Magnetically Controlled Growing Rods Research Articles

Minimally Invasive Controlled Growing Rods for the Surgical Treatment of Early-Onset Scoliosis—A Surgical Technique Video

Background: Spinal deformities in children and adolescents can be easily divided into those occurring and diagnosed before the age of 10—early-onset scoliosis—and those occurring and diagnosed after the age of 10—late-onset scoliosis. When the curvature continues to progress and exceeds a Cobb angle of more than 60–65 degrees, surgical treatment should be considered. The most common treatment procedure for EOS is the surgical correction of the deformity using standard growing rods (SGRs), and in the case of congenital defects with additional hemivertebrae, it is the resection of the hemivertebra and short fusion. Minimally invasive controlled growing rods (MICGRs) need to be distracted every 6–9 months through a minimally invasive approach that involves sedation and neuromonitoring to obtain the best possible correction while minimizing complications. The aim of our study is to present a less-invasive surgical technique for MICGR implantation based on a two-case presentation—early-onset idiopathic scoliosis and congenital kyphosis. The surgical technique is the less-invasive percutaneous and subfascial implantation of MICGRs without long incisions in the back. Conclusions: The use of MICGRs is an alternative and safe surgical technique for patients undergoing surgical treatment for EOS. Without the risk of metallosis, like in other implant systems, and the need for replacement after 2 years of use, like in using magnetically controlled growing rods (MCGRs), the MICGR system can be used as a less-invasive procedure, allowing for the avoidance of many periodic invasive procedures in children with a wider opening of the spine (like in using standard growing rods), minimizing the number of planned hospitalizations, reducing the length of hospital stays, and reducing the physical and mental burdens on young patients, parents, and families.

Spinal height for growth guidance treatment in early onset idiopathic scoliosis: analysis through final surgical treatment.

The growth guidance (GG) method for treatment of early onset scoliosis has as its primary goal the restoration of apical spinal alignment, facilitating normal spinal growth to achieve a suitable adult thoracic height. To evaluate whether GG surgical treatment achieves comparable thoracic and spinal height to distraction-based treatment (DBT) in idiopathic early onset scoliosis (I-EOS) patients. We hypothesized that GG would prove superior to DBT at the time of definitive fusion surgery. All I-EOS patients who underwent GG at a single center were reviewed. T1-L1 and T1-S1 heights were measured using the traditional coronal method as well as the Halifax sagittal spinal length (SSL) technique. The same measurements were obtained from a comparable control group obtained from a multi-center pediatric early onset scoliosis database who underwent treatment with traditional growing rods (TGR) or magnetically controlled growing rods (MCGR). Of the I-EOS patients who underwent GG 2004-2019, 15 patients underwent final fusion after GG completion, with a mean 5.5years of GG treatment prior to fusion (range 2.0-11.4years). Mean age at GG implantation was 8.4years (range 2.0-11.7years); 7 were male and 8 female. GG patients experienced a mean coronal thoracic height increase of 6.2cm during treatment through final fusion, and a mean coronal spinal height increase of 8.8cm. At the time of final fusion, GG patients achieved greater significant mean increases than DBT patients by 2.9cm in coronal thoracic height (p = 0.0023), 4.5cm in coronal spinal height (p = 0.001), and 4.0cm in SSL spinal height (p = 0.01). No GG patient concluded treatment with a thoracic height less than 18cm in either coronal or sagittal plane. Not only did 100% of GG patients reach minimum thoracic height of 18cm at time of final fusion, but GG also proved to be superior to distraction-based constructs in a comparison cohort on 3 of 4 spinal elongation measures. 3.

Autofusion in early-onset scoliosis growing constructs: occurrence, risk factors, and impacts.

Autofusion (AF) during growing rod (GR) instrumentation for early-onset scoliosis (EOS) has been reported, but AF incidence, causation, and clinical implications remain unknown. This article aims to (1) quantify frequency and severity of AF, (2) determine risk factors for AF, and (3) assess the influence of AF on final curve correction and spinal lengthening. EOS patients were prospectively enrolled (2016-2021). Patients underwent evaluation, GR implantation, lengthenings, and posterior spinal fusion (PSF). Cobb angle and spinal length measurements were collected. AF was assessed and graded, with grades I-II being low-grade and III-V being high-grade. Exposure analysis quantified risk factors' impact via odds ratios and Pearson regression correlates. Statistical significance was p ≤ 0.05 or ≥ 0.95. 28 patients, with variable EOS diagnoses, were included. On average, GR were implanted at 8.54-year-old and lengthened over 4.66years. 53.6% of patients received magnetically controlled GR (MCGR) and 46.4% traditional GR (TGR). The average construct bridged 13.4 levels. Over the lengthening period, for all indications, patients averaged 2.9 total open procedures. Curves corrected from 68.5º preoperatively to 35.3º after index GR to 35.6º after PSF. Spinal length increased from 30.0cm preoperatively to 33.9cm after index GR to 39.5cm after PSF. AF grading was: 28.6% Grade I, 25.0% Grade II, 17.9% Grade III, 25.0% Grade IV, and 3.6% Grade V. Idiopathic EOS tended to have lower AF grades (p = 0.37). AF risk factors included GR age < 8 (10.4×, p = 0.01), any interval open procedures (6.3×, p = 0.05), and residual curve > 30º after index GR (13.7×, p = 0.02). Protective factors included preoperative spinal length of > 30.0cm (0.11×,p = 0.01) and index MCGR (0.16×, p = 0.03). Maintenance of Cobb angles from index GR through PSF was relatively better in low-grade patients (p = 0.08). Spinal length gained was no different between low- and high-grade AF (p = 0.50). This largest-to-date evaluation found AF is nearly ubiquitous in GR constructs, but with variable severity. Both risk factors and protective factors coincide with AF. Ultimately, even in high-grade AF, curve correction was maintained, and spinal lengthening was achieved. Level II-prospective cohort study.

