Dorsal arthrodesis of thoracic spine and effects on thorax growth in prepubertal New Zealand white rabbits

Clinical and radiographic evolution of graduate patients treated with magnetically controlled growing rods: results of a French multicentre study of 90 patients

PURPOSE

The purpose of this study was to investigate patients with early-onset scoliosis (EOS) who completed their electromagnetic lengthening rod program to assess the demographics of this population and to analyze the evolution of clinical and radiological parameters and the occurrence of complications.

METHODS

This was a multicenter study with 10 French centers. We collected all patients with EOS who had undergone electromagnetic lengthening between 2011 and 2022. They had to have reached the end of the procedure (graduate).

RESULTS

A total of 90 graduate patients were included. The mean follow-up time over the entire period was 66 months (25.3-109). Of these, only 66 patients (73.3%) underwent definitive spinal arthrodesis at the end of the lengthening phase, whereas 24 patients (26.7%) kept their hardware in situ with a mean follow-up time from the last lengthening of 25 months (3-68). Patients had an average of 2.6 surgeries (1-5) over the entire follow-up. Patients had an average of 7.9 lengthenings for a mean total lengthening of 26.9 mm (4-75). Analysis of the radiological parameters showed a percentage reduction in the main curve of 12 to 40%, depending on the etiology, with an average reduction of 73-44°, and an average thoracic height of 210 mm (171-214) for an average improvement of 31 mm (23-43). There was no significant difference in the sagittal parameters. During the lengthening phase, there were a total of 56 complications in 43 patients (43.9%; n = 56/98), of which 39 in 28 patients (28.6%) resulted in unplanned surgery. In the graduate patients, there were a total of 26 complications in 20 patients (22.2%), all of which resulted in unscheduled surgery.

CONCLUSION

MCGR, allow to decrease the number of surgeries, to progressively improve the scoliotic deformity and to reach a satisfactory thoracic height at the price of an important complication rate linked in particular to the complexity of the management of patients with an EOS.

LEVEL OF EVIDENCE II

Benefits of fixing 3 proximal vertebral bodies vs. 2 in the treatment of early-onset scoliosis with growing rods

Additional proximal fixation for growing rods in early-onset scoliosis (EOS) may offer a more effective and safer option for severe scoliosis patients with hyper-kyphosis. Here, we compared the outcomes of EOS patients treated with growing rods in which 6 proximal anchor points on 3 vertebrae were used vs. 4 proximal anchor points on 2 vertebrae. The records of patients with EOS treated surgically from January 2016 to December 2017 were retrospectively reviewed. In the Proximal 4 group, 2 vertebral bodies were anchored proximally with 4 anchor points; in the Proximal 6 group, 3 vertebral bodies were anchored proximally with 6 anchor points. Forty-two patients (mean age 5.11 ± 1.93 years) were included; 22 Proximal 4 group, 20 Proximal 6 group. Mean follow-up was 40.86 ± 13.49 months. The decrease in main curve Cobb angle postoperatively was significantly greater in the Proximal 6 group (33.22° vs. 19.08°) ( P < 0.05). Cobb thoracic kyphosis (TK) was significantly decreased postoperatively in the Proximal 6 group (mean 20.70°); no significant decrease occurred in the Proximal 4 group. The main curve Cobb angle decrease at last follow-up was significantly greater in the Proximal 6 group (37.84° vs. 24.23°) ( P < 0.05). Cobb TK was significantly decreased at last follow-up in the Proximal 6 group (mean 25.17°, P < 0.05); no significant decrease occurred in the Proximal 4 group. Instrument complications were lower in the Proximal 6 group (15.00% vs. 45.45%) ( P < 0.05). No proximal junctional kyphosis was noted. Fixing 3 proximal vertebral bodies with 6 anchors improves radiographic outcomes of EOS treated with growing rods, and has a lower rate of screw pull-out.

Effects of spinal deformities on lung development in children: a review

Scoliosis before the age of 5 years is referred to as early-onset scoliosis (EOS). While causes may vary, EOS can potentially affect respiratory function and lung development as children grow. Moreover, scoliosis can lead to thoracic insufficiency syndrome when aggravated or left untreated. Therefore, spinal thoracic deformities often require intervention in early childhood, and solving these problems requires new methods that include the means for both deformity correction and growth maintenance. Therapeutic strategies for preserving the growing spine and thorax include growth rods, vertically expandable titanium artificial ribs, MAGEC rods, braces and casts. The goals of any growth-promoting surgical strategy are to alter the natural history of cardiorespiratory development, limit the progression of underlying spondylarthrosis deformities and minimize negative changes in spondylothorax biomechanics due to the instrumental action of the implant. This review further elucidates EOS in terms of its aetiology, pathogenesis, pathology and treatment.

