Premature spinal fusion after insertion of magnetically controlled growing rods for treatment of early-onset scoliosis: illustrative case

BACKGROUND Magnetically controlled growing rod (MCGR) systems have gained attention for their use in the treatment of early-onset scoliosis. Although traditional growing rods require frequent operations to lengthen the construct, MCGR allows for fewer open procedures and more frequent distractions by externally controlling rod elongation. Despite its appealing advantages, MCGR is not without limitations. OBSERVATIONS The authors describe a case of premature spinal autofusion before growing rod removal and termination of rod distraction. LESSONS This case highlights the limitations of MCGR systems, including length of use, body habitus restrictions, and risk of autofusion.

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Paper #20 Health-Related Quality of Life in Early-Onset Scoliosis Patients Treated Surgically: EOSQ Scores in Traditional Growing Rod vs. Magnetically-Controlled Growing Rods

Spine Deformity ◽

10.1016/j.jspd.2016.09.025 ◽

2016 ◽

Vol 4 (6) ◽

pp. 455

Author(s):

Muharrem Yazici ◽

H. Gokhan Demirkiran ◽

Z. Deniz Olgun ◽

Gizem Irem Kinikli ◽

Senol Bekmez ◽

...

Keyword(s):

Quality Of Life ◽

Early Onset ◽

Early Onset Scoliosis ◽

Health Related Quality ◽

Growing Rods ◽

Growing Rod ◽

Related Quality ◽

Health Related ◽

Magnetically Controlled Growing Rods

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Current status of the magnetically controlled growing rod in treatment of early-onset scoliosis: What we know after a decade of experience

Journal of Orthopaedic Surgery ◽

10.1177/2309499019886945 ◽

2019 ◽

Vol 27 (3) ◽

pp. 230949901988694 ◽

Cited By ~ 1

Author(s):

Jason Pui Yin Cheung ◽

Kenneth MC Cheung

Keyword(s):

Early Onset ◽

Skeletal Maturity ◽

Clinical Effectiveness ◽

Early Onset Scoliosis ◽

Current Status ◽

Wound Complications ◽

Growing Rods ◽

Growing Rod ◽

Magnetically Controlled Growing Rod

The magnetically controlled growing rod (MCGR) has had approximately 10 years of clinical experience worldwide. Clinical effectiveness to control early-onset scoliosis is consistent even at final surgery. MCGRs have significantly lower relative percentage of infection or wound complications as compared to traditional growing rods. Most common complications include foundation failure and failure of distraction. Contouring of the rod especially at the proximal segment while accommodating for the straight actuator remains a difficult task and its failure may lead to proximal junctional kyphosis. Unique complications of MCGR include clunking, temporary diminishing distraction gains, and metallosis. Temporary reductions in distraction gains are observed as the MCGR lengthens but return to normal baseline distraction gains after rod exchange. Lack of standardization for rod configuration, distraction strategies and decisions of whether to keep the rods in situ, remove without fusion surgery or to perform spinal fusion at skeletal maturity will require further study.

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Mean 6-Year Follow-up of Magnetically Controlled Growing Rod Patients With Early Onset Scoliosis: A Glimpse of What Happens to Graduates

Neurosurgery ◽

10.1093/neuros/nyy270 ◽

2018 ◽

Vol 84 (5) ◽

pp. 1112-1123 ◽

Cited By ~ 22

Author(s):

Jason Pui Yin Cheung ◽

Karen Yiu ◽

Kenny Kwan ◽

Kenneth M C Cheung

Keyword(s):

Cobb Angle ◽

Early Onset ◽

Skeletal Maturity ◽

Reoperation Rate ◽

Early Onset Scoliosis ◽

Growing Rods ◽

Initial Implantation ◽

Magnetically Controlled Growing Rods ◽

Magnetically Controlled Growing Rod

AbstractBACKGROUNDThere is no agreement on frequency of distractions of magnetically controlled growing rods (MCGRs) but more frequent and smaller amounts of distractions mimic physiological spine growth. The mid- to long-term follow-up and management at skeletal maturity is unknown.OBJECTIVETo analyze patients with mean 6 yr of follow-up and describe the fate of MCGR graduates.METHODSEarly onset scoliosis (EOS) patients treated with MCGRs with minimum 4 yr of follow-up and/or at graduation were studied. Parameters under study included Cobb angle, spine and instrumented lengths, and rod distraction gains. Relationship between timing of rod exchanges with changes in rate of lengthening was studied.RESULTSTen EOS patients with mean 6.1 yr of follow-up were studied. The greatest Cobb angle correction occurred at the initial implantation surgery and was stable thereafter. Consistent gains in T1-12, T1-S1, and instrumented segment were observed. Rate of lengthening reduced after the first year of use but improved back to initial rates after rod exchange. Seven of the ten patients experienced complications with reoperation rate of 40% for rod distraction failure and proximal foundation problems. Only mild further improvements in all radiological parameters were observed pre- and postfinal surgery. No clinically significant curve progression was observed for rod removal only. All postfinal surgery parameters remained similar at postoperative 2 yr.CONCLUSIONThis study provides an outlook of the end of MCGR treatment. Although this is a fusionless procedure, instrumented segments do experience stiffness limiting further correction and length gain during final surgery whether fusion or rod removal is performed.