Radiological Outcomes of Magnetically Controlled Growing Rods for the Treatment of Children with Various Etiologies of Early-Onset Scoliosis-A Multicenter Study.

Background: The management of spinal deformities diagnosed before the age of 10 is critical due to the child's development, skeletal system, and growth mechanism. Magnetically controlled growing rods (MCGRs) are a surgical treatment option for the growing spine. The aim of this study was to analyze the radiological findings of patients treated with MCGRs for early-onset scoliosis (EOS) of various etiologies. We hypothesized that the MCGRs could provide acceptable long-term radiographic results, such as an increase in the T1-T12 and T1-S1 height and significant overall deformity correction. Methods: We retrospectively reviewed 161 EOS patients with a combined total of 302 MCGRs inserted at five institutions between 2016 and 2022 with a mean follow-up of at least two years. The Cobb angle of the major curve (MC), thoracic kyphosis (TK), lumbar lordosis (LL), and T1-T12 and T1-S1 height measurements were assessed before, after, and during the follow-up. Results: Among the 90 female and 71 male patients, there were 51 neurological, 42 syndromic, 58 idiopathic, and ten congenital scoliosis etiologies. Of the patients, 73 were aged under six years old. The mean follow-up time was 32.8 months. The mean age at placement of the MCGRs was 7 years and that at the last follow-up after fusion surgery was 14.5 years. The mean MC before the initial surgery was 86.2°; following rod implantation, it was 46.9°, and at the last follow-up visit, it was 45.8°. The mean correction rate among the etiology subgroups was from 43% to 50% at follow-up. The mean TK was noted as 47.2° before MCGR implantation, 47.1° after MCGR placement, and 44.5° at the last follow-up visit. The mean T1-T12 height increased by 5.95 mm per year, with a mean T1-S1 height of 10.1 mm per year. Conclusions: MCGR treatment allowed for an average correction of the curvature by 50% during the period of lengthening, while controlling any deformity and growth of the spine, with a significant increase in the T1-T12 and T1-S1 values during the observation period. MCGR treatment in EOS carries a risk of complications. While congenital and syndromic EOS often have short and less flexible curves in those groups of patients, single rods can be as effective and safe. Definitive fusion results in the mean final coronal correction between the start of MCGR treatment and after undergoing PSF of approximately 70%. The mean T1-T12 spinal height increased by 75 mm, while the T1-S1 spinal height gained a mean of 97 mm.

Is posterior vertebral arthrodesis at the end of the electromagnetic rod lengthening program necessary for all patients? Comparative analysis of sixty six patients who underwent definitive spinal arthrodesis and twenty four patients with in situ lengthening rods.

Magnetically controlled growing rods (MCGR) should be removed or changed at most twoyears after their implantation in the treatment of patients with early-onset scoliosis (EOS) (Safety notice July 2021). However, in the face of patients at high risk of intraoperative complications and relying on the principle of auto-fusion of the spine, some surgeons would prefer a more wait-and-see attitude. The aim of this study was to report on patients who did not undergo final fusion at the end of the lengthening program with MCGR and to compare them with those who did. This was a multicenter study with ten centres. We collected all graduate patients with EOS who had received MCGR between 2011 and 2022. A total of 66 patients had final fusion at the end of the lengthening program and 24 patients kept MCGRs in situ. The mean total follow-up time was 66months (range, 25.3-109), and the mean follow-up time after final lengthening was 24.9months (range, 3-67.7). Regarding the main curve and thoracic height, there was no significant difference in the percentage of correction over the whole follow-up between the two groups (p = 0.099, p = 0.176) although there was a significant difference between the end of lengthening and the last follow-up (p < 0.001). After completion of the lengthening program, 18 patients who had final fusion developed 24 of the 26 recorded complications (92.3%). Contrary to the manufacturer's published safety notice, not all patients systematically benefited from the removal of the MCGRs. Although arthrodesis significantly improved the scoliotic deformity, no significant difference was found in terms of radiographic outcome between patients who underwent spinal fusion and those who kept the MCGRs in situ.

