Safety and efficacy of growing rod technique for pediatric congenital spinal deformities

Frequent small distractions with a magnetically controlled growing rod for early-onset scoliosis and avoidance of the law of diminishing returns

PURPOSE

To assess the effect of frequent small distractions with a magnetically controlled growing rod (MCGR) on spinal length gain and achieved distraction length in children with early-onset scoliosis (EOS), and to determine whether the law of diminishing returns applies to this group of patients with MCGR.

METHODS

A consecutive series of 3 males and 4 females with EOS who underwent MCGR implantation at a mean age of 10.2 years and were followed up for a mean of 3.8 years were reviewed. Distraction was aimed at 2 mm monthly. The coronal Cobb angle, T1-S1 length gain, and achieved distraction length were measured at 6-monthly intervals.

RESULTS

The mean total number of distractions was 31. Four of the patients had problems that may have affected distractions. The mean coronal Cobb angle improved post-operatively and was maintained throughout the follow-up period. The mean T1-S1 length gain and achieved distraction length varied over the follow-up period and did not diminish with repeated lengthening.

CONCLUSIONS

Frequent small distractions with the MCGR for EOS enable T1-S1 and achieved distraction length gain without significant reduction in gain after repeated lengthening.

Management and outcomes of scoliosis in children with congenital diaphragmatic hernia

PURPOSE

The purpose of this study was to evaluate the management and outcomes of CDH patients with scoliosis.

METHODS

From January 1996 to August 2015, 26 of 380 (7%) CDH patients were diagnosed with scoliosis. Six (23%) were prenatally diagnosed by ultrasound, and 9 (35%) were diagnosed postnatally. The remaining 11 (42%) developed scoliosis after discharge. Mean follow-up was 6.6years.

RESULTS

Among the 15 patients with congenital scoliosis, there were 2 (13%) perinatal deaths. Five of the 13 (38%) survivors required orthopedic surgery, and 2 have required bracing. The mean age at initial surgery was 7years. These five children underwent an average of 2.8 (range 1-7) expansions or revisions. All surgical patients required supplemental oxygen at 28days of life, and 1 required a tracheostomy. None of the 11 patients who developed scoliosis later in life required surgery, but 3 have required bracing. Six of the 11 (55%) required a patch repair for CDH compared to 158 of 264 (60%) CDH patients without scoliosis (p=0.73).

CONCLUSIONS

Early diagnosis of scoliosis in CDH patients is associated with a high rate of surgery. There was not a higher incidence of patch repair among patients who developed scoliosis.

LEVEL OF EVIDENCE

Prognosis. Retrospective study, level II.

Convex Instrumented Hemiepiphysiodesis With Concave Distraction: A Treatment Option for Long Sweeping Congenital Curves

BACKGROUND

Convex hemiepiphysiodesis has been reported to have mixed results in the treatment of congenital spine deformities. Multiple modifications of the original technique were suggested to improve the results. The purpose of this study is to report the results and complications of an instrumented convex growth arrest procedure modified with concave distraction.

METHODS

The records of 11 patients with long sweeping congenital curves (involving multiple anomalous vertebrae) who underwent convex instrumented hemiepiphysiodesis with concave distraction were evaluated. Mean age at index operation was 58 months (range, 29 to 101 mo). Lengthening of the concave distraction rod was done every 6 months. The magnitude of coronal/sagittal deformity and T1-T12 height were measured on the preoperative, postoperative, and latest follow-up radiographs. Average follow-up was 44.9 months (range, 24 to 89 mo).

RESULTS

In the coronal plane, the convex hemiepiphysiodesis segment was corrected from an average of 60.5 to 40.4 degrees postoperatively and further improved to 35.5 degrees at the latest follow-up. The distracted segment was corrected from 33.4 to 15.2 degrees postoperatively and to 12.7 degrees at the latest follow-up. Sagittal plane alignment was minimally affected. The average T1-T12 height was 157.1 mm in the early postoperative period and 181.1 mm at last follow-up. During follow-up, we identified partial pull-out of screws on the distraction side in 5 of the 11 patients and rod breakages in 3 patients. These were revised during planned lengthenings. There were no unplanned surgeries, deep wound infections, nor neurological complications.

CONCLUSIONS

Convex instrumented hemiepiphysiodesis with concave distraction resulted in good curve correction while maintaining the growth of thorax. The correction of the anomalous segment improved over time, proving the effectiveness of the hemiepiphysiodesis. Addition of a concave distraction construct appears to enhance spinal growth, thereby augmenting the hemiepiphysiodesis effect.

Use of Vertical Expandable Prosthetic Titanium Rib (VEPTR) in the Treatment of Congenital Scoliosis Without Fused Ribs

BACKGROUND

Although the vertical expandable prosthetic titanium rib (VEPTR) has been shown to be useful in treating congenital scoliosis (CS) with fused ribs, no studies to date have specifically evaluated the efficacy of VEPTR in the treatment of CS without fused ribs. The purpose of this study was to determine the effectiveness of VEPTR in sagittal/coronal curve correction and spine growth and compare its complication rate to the use of VEPTR in other conditions and to other treatment methods used for CS.

METHODS

A multicenter database was queried for patients with CS without fused ribs treated with VEPTR. Anteroposterior (AP) and lateral radiographs were used to measure parameters at 3 timepoints (preoperative, immediate postoperative, and latest follow-up): coronal Cobb angle, sagittal kyphosis, and thoracic and lumbar spine heights. Clinical data included age, time to follow-up, and complications.

