Skip to main content

Advertisement

SpringerLink
Log in

Rib-to-spine and rib-to-pelvis magnetically controlled growing rods: does the law of diminishing returns still apply?

  • Case Series
  • Published:
Spine Deformity Aims and scope Submit manuscript

Abstract

Purpose

The Law Of Diminishing Returns (LODR) has been demonstrated for traditional growing rods, but there is conflicting data regarding the lengthening behavior of Magnetically Controlled Growing Rods (MCGR). This study examines a cohort of patients with early-onset scoliosis (EOS) with rib-to-spine or rib-to-pelvis-based MCGR implants to determine if they demonstrate the LODR, and if there are differences in lengthening behaviors between the groups.

Methods

A prospectively collected multicenter EOS registry was queried for patients with MCGR with a minimum 2-year follow-up. Patients with rib-based proximal anchors and either spine- or pelvis-based distal anchors were included. Patients with non-MCGR, unilateral constructs, < 3 lengthenings, or missing > 25% datapoints were excluded. Patients were further divided into Primary-MCGR (pMCGR) and Secondary-MCGR (sMCGR).

Results

43 rib-to-spine and 31 rib-to-pelvis MCGR patients were included. There was no difference in pre-implantation, post-implantation and pre-definitive procedure T1–T12 height, T1–S1 height, and major Cobb angles between the groups (p > 0.05). Sub-analysis was performed on 41 pMCGR and 19 sMCGR rib-to-spine patients, and 31 pMCGR and 17 sMCGR rib-to-pelvis patients. There is a decrease in rod lengthenings achieved at subsequent lengthenings for each group: rib-to-spine pMCGR (rho = 0.979, p < 0.001), rib-to-spine sMCGR (rho = 0.855, p = 0.002), rib-to-pelvis pMCGR (rho = 0.568, p = 0.027), and rib-to-pelvis sMCGR (rho = 0.817, p = 0.007). Rib-to-spine pMCGR had diminished lengthening over time for idiopathic, neuromuscular, and syndromic patients (p < 0.05), with no differences between the groups (p > 0.05). Rib-to-pelvis pMCGR neuromuscular patients had decreased lengthening over time (p = 0.01), but syndromic patients had preserved lengthening over time (p = 0.65).

Conclusion

Rib-to-spine and rib-to-pelvis pMCGR and sMCGR demonstrate diminished ability to lengthen over subsequent lengthenings.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6

Similar content being viewed by others

Data availability

This study was performed utilizing the Pediatric Spine Study Group (PSSG) database.

References

  1. Yang S, Andras LM, Redding GJ et al (2016) Early-Onset Scoliosis: a REVIEW of history, current treatment, and future directions. Pediatrics 137(1):e2015–e2709

    Article  Google Scholar 

  2. Campbell RM, Smith MD, Mayes TC et al (2003) The characteristics of thoracic insufficiency syndrome associated with fused ribs and congenital scoliosis. J Bone Joint Surg Am 85(3):399–408

    Article  PubMed  Google Scholar 

  3. Karol LA (2019) The natural history of early-onset scoliosis. J Pediatr Orthop 39(6suppl1):S38–S43

    Article  PubMed  Google Scholar 

  4. Campbell RM, Smith MD, Hell-Vocke AK (2004) Expansion thoracoplasty: the surgical technique of opening-wedge thoracostomy. Surigcal technique. J Bone Joint Surg Am 86-A(Suppl1):51–64

    Article  Google Scholar 

  5. Hell AK, Groenefeld K, Tsaknakis K et al (2018) Combining bilateral magnetically controlled implants parallel to the spine with rib to pelvis fixation Surgical technique and early results. Clin Spine Surg 1(6):239–246

    Article  Google Scholar 

  6. Sankar WN, Skaggs DL, Yazici M et al (2011) Lengthening of dual growing rods and the law of diminishing returns. Spine 36(10):806–809

    Article  PubMed  Google Scholar 

  7. Ahmad A, Subramanian T, Panteliadis P et al (2017) Quantifying the ‘law of diminishing returns on magnetically controlled growing rods.’ Bone Joint J. 99-B:1658–1664

    Article  CAS  PubMed  Google Scholar 

  8. Lebon J, Batailler C, Wargny M et al (2017) Magnetically controlled growing rod in early onset scoliosis: a 30-case multicenter study. Eur Spine J 26:1567–1576