Patients treated by magnetic growing rods for early-onset scoliosis reach the expected average growth.

Magnetic controlled growing rods (MCGRs)areone of the most common proceduresto treatearly-onset scoliosis(EOS). One of the major concerns is that patients treated with MGCR do not reach an adequateheight with MGCR.The present study has one of the largest samplesizesof EOS patients treated by MGCR.This study aimsto demonstrate theefficacy of the treatmentwith MGCR in EOS patients,comparing our resultswiththeestimatedgrowth. Patients were consecutively enrolled from July 2011 to July 2022.The same surgical equipe performed all the procedures. The mean length of the patients was assessed by X-ray (T2-T12 andT2-S1distance) by a team of expert radiologists.The estimated growth by Dimegliowas compared with themean elongation obtained by year. 65 patients were included.16 patients underwent final surgery.In group 1,patients reached agrowthof 3.6 ± 8.7mm(T2-T12) and 9.6 ± 27.6mm(T2-S1).In group 2,patientsgrew5.4 ± 5.7mm(T2-T12) and 9 ± 9mm(T2-S1).81% of the estimated elongation during the treatment was obtained during the first surgery. The difference betweenDimeglio'sestimated growthand thevalueobtained by MGCR was-4.3 ± 8.7mm(T2-T12) and -12.3 ± 12.2mm(T2-S1)in group 1 (p < 0.001) and -1.1 ± 4.2mm(T2-T12) and -6.6 ± 6.0mm(T2-S1) in group2(p = 0.001). MGCR patients reached andoverlappedthe growth target according to the score by Dimeglio. However, the value of growth tended to reduceoverthe years. Lastly,obtainingthe most significant elongation possible at the first surgeryis mandatory,comprising81% of the total value.

Health-related quality of life and clinical outcomes for magnetically controlled growing rod patients after treatment termination.

To determine the health-related quality of life (HRQoL) and clinical outcomes of children with early onset scoliosis (EOS) treated with magnetically controlled growing rods (MCGR) followed to definitive fusion (DF). A retrospective review of EOS patients treated with MCGR and followed to DF was performed. Outcomes included HRQoL scores, radiographic, clinical, and unplanned returns to the operating room (UPROR) data collected at pre-MCGR implantation, immediately post-MCGR implantation, pre-DF, and post-DF. HRQoL scores were collected at least 6months post-DF. Twenty-eight patients (57.1% females, mean age at MCGR insertion 7.19 ± 1.5years, mean pre-MCGR Cobb 64.7° ± 17.6) met inclusion criteria. MCGR treatment resulted in an overall 30.2% improvement in coronal plane deformity following DF. The mean growth rates between MCGR implantation and pre-DF for T1-T12 height and T1-S1 length were 0.33 ± 0.23mm/month and 0.49 ± 0.28mm/month, respectively. Of the 28 included patients, 26 (92.9%) experienced at least one UPROR, with a total of 52 surgical complications occurring in the total cohort, representing 1.9 UPROR/patient. Interestingly, there was a decline in scores reported between post-MCGR implantation and the pre-DF time-point (N = 16, 78.2 ± 14.9 vs 69.7 ± 17.8, p = 0.02). These scores recovered post-DF, resulting in an overall unchanged HRQoL when comparing pre-MCGR to post-DF (N = 11, 79.9 ± 15.1 vs 76.7 ± 17.9, p = 0.44). While MCGR treatment achieves coronal plane deformity control and facilitates spinal growth, only 7.1% of children experienced a complication-free treatment course when followed to definitive fusion. Patients achieved modest curve correction and spinal growth, while maintaining stable HRQoL outcomes between pre-MCGR and post-DF.

Failure to lengthen consensus for the magnetically controlled growing rod (MCGR).

