TY - JOUR
T1 - Lengthening Behavior of Magnetically Controlled Growing Rods in Early-Onset Scoliosis
T2 - A Multicenter Study
AU - Pediatric Spine Study Groups
AU - Heyer, Jessica H.
AU - Anari, Jason B.
AU - Baldwin, Keith D.
AU - Mitchell, Stuart L.
AU - Luhmann, Scott J.
AU - Sturm, Peter F.
AU - Flynn, John M.
AU - Cahill, Patrick J.
AU - Abdulfattah Abdullah, Abdullah Saad
AU - Ahn, Edward
AU - Akbarnia, Behrooz
AU - Akoto, Harry
AU - Albanese, Stephen
AU - Anari, Jason
AU - Anderson, John
AU - Anderson, Richard
AU - Andras, Lindsay
AU - Bauer, Jennifer
AU - Bellaire, Laura
AU - Betz, Randy
AU - Birch, Craig
AU - Blakemore, Laurel
AU - Boachie-Adjei, Oheneba
AU - Bonfield, Chris
AU - Bouton, Daniel
AU - Brassard, Felix
AU - Brockmeyer, Douglas
AU - Brooks, Jaysson
AU - Bumpass, David
AU - Cahill, Pat
AU - Chemaly, Olivier
AU - Cheung, Jason
AU - Cheung, Kenneth
AU - Cho, Robert
AU - Christman, Tyler
AU - Beauchamp, Eduardo Colom
AU - Couture, Daniel
AU - Crawford, Haemish
AU - Crawford, Alvin
AU - Dahl, Benny
AU - Demirkiran, Gokhan
AU - Devito, Dennis
AU - Diab, Mohammad
AU - El Sebaie, Hazem
AU - El-Hawary, Ron
AU - Emans, John
AU - Erickson, Mark
AU - Fabregas, Jorge
AU - Gomez, Jaime
AU - Schulz, Jacob
N1 - Publisher Copyright:
© 2022 Lippincott Williams and Wilkins. All rights reserved.
PY - 2022/12/21
Y1 - 2022/12/21
N2 - Background:The "law of diminishing returns" is described for traditional growing rods. Magnetically controlled growing rods (MCGRs) have become a preferred implant for the surgical treatment of early-onset scoliosis (EOS). We examined a large cohort of patients with EOS to determine whether the law of diminishing returns applies to MCGRs.Methods:A prospectively collected, multicenter registry was queried for patients with EOS treated with MCGRs. Patients with only spine-based implants and a minimum of 2 years of follow-up were included; patients with congenital scoliosis, single rods, <3 lengthenings, or >25% missing data were excluded. Patients were analyzed in 3 cohorts: primary MCGR (pMCGR) had first-time MCGR implants, secondary MCGR (sMCGR) were converted from an MCGR to a new MCGR, and conversion MCGR (cMCGR) were converted from a non-MCGR implant to MCGR.Results:A total of 189 patients in the pMCGR group, 44 in the cMCGR group, and 41 in the sMCGR group were analyzed. From post-MCGR placement to the most recent follow-up or pre-definitive procedure, there were no differences in the changes in major Cobb angle, T1-S1 height, or T1-T12 height over time between the pMCGR and cMCGR groups. There was a decrease in length achieved at subsequent lengthenings in all cohorts (p < 0.01), and the sMCGR group had a significantly poorer ability to lengthen at each subsequent lengthening versus the pMCGR and cMCGR groups (p < 0.02). The 1-year survival rate was 90.5% for pMCGR, 84.1% for sMCGR, and 76.4% for cMCGR; 2-year survival was 61.5%, 54.4%, and 41.4%, respectively; and 3-year survival was 37.6%, 36.7%, and 26.9%, respectively. Excluding MCGRs still expanding, 27.6% of pMCGRs, 8.8% of sMCGRs, and 17.1% of cMCGRs reached the maximum excursion. Overall, 21.7% reached the maximum excursion. Within the pMCGR cohort, idiopathic and neuromuscular etiologies had a decline in lengthening achieved over time (p < 0.001), while syndromic EOS demonstrated a preserved ability to lengthen over time (p = 0.51). When the etiological groups were compared with each other, the neuromuscular group had the least ability to lengthen over time (p = 0.001 versus syndromic, p = 0.02 versus idiopathic).Conclusions:The MCGR experiences the law of diminishing returns in patients with EOS. We found that only 21.7% of rods expanded to within 80% of the maximum excursion.Level of Evidence:Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.
AB - Background:The "law of diminishing returns" is described for traditional growing rods. Magnetically controlled growing rods (MCGRs) have become a preferred implant for the surgical treatment of early-onset scoliosis (EOS). We examined a large cohort of patients with EOS to determine whether the law of diminishing returns applies to MCGRs.Methods:A prospectively collected, multicenter registry was queried for patients with EOS treated with MCGRs. Patients with only spine-based implants and a minimum of 2 years of follow-up were included; patients with congenital scoliosis, single rods, <3 lengthenings, or >25% missing data were excluded. Patients were analyzed in 3 cohorts: primary MCGR (pMCGR) had first-time MCGR implants, secondary MCGR (sMCGR) were converted from an MCGR to a new MCGR, and conversion MCGR (cMCGR) were converted from a non-MCGR implant to MCGR.Results:A total of 189 patients in the pMCGR group, 44 in the cMCGR group, and 41 in the sMCGR group were analyzed. From post-MCGR placement to the most recent follow-up or pre-definitive procedure, there were no differences in the changes in major Cobb angle, T1-S1 height, or T1-T12 height over time between the pMCGR and cMCGR groups. There was a decrease in length achieved at subsequent lengthenings in all cohorts (p < 0.01), and the sMCGR group had a significantly poorer ability to lengthen at each subsequent lengthening versus the pMCGR and cMCGR groups (p < 0.02). The 1-year survival rate was 90.5% for pMCGR, 84.1% for sMCGR, and 76.4% for cMCGR; 2-year survival was 61.5%, 54.4%, and 41.4%, respectively; and 3-year survival was 37.6%, 36.7%, and 26.9%, respectively. Excluding MCGRs still expanding, 27.6% of pMCGRs, 8.8% of sMCGRs, and 17.1% of cMCGRs reached the maximum excursion. Overall, 21.7% reached the maximum excursion. Within the pMCGR cohort, idiopathic and neuromuscular etiologies had a decline in lengthening achieved over time (p < 0.001), while syndromic EOS demonstrated a preserved ability to lengthen over time (p = 0.51). When the etiological groups were compared with each other, the neuromuscular group had the least ability to lengthen over time (p = 0.001 versus syndromic, p = 0.02 versus idiopathic).Conclusions:The MCGR experiences the law of diminishing returns in patients with EOS. We found that only 21.7% of rods expanded to within 80% of the maximum excursion.Level of Evidence:Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.
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U2 - 10.2106/JBJS.22.00483
DO - 10.2106/JBJS.22.00483
M3 - Article
C2 - 36367763
AN - SCOPUS:85144934376
SN - 0021-9355
VL - 104
SP - 2186
EP - 2194
JO - Journal of Bone and Joint Surgery
JF - Journal of Bone and Joint Surgery
IS - 24
ER -