EVALUATION OF THE VEPTR SYSTEM IN THE MANAGEMENT OF SPINAL DEFORMITIES BETWEEN 2008 AND 2014 AT THE

Objective: Traditional surgical treatments, such as on-site fusion and hemiepiphysiodesis, have not addressed chest deformity in its three dimensions, and are usually insufficient and unpredictable for the management of congenital and neuromuscular scoliosis. The application of the Vertical Expandable Prosthetic Titanium Rib (VEPTR) is a technique developed to treat early-onset progressive scoliosis that elongates the spine and thoracic wall, allowing adequate lung development. Methods: A case series retrospective study was conducted. We included 23 patients, including fifteen females and eight males diagnosed with congenital and neuromuscular scoliosis, who were treated with VEPTR type implants between January 2008 and May 2014. We obtained data about the implant and pre and postoperative radiographic images to assess the magnitude of the curve, and we measured the Cobb angle and length after lengthening, as well as evaluating the complications found. Results: There was an improvement in the postoperative Cobb angle. In patients with congenital scoliosis, deformity correction was 8.6% (p=0.014), and in neuromuscular scoliosis, we observed deformity correction of 19.5% (p=0.009). Likewise, we found gains in thoracic height through the device, which results in an average 10% lengthening of the spine in congenital scoliosis. In this study, we identified complications such as material migrations, rib synostosis, pressure zones, rib fracture, hemothorax, and deep wound infection. Conclusion: The natural history of progressive spinal deformity was improved in most of the minors, through the use of VEPTR. This allows us to continue managing patients in the future, in order to make a deeper assessment of its performance in treatment of early onset scoliosis. Level of Evidence III; Therapeutic studies Investigating the results of a treatment.


INTRODUCTION
There are multiple methods for the management of congenital and neuromuscular scoliosis in underage patients. 1Traditional surgical treatments, such as on-site fusion and hemiepiphysiodesis, have not addressed chest deformity in its three dimensions, and are usually insufficient and unpredictable; likewise, arthrodesis hinders the axial growth of the thoracic spine and proper lung development.
That is why, for several years, thanks to Campbell, 2 expansion thoracoplasty with the application of VEPTR (Vertical Expandable Prosthetic Titanium Rib) has been in use.This technique directly treats thoracic insufficiency syndrome, and the related vertebral anomalies. 2,3][6] Based on the effective results of the VEPTR, 8 we have designed a series of cases to investigate the clinical and radiological outcomes of the VEPTR system in the management of spinal deformities in patients at the Instituto de Ortopedia Infantil Roosevelt.

METHODS
The research protocol for this study was approved by our ethics committee and the institutional review board.All authors declare no potential conflict of interest related to this article.It is a case series type retrospective study including 23 patients with congenital or neuromuscular scoliosis with VEPTR implantation between January 2008 and May 2014.Fifteen females and eight males were included.The average age for initial insertion of the VEPTR was 5.9 years (range from 8 months to 12 years).
We collected specific data on implant construction, such as implant type and length; we also assessed complications, including infection, material failure, pressure zones, hemothorax, and synostosis.Preoperative and postoperative radiographs were analyzed by a spine specialist orthopedic surgeon, and a specialist in training.Radiological studies consisted of an AP and panoramic projection of the spine, and the magnitude of the curve was measured using the Cobb method.The total system length in the coronal plane was also measured, prior to VEPTR insertion and after each lengthening.

Statistical analysis
For the quantitative variables, we calculated the central tendency and dispersion measures (standard deviation SD); for the categorical variables, we calculated the proportions.Statistical differences were assessed using the T-student parametric test for related samples, as the variables showed normal distribution.
Analysis were carried out using IBM SPSS Statistics ® , version 21 statistical software.