MCGR lengthening has become an important innovation in treating patients with EOS. An alternative to traditional growing instrumentation, a single surgical procedure is necessary for insertion of the construct, followed by non-invasive lengthening in the outpatient setting. With every new technology emanates a new complication to troubleshoot. Failure to lengthen in the MCGR is a significant cause of revision surgery. Currently, no consensus exists on how to define a MCGR lengthening failure, what steps are necessary after a failure to lengthen, and what factors determine these next steps. The primary goal of this study was to establish a consensus on how to define and navigate a MCGR that fails to lengthen. A series of 3 surveys were distributed to 49 early onset scoliosis surgeons with 37 responses between December 2021 and April 2022. Consensus was defined as at least 70% agreement. 37 of 49 surgeons (75%) responded to the first survey, and all 37 surgeons responded to the following two surveys (100%). Consensus statements were reached on 25% of questions (3/12) from survey 1, 40% of questions (4/10) on survey 2, and 100% of questions (5/5) on survey 3. The questions that reached consensus are detailed in Table 1. Consensus steps to navigate a rod that fails to lengthen 1mm (97%) in the office include retrying during the same visit (78%), changing technique in the office (88%), and not adjusting the interval between lengthening appointments (78%). Table 1 Items that reached consensus from each survey (12 total) Survey Question Response, Consensus Percentage 1 If a rod does not lengthen, do you try again in that office visit?​ Yes, 78% 1 All modes of XR are equivalent when determining failure to lengthen? Yes, 70% 1 If you are unsuccessful at lengthening, you should change the lengthening interval? No, 78% 2 Re-lengthening a rod following a failure to lengthen one should change their technique? Yes, 88% Reposition patient, 100% Alternate rods, 90% No traction in OR, 92.6% 2 Is a MCGR non-operational following 3 consecutive visits where the rod failed lengthening? Yes, 100% 2 Considerations when determining next steps with a non-operational rod? Skeletal Age, 100% Curve Progression, 97% Curve Stiffness, 93.8% Family Convenience, 83% Chronologic Age, 77% Time from Last Lengthening, 70% 2 Can an APP follow your protocol for a rod that has failed to lengthen? Yes, 81% 3 Are you comfortable using either clunk or stall to describe the phenomena of the internal clutch failing within the actuator when lengthening? Yes, 97.3% 3 Clunk/stall try again before an adjustment? Yes, 81% 3 Define failure to lengthen? Less than 1mm length achieved, 97% 3 After two failure to lengthen events do you discuss next surgical steps?​ Yes, 97% 3 Once a rod had been classified as non-operational (no longer lengthening despite interventions) do you consider the underlying diagnosis when making next step decisions? Yes, 97% CONCLUSION: Best clinical practice guidelines using a Delphi method established a consensus on defining failure to lengthen in a MCGR (less than 1mm), appropriate responses to failure to lengthen (re-attempt to lengthen and re-position patient) and a definition for a non-functional MCGR (failure to lengthen 3 consecutive times). This consensus will help standardize research on this important problem. V-expert opinion.

Safety and efficacy of growth-friendly instrumentation for early-onset scoliosis in patients with spinal muscular atrophy type 1 in the disease-modifying treatment era.

To evaluate the safety of growth-friendly instrumentation for early-onset scoliosis (EOS) in patients with spinal muscular atrophy (SMA) type 1 who received disease-modifying treatment (DMT) and analyze short-term efficacy. Retrospective search was conducted between 2017 and 2023. Patients with genetically confirmed SMA type 1 who were surgically treated for spinal deformity and receiving DMTs (nusinersen, risdiplam, or onasemnogene abeparvovec) were included. SMA types 2 and 3 and patients who do not receive DMTs were excluded. Clinical and radiographic data were collected at preoperative, postoperative, and latest follow-up visits. Twenty-eight patients (mean follow-up: 16 months (range 2-41)) were included. The mean age at surgery was 60 months (range 29-96). Fifteen were treated with dual magnetically controlled growing rods (MCGR), four with unilateral MCGR and a contralateral guided growth system, three with Vertical Expandable Prosthetic Titanium Rib (VEPTR®) implants, five with self-distracting systems, and one with traditional dual growing rods. The mean amount of correction was 57% (44°± 17) for scoliosis and 83% (13°± 11) for pelvic obliquity. The mean T1-12 height gain during surgery was 31 mm (±16 mm), while the mean T1 S1 height gain was 51 mm (±24 mm), and instrumented growth was observed during follow-up. Five patients (18%) developed six serious adverse events: three surgical site infections, two anchor failures, and one rod fracture, and all required unplanned reoperations. No neurologic complication, difficulty during nusinersen injections, or respiratory decline was recorded. We report that spinal deformity in this population can be safely treated with growth-friendly instrumentation, with similar complication rates when compared with SMA type 2.

Serum Titanium Levels Remain Elevated But Urine Titanium is Undetectable in Children With Early Onset Scoliosis Undergoing Growth-Friendly Surgical Treatment: A Prospective Study