RESULTS

Twenty-five patients (13 females, 12 males) were identified. The average age at implantation was 5.7 years, with an average follow-up of 50 months. Several parameters improved from preoperative to latest follow-up: coronal Cobb angle (69 to 54 degrees, P<0.0001), thoracic spine height (T1-T12) in the AP (13.3 to 15.9 cm, P<0.0001) and lateral (14.8 to 17.4 cm, P=0.0024) planes, and lumbar spine height (L1-S1) in the AP (8.8 to 11.4 cm, P<0.0001) and lateral (9.9 to 11.9 cm, P=0.0002) planes. Kyphosis increased over the study period (36 to 41 degrees, P=0.6). Fifteen patients (60%) had 41 complications (average 2.75; range, 1 to 12). Twenty-eight complications (68%) were device-related, and 13 (32%) were disease-related. The most common complications were infection, wound dehiscence, and device migration. Six complications (15%) altered the course of treatment. Thoracic spine height increased 79% of expected growth.

CONCLUSION

VEPTR is an effective treatment for patients with CS without fused ribs, as evidenced by improved radiographic parameters and increased spinal height, with a complication rate which is high but similar to other methods of treatment.

LEVEL OF EVIDENCE

Level IV-case series.

The effect of growing Rod treatment on coronal balance during serial lengthening surgeries in early onset scoliosis

Background

Gaining and maintaining spinal balance after surgery is of great importance for early onset scoliosis (EOS). However, tendency of balance on the coronal plane after growing rod surgery has not been studied before. This study evaluated the effect of growing rod treatment on coronal balance (CB) during serial lengthening surgeries in EOS.

Methods

All EOS patients treated with growing rod technique in our hospital from August 2002 to June 2014 were retrospectively reviewed. Radiographic data before the sixth lengthening surgery were measured on the posteroanterior X-ray images, including global CB (C7 plumbline-central sacral vertical line, C7PL-CSVL), regional CB (apical vertebrae-CSVL), Cobb angle of the main curve and pelvic inlet width (PIW). Global CB index and regional CB index were calculated as dividing global CB and regional CB by PIW, respectively. The changes of these parameters during repeated lengthening surgeries were analyzed.

Results

Five hundred seventy Radiographs of 67 patients, including 134 images before and after growing rod insertion surgeries and 436 images pre- and post-lengthening surgeries were measured. Global CB and global CB index did not show significant differences between every two set points during lengthening procedures (P > 0.05). The percentage of patients with C7PL-CSVL distance more than 20 mm roughly ranged from 30 to 45 % during the lengthening process. With regards to regional CB and main curve Cobb angles, there were significant differences between every two adjacent set points during the first five lengthening surgeries (P < 0.05).

Conclusions

Global CB did not significantly change during serial lengthening surgeries and C7PL-CSVL distances of greater than 20 mm comprised of over one third of patients during growing rod treatment. However, worsening regional CB and Cobb angles of the main curve during lengthening intervals were corrected by lengthening manipulation and maintained at a stable level.

Actuator pin fracture in magnetically controlled growing rods: two cases

BACKGROUND CONTEXT

Magnetically controlled growing rods (MCGRs) are used in the management of early-onset scoliosis (EOS). Each MCGR contains a telescopic actuator that serves as the distraction element when stimulated by an external remote controller (ERC), permitting non-invasive lengthening in the outpatient clinic.

PURPOSE

This report highlights a subtle cause of MCGR failure. We present the first two reported cases of lengthening pin fracture in patients with dual-MCGR constructs.

STUDY DESIGN

We present two cases of patients with EOS treated with dual-construct MAGEC (MAGnetic Expansion Control, Ellipse Technologies Inc, Aliso Viejo, CA, USA) MCGRs.

METHODS

A 12-year-old boy presented describing a "popping" sensation in his thoracic spine and resultant grating 36 months following MCGR insertion.

RESULTS

A plain radiograph revealed a subtle fracture of the lengthening pin within the actuator of the right MCGR. Following identification of this case of implant failure, we reviewed the most recent radiographs of all nine of our patients treated with this MCGR in our institution, resulting in the discovery of bilateral MCGR lengthening pin fractures in an otherwise asymptomatic 11-year-old girl.

CONCLUSIONS

Clinicians should have a high index of suspicion of structural implant failure when presented with histories similar to those reported in our first case, or following unsuccessful distraction of MCGRs. In such cases new radiographs should be taken, and all previous images should be reviewed for evidence of this phenomenon. Centers that document MCGR lengthening with ultrasound should obtain plain radiographs every 6 months to evaluate the structural integrity of the implant.

Clinical utility of ultrasound to prospectively monitor distraction of magnetically controlled growing rods

BACKGROUND CONTEXT

Growing rods are commonly used for surgical treatment of skeletally immature patients with scoliosis, but require repeated surgeries for distractions and are fraught with complications. As an alternative, the use of magnetically controlled growing rods (MCGR) allows for more frequent non-invasive distractions to mimic normal growth. However, more plain radiographs are needed to monitor increased distraction frequency, thereby increasing ionizing radiation exposure to the developing child. The use of ultrasound, which emits no radiation, has been found in a cross-sectional study to be reliable in measuring MCGR distractions.

PURPOSE

The study aims to address the prospective clinical utility of ultrasound compared with plain radiographs for assessing MCGR distractions.

STUDY DESIGN

This is a prospective study.

PATIENT SAMPLE

The study includes patients with early-onset scoliosis undergoing distractions after MCGR implant.

OUTCOME MEASURES

The distraction length on plain radiographs and ultrasound was measured.

METHODS

This is a prospective study of patients treated with MCGR. Patients with both single- and dual-rod systems were included. Outpatient distractions were performed at monthly intervals, targeting 2 mm of distraction on each occasion. Assessment of distraction length was monitored by ultrasound at each visit; plain radiographs were taken every 6 months and were compared with ultrasound measurements.