Postoperative changes in rib cage deviation in adolescent idiopathic scoliosis

BACKGROUND

Scoliosis causes changes in the thorax, but it is unclear what type of changes occur in the thoracic profile after scoliosis surgery.

OBJECTIVE

To investigate changes in rib cage deviation in the postoperative period after adolescent idiopathic scoliosis (AIS) surgery.

METHODS

Forty-four patients with AIS with a main right thoracic curvature underwent posterior surgical fusion (PSF), and radiological parameters of the spine and thorax were evaluated.

RESULTS

The correction rates of main thoracic curve (MT)-Cobb angle at immediate after surgery and postoperative follow-up (2 years) were 64% and 66%, respectively. At these two postoperative time points, the correction rates of height of thoracic vertebrae 1 to 12 (T1T12) were 10% and 12%; the correction rates of Rib-vertebra angle difference (RVAD) were 59% and 52%; the correction rates of Apical rib hump prominence (RH) were 58% and 76%; while the correction rates of Apical vertebral body-rib ratio (AVB-R) were 23% and 25%, respectively. Statistical analysis showed that all these radiological parameters at the two postoperative time points were significantly different from the preoperative values (p< 0.001). There were significant correlations between MT-Cobb angle and T1-T12 height (p< 0.001), RVAD (p< 0.001), RH (p< 0.001), and AVB-R (p< 0.001).

CONCLUSIONS

Posterior spinal fusion appears to be effective at correcting scoliosis, and the correction of rib cage deviation also plays an important role.

Outcomes of growing rods in a series of early-onset scoliosis patients with neurofibromatosis type 1

OBJECTIVE

Early-onset scoliosis (EOS) is not uncommon in patients with neurofibromatosis type 1 (NF1). Despite conservative treatment, spinal deformities progress and require early surgical intervention. To avoid potential interference with chest and trunk growth, growing rods (GRs) have been used effectively in EOS of various etiologies. In this study the authors sought to analyze the outcomes of GRs in EOS patients with NF1.

METHODS

This was a retrospective single-center cohort study that included consecutive EOS patients with NF1 who were treated with GRs and were followed up for a minimum of 2 years. Clinical and radiological analyses were performed preoperatively and until the last follow-up.

RESULTS

From to 2008 to 2017, 18 patients (6 male, 12 female) underwent GR surgery (14 single GRs, 4 dual GRs) at a mean age of 8 ± 2.1 years. Mean follow-up was 5 ± 2.4 years. Fifty-five lengthenings were performed at a mean rate of 3 lengthenings per patient (range 0-7). Ten of 14 single GRs (71%) were converted into dual GRs during treatment. No patient underwent definitive posterior spinal fusion (PSF) at GR treatment completion. The mean initial and last follow-up major curves were 57° and 36°, respectively (p < 0.001, 37% correction). The average T1-S1 increase was 13 mm/yr. Six of 9 hyperkyphotic patients had normal kyphosis at last follow-up. There were 26 complications involving 13 patients (72%), with 1 patient who required unplanned revision. The primary complications were instrumentation related, consisting of 17 proximal hook dislodgments, 6 distal pedicle screw pullouts, and 2 rod fractures. Only 1 patient experienced a mechanical complication after dual GR implantation. There were no wound infections.

CONCLUSIONS

The GR technique provided satisfactory spinal deformity control in EOS patients with NF1 while allowing substantial spinal growth. Adequately contoured dual GRs with proximal hooks placed in nondystrophic regions should be used to minimize implant-related complications. Surgeons should not attempt to correct kyphosis at GR implantation.

Dynamic 3D Reconstruction of Thoracic Cage and Abdomen in Children and Adolescents With Scoliosis: Preliminary Results of Optical Reflective Motion Analysis Assessment

BACKGROUND

In patients with untreated scoliosis or in those with posterior spinal instrumented fusion (PSF), the movements of neither the thoracic cage (ThC) nor the abdomen (ABD) during quiet and deep breathing have been well defined in the literature. The purpose of this study was to evaluate kinematic variations in the ThC and ABD during quiet and deep breathing by optical reflective motion analysis (ORMA) in children with scoliosis.

METHODS

The study included 6 healthy children (group A), 7 subjects with untreated scoliosis over 50 degrees (group B), and 8 patients with scoliosis treated by PSF (group C). After anthropometric measurements (standing height, sitting height, arm span, chest perimeter, body weight, body mass index, T1-T12, and L1-L5 length) were obtained, the movements of subjects during quiet and deep breathing were measured with a 10-camera 3-dimensional ORMA system (82 markers) with the subjects in a standard standing position.

