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

Cheung, Jason Pui Yin; Yiu, Karen; Kwan, Kenny; Cheung, Kenneth M.C.

doi:10.1093/neuros/nyy270

Cited by 65 publications

(67 citation statements)

References 32 publications

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“…Out of all the planned revisions, 4 rods (rod 10,11,19,20) were found with structural damages. Although previous studies have suggested that 'clunking' or 'stalling' may occur during rod distractions due to the failure of internal mechanism [23], the clinical records of these rods did not show any evidence of structural damages in distraction clinics prior to the planned revisions.…”

Section: Discussionmentioning

confidence: 99%

Mechanical wear analysis helps understand a mechanism of failure in retrieved magnetically controlled growing rods: a retrieval study

Wei

Hothi

Morganti

et al. 2020

BMC Musculoskelet Disord

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Background: To assess the relationship between mechanical wear and the failure of the internal lengthening mechanism in retrieved MAGnetic Expansion Control (MAGEC) growing rods. Methods: This study included 34 MAGEC rods retrieved from 20 patients. The state of the internal mechanism and mechanical wear were assessed in all the rods using plain radiographs and visual inspection. Metrology was then performed to assess the topography and mechanical wear of the telescopic bars, using a Talyrond 365 (Taylor Hobson, Leicester, UK) roundness measuring machine. Results: Plain radiographs showed evidence of a broken internal mechanism in 29% of retrieved rods. Single-side wear marks were found in 97% of retrieved rods. Material loss was found to significantly increase in rods with a damaged internal mechanism (p < 0.05) and rods with longer time in situ (r = 0.692, p < 0.05). Conclusions: We found an association between damage to the internal mechanism of the rods and (1) patterns of single-side longitudinal wear marks and (2) increased material loss. As the material loss was also found to increase over time of rod in situ, we emphasise the importance of early detection and revision of failed MAGEC rods in clinical practice.

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Section: Discussionmentioning

confidence: 99%

Mechanical wear analysis helps understand a mechanism of failure in retrieved magnetically controlled growing rods: a retrieval study

Wei

Hothi

Morganti

et al. 2020

BMC Musculoskelet Disord

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“…7 The MCGR is lengthened via an external magnet thereby allowing outpatient awake distraction with continuous neurological monitoring. Consistent spinal lengthening and control of the spinal deformity is achievable [7][8][9][10][11][12][13][14] and with its capacity for gradual correction, its indications have been extended to safe gradual correction of severe deformities. 15,16 With more frequent distractions, increased radiation exposure can be avoided with ultrasound.…”

Section: Introductionmentioning

confidence: 99%

“Law of Temporary Diminishing Distraction Gains”: The Phenomenon of Temporary Diminished Distraction Lengths With Magnetically Controlled Growing Rods That Is Reverted With Rod Exchange

Cheung

Bow

Cheung

2020

Global Spine Journal

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Study Design: Prospective study. Objectives: To study the increasing divergence between targeted and achieved distractions observed with magnetically controlled growing rod (MCGR)lengthening, and the relationship of this reduced rate of achieved lengthening with remaining rod length. Methods: Patients with early onset scoliosis (EOS) who underwent MCGRs with minimum 2-year follow-up were consecutively enrolled. Targeted and achieved lengths were compared. Correlation between percentage of lengthening achieved from targeted length was identified with the timing of rod exchanges. Results: A total of 20 patients fulfilled the inclusion criteria. The mean age at index surgery was 9.5 years and mean postoperative follow-up was 68 ± 28 months. Of these, 8 patients had at least one rod exchange that occurred at 23 ± 4 months. A decrease in rate of achieved lengthening was observed when compared with targeted distractions. The achieved lengthening drops from 86% of targeted length at the first distraction to only 58.8% at the 21st distraction episode for the first set of rods. After rod exchange, the average achieved lengthening went back up to 81.3% of the targeted length but subsequently had a gradual reduction to 35% at the 19th distraction episode. Conclusions: We propose a “law of temporary diminishing distraction gains” that MCGR users should be aware of when monitoring rod lengthening. Diminishing distraction length gains is observed as the rod is lengthened and is a phenomenon independent of patient factors. It is only temporary as the rates of achieved lengthening returns to baseline after rod exchange.

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“…Essentially, any type of scoliosis is amenable to MCGR treatment with consistent length gains especially with primary surgery. 28 This has also been shown in congenital scoliosis 23,28,29 and fixation to the pelvis, 30 whereby distraction gains are similar to that found in idiopathic or syndromic patients. However, Keskinen et al 31 have shown that conversion cases do not fare as well in terms of growth gains.…”

Section: Case Selectionmentioning

confidence: 65%

“…Hence, the prevalence of PJK is high with up to 30% in some reports but not all require reoperation (approximately 15%). 28,[41][42][43][44] In general, the proximal levels of T1 or T2 should be avoided if possible as more cranial levels may be needed in the final fusion surgery to address the PJK. Conversion to rib anchors may help prevent these complications and has been well-established in TGR surgery.…”

Section: Anchorsmentioning

confidence: 99%

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

Cheung

2019

J Orthop Surg (Hong Kong)

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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

Abstract: This 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.

Cited by 65 publications

References 32 publications

Mechanical wear analysis helps understand a mechanism of failure in retrieved magnetically controlled growing rods: a retrieval study

Mechanical wear analysis helps understand a mechanism of failure in retrieved magnetically controlled growing rods: a retrieval study

“Law of Temporary Diminishing Distraction Gains”: The Phenomenon of Temporary Diminished Distraction Lengths With Magnetically Controlled Growing Rods That Is Reverted With Rod Exchange

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

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