RESULTS

Nine patients (5 female, 4 male), with a mean of 29 distractions (standard deviation [SD] ±14.3), were recruited. The mean distracted length per 6 months was 5.7 mm (SD ±3.6 mm) on plain radiographs and 5.2 mm (SD ±3.9 mm) on ultrasound for the concave rod, and 6.1 mm (SD ±3.6 mm) on plain radiographs and 5.9 mm (SD ±3.8 mm) on ultrasound for the convex rod. Excellent inter- and intra-rater reliabilities were observed for radiographic and ultrasound measurements. An excellent correlation was noted between the two imaging modalities (r=0.93; p<.0001).

CONCLUSIONS

This is the first prospective study to validate that ultrasound assessment of MCGR distraction lengths was highly comparable with that of plain radiographs. The present study has verified that ultrasound can be used to document length changes by distraction over time and that it had high clinical utility. Ultrasound can be a reliable alternative to plain radiographs, thereby avoiding radiation exposure and its potential detrimental sequelae in the developing child.

A New Classification System to Report Complications in Growing Spine Surgery: A Multicenter Consensus Study

INTRODUCTION

The use of growth-sparing instrumentation in pediatric spinal deformity is associated with a significant incidence of adverse events. However, there is no consistent way to report these complications, allowing for meaningful comparison of different growth-sparing techniques and strategies. The purpose of this study is to develop consensus for a new classification system to report these complications.

METHODS

The authors, who represent lead surgeons from 5 major pediatric spine centers, collaborated to develop a classification system to report complications associated with growing spine surgery. Following IRB approval, this system was then tested using a minimum of 10 patients from each center with at least 2-year follow-up after initial implantation of growing instrumentation to assess ease of use and consistency in reporting complications. Inclusion criteria were only patients who had surgical treatment of early onset scoliosis and did not include casting or bracing.Complications are defined as an unplanned medical event in the course of treatment that may or may not affect final outcome. Severity refers to the level of care and urgency required to treat the complication, and can be classified as device related or disease related. Severity grade (SV) I is a complication that does not require unplanned surgery, and can be corrected at the next scheduled surgery. SVII requires an unplanned surgery, with SVIIA requiring a single trip and SVIIB needing multiple trips for resolution. SVIII is a complication that substantially alters the planned course of treatment. Disease-related complications are classified as grade SVI if no hospitalization is required and grade SVII if hospitalization is required. SVIV was defined as death, either disease or device related.

RESULTS

A total of 65 patients from 5 institutions met enrollment criteria for the study; 56 patients had at least 1 complication and 9 had no complications. There were 14 growing rods, 47 VEPTRs, ,and 4 hybrid constructs. The average age at implant was 4.7 years. There were an average of 5.4 expansions, 1.6 revisions, and 0.8 exchanges per patient. The minimum follow-up was 2 years. The most common complications were migration (60), infection (31), pneumonia (21), and instrumentation failure (23). When classified, the complications were grade I (57), grade IIA (79), grade IIB (10), and grade III (6).

CONCLUSIONS

Well-documented uncertainty in clinical decision making in this area highlights the need for more rigorous clinical research. Reporting complications standardized for severity and impact on the course of treatment in growing spine surgery is a necessary prerequisite for meaningful comparative evaluation of different treatment options. This study shows that although complications were common, only 9% (SVIII) were severe enough to change the planned course of treatment.

SIGNIFICANCE

We propose that future studies reporting complications of different methods of growth-sparing spine surgery use this classification moving forward so that meaningful comparisons can be made between different treatment techniques.

Special article: Update on the magnetically controlled growing rod: tips and pitfalls

Magnetically controlled growing rods (MCGR) have become an important treatment option in young patients with spinal deformities. This device allows for gradual lengthening on an outpatient setting with continuous neurological monitoring in an awake patient. With its growing popularity and interest, this study reports the tips, pitfalls, and complications of the MCGR for management of scoliosis. On 3 June 2015 at the University of Hong Kong, 32 participants from 16 regions shared their experience with MCGR. Current indications for surgery include early-onset scoliosis patients. Adolescent idiopathic scoliosis and congenital scoliosis patients have less favourable outcomes. The number of instrumented levels should be minimised, as all instrumented levels must be included in the definitive fusion surgery. Rod contouring is important and owing to the straight portion of the rod housing the magnet, there is limited proximal rod portion for proper contouring, which may predispose to proximal junctional kyphosis. There is currently no consensus on the rod configuration, timing, frequency, technique, and amount of distraction. Risk factors for distraction failure include larger patients, internal magnets too close to each other, and magnets too close to the apex of the major curve. Future studies should resolve the issues regarding the technique of distraction, optimal frequency and amount of distraction per session. More comprehensive cost analyses should be performed.

