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Does the external remote controller’s reading correspond to the actual lengthening in magnetic-controlled growing rods?

Teoh, Kar Hao, Moideen, Abdul Nazeer, Mukherjee, Kausik, Kamath, Sridhar, James, Stuart H., Jones, Alwyn, Howes, John, Davies, Paul R. and Ahuja, Sashin 2020. Does the external remote controller’s reading correspond to the actual lengthening in magnetic-controlled growing rods? European Spine Journal 29 (4) , pp. 779-785. 10.1007/s00586-020-06335-5

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Purpose Magnetic-controlled growing rods (MCGRs) are now routinely used in many centres to treat early-onset scoliosis (EOS). MCGR lengthening is done non-invasively by the external remote controller (ERC). Our experience suggests that there may be a discrepancy between the reported rod lengthening on the ERC and the actual rod lengthening. The aim of this study was to investigate this discrepancy. Methods This was a prospective series. Eleven patients who were already undergoing treatment for EOS using MCGRs were included in this study. Results One hundred and ninety-two sets of ultrasound readings were obtained (96 episodes of rod lengthening on dual-rod constructs) and compared to their ERC readings. Only 15/192 (7.8%) readings were accurate; 27 readings (14.9%) were false positive; and 8 readings (4.2%) were an underestimation while 142 readings (74.0%) were an overestimation by the ERC. Average over-reporting by the ERC was 5.31 times of the actual/ultrasound reading. When comparing interval radiographs with lengthening obtained on ultrasound, there was a discrepancy with an average overestimation of 1.35 times with ultrasound in our series. There was a significant difference between ERC and USS (p = 0.01) and ERC and XR (p = 0.001). However, there was no significant difference between USS and XR (p > 0.99). Conclusion The reading on the ERC does not equate to the actual rod lengthening. The authors would recommend that clinicians using the MCGR for the treatment of early-onset scoliosis include pre- and post-extension imaging (radiographs or ultrasound) to confirm extension lengths at each outpatient extension. In centres with ultrasound facilities, we would suggest that patients should have ultrasound to monitor each lengthening after distraction but also 6-month radiographs.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Medicine
Publisher: Springer Verlag (Germany)
ISSN: 0940-6719
Date of First Compliant Deposit: 14 May 2021
Date of Acceptance: 29 January 2020
Last Modified: 16 Mar 2024 02:07

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