{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,26]],"date-time":"2026-08-26T14:46:38Z","timestamp":1787755598298,"version":"build-2784847793"},"reference-count":19,"publisher":"Ovid Technologies (Wolters Kluwer Health)","issue":"24","content-domain":{"domain":["lww.com","ovid.com"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2022,12,21]]},"abstract":"<jats:sec>\n                    <jats:title>Background:<\/jats:title>\n                    <jats:p>The \u201claw of diminishing returns\u201d 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.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods:<\/jats:title>\n                    <jats:p>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, &lt;3 lengthenings, or &gt;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.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results:<\/jats:title>\n                    <jats:p>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 &lt; 0.01), and the sMCGR group had a significantly poorer ability to lengthen at each subsequent lengthening versus the pMCGR and cMCGR groups (p &lt; 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 &lt; 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).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions:<\/jats:title>\n                    <jats:p>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.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Level of Evidence:<\/jats:title>\n                    <jats:p>\n                      Therapeutic\n                      <jats:underline>Level III<\/jats:underline>\n                      . See Instructions for Authors for a complete description of levels of evidence.\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.2106\/jbjs.22.00483","type":"journal-article","created":{"date-parts":[[2022,11,11]],"date-time":"2022-11-11T12:04:39Z","timestamp":1668168279000},"page":"2186-2194","update-policy":"https:\/\/doi.org\/10.1097\/lww.0000000000001000","source":"Crossref","is-referenced-by-count":22,"title":["Lengthening Behavior of Magnetically Controlled Growing Rods in Early-Onset Scoliosis"],"prefix":"10.2106","volume":"104","author":[{"given":"Jessica H.","family":"Heyer","sequence":"first","affiliation":[{"name":"Hospital for Special Surgery, New York, NY"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jason B.","family":"Anari","sequence":"additional","affiliation":[{"name":"Children\u2019s Hospital of Philadelphia, Philadelphia, Pennsylvania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Keith D.","family":"Baldwin","sequence":"additional","affiliation":[{"name":"Children\u2019s Hospital of Philadelphia, Philadelphia, Pennsylvania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stuart L.","family":"Mitchell","sequence":"additional","affiliation":[{"name":"University of North Carolina, Chapel Hill, North Carolina"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Scott J.","family":"Luhmann","sequence":"additional","affiliation":[{"name":"Washington University in St. Louis, St. Louis, Missouri"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Peter F.","family":"Sturm","sequence":"additional","affiliation":[{"name":"Cincinnati Children\u2019s Hospital Medical Center, Cincinnati, Ohio"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"John M.","family":"Flynn","sequence":"additional","affiliation":[{"name":"Children\u2019s Hospital of Philadelphia, Philadelphia, Pennsylvania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Patrick J.","family":"Cahill","sequence":"additional","affiliation":[{"name":"Children\u2019s Hospital of Philadelphia, Philadelphia, Pennsylvania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"name":"on behalf of the Pediatric Spine Study Group","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"276","published-online":{"date-parts":[[2022,10,20]]},"reference":[{"issue":"6,","key":"bib1-20250430","doi-asserted-by":"crossref","first-page":"S38","DOI":"10.1097\/BPO.0000000000001351","article-title":"The natural history of early-onset scoliosis","volume":"39","author":"Karol","year":"2019","journal-title":"J Pediatr Orthop."},{"issue":"1","key":"bib2-20250430","doi-asserted-by":"crossref","first-page":"e2015","DOI":"10.1542\/peds.2015-0709","article-title":"Early-Onset Scoliosis: A Review of history, current treatment, and future 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Orthop Surg (Hong Kong)."