Rod Lengthening Research Articles

Increased lengthening frequency does not adversely affect the EOSQ scores in magnetically controlled growing rod surgeries in 133 subjects followed to final fusion.

Magnetically Controlled Growing Rod (MCGR) allows frequent outpatient rod lengthening when treating Early Onset Scoliosis (EOS) patients. But there is lack of expert consensus on the optimal MCGR lengthening interval. EOS 24-Item Questionnaire (EOSQ) is validated for assessing health-related quality of life (HrQOL), family burden, and satisfaction. This is the first study assessing how MCGR lengthening intervals affects patient-perceived outcomes. This is a multicentred cohort study with subjects recruited from 2012 to 2018 and followed till fusion. EOS subjects who underwent MCGR surgeries were grouped into high, mediumor low lengthening interval subgroups based on 16 and 20week cut-offs. Repeated measure analysis was performed on EOSQ's specified 12 domains. EOSQ results were taken: before index surgery, after index surgery, and prior to definitive treatment. Demographic, clinical and radiographic data were included in model adjustment. 133 subjects with mean follow-up of 3.5 (± 1.3)years were included, with 60 males and 73 females; 45 idiopathic, 23 congenital, 38 neuromuscular, and 27 syndromic patients. Mean Cobb angle at surgery was 67° (± 22°) with mean age of 8.3 (± 2.5)years. Between groups, clinical and radiographic parameters were comparable. Higher EOSQ scores in mediumlengthening interval subgroup was present in fatigue (p = 0.019), emotion (p = 0.001), and parental impact (p = 0.049) domains, and overall score (p = 0.046). Trendline contrast between subgroups were present in general health (p = 0.006) and physical function (p = 0.025) domains. Patient-perceived outcome improvements appear similar between lengthening interval subgroups. All MCGR lengthening intervals were tolerated by patients and family, with no negative impact observed. Prognostic Level III.

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.

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.

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.

Predictors of Rod Length Gain and Sagittal Alignment Change After Magnetically Controlled Growing Rod Lengthening.

This was a retrospective cohort study. There are preoperative characteristics that predict rod lengthening of magnetically controlled growing rods (MCGR). The lengthening of MCGR will lead to increased kyphosis. The amount of length gained by MCGR is variable, and predictors are lacking. Similarly, sagittal plane changes over the MCGR lengthening period have not been investigated. Patients with MCGR and a minimum 2-year follow-up were identified and those with previous spine surgery were excluded. Preimplantation, postimplantation, and last follow-up postlengthening radiographs were examined. Multiple linear regression analyses were used for rod length gain predictors. Fifty-six patients with early-onset scoliosis met inclusion criteria: nine idiopathic, five congenital, 14 neuromuscular, 20 syndromic, and eight skeletal dysplasia patients. No difference was seen between subtypes of early-onset scoliosis for rod length gain ( P =0.62). Shorter preoperative T1-T12 height and higher curve correction rate after implantation were significant predictors for rod length gain ( P <0.001). Preoperative major curve magnitude and kyphosis were not significant predictors. Flattening of the spine around the actuator and compensative increase in T1-T5 kyphosis were seen secondarily after MCGR implantation. Maximum sagittal kyphosis, T1-T5 kyphosis, and T5-T12 kyphosis did not change during lengthening. Lumbar lordosis significantly decreased postimplantation (first erect) but then increased during lengthening. Pelvic incidence and sacral slope both increased during lengthening, but this may be age related. Patients who gained the most rod length with MCGR were those with an initially shorter T1-T12 height and better initial curve correction at implantation, likely representing that implants work best in small patients with flexible curves. Diagnosis, preoperative curve magnitude, and thoracic kyphosis were not related to rod length gain. Thoracic kyphosis did not deteriorate over the lengthening phase. Level III-retrospective cohort study.