    Article  PubMed  Google Scholar 

  9. Gardner A, Beaven A, Marks D et al (2017) Does the law of diminishing returns apply to the lengthening of the MCGR rod in early onset scoliosis with reference to growth velocity? J Spine Surg 3(4):525–530

    Article  PubMed  PubMed Central  Google Scholar 

  10. Cheung JPY, Bow C, Samartzis D et al (2016) Frequent small distractions with a magnetically controlled growing rod for early-onset scoliosis and avoidance of the law of diminishing returns. J Orthop Surg (Hong Kong) 24(3):332–337

    Article  PubMed  Google Scholar 

  11. El-Hawary R, Samdani A, Wade J et al (2016) Rib-based distraction surgery maintains total spine growth. J Pediatr Orthop 36:841–846

    Article  PubMed  Google Scholar 

  12. Lorenz HM, Braunschweig L, Badwan D et al (2019) High correlation between archived and expected distraction using magnetically controlled growing rods (MCGR) with rib to pelvis fixation in pediatric spine deformity. J Pediatr Orthop 39(5):e334–e338

    Article  PubMed  Google Scholar 

  13. El-Hawary R, Chukwunyerenwa CK, Gauthier LE et al (2020) Distraction-based surgeries increase thoracic sagittal spine length after ten lengthening surgeries for patients with idiopathic early-onset scoliosis. Spine Deform 8(2):303–309

    Article  PubMed  Google Scholar 

  14. Klyce W, Mitchell SL, Pawelek J et al (2020) Characterizing use of growth-friendly implants for early onset scoliosis: a 10-year update. J Pediatr Orthop 40(8):e740–e746

    Article  PubMed  Google Scholar 

  15. Murphy RF, Neel GB, Barfield WR et al (2022) Trends in the utilization of implants in index procedures for early onset scoliosis from the pediatric spine study group. J Pediatr Orthop 42(9):e912–e916

    Article  PubMed  Google Scholar 

  16. Lorenz HM, Hecker MM, Braunschweig L et al (2020) Continuous lengthening potential after four years of magnetically controlled spinal deformity correction in children with spinal muscular atrophy. Sci Rep 10(1):22420

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  17. MAGEC® Questions. NuVasive. Accessed March 28, 2022. https://www.nuvasive.com/magec-questions/

  18. Cheung JPY, Yiu KKL, Samartzis D et al (2018) Rod lengthening with the magnetically controlled growing rod. Spine 43(7):E399–E405

    Article  PubMed  Google Scholar 

  19. Cheung JPY, Bow C, Cheung KMC (2020) “Law of temporary diminishing distraction gains”: the phenomenon of temporary diminished distraction lengths with magnetically controlled growing rods that is reverted with rod exchange. Global Spine J. https://doi.org/10.1177/2192568220948475

    Article  PubMed  PubMed Central  Google Scholar 

  20. Shetty AP, Nikhil KV, Renjith KR et al (2019) Proximal anchor constructs and its influence on surgical outcome in growth rod technique; a comparison between rib hooks and pedicle screws. Spine Deform 7(6):979–984

    Article  PubMed  Google Scholar 

  21. Matsumoto H, Fields MW, Roye RD, Roye DP, Skaggs D, Akbarnia BA, Vitale MG (2021) Complications in the treatment of EOS: Is there a difference between rib vs. spine based proximal anchors? Spine Deform 9(1):247–253

    Article  PubMed  Google Scholar 

  22. Smith JT (2001) Bilateral rib-to-pelvis technique for managing early-onset scoliosis. Clin Orthop Relat Res 469(5):1349–1355

    Article  Google Scholar 

  23. Johnson MA, Cahill PJ, Qiu C, Lott C, Mayer OH, Flynn JM, Anari JB (2020) Comparison of T1–S1 spine height of postoperative rib-based implant patients with age-matched peers. J Pediatr Orthop 40(7):344–350

    Article  PubMed  Google Scholar 

  24. Samdani AF, Ranade A, Dolch HJ et al (2009) Bilateral use of the vertical expandable prosthetic titanium rib attached to the pelvis: a novel treatment for scoliosis in the growing spine. J Neurosurg Spine 10(4):287–292

    Article  PubMed  Google Scholar 

  25. Ruggieri V, Sinder B, Qiu C, et al. Surgeon distraction forces in open lengthening’s exceed MCGR maximums: an in vivo biomechanical study. ICEOS 2020 Virtual Annual Meeting abstract.