Early-onset scoliosis: current treatment

Early-onset scoliosis, which appears before the age of 10, can be due to congenital vertebral anomalies, neuromuscular diseases, scoliosis-associated syndromes, or idiopathic causes. It can have serious consequences for lung development and significantly reduce the life expectancy compared to adolescent scoliosis. Extended posterior fusion must be avoided to prevent the crankshaft phenomenon, uneven growth of the trunk and especially restrictive lung disease. Conservative (non-surgical) treatment is used first. If this fails, fusionless surgery can be performed to delay the final fusion procedure until the patient is older. The gold standard delaying surgical treatment is the implantation of growing rods as described by Moe and colleagues in the mid-1980s. These rods, which are lengthened during short surgical procedures at regular intervals, curb the scoliosis progression until the patient reaches an age where fusion can be performed. Knowledge of this technique and its complications has led to several mechanical improvements being made, namely use of rods that can be distracted magnetically on an outpatient basis, without the need for anesthesia. Devices based on the same principle have been designed that preferentially attach to the ribs to specifically address chest wall and spine dysplasia. The second category of surgical devices consists of rods used to guide spinal growth that do not require repeated surgical procedures. The third type of fusionless surgical treatment involves slowing the growth of the scoliosis convexity to help reduce the Cobb angle. The indications are constantly changing. Improvements in surgical techniques and greater surgeon experience may help to reduce the number of complications and make this lengthy treatment acceptable to patients and their family. Long-term effects of surgery on the Cobb angle have not been compared to those involving conservative "delaying" treatments. Because the latter has fewer complications associated with it than surgery, it should be the first-line treatment for most cases of early-onset scoliosis.

Serial derotational casting in congenital scoliosis as a time-buying strategy

BACKGROUND

Serial casting is an effective treatment modality in early-onset idiopathic scoliosis; however, the role of this method in congenital scoliosis is not well studied.

METHODS

A total of 11 patients with progressive congenital scoliosis were treated with serial cast application. Age at initial cast application, magnitudes of the congenital, compensatory and sagittal deformities, coronal balance, T1 to T12 height, number of casts and time-in cast per patient, subsequent surgical interventions, and complications were evaluated.

RESULTS

Mean age at the first cast application was 40 months, and the average number of cast changes was 6.2 per patient. There were no major complications. The average precasting curve magnitude was 70.7 degrees (range, 44 to 88 degrees) and was significantly reduced to 55.1 degrees (range, 16 to 78 degrees) at the latest follow-up (P=0.005). The average precasting compensatory curve was 55.8 degrees (range, 38 to 72 degrees) and was significantly reduced to 39.8 degrees (range, 23 to 62 degrees) at the latest follow-up (P=0.017). Average T1 to 12 height increased from 12.8 cm at post-first cast to a 14.6 cm at the latest follow-up (P=0.04). Average time in cast was 26.3 months (range, 13 to 49 mo). During the treatment period, none of the patients required surgery for curve progression.

CONCLUSIONS

Serial derotational casting is a safe and effective time-buying strategy to delay the surgical interventions in congenital deformities in the short-term follow-up.

LEVEL OF EVIDENCE

Level IV, case series.

Apical and intermediate anchors without fusion improve Cobb angle and thoracic kyphosis in early-onset scoliosis

BACKGROUND

The main goal of treatment in early-onset scoliosis is to obtain and maintain curve correction while simultaneously preserving spinal, trunk, and lung growth. This study introduces a new surgical strategy, called the modified growing rod technique, which allows spinal growth and lung development while controlling the main deformity with apical and intermediate anchors without fusion. The use of intraoperative traction at the initial procedure enables spontaneous correction of the deformity and decreases the need for forceful correction maneuvers on the immature spine and prevents possible implant failures. This study seeks to evaluate (1) curve correction; (2) spinal length; (3) number of procedures performed; and (4) complications with the new approach.

DESCRIPTION OF TECHNIQUE

In the initial procedure, polyaxial pedicle screws were placed with a muscle-sparing technique. Rods were placed in situ after achieving correction with intraoperative skull-femoral traction. The most proximal and most distal screws were fixed and the rest of the screws were left with nonlocked set screws to allow vertical growth. The lengthening reoperations were performed every 6 months.

METHODS

Between 2007 and 2011, we treated 19 patients surgically for early-onset scoliosis. Of those, 16 (29%) were treated with the modified growing rod technique by the senior author (AH); an additional three patients were treated using another technique that was being studied at the time by one of the coauthors (CO); those three were not included in this study. The 16 children included nine girls and seven boys (median, 5.5 years of age; range, 4-9 years), and all had progressive scoliosis (median, 64°; range, 38°-92°). All were available for followup at a minimum of 2 years (median, 4.5 years; range, 2-6 years).

RESULTS

The initial curve Cobb angle of 64° (range, 38°-92°) improved to 21° (range, 4°-36°) and was maintained at 22° (range, 4°-36°) throughout followup. Preoperative thoracic kyphosis of 22° (range, 18°-46°) was maintained at 23° (range, 20°-39°) throughout followup without showing any substantial change. There was a 47 mm (range, 38-72 mm) increase in T1-S1 height throughout followup. The mean number of lengthening operations was 5.5 (range, 4-10). The mean T1-S1 length gain from the first lengthening was 1.18 cm (range, 1.03-2.24 cm) and decreased to 0.46 cm (range, 0,33-1.1 cm) after the fifth lengthening procedure (p = 0.009). The overall complication rate was 25% (four of 16 patients) and the procedural complication rate was 7% (seven of 102 procedures). We did not experience any rod breakages or other complications apart from two superficial wound infections managed without surgery during the treatment period. The only implant-related complications were loosening of two pedicle screws at the uppermost foundation in one patient.

CONCLUSIONS

In this preliminary study, the modified growing rod technique with apical and intermediate anchors provided satisfactory curve control, prevented progression, maintained rotational stability, and allowed continuation of trunk growth with a low implant-related complication rate.

The effect of serial growing rod lengthening on the sagittal profile and pelvic parameters in early-onset scoliosis

STUDY DESIGN

Retrospective case series.

OBJECTIVE

To report the effect of repeated growing rod (GR) lengthenings on the sagittal and pelvic profile in patients with early-onset scoliosis.

SUMMARY OF BACKGROUND DATA

Posterior distraction-based GRs have gained popularity as a technique for the surgical management of early-onset scoliosis. However, there are no published studies on the effect of serial GR lengthenings on sagittal balance, thoracic kyphosis (TK), lumbar lordosis (LL), and pelvic parameters.