The magnetic field strength and the force distance dependency of the magnetically controlled growing rods used for early onset scoliosis

Magnetically controlled growing rods (MCGR’s) have revolutionized the treatment of early-onset scoliosis (EOS) because painless lengthenings can be done in the outpatient clinic without anesthesia. Untreated EOS leads to respiratory insufficiency and reduced life expectancy. However, MCGR’s have inherent complications like non-functioning of the lengthening mechanism. We quantify an important failure mechanism and give advice on how to avoid this complication. The magnetic field strength was measured on new/explanted rods at different distances between the external remote controller and the MCGR and likewise in patients before/after distractions. The magnetic field strength of the internal actuator decayed fast with increasing distances and plateaued at 25–30 mm approximating zero. Two new and 12 explanted MCGRs was used for the lab measurements of the elicited force using a forcemeter. At a distance of 25 mm, the force was reduced to approximately 40% (ca. 100 N) compared to zero distance (ca. 250 N), most so for explanted rods. This is used to point out the importance of minimizing the implantation depth to ensure proper functionality of the rod lengthening in clinical use for EOS patients. A distance of 25 mm from skin to MCGR should be considered a relative contraindication to clinical use in EOS patients.

A Modified Self-Growing Rod Technique for Treatment of Early-Onset Scoliosis.

The patient is positioned prone on a radiolucent table, and the spine is prepared and draped in a standard fashion. A posterior midline skin incision is made from the upper to the lower instrumented level. Subperiosteal exposure of the spine is carried out, ensuring that capsules of the facet joints are spared. Pedicle screws are inserted bilaterally at the cranial and caudal ends of the instrumentation. Fixation with pedicle screws of at least 3 levels at the top and bottom end is usually advised; in nonambulatory patients with pelvic obliquity, caudal fixation can be extended to the pelvis with bilateral iliac screws. Sublaminar wires are positioned bilaterally at every level between the cranial and caudal ends of the instrumentation and are passed as medially as possible to avoid damage to the facet joints. Four 5-mm cobalt-chromium rods are cut, contoured, and inserted at each end of the construct. Ipsilateral rods are secured with use of sublaminar wires, making sure that they overlap over a sufficient length to allow for the remaining spinal growth. Correction of the deformity is achieved with use of a combination of cantilever maneuvers and apical translation by progressive and sequential tightening of the sublaminar wires. The wound is closed in layers over a subfascial drain. The patient is allowed free mobilization after surgery. No postoperative brace is required. Nonoperative alternative treatment for EOS includes serial cast immobilization and bracing4. Alternative surgical treatments include traditional growing rods5, magnetically controlled growing rods6, the vertical expandable prosthetic titanium rib-expansion technique7, and the Shilla technique8. The use of compression-based systems (i.e., staples or tether)9 or early limited fusion has also been reported by other authors. The main advantage of our technique is that it relies on physiological spinal growth and does not require surgery or external devices for rod lengthening, which is particularly beneficial in frail patients with a neuromuscular disease in whom repeated surgery is not advised. Segmental fixation by sublaminar wires allows good control of the deformity apex during growth. Concerns regarding early fusion of the spine have not been confirmed in our mid-term follow-up study10. This technique allows correction of the deformity and continuous spinal growth in the years following surgery. At 6.0 years postoperatively, the average main curve correction was reported to be 61% and the average pelvic obliquity correction was 69%. The spine was reported to lengthen an average of 40.9 mm (range, 14.0 to 84.0 mm) immediately postoperatively, and the T1-S1 segment was reported to continue growing at 10.5 mm/year (range, 3.6 to 16.5 mm/year) thereafter10. The most common complication is rod breakage at the thoracolumbar junction, which seems to be more common in patients with idiopathic or cerebral palsy EOS and during the pubertal growth spurt10. Subperiosteal exposure of the spine should be carried out, making sure to preserve facet joints in the unfused area of the spine.Achieve segmental fixation with use of sublaminar wires at every level and pedicle screws at the top and bottom ends of the instrumentation.If pelvic imbalance is present and the patient is nonambulatory, pelvic fixation with iliac screws is advised.First round correction of the deformity is achieved with a cantilever technique; correction fine-tuning can be performed by tightening sublaminar wires.Consider utilizing thicker rods in cases of idiopathic or cerebral palsy EOS. EOS = early-onset scoliosisAP = anteroposteriorEV = end vertebraSSEP = somatosensory evoked potentialsMEP = motor evoked potentialsPJK = proximal junctional kyphosisSMA = spinal muscular atrophyCP = cerebral palsyPACU = post-anesthesia care unit.

