Reducing radiation exposure in early-onset scoliosis surgery patients: novel use of ultrasonography to measure lengthening in magnetically-controlled growing rods

Stokes, Oliver M.; O'Donovan, E; Samartzis, Dino; Bow, Cora; Luk, Keith Dip Kei; Cheung, Kenneth M.C.

doi:10.1016/j.spinee.2014.01.039

Cited by 52 publications

(42 citation statements)

References 36 publications

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“…A recent clinical study suggests that patients previously treated with the traditional growing rods can be converted to MCGRs with comparable positive results [12]. Clinical cases reporting pin fracture and failure to distract have been published over the last 2 years [11][12][13][14][15]; this is the first retrieval paper using state-of-the-art forensic analysis to determine the mechanism leading to pin fracture. We examined nine retrieved MCGRs and found that a third of them had a fractured pin.…”

Section: Discussionmentioning

confidence: 99%

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Analysing a mechanism of failure in retrieved magnetically controlled spinal rods

et al. 2017

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Purpose We aim to describe a mechanism of failure in magnetically controlled growth rods which are used for the correction of the early onset scoliosis. Methods This retrieval study involved nine magnetically controlled growth rods, of a single design, revised from five patients for metal staining, progression of scoliosis, swelling, fractured actuator pin, and final fusion. All the retrieved rods were radiographed and assessed macroscopically and microscopically for material loss. Two implants were further analysed using micro-CT scanning and then sectioned to allow examination of the internal mechanism. No funding was obtained to analyse these implants. There were no potential conflicts interests. Results Plain radiographs revealed that three out of nine retrieved rods had a fractured pin. All had evidence of surface degradation on the extendable telescopic rod. There was considerable corrosion along the internal mechanism. Conclusions We found that a third of the retrieved magnetically controlled growth rods had failed due to pin fracture secondary to corrosion of the internal mechanism. We recommend that surgeons consider that any inability of magnetically controlled growth rods to distract may be due to corrosive debris building up inside the mechanism, thereby preventing normal function.

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Section: Discussionmentioning

confidence: 99%

“…The lengthening procedure lasts approximately 40 s per rod and the total length is measured using a plain radiograph [8]. Recent studies have also investigated the reliability of other imaging modalities, including ultrasound [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Analysing a mechanism of failure in retrieved magnetically controlled spinal rods

et al. 2017

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“…However, loosening of anchor points, ploughing of screws or rod fractures can only be detected on radiographs. Recently published results showing equivalent measurements with ultrasound and radiographs [27,28]. In our institution we have gained ample experience with ultrasound but have not established it as a routine to substitute radiography.…”

Section: Discussionmentioning

confidence: 99%

A Minimum of Two Years Results of Magnetically Controlled Growing Rods for Early Onset Scoliosis

Burstein¹,

Rupprecht²,

Kunkel³

et al. 2017

J Spine

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Objectives: To determine mid-term results and complications of a single center on magnetically controlled growing rod (MCGR) technique in Early Onset Scoliosis (EOS). Recently a number of preliminary reports about safety and effectiveness of MCGR have been published. We present a minimum of two years follow up of the MCGR treatment. All patients were treated in one center with the same protocol.Methods: 22 patients with EOS of different etiologies underwent primary surgical treatment with MCGR in double rod technique. There were 15 female and 7 male patients. Average age at surgery was 8.8 (range 4.6-14.3). Mean follow-up was 31 (24-46) months. Cobb angle changes, T1-T12 and T1-S1 length were calculated. Results were analyzed to measure correction of spinal deformity and gain in spinal length. Results:The mean preoperative curve measured 61° (40-96) and improved to 28° (11-53) (p<0.001) after surgery. At follow-up the Cobb angle was further reduced to 26° (11-64) (p=0.54). The T1-T12-as well as the T1-S1-length increased significantly (p<0.001). The average preoperative thoracic kyphosis decreased from 44° (-32-86) to 28° (9-50) after surgery, respectively to 35° (8-62) at time of FU. Four patients developed a junctional kyphosis. Three of them had to be revised. One patient developed a lumbar "adding on", one patient a deep wound infection and in another patient a screw pullout occurred that all required revision. Conclusion:The study supports that the MCGR is an efficient and safe technique to treat EOS. Morbidity and complications are less than treatment with conventional GR´s. After 2 years transcutaneous lengthening is still possible without loss of correction and autofusion has not yet been detected.

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“…This concern was addressed by using outpatient ultrasound to document distraction. [15] More widespread adoption of MCGRs has now led to clinical scenarios where magnetic resonance imaging (MRI) would be a useful investigation in patients who have MCGRs implanted such as patients with known conditions including neurofibromatosis where neural symptoms subsequently occur. Indeed there have been circumstances where MCGRs have not been implanted due to concerns over safety of future MRI.…”

Section: Introductionmentioning

confidence: 99%

“…[16] MCGRs contain a rare earth magnet, therefore the manufacturer advises that the device is not compatible with MRI. [15] Theoretical concerns include: deactivation of the MCGR magnet preventing subsequent lengthening, lengthening, shortening or dislodgement of the device due to the torque resulting from the internal ferromagnetic material when a patient moves within the MRI magnetic field, or excessive heating due to eddy currents generated by the radiofrequency fields associated with MRI, leading to tissue damage. The implications of these potential effects range from the need to exchange the implant, with significant associated costs, to actual harm to the patient, which could include neural damage.…”

Section: Introductionmentioning

confidence: 99%

Safety and compatibility of magnetic-controlled growing rods and magnetic resonance imaging

et al. 2015

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Disclosures: Ellipse Technologies donated the 2 magnetically controlled growing rods that were used in this study.OMS has previously received travel grants from Ellipse Technologies to support attendance at academic spinal meetings. OMS has previously received an honorarium from Ellipse Technologies for preparing and delivering a symposium at an academic spinal meeting. None of these disclosures relates to this study.The authors have no other financial or competing interests to disclose in relation to this work. Purpose:Magnetically controlled growth rods (MCGRs) are a new technology for the management of early-onset paediatric deformity enabling guided spinal growth by controlling the curvature. These rods contain a rare-earth magnet and are contraindicated for MRI. We have investigated the behavior MCGRs to determine whether MRI adversely affects rod properties and to determine the extent of image distortion. Methods:This is an in-vitro experiment using two magnetic growth rods secured in a 1.5 T MRI. A gradient echo sequence MRI was performed to evaluate whether the rods elongated, contracted or rotated during scanning and a phantom model was used to evaluate the amount of artifact induced.Results:The rod was not activated or subsequently impaired by the process of MRI. Image distortion of 28.9 cm was seen with the phantom model measured from the magnet housing. Conclusions:This study has demonstrated that there are no detrimental effects of MRI on the MCGR and imaging of the head and neck phantom can still be interpreted. Further in-vivo study is warranted.

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Reducing radiation exposure in early-onset scoliosis surgery patients: novel use of ultrasonography to measure lengthening in magnetically-controlled growing rods

Cited by 52 publications

References 36 publications

Analysing a mechanism of failure in retrieved magnetically controlled spinal rods

Analysing a mechanism of failure in retrieved magnetically controlled spinal rods

A Minimum of Two Years Results of Magnetically Controlled Growing Rods for Early Onset Scoliosis

Safety and compatibility of magnetic-controlled growing rods and magnetic resonance imaging

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