METHODS

We retrospectively reviewed data from a multicenter early-onset scoliosis database. Forty-three patients who were able to walk with minimum 2-year follow-up who underwent single- or dual-GR surgery were included for review. Mean number of lengthenings was 6.4 (range, 3-16). Mean preoperative age was 5.6 years (standard deviation, 2.4 yr), and mean follow-up was 3.5 years. Maximum TK, LL, and sagittal balance were assessed preoperatively, after index surgery, and at the latest follow-up.

RESULTS

There was a significant decrease both in TK and LL after index surgery, which then increased during the lengthening period. There was a significant increase in both proximal junctional kyphosis and distal junctional angle. Pelvic parameters (pelvic tilt, pelvic incidence, sacral slope) were unchanged during the treatment period. Significant improvement was observed in sagittal balance. There was a correlation between the change in TK and change in LL.

CONCLUSION

TK decreased after index surgery and increased between the index surgery and the latest follow-up, which was accompanied by an increase in LL. All-screw proximal constructs had mean 9° more proximal junctional kyphosis than all-hook proximal constructs. An increase in proximal junctional kyphosis and distal junctional angle was found during the treatment period. Although there was an independent effect of number of lengthenings on TK, there was no significant detrimental effect on other sagittal spinopelvic parameters. GRs had a positive effect on sagittal vertical axis, which returned patients to a more neutral alignment through the course of treatment.

LEVEL OF EVIDENCE

4.

Staged Placement of Growing Rods for Metabolic Bone Disease and Insufficient Bone Quality: A Report of Two Cases

CASE

We present two cases of successful staged placement of standard growing-rod instrumentation for early-onset scoliosis in children with metabolic bone disease and poor bone quality.

CONCLUSION

Because use of growing-rod surgery is increasing throughout the world, we propose that a staged approach to placement of growing rods is a practical and safe option for surgeons who encounter patients with early-onset scoliosis and concomitant poor bone quality.

Recent advances in the management of early onset scoliosis

As the undesired results of early spinal fusion have become apparent, "growth-friendly" management methods for early onset scoliosis have been increasing during recent years. Current literature supports the use of repeated corrective cast applications as the initial management for most early onset progressive spinal deformities as either definitive treatment or as a temporizing measure. If casting is not an option or the deformity cannot be controlled via casting, one of the growth-friendly instrumentation techniques is chosen. Growth-friendly surgical methods and implants have been evolving as understanding of the disease improves.

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

BACKGROUND CONTEXT

Magnetically-controlled growing rod (MCGR) technology has been reported for the treatment of early-onset scoliosis (EOS). Such technology allows for regular and frequent outpatient rod distractions without the need for additional surgery. However, pre- and postdistraction spine radiographs are required to verify the amount of lengthening. This increased exposure to ionizing radiation in developing children significantly increases their risk profile for radiation-induced cancer and noncancerous morbidity.

PURPOSE

This study addressed the first and novel application and reliability of the use of ultrasonography, that has no ionizing radiation exposure, as an alternative to plain radiographs in the visualizing and confirming of rod distractions.

STUDY DESIGN

A prospective study.

PATIENT SAMPLE

Six EOS patients who underwent surgical treatment with MCGRs were prospectively recruited.

OUTCOME MEASURES

Imaging measurements based on ultrasound and plain radiographs.

METHODS

All patients were imaged via ultrasound, ease of rod identification was established, and the reliability and reproducibility of optimal reference point selection assessed blindly by three individuals. The clinical algorithm, using ultrasound, was subsequently implemented. Plain radiographs served as controls.

RESULTS

Assessment of the rod's neck distance on ultrasound demonstrated a high degree of interrater reliability (a=0.99; p<.001). Intrarater reliability remained high on repeat measurements at different time intervals (a=1.00; p<.001). Satisfactory interrater reliability was noted when measuring the rod's neck (a=0.73; p=.010) and high reliability was noted in assessing the housing of the rod (a=0.85; p=.01) on plain radiographs. Under blinded conditions, 2 mm rod distraction measured on radiographs corresponded to 1.7 mm distraction on the ultrasound (standard deviation: 0.24 mm; p<.001). Subsequently, the clinical algorithm using ultrasound, instead of radiographs, has been successfully implemented.

CONCLUSIONS

This is the first study to report the use of a novel technique using noninvasive, nonionizing ultrasound to reliably document rod distractions in EOS patients. A high level of inter- and intrarater reliabilities were noted. More importantly, the use of ultrasonography may result in fewer whole spine radiographs from being taken in patients who have had MCGRs implanted for EOS; thereby decreasing their exposure to ionizing radiation and the potential risk of future radiation-induced diseases.

One-stage posterior osteotomy with short segmental fusion and dual growing rod technique for severe rigid congenital scoliosis: the preliminary clinical outcomes of a hybrid technique

STUDY DESIGN

Retrospective study.

OBJECTIVE

To evaluate the clinical outcomes of the hybrid technique of 1-stage posterior osteotomy with short segmental fusion and dual growing rod (GR) technique for severe rigid congenital scoliosis.

SUMMARY OF BACKGROUND DATA

As some types of congenital scoliosis consist of long curve including sharp deformities producing enormous asymmetric growth at apex, they cannot be well corrected with osteotomy and short segmental fusion. GR technique may be the best option. However, enormous asymmetric growth potential due to the sharp deformities at the apex will increase risk of complications, especially implant failures.