RESULTS

No significant differences were observed in sex, age, weight, height, or arm span (P>0.05). Significant differences were observed in the chest perimeter, Cobb angle, and body mass index (P<0.05). ThC and ABD movements during quiet and deep breathing decreased significantly in group B and C when compared with group A (P<0.05). Group B showed decreased expansion of the ThC (-52.4% to -58.3%) and relatively increased motion of the ABD compared with groups A and C (P<0.001). However, ABD expansion remained lower in group B than in groups A and C (-32.8% and -5.7%). PSF does not completely eliminate transverse plane kinematics, although a greater reduction was observed at instrumented than noninstrumented levels (-60.8% vs. -35.1%; P<0.05).

CONCLUSIONS

ORMA is a useful tool for assessing alterations in the kinematics of the ThC and ABD caused by severe scoliosis and/or PSF. Compared with normal subjects, patients with severe scoliosis had poorer and less effective kinematics of the ThC and ABD. In contrast, operated subjects had better and more effective kinematics of the ThC and ABD, breathing curves, thoracic expansion, and abdominal movements closer to normal compared with patients with severe, untreated deformity.

LEVEL OF EVIDENCE

Level III.

Serial elongation derotation flexion casting in children with infantile and juvenile scoliosis

Infantile (IS) and juvenile scoliosis (JS) are among the most challenging conditions pediatric orthopedic surgeons are facing in the present days. However, the best treatment of IS and JS is still debated and it remains controversial, at least for some aspects. Untreated early onset spinal deformities may lead to pulmonary and heart compromise. Growth friendly surgical techniques imply multiple distractions with increased risk of auto-fusion, infection and curve stiffening. Serial casting has been proven to be a valuable option to treat children with early onset scoliosis (EOS) in an attempt to delay surgery (in most cases) or to cure the disease (in few cases). More than five decades ago, Cotrel and Morel from France, introduced the Elongation-Derotation-Flexion (EDF) casting technique. EDF cast is a custom-made thoracolumbar cast that corrects the deformed spine three-dimensionally. Serial EDF casting is able to modulate spinal growth and it can-at least in some cases-prevent the progression of the spinal deformity. Today, serial EDF casting technique has become one of the accepted treatment options for the management of children with IS and JS. The main objective of this work is to describe the EDF serial casting technique for the treatment of children with IS and JS, as well as to highlight its advantages and its limits by providing a review of the most recent literature.

The immature spine: growth and idiopathic scoliosis

Untreated progressive scoliosis can have negative effects on the growing spine as asymmetrical forces will act on the growth plates of the vertebral column (>130 growth plates). Spinal growth can be considered as a mixture of hierarchy, synchronization, and harmony: the slightest error can lead to a complex malformation; it is also a very dynamic process although it does not progress linearly: periods of acceleration are followed by periods of deceleration. Remaining growth is a determining factor for the worsening of idiopathic scoliosis (IS): the younger is the child, the higher is the risk of progression, and the more severe will be the disease. After birth, growth of the spine is not linear, and three periods can be identified: (I) between birth and age 5 years; (II) between age 5 and 10 years of age; (III) between age 10 and skeletal maturity. Spine and thoracic cage growth are correlated, although their growth is not synchronous. Timely control of the spinal deformity and its correction are mandatory to restore-as soon as possible-the harmony and the hierarchy of growth between the different growth plates. If action is delayed, the abnormal growth and the subsequent anatomical modifications will lead to a progressive, evolutive, and irreversible clinical picture. This article aims to provide a comprehensive review of how spinal deformities can affect the normal spine and thoracic cage growth.

Thoracic cage volume and dimension assessment by optoelectronic molding in normal children and adolescents during growth

PURPOSE

The thoracic spine, the chondral and osseous ribs, and the sternum together make up the thoracic cage. These elements are strictly correlated, although their growth is not synchronous. The purpose of this study is to provide a comprehensive data set of thoracic dimensions and non-invasive volumetric assessment in a large cohort of males and females from early childhood to young adult age.

METHODS

In all, 622 healthy individuals (406 girls, 216 boys) aged 6-18 years were consecutively enrolled between 2006 and 2016. All had to be healthy with no history of spinal deformity, or any lung, cardiovascular, systemic or neuromuscular disease. The optical ORTEN system for trunk surface data acquisition was used to calculate thoracic cage volume (V) and perimeter (Pe), anterior-posterior depth (AP) and transverse diameter (TD), AP/TD ratio, sternal length (St), and T1-T12 distance (Tle) in all patients.