Background: Elevated serum titanium levels have been found in patients with early onset scoliosis (EOS) treated with traditional growing rods (TGR), magnetically controlled growing rods (MCGR), and vertical expandable prosthetic titanium rib (VEPTR). No studies have investigated whether serum titanium remains persistently elevated and if titanium is excreted. Our purpose was to compare serum titanium levels in patients with EOS with growth-friendly instrumentation to age-matched controls and evaluate urine titanium and serial serum titanium levels in patients with EOS. Methods: This was a prospective case-control study. Patients with EOS with TGR, MCGR, or VEPTR underwent urine titanium and serial serum titanium collection at a minimum 6-month interval. Control patients did not have a history of metal implant insertion and underwent serum titanium collection before fracture fixation. Results: Twenty patients with EOS (6 TGR, 8 MCGR, and 6 VEPTR) and 12 controls were analyzed. The control group had no detectable serum titanium (0 ng/mL), whereas the patients with EOS had a median serum titanium of 4.0 ng/mL (P &lt; 0.001). Analysis of variance showed significantly higher median serum titanium levels in the MCGR and VEPTR groups than the TGR group at time point 1 (5.5 vs 6.0 vs 2.0 ng/mL, P = 0.01) and time point 2 (6.5 vs 7.5 vs 2.0 ng/mL, P &lt; 0.001). Binary comparisons showed a significant difference in serum titanium level between TGR and MCGR (time point 1: P = 0.026, time point 2: P = 0.011) and TGR and VEPTR (time point 1: P = 0.035, time point 2: P = 0.003). However, there was no difference between MCGR and VEPTR (time point 1: P = 0.399, time point 2: P = 0.492) even though the VEPTR group had a longer duration of follow-up (P = 0.001) and a greater number of lengthenings per patient at the first serum collection (P = 0.016). No patients with EOS had detectable urine titanium. Conclusions: Patients with EOS treated with titanium alloy growth-friendly instrumentation had elevated serum titanium levels compared with age-matched controls that persisted over time with no evidence of renal excretion. Additional studies are necessary to assess for local and systemic accumulation of titanium and the significance of long-term exposure to titanium in growing children. Level of Evidence: Level III, therapeutic.

Magnetically Controlled Growing Rods Graduation: Lessons From a Single-center Series of 48 Patients.

Magnetically controlled growing rod (MCGR) treatment for early-onset scoliosis (EOS) has become a widely utilized method of deformity control, but long-term follow-up reports are sparse. We evaluated the outcomes of a large group of consecutive pediatric patients diagnosed with EOS who were treated by MCGR to the endpoint of definitive spinal fusion in a single center. We hypothesized that lessons learned from treating a large volume of MCGR patients would lower the complication rate in comparison to what was previously reported by other studies. The records of 48 EOS patients with varied etiologies who were treated by MCGR between 2012 and 2022 and reached the end of treatment were analyzed retrospectively for baseline and final radiographic measurements and surgery-related complications. The mean percent of improvement in the major coronal deformity was 51.7±25.0% and the mean T1 to T12 total growth was 52.9±21.9mm. The total complication rate was 22.9% of which 12.5% required a single unplanned surgery, 6.3% required multiple unplanned surgeries, and 4% did not require any unplanned surgery. MCGR treatment provides adequate control of EOS, enabling satisfactory growth of the thoracic spine. The complication rate in a single large volume center is moderate. IV.

Growth-preserving instrumentation for early onset scoliosis

Early onset scoliosis is defined as aspinal deformity originating in the first 10years of life. Growth-preserving spinal instrumentation has therefore been designed to preserve growth of spine and chest wall and lungs to avoid serious pulmonary complications after early spine fusion. Indications, surgical technique and results of the vertical expandable prosthetic titanium rib (VEPTR) technique, traditional growing rods (TGR), and magnetically controlled growing rods (MCGR) will be described. Indications for VEPTR are so-called mixed congenital deformities (type3) associated with vertebral malformations in association with chest wall deformities, especially fused ribs. There are also indications for neuromuscular or syndromic early onset scoliosis with bilateral rib-to-ilium constructs. However, most of those deformities are currently treated with either GR or MCGR in most centers. GR and MCGR are currently the treatment of choice for the majority of early onset scoliosis. There is no indication for growth-preserving strategies if the patients are mature or there is only little growth remaining. In these cases, final fusion should be performed. While the VEPTR technique involves an extensive approach with muscular dissections to the thoracic cage including rib osteotomies and thoracotomies, treatment with TGR or MCGR is minimally invasive, only exposing proximal and distal anchor points, leaving most of the spine including the apex undisturbed. Early mobilization is usually possible after 24-48 h. Braces may have to be prescribed for patients with osteopenia, noncompliance, or arisk to fall. Since 2005, more than 200patients were treated with the VEPTR technique, more than 200 patients with the MCGR technique, and about 30patients with the TGR technique in our department. Complication rates are high with all techniques including the law of diminishing returns, autofusion, bone anchor-related complications like loosening or migration of implants, failure to distract and proximal junctional kyphosis. In our own series of 13patients below age 3years, VEPTR proved to be effective for mixed deformities. In other studies, we were able to show that physiological growth with MCGR can be maintained for 2-3years but spinal growth declines after that period with acceptable complications. Complication rates in most studies are lower with MCGR compared to TGR and VEPTR. Therefore, it is currently the treatment of choice for most early onset scoliosis patients.