METHODS

Seven patients (2 males, 5 females) undergoing this hybrid technique for severe rigid congenital scoliosis were retrospectively reviewed. The patients' charts were reviewed. The analysis included age at initial surgery and the latest follow-up, number and frequency of lengthening, and complications. Radiographical evaluation included measured changes in scoliosis Cobb angle, thoracic kyphosis, lumbar lordosis, trunk shift, length of T1-S1, and instrumentation.

RESULTS

The mean follow-up was 53.3 (30-77) months. The mean age at the initial surgery is 5.9 (2-10) years. The averaged lengthenings were of 5.3 per patient. The mean scoliosis improved from 81.4° to 40.1° after initial surgery and was 41.0° at the latest follow-up. The average T1-S1 length was of 1.23 cm per year. The space available for lung ratio increased from 0.86 to 0.96.

CONCLUSION

Osteotomy with short fusion could help to improve the correction of the GR and eliminate the large asymmetric growth potential around the apex, with little influence to the length of the spine. Dual GR technique could maintain correction achieved at initial surgery while allowing spinal growth to continue. This hybrid technique may be an option for young patients who present sharp deformities with large asymmetric growth potential in a long congenital spinal deformity.

LEVEL OF EVIDENCE

4.

Growth-sparing spinal instrumentation in skeletal dysplasia

STUDY DESIGN

Retrospective case series.

OBJECTIVE

To report the outcomes of distraction-based, growth-sparing spinal instrumentation in patients with skeletal dysplasia.

SUMMARY OF BACKGROUND DATA

Patients with skeletal dysplasia with spinal deformity often undergo early fusion, further compromising an already small chest. Nonfusion techniques may provide a safe alternative and allow for thoracic growth.

METHODS

Between 2004 and 2010, 12 children with a diagnosis of various types of skeletal dysplasia underwent growth-sparing spinal instrumentation for severe spinal deformities. The mean duration of treatment with growing rods was 57 months (42-84 mo). Nine patients were treated with growing rods (8 dual, 1 single), and 3 were treated with vertical expandable prosthetic titanium rib (VEPTR; Synthes). Preoperative, initial postoperative, and final follow-up anteroposterior and lateral spine radiographs were measured for magnitude of deformity, junctional kyphosis, and implant failure.

RESULTS

The major curve Cobb angle improved from a mean of 79° preoperatively to a mean of 41° at the last follow-up (52%). There was a decrease in mean thoracic kyphosis from 77° preoperatively to 64° at final follow-up and an increase in mean lumbar lordosis from 58° preoperatively to 63° at final follow-up. The mean space available for the lungs increased by 26 mm on the concave and 24 mm on the convex side. Six patients required revision surgery for proximal junctional kyphosis. There were 4 rod failures and 6 hook and 8 screw dislodgements. One patient with vertical expandable prosthetic titanium rib had failed rib fixation that required revision.

CONCLUSION

Growth-sparing spinal instrumentation in patients with skeletal dysplasia and severe spinal deformity has a high complication and revision rate, and surgeons should closely monitor these patients. The complication rate is comparable with previous reports on patients with other diagnoses. However, deformities were well controlled, some trunk growth was achieved, and fusion surgery was delayed in all cases.

LEVEL OF EVIDENCE

4.

Finite element simulation of a scoliotic spine with periodic adjustments of an attached growing rod

Early Onset Scoliosis (EOS) is a deformity of spine which occurs during growth. Spinal growing rod instrumentation is currently a procedure of early onset scoliosis management and newer technologies to treat scoliosis without fusion hold the exciting promise of a new paradigm in spinal deformity care. A Finite Element Model (FEM) of a scoliotic spine was created and enhanced to simulate spine growth after the attachment of a growing rod. Growing rod instrumentation was included utilizing FEA to accurately simulate the required 3D forces and moments to achieve the desired correction. We measured forces on the rods and the spine during adjustment periods (for correction of the spinal deformity) and during growth periods. For this study, a two-year period was simulated with adjustments at six month intervals. The FEM allowed us to collect data during growth periods from sensors which are only accessible during the surgical procedures.

Surgical site infection following spinal instrumentation for scoliosis: a multicenter analysis of rates, risk factors, and pathogens

BACKGROUND

Surgical site infection following correction of pediatric scoliosis is well described. However, we are aware of no recent multicenter study describing the rates of surgical site infection, and associated pathogens, among patients with different etiologies for scoliosis.

METHODS

A multicenter, retrospective review of surgical site infections among pediatric patients undergoing spinal instrumentation to correct scoliosis was performed at three children's hospitals in the United States. Study subjects included all patients undergoing posterior spinal instrumentation from January 2006 to December 2008. Surgical site infections were defined according to the Centers for Disease Control and Prevention's National Healthcare Safety Network case definition, with infections occurring within one year after surgery.

RESULTS

Following the analysis of 1347 procedures performed in 946 patients, surgical site infection rates varied among procedures performed in patients with different scoliosis etiologies. Procedures performed in patients with neuromuscular scoliosis had the highest surgical site infection rates (9.2%), followed by those performed in patients with syndromic scoliosis (8.8%), those performed in patients with other scoliosis (8.4%), those performed in patients with congenital scoliosis (3.9%), and those performed in patients with idiopathic scoliosis (2.6%). Surgical site infection rates varied among procedures in patients undergoing primary spinal arthrodesis based on etiology, ranging from 1.2% (95% confidence interval, 0.1% to 1.3%) in patients with idiopathic scoliosis to 13.1% (95% confidence interval, 8.4% to 17.8%) in patients with neuromuscular scoliosis. Surgical site infection rates following primary and revision procedures were similar among patients with different etiologies. In distraction-based growing constructs, rates were significantly lower for lengthening procedures than for revision procedures (p = 0.012). Multivariate analysis demonstrated that non-idiopathic scoliosis and extension of instrumentation to the pelvis were risk factors for surgical site infections. The three most common pathogens were Staphylococcus aureus (25.0% [95% confidence interval, 17.8% to 32.2%]), coagulase-negative staphylococci (17.1% [95% confidence interval, 10.9% to 23.3%]), and Pseudomonas aeruginosa (10.7% [95% confidence interval, 5.6% to 15.8%]). Overall, 46.5% (95% confidence interval, 35.5% to 57.5%) of surgical site infections contained at least one gram-negative organism; 97.0% (95% confidence interval, 90.8% to 100.0%) of these infections were in patients with non-idiopathic scoliosis.