},{"issue":"5","key":"bib9-20250430","doi-asserted-by":"crossref","first-page":"829","DOI":"10.1016\/j.jspd.2019.01.002","article-title":"Outcomes of primary and conversion magnetically controlled growth rods are different at two-year follow-up: results of North American release","volume":"7","author":"Hung","year":"2019","journal-title":"Spine Deform."},{"issue":"10","key":"bib10-20250430","doi-asserted-by":"crossref","first-page":"3294","DOI":"10.1007\/s00586-016-4597-y","article-title":"Preliminary comparison of primary and conversion surgery with magnetically controlled growing rods in children with early onset scoliosis","volume":"25","author":"Keskinen","year":"2016","journal-title":"Eur Spine J."},{"issue":"2","key":"bib12-20250430","doi-asserted-by":"crossref","first-page":"221","DOI":"10.1177\/2192568220948475","article-title":"\u201cLaw of temporary diminishing distraction gains\u201d: the phenomenon of temporary diminished distraction lengths with magnetically controlled growing rods that is reverted with rod exchange","volume":"12","author":"Cheung","year":"2022","journal-title":"Global Spine J."},{"issue":"3","key":"bib13-20250430","doi-asserted-by":"crossref","first-page":"e133","DOI":"10.1097\/BPO.0000000000001119","article-title":"Observed length increases of magnetically controlled growing rods are lower than programmed","volume":"38","author":"Gilday","year":"2018","journal-title":"J Pediatr Orthop."},{"issue":"17","key":"bib14-20250430","doi-asserted-by":"crossref","first-page":"1201","DOI":"10.1097\/BRS.0000000000003048","volume":"44","author":"Lampe","year":"2019","journal-title":"Spine (Phila Pa 1976)."},{"issue":"10","key":"bib15-20250430","doi-asserted-by":"crossref","first-page":"3371","DOI":"10.1007\/s00586-015-4223-4","article-title":"Radiological and clinical assessment of the distraction achieved with remotely expandable growing rods in early onset scoliosis","volume":"25","author":"Rolton","year":"2016","journal-title":"Eur Spine J."},{"issue":"9","key":"bib16-20250430","doi-asserted-by":"crossref","first-page":"1187","DOI":"10.1302\/0301-620X.100B9.BJJ-2018-0031.R2","article-title":"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","volume":"100-B","author":"Subramanian","year":"2018","journal-title":"Bone Joint J."},{"issue":"6","key":"bib17-20250430","doi-asserted-by":"crossref","first-page":"787","DOI":"10.1016\/j.jspd.2018.03.009","article-title":"Maximal force generated by magnetically controlled growing rods decreases with rod lengthening","volume":"6","author":"Poon","year":"2018","journal-title":"Spine Deform."},{"issue":"9","key":"bib18-20250430","doi-asserted-by":"crossref","first-page":"984","DOI":"10.1097\/BRS.0b013e31816c8b4e","article-title":"Dual growing rod technique followed for three to eleven years until final fusion: the effect of frequency of lengthening","volume":"33","author":"Akbarnia","year":"2008","journal-title":"Spine (Phila Pa 1976)."},{"issue":"1","key":"bib19-20250430","doi-asserted-by":"crossref","first-page":"41","DOI":"10.2106\/JBJS.20.02108","article-title":"Matched Comparison of Magnetically Controlled Growing Rods with Traditional Growing Rods in Severe Early-Onset Scoliosis of \u226590\u00b0: An Interim Report on Outcomes 2 Years After Treatment","volume":"104","author":"Saarinen","year":"2022","journal-title":"J Bone Joint Surg Am."},{"issue":"3","key":"bib20-20250430","doi-asserted-by":"crossref","first-page":"170","DOI":"10.1097\/BRS.0000000000003215","article-title":"Spinal lengthening with magnetically controlled growing rods: data from the largest series of explanted devices","volume":"45","author":"Rushton","year":"2020","journal-title":"Spine (Phila Pa 1976)."}],"container-title":["Journal of Bone and Joint Surgery"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.ovid.com\/10.2106\/JBJS.22.00483","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,26]],"date-time":"2026-08-26T13:45:40Z","timestamp":1787751940000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.ovid.com\/10.2106\/JBJS.22.00483"}},"subtitle":["A Multicenter Study"],"short-title":[],"issued":{"date-parts":[[2022,10,20]]},"references-count":19,"journal-issue":{"issue":"24","published-print":{"date-parts":[[2022]]}},"URL":"https:\/\/doi.org\/10.2106\/jbjs.22.00483","relation":{},"ISSN":["0021-9355","1535-1386"],"issn-type":[{"value":"0021-9355","type":"print"},{"value":"1535-1386","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,10,20]]}}}