The Evaluation of Serum Metal Ion Levels and Metallosis in Graduated Patients With Magnetically Controlled Growing Rods.

Magnetically controlled growing rods (MCGR) aim to control curve progression while limiting surgical burden in children with early-onset scoliosis. Systemic and local distribution of metal debris has been documented in children with spinal implants. The aim of the study was to assess serum metal ion levels and local metal debris-related changes at the conclusion of MCGR treatment. Between February 2019 and September 2022, all patients who had a conversion to definitive fusion at the completion of MCGR treatment in our institution were invited to participate in this study. Consenting patients had serum metal ion levels drawn (titanium, cobalt, and chromium) and histologic analyses of peri-implant tissue samples. We enrolled 24 children who underwent definitive fusion post-MCGR treatment for early-onset scoliosis. The average age at definitive fusion was 13.3 years (range: 11 to 17 y). The average length of MCGR treatment was 4.8 years (range: 1.5 to 6.8 y). At the end of the MCGR treatment, 23 (96%) patients had elevated serum metal ion levels. Mean serum titanium levels were 165.4 nmol/L (range: 30 to 390 nmol/L), mean serum cobalt levels were 4.6 nmol/L (range: 1.2 to 14 nmol/L), and mean serum chromium levels were 14 nmol/L (range: 2.4 to 30 nmol/L). Peri-implant soft tissue histologic analysis demonstrated local metal debris and foreign body reactions in all patients. At the completion of MCGR treatment, the majority of patients demonstrate elevated serum metal ion levels and local metal debris-related peri-implant soft tissue changes. Although there is no current literature to suggest these findings are harmful, further research as to the clinical significance is required. Level IV.

Magnetically controlled growing rod treatment for early-onset scoliosis: analysis of 52 consecutive cases demonstrates improvement of coronal deformity.

The purpose of this study was to report the radiographic results and complications of magnetically controlled growing rod (MCGR) treatment in patients with early-onset scoliosis (EOS). Patient records and radiographs from a consecutive series of patients treated with MCGR for EOS at two Swedish institutions were reviewed retrospectively. Radiographic analysis included Cobb angle, T1-T12 height, T1-S1 height, thoracic kyphosis, and lung height. Subgroup analyses were performed on primary versus conversion cases and single versus dual rods using one-way analysis of variance (ANOVA) and independent samples t-test. Fifty-two cases treated with MCGR (24 single rods, 28 dual rods) were included from local surgical records into this cohort study, 32 primary and 20 converted from other growth friendly surgical treatment. Mean age at MCGR implantation was 7.4 (2.0-14.6) years old in the primary group and 9.3 (5.0-16.1) years old in the converted group. Mean follow-up time was 3.7 (2.0-7.6) years. Mean (standard deviation; SD) Cobb angle of the major curve changed from 62° (17°) preoperatively to 42° (16°) postoperatively to 46° (18°) at final follow-up (P<0.001). Mean (SD) overall thoracic kyphosis changed from 41° (19°) preoperatively to 32° (14°) postoperatively to 39° (17°) at final follow-up (P=0.018). Mean T1-T12 height was 177 mm (34 mm) preoperatively, 183 mm (35 mm) immediate postoperative and 199 mm (35 mm) at final follow-up (P=0.047). The mean T1-T12 height increased significantly in the primary group but not in the converted group. The number of surgeries was 114 (78 planned, 36 unplanned). The rate of unplanned surgeries did not differ significantly between single and dual rods. The total number of complications was 70 of which 38 were implant related. The overall mean complication rate was 1.4 (0-4). There were no significant differences in complication rates between subgroups. MCGR treatment enabled and maintained correction of spinal deformity while allowing spinal growth. There were no significant differences in complication rates or unplanned surgeries between the groups treated with single or dual rods.

No Benefits in Using Magnetically Controlled Growing Rod as Temporary Internal Distraction Device in Staged Surgical Procedure for Management of Severe and Neglected Scoliosis in Adolescents.