RESULTS

The overall average age was 11.1 ± 2.5 years (4-18) for girls and 11.0 ± 3.1 years (4-18) for boys. Average growth parameters were: standing height 146.2 ± 14.6 cm (103-172) for girls and 146.4 ± 20.0 cm (94-192) for boys, sitting height 75.4 ± 8.6 cm (61-91) for girls and 75.5 ± 10.3 cm (60-99) for boys, weight 37.6 ± 10.4 kg (16-65) for girls and 38.3 ± 14.3 kg (13.7-104) for boys, BMI 16.7 ± 3.7 (18.5-26) for girls and 17.0 ± 3.3 (18.7-34.3) for boys. At age 6-8 years: V was 52.5% of its final size in girls and 44.9% in boys; Pe was 80.2% its final length in girls and 76.8% in boys; St reached 68% of its final size in girls and 66.9% in boys; Tle reached 73.3% of its final length in girls and 71.2% in boys. At skeletal maturity, thoracic cage volume in boys was 19.4% greater than in girls (p < 0.05). AP/TD ratio remained < 1 in all age groups and did not differ between genders (p > 0.05).

CONCLUSION

Growth of the thoracic cage is shown to be a gradual process that is more linear than previously reported. Only small increases in annual growth rates were observed during the pubertal growth spurt. The most important events characterizing thoracic cage development occurred during the first few years of postnatal growth. The circular cross-section of the very young child's thorax reached adult-like proportions together with its ovoid shape before age 6 years.

Minimizing Spine Autofusion With the Use of Semiconstrained Growing Rods for Early Onset Scoliosis in Children

BACKGROUND

A new growing rod (GR) design, the semiconstrained growing rod (SCGR), with the added advantage of axial rotation freedom within the components, has been introduced at our center which has been shown to be growth friendly. We hypothesize that the SCGR system would reduce autofusion in vivo, thereby maximizing the coronal plane correction, T1-S1 growth, and the final correction achieved at definitive fusion for children with an early onset scoliosis.

METHODS

In total, 28 patients had either single or dual 5.5 mm diameter SCGR placed minimally invasively through a submuscular approach. Surgical lengthening procedures occurred approximately every 6 months until the definitive fusion procedure was performed for 18 patients. Scoliosis, kyphosis, and lordosis angles, T1-S1 trunk length, and any complications encountered were evaluated.

RESULTS

For the full cohort, before GR insertion, the mean major Cobb curve angle was 72.4 degrees (SD, 18.8; range, 45 to 120), mean T1-S1 trunk length was 282 mm (SD, 59; range, 129 to 365), and at the latest follow-up (mean 6.9 y, SD 3.3, range 2.0 to 13.0), 38.8 degrees (SD, 17.5; range 10 to 90) and 377 mm (SD, 62; range, 225 to 487), respectively. For the subset of 18 patients who have had their final instrumented fusion surgery, the definitive surgery procedure alone produced a correction of the major Cobb curve angle by mean 20.3 degrees (SD, 16.1; P<0.0001), and an increase in the T1-S1 trunk length of mean 31.7 mm (SD, 23.1; P<0.0001). There were 14 complications involving 11 of the 28 patients, giving rise to 5 unplanned surgical interventions and 1 case where GR treatment was abandoned.

CONCLUSIONS

SCGR patients exhibited statistically significant increase in T1-S1 trunk length and statistically significant decrease in the severity of scoliosis over the course of GR treatment and again, importantly, with the definitive fusion surgery, suggesting that autofusion had been minimized during GR treatment with relatively low complication rates.

LEVEL OF EVIDENCE

Level IV-case series.

Growing Rods Are an Effective Fusionless Method of Controlling Early-Onset Scoliosis Associated With Neurofibromatosis Type 1 (NF1): A Multicenter Retrospective Case Series

BACKGROUND

Spinal deformities associated with neurofibromatosis type 1 (NF1) often have an early onset. These curves frequently develop dysplastic features. Rapid progression is common, and is often difficult to control with casting or bracing. Spinal fusion at a young age can potentially interfere with chest and trunk growth. Growing rods (GRs) have been used in early-onset scoliosis (EOS) effectively. The purpose of this study was to evaluate GR use in NF1.

METHODS

Retrospective data collection was performed from a multicenter EOS database with additional patients from our own institute. Each patient had a genetic diagnosis of NF1 and was treated with GR. Results were compared with reported results of GR in EOS in the literature.

RESULTS

Fourteen patients from 5 centers underwent a total of 71 procedures with an average follow-up of 54 months. Mean age at surgery was 6.8 years. Means of initial and final curves were 74 and 36 degrees, respectively (51% correction). Spine grew at an average of 39 mm (11.2 mm per year). Implant-related complications were the most common (8/14, 57%), including failure of proximal construct (5/14), rod breakage (2/14), and prominent implants (1/14). There was no significant difference between screws and hooks as proximal anchors (Fischer test). Two patients had deep infection that needed debridement.