Long-term outcomes of ilio-sacral screws in minimally invasive bipolar fusionless technique for neuromuscular scoliosis: a retrospective study in 167 patients.

Pelvic fixation in patients with neuromuscular scoliosis is difficult, due to their fragile general condition and poor bone quality. Many techniques have been described, associated with high rates of mechanical complications. The objective of this work was to evaluate the mechanical complications and long-term radiological results of ilio-sacral screw pelvic fixation. 167 consecutive patients with neuromuscular scoliosis who underwent minimally invasive bipolar fixation with ilio-sacral screw pelvic fixation were retrospectively reviewed. The instrumentation consisted in a bilateral sliding rods construct extended from T1 to the sacrum, anchored proximally by double-hook claws and distally by ilio-sacral screws through a minimally invasive approach. Mechanical complications and radiographic measurements (angle of the major coronal curve, pelvic obliquity, lumbar lordosis) were evaluated preoperatively, postoperatively, and at the last follow-up. Mean operative age was 12 ± 3years, and follow-up 6.4years (3.0-10.4years). Pelvic obliquity decreased from 20° preoperatively to 5° (77% correction) at last follow-up, Angle of the major coronal curve from 75° to 36° (52% correction), and lumbar lordosis from 28° to 38°. 16 mechanical complications in nine patients occurred: screw prominence (n = 1), connector failure (n = 4), screw malposition (n = 11). Unplanned surgery was required in seven cases, two were managed during rod lengthening, seven did not require treatment. In this series of neuromuscular patients operated by ilio-sacral screws as pelvic fixation, the results were stable with a mean follow-up of more than 6years and the complication rate was reduced comparatively to the literature.

How much does depth matter? Magnetically controlled growing rod distraction directly influenced by rod tissue depth.

Magnetically controlled growing rod (MCGR) for the treatment of early-onset scoliosis (EOS) is a relatively innovative technique. MCGR benefits over traditional growing rods are known but limitations and complications are being revealed. The purpose of this study was to examine the importance of tissue depth on rod lengthening. A single-institution retrospective review of 72 MCGR patients was performed. Ultrasound measured rod distraction. Differences in programmed and actual distraction, and complications were recorded. Tissue depths and achieved length were averaged and used to construct a regression to account for variability. Percentage of std and offset orientation rod lengthening relative to the programmed distraction was inversely proportional to rod depth (std R = 0.50, p = 0.002) (offset R = 0.60, p < 0.001). Expected std rod lengthening achieved decreased by 1.46%/mm depth. Expected offset rod lengthening achieved decreased by 1.68%/mm depth. 28 pts (38.9%) sustained complications. Age, sex, BMI, standard tissue depth, and/or offset tissue depth had no predictive ability with respect to complications sustained (overall model R = 0.31, p = 0.36). In a series of EOS surgical patients treated with MCGRs, the relationship between percentage of programmed lengthening achieved as well as total lengthening was inversely proportional to tissue depth of the rod. There was a trend towards increasing frequency of complications recorded with decreasing tissue depth though this was not significant. These data can help with surgical planning during MCGR placement.

Inter- and intrarater reliability of measuring lengthening of magnetically controlled growing rods on digital radiographs.