  26. Akbarnia BA, Yaszay B, Tazici M et al (2014) Biomechanical evaluation of 4 different foundation constructs commonly used in growing spine surgery: are rib anchors comparable to spine anchors? Spine Deform 2(6):437–443

    Article  PubMed  Google Scholar 

  27. El-Bromboly Y, Hurry J, Padhye K et al (2021) The effect of proximal anchor choice during distraction-based surgeries for patients with nonidiopathic early-onset scoliosis: a retrospective multicenter study. J Pediatr Orthop 41(5):290–295

    Article  PubMed  Google Scholar 

  28. Tsaknakis K, Schmalz T, Freslier M et al (2022) Limited trunk motion and posterior pelvic tilting in ambulatory children treated with bilateral rib to pelvis implants for spinal deformity control. J Pediatr Orthop B 31(1):72–77

    Article  PubMed  Google Scholar 

  29. Ramirez B, Olivella G, Rodriguez O et al (2020) Incidence of complications in the management of non-ambulatory neuromuscular early-onset scoliosis with a rib-based growing system: high- versus low-tone patients. Eur J Orthop Surg Traumatol 30(4):621–627

    Article  PubMed  Google Scholar 

  30. Heflin JA, Cleveland A, Ford SD et al (2015) Use of rib-based distraction in the treatment of early onset scoliosis associated with neurofibromatosis type 1 in the young child. Spine Deform 3(3):239–245

    Article  PubMed  Google Scholar 

  31. Ramirez N, Flynn JM, Smith JT et al (2015) Use of the S-hook for pelvic fixation in rib-based treatment of early-onset scoliosis: a multicenter study. Spine (Phila Pa 1976) 40(11):816–822

    Article  PubMed  Google Scholar 

  32. Meza BC, Shah AS, Vitale MG et al (2020) Proximal anchor fixation in magnetically controlled growing rods (MCGR): preliminary 2-year results of the impact of anchor location and density. Spine Deform 8(4):793–800

    Article  PubMed  Google Scholar 

  33. Heflin JA, Fedorak GT, Presson AP et al (2018) Surgeon experience does not change rate of perioperative surgical complication in rib-based distraction surgery for early onset scoliosis. Spine Deform 6(5):600–606

    Article  PubMed  Google Scholar 

  34. Skaggs KF, Brasher AE, Johnston CE et al (2013) Upper thoracic pedicle screw loss of fixation causing spinal cord injury: a review of literature and multicenter case series. J Pediatr Orthop 33(1):75–79

    Article  PubMed  Google Scholar 

  35. Bekmez S, Kocyigi A, Olgun ZD et al (2018) Pull-out of upper thoracic pedicle screws can cause spinal canal encroachment in growing rod treatment. J Pediatr Orthop 38(7):e388–e403

    Article  Google Scholar 

Download references

Funding

This study was performed utilizing the Pediatric Spine Study Group database. PSSG is supported by the Pediatric Spine foundation, which receives funding from DePuy Synthes Spine, Medtronic, Nuvasive, OrthoPediatrics, and Zimmer Biomet.

Author information

Authors and Affiliations

  1. Department of Pediatric Orthopaedics, Hospital for Special Surgery, New York, NY, USA

    Jessica H. Heyer

  2. Department of Orthopaedic Surgery, Children’s Hospital of Philadelphia, 3500 Civic Center Blvd, Philadelphia, PA, 19104, USA

    Jason B. Anari, Keith D. Baldwin, John M. Flynn, Wudbhav N. Sankar & Patrick J. Cahill