RESULTS
During the period analyzed, 23 VEPTR implantation procedures were performed that met the selection criteria.65% of the patients were females, with a mean age of 5.9 years (± 3.2 SD).86.6% (n=19) had been diagnosed with congenital scoliosis, and 17.4% (n=4) with neuromuscular scoliosis.A total of 78 system lengthening surgeries were performed, with an average of 3.4 (± 1.7 SD) lengthenings per patient and follow-ups every 29 months (6 to 63 months), on average.The study parameters are shown in Table 1.
In regards to the surgical procedure, we found that the mean surgical time for system placement was 188 ± 54.8 minutes, and for the lengthening procedures, 105 ± 36.5 minutes.Intraoperative bleeding during the system placement and lengthening procedures was 208.5 ± 201.89 mL and 53.05 ± 65.22 mL respectively.
The average preoperative Cobb angle was 58.14° ± 20.02°, and the post-lengthening Cobb angle was 50.96° ± 14.57, with an average correction of 7.18°, which is statistically significant (p=0.003).It should be noted that we did not perform the preoperative Cobb angle measurement for two patients, as they received extra-institutional management.
We identified two complications during the first surgical time: a rib fracture and a surgery site infection that required lavage and debridement in the operating room.Complications during the lengthening procedures included anchoring failure after lengthening (this was surgically corrected during the following lengthening), a costal synostosis, a costoscapular synostosis, a sacral pressure zone, a hemothorax, and a deep infection.There were two patients that experienced device migrations which were corrected in the following lengthening.One patient required multiple lavages and debridements due to a device-related deep infection.
We carried out an analysis in subgroups, depending on the type of scoliosis, to assess the results in patients who received the VEPTR system (Table 2).
Nineteen patients with congenital scoliosis were treated with this system.Some showed and associated Dysmorphic syndrome, horseshoe kidney, Noonan syndrome, VACTERL association, Klippel-Feil syndrome, Moebius syndrome, and myelomeningocele, among others.This group includes the two patients for whom we did not have the preoperative Cobb angle data.We assessed the VEPTR management of neuromuscular scoliosis in 4 patients with the following backgrounds: one with bilateral cerebral paralysis, two with myelomeningocele, and one with VACTERL association.
On average, patients diagnosed with congenital scoliosis were followed-up for 33 months (9-63 months), while patients with neuromuscular scoliosis were followed-up for 12 months (5-30 months).
Due to the simple size and the heterogeneity of the groups, no comparisons were made between groups.However, we assessed the magnitude of the scoliosis correction for each group, considering the Cobb angle and spine length during the pre-and postoperative periods (Figures 1 and 2).
For patients with congenital scoliosis, the average preoperative Cobb angle was 51.12° ± 13.74 degrees, and the mean postoperative Cobb angle was 46.70° ± 11.83 degrees, demonstrating a reduction in the magnitude of the deformity of 8.6%, which is statistically significant (p=0.014);we also found significant lengthening of the spine, measured through the system, with a preoperative length of 183.80 ± 53.90 mm, and a postoperative length of 203.87 ± 57.18 mm, demonstrating a 10% (p=0.002)gain in spinal length.
In patients with neuromuscular scoliosis, the preoperative Cobb angle was 88.00 ± 13.97 degrees, and the mean postoperative Cobb angle was 70.81 ± 9.94 degrees, demonstrating a statistically significant 19.5% (p=0.009)reduction in the magnitude of the deformity.Comparison between the pre-and postoperative spine angles was possible, due to the available sample size.

DISCUSSION
Pathologies affecting the spine during early childhood include Scoliosis, which may be of the idiopathic, congenital, or neuromuscular types.
In the past, patients with early-onset scoliosis were managed with body casts; later on, the use of fixations and short arthrodesis, including hemiepiphysiodesis, were the treatment of choice, but these resulted in a short chest with severe breathing restrictions, due to the notable reduction in chest capacity. 9e current concept of this pathology has dramatically changed with the appearance of spinal distraction systems, including growth rods such as costal distraction systems, including the VEPTR progressive lengthening system; 10 the purposes of this system are to allow proper growth of the rib cage and the compromised hemithorax, and to control the deformity of the spine, allowing its growth. 11n order to better defining the indications and results of patients treated with VEPTR, we report here the data from mid-term followup.Data for this study were added to a database of the Instituto de ortopedia infantil Roosevelt, including data on specific preoperative and postoperative clinical and radiographic assessments.Based on this database, we identified 23 children with congenital   Since the advent of VEPTR for chest expansion, by broadening the available space for optimum lung development, an improvement has been seen in bone deformities of the spine.Therefore, this system is now used to address early onset scoliosis.This treatment is indicated in children who still have lung growth potential.
In our study, we had 23 patients with spinal deformities, nineteen with congenital scoliosis and four with neuromuscular scoliosis.We found in our series that the majority of patients showed an improvement in the Cobb angle and a reduction in the magnitude of the deformity; in those with congenital scoliosis, the average correction  Out of the total followed-up sample, we saw three patients who completed treatment with VEPTR, and who were then taken to final surgery with success.The remaining 21 patients are still growing, with favorable clinical and radiological progress.
Challenges of this treatment, as shown in prior studies, include the demand for multiple procedures, skin problems, and device migration. 12,13In this study, we identified two migrations of the material, one costal synostosis, one costoscapular synostosis, one sacral pressure zone, costal fracture, one patient with hemothorax, and one deep infection.Device migrations were surgically corrected in the next lengthening.One patient was submitted to multiple lavages and debridements due to a device related deep infection.

CONCLUSIONS
We presented a case series-type retrospective research study to assess the efficacy of VEPTR, and thoracotomy expansion in patients with multiple spine anomalies.As of the time of follow--up, the technique has proven successful for improving thorax height and spine deformity.The complication rate is similar to that of prior descriptions in other studies and in the use of other lengthening devices.Despite the small number of cases in our study, it reveals the efficacy of the system in our Institute and in Colombia, where no studies of this type are available.This allows us to continue managing patients in the future, in order to make a more in-depth assessment of its performance in treatment of early onset scoliosis.
* There were no presurgical studies available, patients with extrainstitutional management.

Table 2 .
General characteristics of patients with VEPTR system by diagnosis SD: Standard Deviation.