CONCLUSIONS

This retrospective pooled data study is the first report on the treatment of early-onset NF1 scoliosis with GRs. The use of GRs in these patients effectively controls the spinal deformity and facilitates growth of the spine. The complications were no greater than those seen in other conditions causing EOS. Failure of proximal anchors was found to be the most common complication.

LEVEL OF EVIDENCE

Level IV-retrospective case series.

Three-dimensional and volumetric thoracic growth in children with moderate idiopathic scoliosis compared with normal

We aimed to measure thoracic dimensions and volume in relation to growth and verify the influence of scoliosis on thoracic growth. A reference group of 294 healthy volunteers was compared with a group of 557 patients with idiopathic scoliosis ranging in age from 3 to 25 years. The optical ORTEN system for trunk surface data acquisition was used to calculate thoracic volume, perimeter, anterior-posterior and transversal diameters, T1-T12 length, and sternal length. There was no significant difference in thoracic dimensions and volume between scoliosis and reference groups in either girls or boys. Thoracic volume correlated with weight and with sitting height. The transversal diameter represented ∼30%, the anterior-posterior diameter 20%, and the thoracic perimeter 100% of sitting height. Mild and moderate scoliosis does not affect thoracic diameters and volume at any stage of growth. Relationships between thoracic parameters and sitting height are valuable indicators in clinical practice. They do not differ between normal individuals and scoliotic patients with moderate trunk asymmetry.

Radiologic and histological observations in experimental T1-T12 dorsal arthrodesis: A qualitative description of T1-T12 segment and other body parts involved, between prepubertal age and skeletal maturityxs

BACKGROUND

This experimental study provides a qualitative description and the morpho-structural features of the fusions taking place in the thoracic spine between prepubertal age and skeletal maturity. There is a lack of informations regarding the influence of partial or total dorso-thoracic vertebral arthrodesis on the development of the thoracic cage as well as its potential effects on different intra and extra-thoracic organs. This study admits the hypothesis that vertebral arthrodesis may have influence on other body areas and so, it intends to verify the possible secondary involvement of other body parts, such as intervertebral discs, cervical and thoracic spinal ganglia, sternocostal cartilage, ovaries and lungs.

MATERIALS AND METHODS

Fifty-four female New Zealand white rabbits were submitted to dorsal arthrodesis. The radiologic imaging and light microscopy histological pictures were taken and studied in all. Computed tomography (CT) scan measurements were performed in operated and sham operated rabbits at different time. Similarly, histological specimens of intervertebral discs, cervical and thoracic spinal ganglia, sternocostal cartilage, ovaries and lungs were analyzed at different times. The study ended at the age of 17-18 months.

RESULTS

Most rabbits had formed a fusion mass, which was only fibrous at first, then osteofibrous and finally, in the older subjects, structured in lamellar-osteon tissue. Intervertebral foramens were negatively involved in vertebral arthrodesis, as shown by CT scans. Intervertebral discs showed irregular aspects. The increase of atresic follicles and the reduction of primordial follicles in operated rabbits led to the hypothesis of a cause-effect relationship between arthrodesis and modified hormonal status. Dorsal root ganglia showed microscopic alterations in operated rabbits especially.

CONCLUSIONS

The process of fusion mass and bone formation, associated with the arthrodesis, involves at different degrees of the vertebral bodies, discs and intervertebral foramens, ganglia and spinal nerve roots.

The effect of vertical expandable prosthetic titanium rib on growth in congenital scoliosis

Aims:

In the treatment of thoracic insufficiency syndrome, the main aim is to maintain spinal and thoracic growth in order to continue respiratory functions. Vertical expandable prosthetic titanium rib (VEPTR) device application is a method of choice especially in the congenital cases with a thoracic deformity. In our study, we evaluated the effect of VEPTR on growth in congenital scoliosis.

Materials and Methods:

Four female patients in whom VEPTR was applied were retrospectively evaluated. Anteroposterior (AP) and lateral Cobb angles that were measured preoperatively and during the last control, space available for lung (SAL), T1-S1 and T1-T12 distances, coronal and sagittal balances were compared.

Results:

Four female patients in whom VEPTR was applied were retrospectively evaluated. AP and lateral Cobb angles that were measured preoperatively and during the last control, SAL, T1-S1, and T1-T12 distances, coronal and sagittal balances were compared.

Conclusions:

VEPTR may provide a good correction, and we observed a growth in the spine height and SAL following the treatment of congenital deformities. Long-term, multicenter, prospective studies that compare the spinal height, respiratory functions, the severity of the deformity, and the spinal balance are required in order to evaluate the efficacy of VEPTR.