  3. Department of Orthopaedics, University of North Carolina, Chapel Hill, NC, USA

    Stuart L. Mitchell

  4. Department of Orthopaedics, Children’s Hospital of Los Angeles, Los Angeles, CA, USA

    Lindsay M. Andras

  5. Department of Orthopaedics, Cedars Sinai, Los Angeles, CA, USA

    David L. Skaggs

  6. Department of Orthopaedics, University of Utah Health, Salt Lake City, UT, USA

    John T. Smith

  7. Department of Orthopaedic Surgery, Shriners Children’s Pediatric Specialty Care, St. Louis, MO, USA

    Scott J. Luhmann

  8. Department of Orthopaedics, UCSF Benioff Children’s Hospitals, San Francisco, CA, USA

    Ishaan Swarup

  9. Department of Orthopaedics, Gilette Children’s, St. Paul, MN, USA

    Walter H. Truong

  10. Department of Orthopaedics, Scottish Rite for Children, Dallas, TX, USA

    Jaysson T. Brooks

  11. Children’s Orthopaedic and Scoliosis Surgery Associates, St. Petersburg, FL, USA

    Ryan Fitzgerald

  12. Department of Orthopaedics, Univeristy of Michigan, Michigan Medicine, Ann Arbor, MI, USA

    Ying Li

Authors
  1. Jessica H. Heyer
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Jason B. Anari
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Keith D. Baldwin
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Stuart L. Mitchell
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. John M. Flynn
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Wudbhav N. Sankar
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Lindsay M. Andras
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. David L. Skaggs
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. John T. Smith
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. Scott J. Luhmann
    View author publications

    You can also search for this author in PubMed Google Scholar

  11. Ishaan Swarup
    View author publications

    You can also search for this author in PubMed Google Scholar

  12. Walter H. Truong
    View author publications

    You can also search for this author in PubMed Google Scholar

  13. Jaysson T. Brooks
    View author publications

    You can also search for this author in PubMed Google Scholar

  14. Ryan Fitzgerald
    View author publications

    You can also search for this author in PubMed Google Scholar

  15. Ying Li
    View author publications

    You can also search for this author in PubMed Google Scholar

  16. Patrick J. Cahill
    View author publications

    You can also search for this author in PubMed Google Scholar

Consortia

Pediatric Spine Study Group

Contributions

Conception of design or work: JHH, JBA, KDB, SLM, JMF, PSSG, PJC. Data Collection: JHH, JBA, PSSG, PJC. Writing-original draft preparation: JHH, JBA, KDB, SLM, JMF. Revision of work; approval of final version of manuscript; agree to be accountable for the work: JHH, JBA, KDB, SLM, JMF, WNS, LMA, DLS, JTS, SJL, IS, WHT, JTB, RF, YL, PSSG, PJC.

Corresponding author

Correspondence to Patrick J. Cahill.

Ethics declarations

Conflict of interest

The Pediatric Spine Study Group is supported by the Pediatric Spine Foundation, which receives funding from Nuvasive. Patrick J. Cahill, Keith D. Baldwin, Jessica H. Heyer, John M. Flynn, Ishaan Swarup, Jaysson Brooks, Walter Truong, Stuart Mitchell, Jason Anari, Ryan Fitzgerald and Scott Luhmann have no conflicts of interest to declare that are relevant to the content of this article. Ying Li receives personal fees from Medtronic. John Smith is a consultant for Wishbone and Zimvie, and receives royalties from Globus. Wudbhav Sankar receives consulting fees from OrthoPediatrics and Siemens. David Skaggs receives research grants from NuVasive, consults for ZimmerBiomet, Globus Medical, Top Doctors and Orthobullets, and holds stock in Zipline Medical Inc, Green Sun Medical, and Orthobullets. He is a paid lecturer for ZimmerBiomet, holds patents with Medronic and ZimmerBiomet, and receives royalties from Medtronic, ZimmerBiomet, and Globus Medical. Lindsay Andras serves on the Speakers Buraeu for Nuvasiv and Medtronic, receives grant support from POSNA, holds stock in EliLilly, and is on the Scoliosis Research Society Board of Directors.

Ethical approval

The institutional review boards (IRBs) of each participating site approved of the participation in the study prior to collection of patient data.

Consent to participate

Informed consent was obtained from all patients (or their legal guardians) at each participating institution at the onset of the study.

Consent for publication

Patients (or their legal guardians) were individually consented at each participating institution for inclusion of their data in published studies; all data is deidentified by the PSSG database. There is no identifiable data or imaging included in this study.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Heyer, J.H., Anari, J.B., Baldwin, K.D. et al. Rib-to-spine and rib-to-pelvis magnetically controlled growing rods: does the law of diminishing returns still apply?. Spine Deform 11, 1517–1527 (2023). https://doi.org/10.1007/s43390-023-00718-6

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s43390-023-00718-6

Keywords

Search

Navigation