Abstract
Purpose
The purpose of this study was to evaluate mid-term outcomes of magnetically controlled growing rods (MCGR), evaluate factors associated with unplanned return to the operating room (UPROR) vs achieving full length. Full length was defined as achieving > 85% of the elongating portion of the rod.
Methods
IRB approved retrospective single site study. 106 patients underwent MCGR between 2014 and 2020, 58 met inclusion criteria, all genders, ethnicities, and etiologies were included. Patients with < 1 year follow-up or previous instrumentation were excluded.
Results
Follow-up averaged 43 months. 23 patients achieved full length 13 were revised to a new MCGR and 10 to a fusion; 5 were fused due to skeletal maturity; 12 were still lengthening; 2 were being observed; 16 experienced UPROR. Major curves improved from 80° (50–114) preoperative to 40° (7–78) at most recent follow-up or prior to revision, and 24° (4–57) after fusion. Fusion patients averaged 1.3 (1–4) procedures prior to fusion and gained 75 mm (38–142) in T1–S1 length. 16 patients experienced UPROR, 11 were male (p = 0.0238). All failures to elongate were male as was the rod fracture. Age was not correlated with UPROR (p = 0.318), but did correlate with implant-specific causes of UPROR. Specifically, anchor failure was associated with younger age and rod failure with older age at implantation (p = 0.013). There was no correlation between UPROR and major curve, flexibility or kyphosis.
Conclusion
This is the largest site study evaluating mid-term outcomes in MCGR patients. At > 3.5 year follow-up 47% were electively revised, 27% underwent UPROR, 26% were still lengthening, and 3% were being observed. UPROR was associated with male gender and age at implantation was associated with implant-related causes of UPROR. MCGR continues to have high complication rates, better knowledge of MCGR outcomes may improve patient education, surgical timing, and decision-making.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Meza BC, Shah SA, 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. https://doi.org/10.1007/s43390-020-00102-8
Vitale MGMH, Feinberg N et al (2015) Paper #35 proximal rib vs proximal spine anchors in growing rods: a multicenter prospective cohort study. Spine Deform 3:626–627
Bess S, Akbarnia BA, Thompson GH et al (2010) Complications of growing-rod treatment for early-onset scoliosis: analysis of one hundred and forty patients. J Bone Jt Surg Am 92(15):2533–2543. https://doi.org/10.2106/JBJS.I.01471
Sankar WN, Skaggs DL, Yazici M et al (2011) Lengthening of dual growing rods and the law of diminishing returns. Spine (Phila Pa 1976) 36(10):806–809. https://doi.org/10.1097/BRS.0b013e318214d78f
Smith JR, Samdani AF, Pahys J et al (2009) The role of bracing, casting, and vertical expandable prosthetic titanium rib for the treatment of infantile idiopathic scoliosis: a single-institution experience with 31 consecutive patients. Clinical article. J Neurosurg Spine 11(1):3–8. https://doi.org/10.3171/2009.1.SPINE08253
Choi E, Yazsay B, Mundis G et al (2016) Implant complications after magnetically controlled growing rods for early onset scoliosis: a multicenter retrospective review. J Pediatr Orthop. https://doi.org/10.1097/BPO.0000000000000803
Kwan KYH, Alanay A, Yazici M et al (2017) Unplanned reoperations in magnetically controlled growing rod surgery for early onset scoliosis with a minimum of two-year follow-up. Spine (Phila Pa 1976). https://doi.org/10.1097/BRS.0000000000002297
Subramanian T, Ahmad A, Mardare DM et al (2018) A six-year observational study of 31 children with early-onset scoliosis treated using magnetically controlled growing rods with a minimum follow-up of two years. Bone Jt J 100-B(9):1187–1200. https://doi.org/10.1302/0301-620X.100B9.BJJ-2018-0031.R2
Cheung JPY, Zhang T, Bow C et al (2020) 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) 45(6):E346–E351. https://doi.org/10.1097/BRS.0000000000003268
Kwan KYH, Alanay A, Yazici M et al (2017) Unplanned reoperations in magnetically controlled growing rod surgery for early onset scoliosis with a minimum of two-year follow-up. Spine (Phila Pa 1976) 42(24):E1410–E1414. https://doi.org/10.1097/BRS.0000000000002297
Akbarnia BA, Pawelek JB, Cheung KM et al (2014) Traditional growing rods versus magnetically controlled growing rods for the surgical treatment of early-onset scoliosis: a case-matched 2-year study. Spine Deform 2(6):493–497. https://doi.org/10.1016/j.jspd.2014.09.050
Hell AK, Braunschweig L, Behrend J et al (2019) Health-related quality of life in early-onset-scoliosis patients treated with growth-friendly implants is influenced by etiology, complication rate and ambulatory ability. BMC Musculoskelet Disord 20(1):588. https://doi.org/10.1186/s12891-019-2969-2
Bekmez S, Afandiyev A, Dede O et al (2019) Is magnetically controlled growing rod the game changer in early-onset scoliosis? A Preliminary Report. J Pediatr Orthop 39(3):e195–e200. https://doi.org/10.1097/BPO.0000000000001268
Erdogan S, Polat B, Atici Y et al (2019) Comparison of the effects of magnetically controlled growing rod and traditional growing rod techniques on the sagittal plane in the treatment of early-onset scoliosis. J Korean Neurosurg Soc 62(5):577–585. https://doi.org/10.3340/jkns.2019.0094
Teoh KH, Winson DM, James SH et al (2016) Do magnetic growing rods have lower complication rates compared with conventional growing rods? Spine J 16(4 Suppl):S40-44. https://doi.org/10.1016/j.spinee.2015.12.099
Watanabe K, Uno K, Suzuki T et al (2013) Risk factors for complications associated with growing-rod surgery for early-onset scoliosis. Spine (Phila Pa 1976) 38(8):E464-468. https://doi.org/10.1097/BRS.0b013e318288671a
Funding
POSNA Research Startup Grant; Shriners Hospital for Children Directed Research Grant.
Author information
Authors and Affiliations
Contributions
MCW: conception/design, data acquisition, analysis, interpretation, drafted/revised work, approved final version. DB: conception/design, interpretation, drafted/revised work, approved final version. All authors agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
Corresponding author
Ethics declarations
Conflict of interest
Dr. Welborn reports grants from POSNA, grants from Shriners Hospital for Children, during the conduct of the study; personal fees and other from Depuy Synthes, personal fees from Nuvasive, personal fees from Stryker/K2M, personal fees from and Zimmer/Biomet outside the submitted work. Dr. Bouton reports during the conduct of the study; personal fees from Medtronic outside the submitted work.
Ethical approval (IRB)
This is a Western IRB approved study. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee (Western Copernicus Group (WCG)/Western Institutional Review Board (WIRB) on Feb 19, 2020 study number 1275477) and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
Informed consent
Informed consent was obtained from all patients and their parents.
Rights and permissions
About this article
Cite this article
Welborn, M.C., Bouton, D. Outcomes of MCGR at > 3 year average follow-up in severe scoliosis: who undergoes elective revision vs UPROR?. Spine Deform 10, 457–463 (2022). https://doi.org/10.1007/s43390-021-00424-1
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s43390-021-00424-1