The aim of this study was to determine inter- and intraobserver reliability of delta rod extension, and total rod length measured on digital x-rays in patients with early onset scoliosis (EOS) treated with magnetically controlled growing rods (MCGR). For the last decade, patients with EOS have been treated with MCGR. Replacement of MCGR relies heavily on the measurement done at every lengthening session. Only a few studies have looked at inter- and intraobserver reliability of rod lengthening, and none have used the delta extension before. 202 radiographs presented in random order were rated and measured twice with at least a 14-day interval and differing order of the radiographs. The measuring was done at both rods. All x-rays came from 15 patients diagnosed with EOS and treated with MCGR from 2009 until 2019. The total extension length and the delta extension (the difference in total extension length between two lengthening in succession) were measured, and the intraclass correlation coefficient (ICC) calculated for both measurements RESULTS: Intrarater ICC scores varied from moderate to good, but non-significantly. Interrater reliability increased significantly from moderate (ICC 0.72 [0.68; 0.76] and 0.73 [0.69; 0.77] to excellent (ICC 0.91 [0.88; 0.93] and 0.97 [0.96: 0.98]), when examining delta extension every sixth instead of every second month. Measuring rod lengthening on x-rays can be done every 6months, with an ample reliability. The ICC's for the delta extension with 2-3months interval were only moderately precise, compared to the near perfect ICC's for the total extension length.

Minimally Invasive Fusionless Surgery for Scoliosis in Spinal Muscular Atrophy: Long-term Follow-up Results in a Series of 59 Patients.

Treatment of spinal muscular atrophy (SMA) scoliosis has evolved in the last decade, with the emergence of fusionless surgical techniques that allow correction of the deformity before the end of growth spurt. These techniques are expected to delay definitive spine fusion and preserve trunk growth. The aim was to evaluate long-term clinical, radiologic, and respiratory outcomes of a minimally invasive fusionless surgery (MIFLS) in SMA scoliosis. All children affected with SMA scoliosis who underwent MIFLS in our department from 2011 to 2019 were included. The instrumentation consisted in a bilateral sliding rod construct from T1 to the sacrum, anchored proximally by double-hook claws and distally by iliosacral screws. Clinical, genetic, respiratory and radiographic data were retrospectively reviewed. A patient's satisfaction survey was performed. A total of 59 children with genetic confirmation of SMA (9SMA1c, 47SMA2, and 3SMA3) underwent MIFLS at a mean age of 11±1.9 years. All of them were nonwalker at the time of surgery. Twenty-six were treated with intrathecal Nusinersen. Mean follow-up was 5.2 years (2 to 9.6 y). Mean major coronal curve improved from 79±15 to 41±16 degrees and pelvic obliquity decreased from 24±11 to 5.9±4 degrees. Mean space available for lung improved from 77% to 93%. Mechanical or infectious complications occurred in 9 patients, with removal of the implant in 1. 6 children required unplanned surgeries. Postoperative bracing was needed in 13 children. Mean gain weight 3 years after the first surgery was 6 kg. 91.5% of patients had a positive satisfaction of the surgery. There was no significant impact in respiratory function postoperatively. Only 30 children required rod lengthening procedures, with a mean interval between procedures of 1.9 years (0.5 to 3.7 y). No arthrodesis was required at last follow-up in any patient. Bipolar MIFLS in SMA preserves spinal and thoracic growth without interference with respiratory function. It provides a significant correction of spinal deformity and pelvic obliquity, having a reduced rate of complications. The correction of spinal deformity was maintained at long term, not requiring definitive fusion at the end of growth. Level IV.

Growing-rod implantation improves nutrition status of early-onset scoliosis patients: a case series study of minimum 3-year follow-up

BackgroundEarly onset scoliosis (EOS) may cause malnutrition in affected patients. Growing-rod treatment has been an effective protocol for treating EOS. The objective of this study is to demonstrate whether growing-rod treatment improves nutritional status of EOS patients.MethodsFifty-two EOS patients who had dual growing-rod surgery was enrolled. The minimum follow-up was 3-years. Their body weights were normalized based on the data of two National Population Census of China. Z-scores were used to indicate the standard deviation from the median body weight-for-age.ResultsThe median follow-up time was 6 years. Preoperatively, the prevalence of malnutrition (Z < − 2) was 21.2%, and reduced to 9.6% at the end of the follow-up. Preoperatively, the average Z-score was − 0.94, and it increased to − 0.65 at the latest follow-up (p < 0.05). Patients with preoperative Z-score below − 1 had more significant increase of Z-scores (− 2.15 vs − 1.26, p < 0.001). A significant negative correlation between the change of Z-score and the preoperative Z-score (correlation coefficient − 0.65, p < 0.001).ConclusionsThe growing rod surgery and lengthening procedures significantly improves the nutrition status of EOS patients. The body weight gains are more significant in patients with lower body weights.