Severe spinal curvatures (SSCs) in children and adolescents have long been treated with preoperative Halo traction, in its various variations. There are also several radical techniques available for the management of neglected SSCs, such as osteotomies; however, these can be risky. Comparing the treatment outcomes when using preoperative Halo Gravity Traction (HGT) against the use of a Magnetically Controlled Growing Rod (MCGR) as a temporary internal distraction (TID) device, we evaluated the differences in surgical and radiological outcomes. We conducted a retrospective study of 30 patients with SSCs, treated with HGT followed by posterior spinal fusion (PSF; Group 1, n = 18) or treated using a temporary MCGR as a TID followed by PSF (Group 2, n = 12). All patients underwent surgical treatment between 2016 and 2022. The inclusion criteria were SSC > 90°, flexibility < 30%, and the use of preoperative HGT followed by PSF or the two-stage surgical procedure with initial TID rod placement (Stage 1) followed by PSF (Stage 2). The evaluated parameters were as follows: rib hump, trunk height, and radiographic outcomes. All parameters were collected preoperatively, after the initial surgery, after final correction and fusion, and during the final follow-up. In Group 1, we evaluated 18 patients with a mean age of 15.5 years; in Group 2, we evaluated 12 patients with a mean age of 14.2 years. The interval between the staged procedures averaged 32.7 days. The mean preoperative main curves (MC) were 118° and 112° in Group 1 and Group 2, respectively. After definitive surgery, the MC was corrected to 42° and 44° in G1 and G2, respectively. The mean percentage correction of the MC was similar in both groups (65% vs. 61% in G1 and G2, respectively). The mean preoperative thoracic kyphosis was 92.5° in G1 and 98° in G2, corrected to 43.8° in G1 and 38.8° in G2. Trunk height increased by 9 cm on average. There are no benefits in using a MCGR as a temporary internal distraction device in the management of neglected scoliosis in adolescents. Surgical treatment of severe scoliosis may be safe, with a reduced risk of potential complications, when using preoperative HGT. A specific intraoperative complication when using a MCGR as a temporary internal distraction device was a 50% risk of transient neuromonitoring changes, due to significant force applied to the spine and radical distraction of the spine. We achieved similar clinical, radiographic, and pulmonary function outcomes for both techniques. The use of HGT causes less blood loss with a shorter overall time under anesthesia. Partial correction significantly aids the subsequent operation by facilitating a gradual reduction in the curvature, thereby reducing the difficulty of surgical treatment and the risk of neurological deficits.

Rib-to-spine and rib-to-pelvis magnetically controlled growing rods: does the law of diminishing returns still apply?

The Law Of Diminishing Returns (LODR) has been demonstrated for traditional growing rods, but there is conflicting data regarding the lengthening behavior of Magnetically Controlled Growing Rods (MCGR). This study examines a cohort of patients with early-onset scoliosis (EOS) with rib-to-spine or rib-to-pelvis-based MCGR implants to determine if they demonstrate the LODR, and if there are differences in lengthening behaviors between the groups. A prospectively collected multicenter EOS registry was queried for patients with MCGR with a minimum 2-year follow-up. Patients with rib-based proximal anchors and either spine- or pelvis-based distal anchors were included. Patients with non-MCGR, unilateral constructs, < 3 lengthenings, or missing > 25% datapoints were excluded. Patients were further divided into Primary-MCGR (pMCGR) and Secondary-MCGR (sMCGR). 43 rib-to-spine and 31 rib-to-pelvis MCGR patients were included. There was no difference in pre-implantation, post-implantation and pre-definitive procedure T1-T12 height, T1-S1 height, and major Cobb angles between the groups (p > 0.05). Sub-analysis was performed on 41 pMCGR and 19 sMCGR rib-to-spine patients, and 31 pMCGR and 17 sMCGR rib-to-pelvis patients. There is a decrease in rod lengthenings achieved at subsequent lengthenings for each group: rib-to-spine pMCGR (rho = 0.979, p < 0.001), rib-to-spine sMCGR (rho = 0.855, p = 0.002), rib-to-pelvis pMCGR (rho = 0.568, p = 0.027), and rib-to-pelvis sMCGR (rho = 0.817, p = 0.007). Rib-to-spine pMCGR had diminished lengthening over time for idiopathic, neuromuscular, and syndromic patients (p < 0.05), with no differences between the groups (p > 0.05). Rib-to-pelvis pMCGR neuromuscular patients had decreased lengthening over time (p = 0.01), but syndromic patients had preserved lengthening over time (p = 0.65). Rib-to-spine and rib-to-pelvis pMCGR and sMCGR demonstrate diminished ability to lengthen over subsequent lengthenings.

Pin Fracture in Magnetically Controlled Growing Rods: Influence of the Year of Manufacture.

Magnetically controlled growing rods (MCGRs) have a known issue with fracture of the internal locking pin resulting in early revisions. The manufacturer reported that rods manufactured before March 26, 2015, had a 5% risk of locking pin fracture. Locking pins made after this date are thicker in diameter and of a tougher alloy; their rate of pin fracture is not known. The aim of this study was to better understand the impact of the design changes on the performance of MCGRs. This study involves 46 patients with 76 removed MCGRs. Forty-six rods were manufactured before March 26, 2015, and 30 rods after that date. Clinical and implant data were collected for all MCGRs. Retrieval analysis comprised plain radiographs evaluations, force and elongation testing, and disassembly. The 2 patient groups were statistically comparable. We found that 14 of 27 patients implanted with rods manufactured before March 26, 2015 (group I) had a fracture of their locking pins. Three of the 17 patients with rods manufactured after this date (group II) were also found to have a fractured pin. Retrieved rods collected at our center and made after March 26, 2015, had far fewer locking pin fractures than those made before this date; this may be due to the change in pin design.

