angle of 30 to 65 degrees. In Europe Reflect from Globus (Audobon, PA) is CE-approved, and was recently also approved by the FDA under the HDE program. Currently there is an initiative undertaken by the Setting Scoliosis Straight Foundation to obtain consensus regarding nomenclature used in tether treatment. The goal of this work is to make it easier to compare results from different series especially regarding classification of growth potential, what curve types to treat, and the use of one or two tethers.

References

1. Crawford, C. H., & Lenke, L. G. (2010). Growth modulation by means of anterior tethering resulting in progressive correction of juvenile idiopathic scoliosis: A case report. Journal of Bone and Joint Surgery, 92(1), 202–209. https://doi.org/10.2106/JBJS.H.01728
2. Meyers, J., Eaker, L., von Treuheim, T. D. P., Dolgovpolov, S., & Lonner, B. (2021). Early operative morbidity in 184 cases of anterior vertebral body tethering. Scientific Reports, 11(1). https://doi.org/10.1038/s41598-021-02358-0
3. Newton, P. O., Kluck, D. G., Saito, W., Yaszay, B., Bartley, C. E., & Bastrom, T. P. (2018). Anterior spinal growth tethering for skeletally immature patients with scoliosis: A retrospective look two to four years postoperatively. Journal of Bone and Joint Surgery - American Volume, 100(19), 1691–1697. https://doi.org/10.2106/JBJS.18.00287
4. Newton, P. O., Parent, S., Miyanji, F., Alanay, A., Lonner, B. S., Neal, K. M., Hoernschemeyer, D. G., Yaszay, B., Blakemore, L. C., Shah, S. A., Bastrom, T. P., Buckland, A., Alanay, A., Samdani, A., Jain, A., Lonner, B., Roye, B., Cho, B., Yaszay, B., … Upasani, V. (2022). Anterior Vertebral Body Tethering Compared with Posterior Spinal Fusion for Major Thoracic Curves: A Retrospective Comparison by the Harms Study Group. Journal of Bone and Joint Surgery, 104(24), 2170–2177. https://doi.org/10.2106/JBJS.22.00127
5. Newton, P. O., Takahashi, Y., Yang, Y., Yaszay, B., Bartley, C. E., Bastrom, T. P., & Munar, C. (2022). Anterior vertebral body tethering for thoracic idiopathic scoliosis leads to asymmetric growth of the periapical vertebrae. Spine Deformity, 10(3), 553–561. https://doi.org/10.1007/s43390-021-00464-7
6. Pahys, J. M., Samdani, A. F., Hwang, S. W., Warshauer, S., Gaughan, J. P., & Chafetz, R. S. (2022). Trunk Range of Motion and Patient Outcomes after Anterior Vertebral Body Tethering Versus Posterior Spinal Fusion: Comparison Using Computerized 3D Motion Capture Technology. Journal of Bone and Joint Surgery, 104(17), 1563–1572. https://doi.org/10.2106/JBJS.21.00992
7. Trobisch, P., Baroncini, A., Berrer, A., & Da Paz, S. (2022). Difference between radiographically suspected and intraoperatively confirmed tether breakages after vertebral body tethering for idiopathic scoliosis. European Spine Journal, 31(4), 1045–1050. https://doi.org/10.1007/s00586-021-07107-5