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Systematic investigation of metallosis associated with magnetically controlled growing rod implantation for early-onset scoliosis

The Bone & Joint Journal ◽

10.1302/0301-620x.102b10.bjj-2020-0842.r1 ◽

2020 ◽

Vol 102-B (10) ◽

pp. 1375-1383

Author(s):

Teng Zhang ◽

K. Y. Sze ◽

Z. W. Peng ◽

Kenneth M. C. Cheung ◽

Y. F. Lui ◽

...

Keyword(s):

Early Onset ◽

Systematic Investigation ◽

Early Onset Scoliosis ◽

Metal Contact ◽

Tissue Samples ◽

Growing Rods ◽

Control Tissue ◽

Metal On Metal ◽

Magnetically Controlled Growing Rods ◽

Magnetically Controlled Growing Rod

Aims To investigate metallosis in patients with magnetically controlled growing rods (MCGRs) and characterize the metal particle profile of the tissues surrounding the rod. Methods This was a prospective observational study of patients with early onset scoliosis (EOS) treated with MCGRs and undergoing rod exchange who were consecutively recruited between February 2019 and January 2020. Ten patients were recruited (mean age 12 years (SD 1.3); 2 M:8 F). The configurations of the MCGR were studied to reveal the distraction mechanisms, with crucial rod parts being the distractable piston rod and the magnetically driven rotor inside the barrel of the MCGR. Metal-on-metal contact in the form of ring-like wear marks on the piston was found on the distracted portion of the piston immediately outside the barrel opening (BO) through which the piston rod distracts. Biopsies of paraspinal muscles and control tissue samples were taken over and away from the wear marks, respectively. Spectral analyses of the rod alloy and biopsies were performed to reveal the metal constituents and concentrations. Histological analyses of the biopsies were performed with haematoxylin and eosin staining. Results Titanium (Ti), vanadium (V), and neodymium (Nd) concentrations in the biopsies taken near the wear marks were found to be significantly higher than those in the control tissue samples. Significantly increased Nd concentrations were also found in the tissues near the barrel of the MCGR. Chronic inflammation was revealed by the histological studies with fibrosis and macrophage infiltration. Black particles were present within the macrophages in the fibrotic tissues. Conclusion Ti and V were generated mainly at the BO due to metal-on-metal contact, whereas the Nd from the rotor of the MCGR is likely released from the BO during distraction sessions. Phagocytotic immune cells with black particles inside raise concern regarding the long-term implications of metallosis. Cite this article: Bone Joint J 2020;102-B(10):1375–1383.

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Management and results of early-onset scoliosis with dual magnetically controlled growing rods: Additional preliminary results of spinal fusion surgery

Joint Diseases and Related Surgery ◽

10.52312/jdrs.2021.49 ◽

2021 ◽

Vol 32 (2) ◽

pp. 478-488

Author(s):

Ömer Faruk Kılıçaslan ◽

Mehmet Ali Tokgöz ◽

Şevket Bütün ◽

Vugar Nabi ◽

Serdar Akalın

Keyword(s):

Spinal Fusion ◽

Early Onset ◽

Early Onset Scoliosis ◽

Fusion Surgery ◽

Growing Rods ◽

Spinal Fusion Surgery ◽

Length Increase ◽

The Mean ◽

Magnetically Controlled Growing Rods

Objectives: The aim of this study was to evaluate the clinical and radiographic outcomes and complications of dual magnetically controlled growing rods (MCGRs) in the treatment of early-onset scoliosis (EOS) and to investigate the results of patients with definitive spinal fusion following MCGR. Patients and methods: A total of 15 patients (7 males, 8 females; mean age: 8.7±1.7 years; range, 6 to 10 years) with EOS who underwent dual MCGR and were prospectively followed between February 2013 and March 2019 were included in this retrospective study. The Cobb angle, thoracic kyphosis, and the length of the spine between T1-T12 and T1-S1 were measured on preoperative, postoperative, and follow-up radiographs. The 24-Item Early-Onset Scoliosis Questionnaire (EOSQ-24) was used to assess the functional outcomes before and after the operation. All complications during the treatment were recorded. Results: The mean follow-up was 27.8±10.4 (range, 12 to 60) months. The mean curve correction immediately after the index surgery and latest follow-up was 47.6% and 42.4%, respectively (p>0.05). At the last follow-up, there were no significant changes in mean Cobb and kyphosis angles. The mean T1-T12 length increase was 26.2±7.1 (range, 16 to 40) mm, while the mean T1-S1 length increase was 43.3±15.0 (range, 24 to 70) mm. Complications developed in four (26.6%) of 15 patients. Definitive spinal fusion surgery was performed in seven patients. Total mean Cobb angle difference between the final follow-up and fusion surgery was 9.3° (p=0.016) and kyphosis angle difference was -2.1° (p=0.349). After fusion surgery, total lengthening in T1-T12 and T1-S1 distance was 10.5 mm (p=0.036) and 15.0 mm (p=0.022), respectively. A significant increase in all subdomain scores of the EOSQ-24 (p<0.05), except for financial impact, was recorded in all patients. Conclusion: Dual MCGR technique is an effective, reliable, and robust treatment alternative for primary EOS. However, surgeons should be aware of the relatively high rate of complications. In addition, residual deformity can be corrected successfully with definitive surgery.

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