Ultrasound measurement of magnetically controlled growing rod (MAGEC) lengthening. An intra and interobserver reliability study

Ultrasound measurement of magnetically controlled growing rod (MAGEC) lengthening. An intra and interobserver reliability study

Can spinal deformity patients maintain proper arm positions while undergoing full-body X-ray?

The compliance rate of arm positioning during full-body X-rays varies depending on operative status (preoperative vs postoperative), age, and diagnosis. Retrospective cohort. Despite the importance of patients maintaining arms in the same position in preoperative and postoperative standing films, patients are known to have their arms in varying positions, confounding radiographic interpretation and making global sagittal and coronal spinal balance assessment variable and potentially less reliable. This study seeks to examine arm position compliance among adult and pediatric surgical spinal deformity patients undergoing total body X-rays over the course of 4years (2015-2018). A retrospective radiographic review was performed on 382 spinal deformity patients from July 2015 to July 2018. The study's dependent variable of interest was standardized arm position (fingers on the clavicles with shoulders in 45° of forward elevation while the patient is in a free-standing posture) observed during full-body X-rays obtained for spinal deformity evaluation. Deviations and compliance to the standard protocol for full-body X-ray arm positioning was recorded and analyzed across various independent factors, including year of surgery, pre- and postoperative periods, type of spine surgery, and patient age. Chi-square and Cochran-Armitage analyses were performed to study categorical and trends, respectively. The overall compliance rate for maintaining standardized arm position was 90% for all 370 patients (277 adult and 93 pediatric), in preoperative and postoperative setting. Adults were more likely to follow protocol than pediatric patients (92.9% vs. 82.4%, P value = 0.003). The postoperative setting observed a significantly lower overall compliance rate when compared to the preoperative period (67.8% vs. 87.0%, P value < 0.0001). Patients undergoing neuromuscular scoliosis (73.3%), vertebral column resection (VCR) (70%), and growing rod lengthening (GRL) (57.1%) had the lowest overall compliance rate in the preoperative setting. In the postoperative setting, patients with GRL, VCR, revision congenital scoliosis, congenital scoliosis, neuromuscular scoliosis, and pedicle subtraction osteotomy (PSO) surgeries were compliant less than or equal to 50% of the time. From 2015 to 2018, there was an overall statistically significant increase in compliance rate (61.1% to 90.6%). Over the study period, adult patients became significantly more compliant to protocol. This was not observed in the pediatric population. This study documented the patient compliance rate of maintaining standardized arm position during full-body X-rays of spinal deformity patients. The overall compliance rate was 90.0% for all patients in the preoperative and postoperative setting. Risk factors for lower compliance rates included patients that were pediatric, postoperative, neuromuscular, and those who underwent a complex vertebral osteotomy or GRL. There was a trend showing improved compliance rate throughout the 4-year study period, which highlights the importance of having an ancillary staff who is comfortable with a consistent standard of care protocol. These results should help other centers optimize arm positioning in their patients undergoing full-body X-rays in the future.

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

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.

Contouring the magnetically controlled growing rods: impact on expansion capacity and proximal junctional kyphosis.