Effect of thoracic arthrodesis in prepubertal New Zealand white rabbits on cardio-pulmonary function

BACKGROUND

This experimental study was aimed at evaluating the type of cardiac and pulmonary involvement, in relation to changes of the thoracic spine and cage in prepubertal rabbits with nondeformed spine following dorsal arthrodesis. The hypothesis was that T1-T12 arthrodesis modified thoracic dimensions, but would not modify cardiopulmonary function once skeletal maturity was reached.

MATERIALS AND METHODS

The study was conducted in 16 female New Zealand White (NZW) rabbits. Nine rabbits were subjected to T1-T12 dorsal arthrodesis while seven were sham-operated. Echocardiographic images were obtained at 12 months after surgery and parameters for 2-dimensional and M-mode echocardiographic variables were assessed. One week before echocardiographic examination, blood samples were withdrawn from the animals' central artery of the left ear to obtain blood gas values. One week after echocardiographic assessment, a thoracic CT scan was performed under general anesthesia. Chest depth (CD) and width (CW), thoracic kyphosis (ThK) and sternal length (StL) were measured; thoracic index (ThI), expressed as CD/CW ratio. All subjects were euthanized after the CT scan. Heart and lungs were subsequently removed to measure weight and volume.

RESULTS

The values for 2-dimensional and M-mode echocardiographic variables were found to be uniformly and significantly higher, compared to those reported in anesthetized rabbits. CD, ThK, and StL were considerably lower in operated rabbits, as compared to the ones that were sham-operated. Similarly, the ThI was lower in operated rabbits than in sham-operated ones.

CONCLUSION

Irregularities in thoracic cage growth resulting from thoracic spine arthrodesis did not alter blood and echocardiographic parameters in NZW rabbits.

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.

Thoracic cage plasticity in prepubertal New Zealand white rabbits submitted to T1-T12 dorsal arthrodesis: computed tomography evaluation, echocardiographic assessment and cardio-pulmonary measurements

PURPOSE

We aimed to describe the morphological changes in the thoracic cage and spinal column induced in New Zealand White (NZW) prepubertal rabbits subjected to dorsal arthrodesis and observed at skeletal maturity by computed tomography (CT) scans. This was done to evaluate the plasticity of the thoracic cage of rabbits with non-deformed spine, by highlighting its modifications after spinal arthrodesis. Emogas data analysis, echocardiographic assessment and cardio-pulmonary measurements completed the evaluation.

METHODS

Surgery was performed in 16 female rabbits, 6 weeks old. Nine were subjected to T1-T12 dorsal arthrodesis, while seven were sham-operated. Surgery involved the implant of two C-shaped stainless steel bars and heterologous bone graft. CT scans were performed before surgery, 2, 6 and 12 months after surgery. One week after the last CT scan, echocardiographic and emogas evaluations were performed.

RESULTS

Chest depth (8%), thoracic kyphosis (ThK) (23%), dorsal and ventral length of the thoracic spine (11%) and sternal length (7%) were significantly reduced in operated compared to sham-operated rabbits. Mean values ± standard deviation (SD) of PaCO2, PaO2 and sO2 were not significantly different. Mean values ± SD of echocardiographic measurements were not significantly different between the two groups of rabbits, except for thickness of the interventricular septum in systole, contractile capacity of the left ventricle and ejection fraction.

CONCLUSIONS

T1-T12 dorsal arthrodesis in prepubertal NZW rabbits with non-deformed spine induced changes of the thoracic cage morphology. However, those changes are source of cardio-pulmonary complications not severe enough to reproduce a clinical picture comparable to thoracic insufficiency syndrome in humans.

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.

The growing spine: how spinal deformities influence normal spine and thoracic cage growth

PURPOSE

This article aims to provide an overview of how spinal deformities can alter normal spine and thoracic cage growth.

METHODS

Some of the data presented in this article are gathered from studies performed in 1980 and 1990, and their applicability to populations of different ethnicity, geography or developmental stage has not yet been elucidated. In the present article, older concepts have been integrated with newer scientific data available to give the reader the basis for a better understanding of both normal and abnormal spine and thoracic cage growth.

RESULTS

A thorough analysis of different parameters, such as weight, standing and sitting height, body mass index, thoracic perimeter, arm span, T1-S1 spinal segment length, and respiratory function, help the surgeon to choose the best treatment modality. Respiratory problems can develop after a precocious vertebral arthrodesis or as a consequence of pre-existing severe vertebral deformities and can vary in patterns and timing, according to the existing degree of deformity. The varying extent of an experimental arthrodesis also affects differently both growth and thoracopulmonary function.