CONCLUSIONS

Surgical site infection rates were significantly higher following procedures in patients with non-idiopathic scoliosis (p < 0.001). Lengthening procedures had the lowest rate of surgical site infection among patients with early onset scoliosis who had undergone instrumentation with growing constructs. Gram-negative pathogens were common and were most common following procedures in patients with non-idiopathic scoliosis. These findings suggest a role for targeted perioperative antibiotic prophylaxis to prevent surgical site infection following pediatric scoliosis instrumentation procedures.

Some Connectors in Distraction-based Growing Rods Fail More Than Others

STUDY DESIGN

Retrospective review of a prospectively collected patient cohort.

OBJECTIVES

This study examined the rate of failure of various types of spinal rod connectors in distraction-based growing rod constructs for early-onset scoliosis.

SUMMARY OF BACKGROUND DATA

Distraction-based growing rods have a high rate of reported complications.

METHODS

We performed a retrospective review of a single surgeon's consecutive cases with growing rod constructs for early-onset scoliosis. Connector failure was defined as loosening of the connector-rod interface, which resulted in shortening of the construct and loss of distractive force. We included 30 patients with average age of 5 years (range, 1-10 years) with diagnoses of congenital scoliosis (15), neuromuscular (10), idiopathic (4), and other (1). Minimum follow-up was 2 years, with a mean follow-up of 49 months (range, 24-83 months).

RESULTS

Of 98 connectors, there were 12 connector failures (12.2%) in 9 patients. In all failures, the set screw loosened, resulting in rod slippage. On average, failures occurred 25.5 months after the index procedure, and after the third lengthening. Simple side-to-side closed connectors with circular slots had the highest rate of slippage (7 of 17; 41%). Side-to-side connectors with V-groove slots that mechanically lock the rod had 10 times fewer failures, (1 of 27; 4%) (p = .006). Only 1 of 34 longitudinal connectors failed (3%) (p = .002). The average T1-S1 gain during growth was 6.5 mm/year for patients with a connector failure and 9.0 mm/year for those who did not (p = .25). Connectors failed in dual rods (6 of 18; 33%) and single rods (6 of 15; 40%) at similar rates (p = .97).

CONCLUSIONS

Connector failure in distraction-based growing rods is associated with 28% less T1-S1 gain. Side-to-side connectors with circular slots had a failure rate of 41% compared with side-to-side connectors with V-groove slots (4%). Longitudinal connectors had a failure rate of 4%.

Dual growing rods technique for congenital scoliosis: more than 2 years outcomes: preliminary results of a single center

STUDY DESIGN

Retrospective study.

OBJECTIVE

To evaluate clinical outcomes of dual growing rod (GR) technique in treating children with congenital scoliosis (CS).

SUMMARY OF BACKGROUND DATA

Published reports on the dual GR technique results of early-onset scoliosis demonstrate it to be safe and effective. However, the use of GR in congenital spinal deformities is controversial, and there have been no reports on the results and complications of dual GR technique for CS with large series of patients.

METHODS

During 2004 to 2009, a total of 30 patients with CS underwent dual GR procedures. Of the 159 total procedures conducted within the treatment period, 125 were lengthenings with an average of 4.2 lengthenings per patient. Five patients with severe rigid deformity or kyphosis had an osteotomy at apex vertebra with short segmental fusion. The analysis included age at initial surgery and final fusion (if applicable), number and frequency of lengthenings, and complications. Radiographical evaluation was conducted.

RESULTS

The mean scoliosis improved from 72.3° to 34.9° after initial surgery and was 35.2° at the last follow-up or after final fusion. T1-S1 length increased from 25.42 to 29.03 cm after initial surgery and to 33.32 cm at last follow-up or after final fusion with an average T1-S1 length increase of 1.49 cm per year. The space available for lung ratio in patients with thoracic curves improved from 0.84 to 0.96 at the latest follow-up. Three patients reached final fusion. Complications occurred in 7 of the 30 patients, and they had a total of 13 complications.

CONCLUSION

The dual GR technique is safe and effective in the treatment of selected cases of long, complex CS. It maintains correction achieved at initial surgery while allowing spinal growth to continue. And it has an acceptable rate of complications. The osteotomy at the apex vertebra with short segmental fusion of the severe rigid scoliosis or the patients with kyphosis could help to improve the correction and decrease the implant failures, with little influence on the length of the spine.

Magnetically controlled growing rods for severe spinal curvature in young children: a prospective case series

BACKGROUND

Scoliosis in skeletally immature children is often treated by implantation of a rod to straighten the spine. Rods can be distracted (lengthened) as the spine grows, but patients need many invasive operations under general anaesthesia. Such operations are costly and associated with negative psychosocial outcomes. We assessed the effectiveness and safety of a new magnetically controlled growing rod (MCGR) for non-invasive outpatient distractions.