An in vivo analysis of implanted programmable device interference during magnetically controlled growing rod lengthenings: a story of 129 lengthenings.

Early-onset scoliosis (EOS) is often treated with magnetically controlled growing rods (MCGR) which can be lengthened with a magnetic external remote control (ERC). Many individuals with EOS have concomitant medical conditions which are managed with other implanted programmable devices (IPD). Some providers are concerned that the magnetic field generated during MCGR lengthening may interfere with other IPD, such as ventriculoperitoneal shunts (VPS), intrathecal baclofen pumps (ITBP), vagal nerve stimulators (VNS), and cochlear implants (CI). The aim of this study was to evaluate the safety of MCGR lengthenings in patients with EOS and other IPD. This single-center, single-surgeon case series followed 12 patients with 13 IPD as they underwent treatment with MCGR. Post MCGR lengthening, monitoring of patient symptoms, and interrogation of IPD were conducted to evaluate for magnetic interference. After 129 MCGR lengthenings, post-lengthening VPS interrogation found 2 instances of potential interference in settings (both in Medtronic Strata shunts); however, no pre-lengthening interrogation was completed to confirm if these changes occurred prior to or during the lengthening procedure. ITBP interrogation found no changes, and there were no patient-reported adverse effects related to VNS or CI function. It is safe and effective to utilize MCGR in patients with IPD. However, the possibility of magnetic interference must be considered, particularly in individuals with VPS. We recommend approaching with the ERC from a caudal direction to minimize potential interference and all patients be monitored during treatment. If possible, IPD settings should be assessed pre-lengthening, confirmed afterwards and readjusted if necessary. Level IV.

Is spinal height gain associated with rod orientation and the use of cross-links in magnetically controlled growing rods in early-onset scoliosis?

Optimal orientation for magnetically controlled growing rods (MCGRs) is unclear. The objective of this study was to investigate associations of rod orientation with implant-related complications (IRCs) and spinal height gains. Using an international early-onset scoliosis (EOS) database, we retrospectively reviewed 57 patients treated with dual MCGRs from May 2013 to July 2015 with minimum 2-year follow-up. Outcomes of interest were IRCs and left/right rod length gains and thoracic (T1-T12) and spinal (T1-S1) heights. We compared patients with two rods lengthened in the cephalad ( standard; n = 18) versus opposite ( offset; n = 39) directions. Groups did not differ in age, sex, BMI, duration of follow-up, EOS cause, ambulatory status, primary curve magnitude, baseline thoracic height, or number of distractions/year. We compared patients whose constructs used ≥1 cross-link (CL group; n = 22) versus no CLs (NCL group; n = 35), analyzing thoracic height gains per distraction ( α = 0.05). Offset and standard groups did not differ in left or right rod length gains overall or per year or in thoracic or spinal height gain. Per distraction, the CL and NCL groups did not differ significantly in left or right rod length or thoracic or spinal height gain. Complications did not differ significantly between rod orientation groups or between CL groups. MCGR orientation and presence of cross-links were not associated with differences in rod length gain, thoracic height, spinal height, or IRCs at 2-year follow-up. Surgeons should feel comfortable using either MCGR orientation. Level of evidence: 3, retrospective.

Increasing soft tissue depth is associated with stalling of magnetically controlled growing rods

Magnetically controlled growing rods (MCGR) represent the most used implant for the treatment of early onset scoliosis (EOS). These implants lengthen through the application of a remote magnetic field but distraction force generation has been negatively correlated with increasing soft tissue depth. Given the high rate of MCGR stalling, we proposed to investigate the impact of preoperative soft tissue depth on the rate of MCGR stalling at a minimum of 2 years following implantation. A single-center, retrospective review of prospectively enrolled children with EOS treated with MCGR was performed. Children were included if they had a minimum of 2-years follow-up after implantation and underwent advanced spinal imaging (MRI or CT) preoperatively within a year of implantation. The primary outcome was the development of MCGR stall. Additional measures included radiographic deformity parameters and gain in MCGR actuator length. About 55 patients were identified with 18 having preoperative advanced imaging allowing tissue depth measurement (Mean 5.99 ± 1.9 years, 83.3% female, mean Cobb 68.6 ± 13.8°). At a mean follow-up of 46.1 ± 11.9 months, 7 patients (38.9%) experienced stalling. MCGR stalling was associated with increased preoperative soft tissue depth (21.5 ± 4.4 mm vs. 16.5 ± 4.1 mm; p=.025) and increased BMI (16.3 ± 1.6 vs. 14.5 ± 0.9; p=.007). Greater preoperative soft tissue depth and BMI were associated with the development of MCGR stalling. This data supports previous studies showing that the distraction capacity of MCGR diminishes with increased soft tissue depth. Further research is needed to validate these findings and their implications on the indications for MCGR implantation.