CONCLUSIONS

Growth is a succession of acceleration and deceleration phases and a perfect knowledge of normal growth parameters is mandatory to understand the pathologic modifications induced on a growing spine by an early onset spinal deformity. The challenges associated with the growing spine for the surgeon include preservation of the thoracic spine, thoracic cage, and lung growth without reducing spinal motion.

"Growth friendly" spine surgery: management options for the young child with scoliosis

The natural history of early onset scoliosis is dismal and associated with poor pulmonary function and increased mortality. Although limited in situ fusion may be appropriate for certain types of congenital scoliosis deformities, spinal deformity that affects young children often requires a "growth friendly" surgical approach that allows for curve control while maintaining growth of the spine and thorax. Growth-friendly surgical management of early onset scoliosis can follow a distraction-based (ie, growth rods, vertical expandable prosthetic titanium rib [Synthes, West Chester, PA]), guided-growth (ie, Luque trolley technique, Shilla technique), or compression-based (ie, tethers, staples) strategy.

Fusionless procedures for the management of early-onset spine deformities in 2011: what do we know?

While attempts to understand them better and treat them more effectively, early-onset deformities have gained great pace in the past few years. Large patient series with long follow-ups that would provide high levels of evidence are still almost non-existent. That there is no safe treatment algorithm defined and agreed upon for this patient population continues to pose a challenge for pediatric spine surgeons. In this review, authors who are well known for their research and experience in the treatment of early-onset scoliosis (EOS) have come together in order to answer those questions which are most frequently asked by other surgeons. The most basic eight questions in this field have been answered succinctly by these authors and a current overview is provided.

Porcine model of early onset scoliosis based on animal growth created with posterior mini-invasive spinal offset tethering: a preliminary report

Several models of scoliosis were developed in the past 10 years. In most of them, deformations are induced in old animals and required long time observation period and a chest wall ligation ± resection. The purpose of the study was to create a scoliosis model with a size similar to an early onset scoliosis and an important growth potential without chest wall injuring. An original offset implant was fixed posteriorly and connected with a cable in seven (6 + 1 control) one-month-old Landrace pigs. The mean initial spinal length (T1-S1) was 25 cm and the mean weight was 9 kg. After 2 months observation, spinal deformities were assessed with a three dimension stereographic analysis. In four animals, the cable was sectioned and the deformities followed-up for next 2 months. No post-operative complication was observed. Mean weight growth was 10 kg/month and mean spine lengthening (T1-S1) was 7 cm/month. In 2 months, we obtained structural scoliotic curves with vertebral and disk wedging which were maximal at the apex of the curve. Mean frontal and sagittal Cobb angles was 45°. Chest wall associated deformities were similar to those observed in scoliotic deformities and were correlated to spinal deformities (p = 0.03). The cable section resulted in a partial curve regression influenced by disk elasticity and could probably be influenced by gravity loads (Decrease of the Cobb angle of 30% in the sagittal plane and 45% in the frontal plane). According to the results, the model creates a structural scoliosis and chest wall deformity that is similar to an early onset scoliosis. The spinal deformities were obtained quickly, and were consistent between animals in term of amount and characteristic.

Expansion thoracoplasty improves respiratory function in a rabbit model of postnatal pulmonary hypoplasia: a pilot study

STUDY DESIGN

Using a rabbit model of postnatal pulmonary hypoplasia, we investigated how expansion thoracoplasty affected growth of the spine and lungs.

OBJECTIVE

By constricting the hemithorax in a growing rabbit to create postnatal pulmonary hypoplasia, we quantified how expansion thoracoplasty affects lung volume, respiratory function, alveolar morphology, and spine growth.

SUMMARY OF BACKGROUND DATA

In children with thoracic insufficiency syndrome, expansion thoracoplasty of the constricted hemithorax improves respiratory function and controls scoliosis. We hypothesize that expansion thoracoplasty of the constricted hemithorax improves pulmonary hypoplasia by allowing the lung to expand, improving respiratory function and stimulating lung growth.

METHODS

Postnatal pulmonary hypoplasia and scoliosis were induced in 5-week old rabbits by constricting left ribs 3 to 8. Expansion thoracoplasty through the fused ribs was performed at 10 weeks. These were compared with Disease rabbits allowed to grow with a constricted left hemithorax and Normal rabbits. Spine and thoracic deformity, right and left lung volumes were measured on reconstructed 3-dimensional computed tomography images and functional residual capacity measured by plethysmography. At maturity, lungs were excised and quantitative histology performed to measure alveolar air fraction and surface density.