To quantitatively determine the relationship between the contouring of themagnetically controlled growing rods (MCGR), their expansion capacity and the risk of developing proximal junctional kyphosisin early onset scoliosis (EOS). MCGRs allow gradual expansion and correction of the spinal deformity in EOS while reducing the need for repeated surgeries. As the expansion of the MCGRs is controlled externally, several factors can impact the discrepancy between the intended and actual expansions of the rods. The expansion capacity of the growing rods as a function of the expanded length has been tested in experimental setups; however, no study has evaluated the role of contouring of the MCGRs on its function and long-term surgical outcome. A total of 25 EOS patients, a total of 48 MCGRs, with right thoracic curves, were studied retrospectively. All patients had two view spinal radiographs at pre-operative, after MCGR implantation, and after 6 lengthening visits. The first post-operative radiographs were used to calculate the 3D contour of the MCGR at the proximal end. 2D ultrasound images before and after lengthening visits were used to measure the rod lengthening at each visit. The relationship between the increase in the rod length and rod curvature was determined. Finally, the rod curvature was correlated to the changes in proximal junctional kyphosis (PJK) angle between the pre-operative and the most recent follow-up, i.e., after 6 visits. The average rod 3D angle at the proximal end was 13.5° ± 9.7° [0°-37.2°]. The overall increased length after six lengthening visits for the rod at the concave side was 18.8mm and at the convex side was 16.9mm. 62% of the patients with a contoured rod at the proximal end developed a PJK exceeding 10° whereas in patients with a straight rod PJK occurred in 9.1%. Contouring the MCGR impacts both the mechanics of the rod expansion and the prevalence of PJK in EOS patientpopulation.

Can You Stall a Baclofen Pump During a Magnetic Rod Lengthening?

Baclofen pumps are susceptible to magnetic forces because of the internal drug delivery mechanism. Magnetically controlled growing rods, sometimes implanted in the patients who have pumps, are lengthened using a device that generates a magnetic field. No previous study has determined if the external remote controller (ERC) can stall a baclofen pump during a rod lengthening. Two baclofen pumps were placed in proximity to the ERC while it generated a magnetic field. This process was repeated with variations in the distance between pump and ERC, speed (dose) of the pump, lengthening time, and position of the ERC relative to the pump. The presence or absence of a stall was recorded. To stall a baclofen pump, the ERC needed to be running consistently for at least 30 mm of lengthening. The pump would not stall if it was >1 cm away from the ERC. The pump was more likely to stall if it was positioned in front of or behind the magnetic field, as opposed to the center of the field. As long as the baclofen pump is >1 cm away from the ERC, the pump will not stall, regardless of the length of time the ERC generates a magnetic field.

Is routine intraoperative neuromonitoring necessary in growing rod lengthening procedures? A retrospective, observational study.

To investigate whether intraoperative neuromonitoring (IONM) may be avoided in growing rod lengthening procedures in early onset scoliosis (EOS). A total of 636 primary growing rod surgeries and lengthening procedures were performed in 112 patients with EOS. Traditional growing rods (TGR) or magnetically controlled growing rods (MCGR) were implanted and subsequent lengthening procedures were done at stipulated intervals. Combined multi-modality IONM was used in all index surgeries-but was only used in lengthening procedures in patients with existing spinal cord abnormality or a history of neurosurgical procedure for the same, patients with prior history of a neuromonitoring alert in their index surgery and when lengthening was accompanied by an implant exchange/revision. All the remaining growing rod lengthening procedures were carried out without IONM. Hospital records and operation notes were retrospectively reviewed with focus on details of neurological events/complications. In 112 primary growing rod applications (TGR = 96, MCGR = 16) and 524 lengthening procedures (TGR = 444, MCGR = 80), intraoperative neuromonitoring 'alerts' were encountered in 6/112 index surgeries and temporary postoperative neurological deficits were seen in 2/112 index surgeries. No intraoperative neuromonitoring event or postoperative neurological complication was encountered in 524 lengthening procedures-irrespective of whether they were carried out along with implant exchange, or in patients with spinal cord abnormality or prior neuromonitoring event during index surgery. While IONM should be used in primary growing rod application surgeries, its use may be avoided in lengthening and implant exchange procedures in a resource-limited setting. Level 3.

Characterizing Use of Growth-friendly Implants for Early-onset Scoliosis: A 10-Year Update.