METHODS

We implanted the MCGR in five patients, two of whom have now reached 24 months' follow-up. Each patient underwent monthly outpatient distractions. We used radiography to measure the magnitude of the spinal curvature, rod distraction length, and spinal length. We assessed clinical outcome by measuring the degree of pain, function, mental health, satisfaction with treatment, and procedure-related complications.

FINDINGS

In the two patients with 24 months' follow-up, the mean degree of scoliosis, measured by Cobb angle, was 67° (SD 10°) before implantation and 29° (4°) at 24 months. Length of the instrumented segment of the spine increased by a mean of 1·9 mm (0·4 mm) with each distraction. Mean predicted versus actual rod distraction lengths were 2·3 mm (1·2 mm) versus 1·4 mm (0·7 mm) for patient 1, and 2·0 mm (0·2 mm) and 2·1 mm (0·7 mm) versus 1·9 mm (0·6 mm) and 1·7 mm (0·8 mm) for patient 2's right and left rods, respectively. Throughout follow-up, both patients had no pain, had good functional outcome, and were satisfied with the procedure. No MCGR-related complications were noted.

INTERPRETATION

The MCGR procedure can be safely and effectively used in outpatient settings, and minimises surgical scarring and psychological distress, improves quality of life, and is more cost-effective than is the traditional growing rod procedure. The technique could be used for non-invasive correction of abnormalities in other disorders.

FUNDING

Ellipse Technologies.

Growing rod concepts: state of the art

INTRODUCTION

Early-onset spinal deformities present multiple challenges to the surgeon. They may be rapidly progressive and unresponsive to conservative treatment, necessitating surgical intervention at an early age.

MATERIALS AND METHODS

This text attempts to provide a review of current literature and to summarize the authors' opinions.

RESULTS

This paper attempts to concisely review available literature regarding the growing rod's inception, evolution, technique, results, and complications and answers some of the controversy still surrounding it.

CONCLUSIONS

The growing rod is one of the first, most evolved, most popular and one of the most heatedly discussed technique of fusionless spinal instrumentation.

Convex instrumented hemiepiphysiodesis with concave distraction: a preliminary report

BACKGROUND

The convex growth arrest (CGA) procedure has been well accepted for treatment of congenital scoliosis as it is a simpler procedure with successful results. However, unpredictability of curve behavior, slow and usually inadequate correction, and necessity of anterior surgery for completeness of the epiphysiodesis are its shortcomings.

QUESTIONS/PURPOSES

In a preliminary study we asked whether a modification of the CGA procedure using convex instrumented hemiepiphysiodesis with concave distraction would correct the coronal plane Cobb angles and would correct or maintain sagittal plane local and global kyphosis angles. We also identified complications.

PATIENTS AND METHODS

We retrospectively reviewed five female patients who underwent the modified procedure. Their mean age at the index operation was 40 months (range, 17-55 months). The patients underwent concave distractions every 6 months. The magnitude of the convex instrumented and concave distracted curves and sagittal plane parameters were determined on the preoperative and most recent followup radiographs. Minimum followup was 26 months (mean, 34 months; range, 26-40 months).

RESULTS

In the coronal plane, the preoperative magnitude of the convex instrumented congenital curve averaged 48°. It was corrected to 36° (25%) postoperatively and was further improved to 27° (44%) at the latest followup. For the distracted segment, the mean preoperative curve was 35°, corrected to 16° postoperatively and to 8° at the latest followup, for an average correction of 77%. Sagittal plane alignment was minimally affected from the procedure. In four of the five patients we identified partial pullout of screws for the concave distraction; these were revised at the time of planned lengthening.

CONCLUSIONS

This procedure may obviate the need for multiple osteotomies and long thoracic fusions in young children with long sweeping thoracic deformities involving multiple anomalous vertebrae. Implant-related complications on the concave side may be avoided using paired pedicle screws at the proximal and distal anchor sites.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the guidelines online for a complete description of level of evidence.

Surgical and conservative treatment of patients with congenital scoliosis: α search for long-term results

Background

In view of the limited data available on the conservative treatment of patients with congenital scoliosis (CS), early surgery is suggested in mild cases with formation failures. Patients with segmentation failures will not benefit from conservative treatment. The purpose of this review is to identify the mid- or long-term results of spinal fusion surgery in patients with congenital scoliosis.

Methods

Retrospective and prospective studies were included, reporting on the outcome of surgery in patients with congenital scoliosis. Studies concerning a small numbers of cases treated conservatively were included too. We analyzed mid-term (5 to 7 years) and long-term results (7 years or more), both as regards the maintenance of the correction of scoliosis and the safety of instrumentation, the early and late complications of surgery and their effect on quality of life.

Results

A small number of studies of surgically treated patients were found, contained follow-up periods of 4-6 years that in the most cases, skeletal maturity was not yet reached, and few with follow-up of 36-44 years. The results of bracing in children with congenital scoliosis, mainly in cases with failure of formation, were also studied.

Discussion

Spinal surgery in patients with congenital scoliosis is regarded in short as a safe procedure and should be performed. On the other hand, early and late complications are also described, concerning not only intraoperative and immediate postoperative problems, but also the safety and efficacy of the spinal instrumentation and the possibility of developing neurological disorders and the long-term effect these may have on both lung function and the quality of life of children.

Conclusions

Few cases indicate the long-term results of surgical techniques, in the natural progression of scoliosis. Similarly, few cases have been reported on the influence of conservative treatment.

In conclusion, patients with segmentation failures should be treated surgically early, according to the rate of deformity formation and certainly before the pubertal growth spurt to try to avoid cor- pulmonale, even though there is lack of evidence for that in the long-term. Furthermore, in patients with formation failures, further investigation is needed to document where a conservative approach would be necessary.