RESULTS

Expansion thoracoplasty of the constricted left hemithorax improved scoliosis but increased left lung volumes only moderately compared with Disease rabbits. For Disease and Thoracoplasty Treated rabbits, a compensatory increase in the volume of the right lung maintained total lung volumes equivalent to Normal. Alveolar air space fraction was greater in Disease rabbits, suggestive of emphysema improved by expansion thoracoplasty. Capillaries adjacent to the alveoli were prominent in Thoracoplasty Treated rabbits.

CONCLUSION

Expansion thoracoplasty reduces scoliosis and increases the volume of the constricted hemithorax, but the relative increase in the ipsilateral lung volume is small since compensatory hypertrophy of the contralateral lung also occurred. Expansion thoracoplasty may improve respiratory function by increasing alveolar capillaries and preventing emphysematous changes.

Dorsal arthrodesis in prepubertal New Zealand white rabbits followed to skeletal maturity: Effect on thoracic dimensions, spine growth and neural elements

BACKGROUND

Several studies have shown that severe spinal deformity and early arthrodesis can adversely affect the development of the spine and thorax by changing their shape and reducing their normal function. This article analyzes the consequences of posterior fusion on the growth of spine, thorax and neural elements in New Zealand white rabbits and compares with similar human data.

MATERIALS AND METHODS

The first section of the article analyzes the consequences of T1-T6 dorsal arthrodesis on the growth of the spine, sternum, thorax volume and neural elements in 12 prepubertal female New Zealand white rabbits, through a study of CT scans and histology specimens. The second part, evaluates thoracic dimensions in 21 children with spinal arthrodesis for treatment of deformity performed prior to nine years of age.

RESULTS

Dorsal arthrodesis in prepubertal rabbits changes thoracic growth patterns. In operated rabbits thoracic depth grows more slowly than thoracic width. The sternum as well as length of thoracic vertebral bodies in the spinal segment T1-T6 show reduced growth. Children undergoing spinal arthrodesis before nine years of age were noted to have shortened height, short trunk and disproportionate body habitus at skeletal maturity. Observed spine height and chest dimension values were reduced compared to the expected norms. The ratio between chest width and chest depth was below normal values.

CONCLUSIONS

The first part of the study shows that thoracic dorsal arthrodesis in prepubertal New Zealand white rabbit influences thoracic, spine growth and affects the shape of pseudo unipolar neurons of the dorsal root ganglia. The second part demonstrates that children treated before nine years of age have significantly reduced spine height and thoracic dimensions. The thorax becomes elliptical as chest depth grows less than chest width. Both experimental and clinical findings contribute to explain reduced chest growth and subsequent thoracic growth disturbance in patients treated with early arthrodesis.

Fusionless instrumentation systems for congenital scoliosis: expandable spinal rods and vertical expandable prosthetic titanium rib in the management of congenital spine deformities in the growing child

STUDY DESIGN

Review of relevant literature including personal opinions.

OBJECTIVE

To review the current researches investigating the efficacy of growing rod and thoracic expansion techniques in the treatment of congenital spine deformity of young children, and to highlight the contrasting advantages and limitations in the fusionless treatment of progressive congenital scoliosis.

SUMMARY OF BACKGROUND DATA

Congenital scoliosis has the potential for severe spinal deformity and thoracic insufficiency syndrome (TIS). Conventional fusion treatments in children tend to shorten the spine further exacerbating trunk shortening and TIS. In the surgical treatment of congenital spinal deformities in young children, while reconstructing the spinal deformity, one should simultaneously pursue preserving the growth potential of the vertebrae, improving the volume, symmetry, and functions of the thorax, and protecting this improvement during the growth. Today, employed in the treatment of spinal deformities of young children, there are 2 deformity reconstruction methods serving these targets: Growing rod technique and vertical expandable prosthetic titanium rib (VEPTR) with or without expansion thoracostomy.

METHODS

Peer-reviewed research articles and major international meeting presentations were reviewed. Methods were compared in terms of advantages and limitations.

RESULTS

The growing rod technique is a safe and reliable method in the treatment of congenital spine deformity of young children who present some flexibility in the anomalous segment, or when the congenital anomaly involves a vertebral segment too long for resection, or with compensating curve with structural pattern concomitant to the congenital deformity. Expansion thoracostomy and VEPTR are the appropriate choice for severe congenital spine deformity when a large amount of growth remains. Although ventilator dependence is significantly decreasing, thoracic volume and space available for the lung are increased after expansion thoracostomy and VEPTR.

CONCLUSION

Growing rod technique should be used in patients where the primary problem is at the vertebral column. If the patient has rib fusions and/or TIS has developed, in other words, if the primary problem involves the thoracic cage, expansion thoracostomy and VEPTR should be an appropriate option.