Growth-friendly treatment of early-onset scoliosis (EOS) has changed with the development and evolution of multiple devices. This study was designed to characterize changes in the use of growth-friendly implants for EOS from 2007 to 2017. We queried the Pediatric Spine Study Group database for patients who underwent index surgery with growth-friendly implants from July 2007 to June 2017. In 1298 patients, we assessed causes of EOS; preoperative curve magnitude; age at first surgery; patient sex; construct type; lengthening interval; incidence of "final" fusion for definitive treatment; and age at definitive treatment. α=0.05. From 2007 to 2017, the annual proportion of patients with idiopathic EOS increased from 12% to 33% (R=0.58, P=0.006). Neuromuscular EOS was the most common type at all time points (range, 33% to 44%). By year, mean preoperative curve magnitude ranged from 67 to 77 degrees, with no significant temporal changes. Mean (±SD) age at first surgery increased from 6.1±2.9 years in 2007 to 7.8±2.5 years in 2017 (R=0.78, P<0.001). As a proportion of new implants, magnetically controlled growing rods increased from <5% during the first 2 years to 83% in the last 2 years of the study. Vertically expandable prosthetic titanium ribs decreased from a peak of 48% to 6%; growth-guidance devices decreased from 10% to 3%. No change was seen in mean surgical lengthening intervals (range, 6 to 9 mo) for the 614 patients with recorded lengthenings. Final fusion was performed in 88% of patients who had undergone definitive treatment, occurring at a mean age of 13.4±2.4 years. From 2007 to 2017, neuromuscular EOS was the most common diagnosis for patients treated with growth-friendly implants. Patient age at first surgery and the use of magnetically controlled growing rods increased during this time. Preoperative curve magnitude, traditional growing rod lengthening intervals, and rates of final fusion did not change. Level II.

One-Way Self-Expanding Rod for Early-Onset Scoliosis: A Prospective Observational Study of 20 Patients

Background: Progressive early-onset scoliosis (EOS) raises major challenges for surgeons, as growth must be preserved. With conventional growing rods, the need for repeated surgery for rod lengthening is associated with numerous complications, high costs, and a heavy psychosocial burden on the patient and family. We assessed the safety and efficacy of a new One-Way Self-Expanding Rod (OWSER). Methods: This prospective single-centre phase 2 study included two groups of children with progressive EOS treated by the OWSER in 2016-2017: ten received a unilateral construct to treat progressive non-neuromuscular curves and ten others a bilateral construct for neuromuscular scoliosis. Clinical and radiological data were assessed at surgery then 3, 6, 12, and 18 months later. The primary endpoint was success defined as absence of repeated surgery or Cobb angle progression <15° at 12 months. Findings: In the non-neuromuscular group, rod expansion occurred in 50% of patients [95CI, 19-81]; in the 5 other patients, rotational conflict at the flat part of the rod prevented rod expansion, 4 of them required surgery within the first 12 months. Rod expansion occurred spontaneously and during monthly traction sessions in all ten neuromuscular patients [95%CI, 69-100], without mechanical or device-related complications, and residual pelvic obliquity was improved by -3° [-6·0 to 9·5] at 18 months. Lung function improved in the non-neuromuscular group. Interpretation: Used in a bilateral construct, the OWSER seems safe and less aggressive than traditional growing rods. It should avoid further surgery and reduce the complication rate. The bilateral construct seemed effective in correcting EOS in our small sample. The OWSER may be the treatment of choice for progressive spinal deformities in skeletally immature children. Trial Registration: ClinicalTrials.gov: NCT02266667. Funding Statement: Euros Company, SAS. Declaration of Interests: LM received grant and research support from Euros Company SAS and is a co-designer of the device. All other authors declare that they have no conflicts of interest. Ethics Approval Statement: All parents or guardians provided written informed consent. The study protocol was sponsored by the Assistance Publique-Hopitaux de Paris and approved by the appropriate ethics committee (Comite de Protection des Personnes Ile-de France 2, n° 2014-06-10) and Agence Nationale de Securite du Medicament (ANSM, DMTCOS/DMCHIR/LAB/2014-A01043-44-A).