CORRECTION OF SEVERE STIFF SCOLIOSIS THROUGH EXTRAPLEURAL INTERBODY RELEASE AND OSTEOTOMY ( LIEPO )

Objective: To report a new technique for extrapleural interbody release with transcorporal osteotomy of the inferior vertebral plateau (LIEPO) and to evaluate the correction potential of this technique and its complications. Method: We included patients with scoliosis with Cobb angle greater than 90° and flexibility less than 25% submitted to surgical treatment between 2012 and 2016 by the technique LIEPO at the National Institute of Traumatology and Orthopedics (INTO). Sagittal and coronal alignment, and the translation of the apical vertebra were measured and the degree of correction of the deformity was calculated through the pre and postoperative radiographs, and the complications were described. Results: Patients had an average bleed of 1,525 ml, 8.8 hours of surgical time, 123° of scoliosis in the preoperative period, and a mean correction of 66%. There was no case of permanent neurological damage and no surgical revision. Conclusion: The LIEPO technique proved to be effective and safe in the treatment of severe stiff scoliosis, reaching a correction potential close to the PEISR (Posterior extrapleural intervertebral space release) technique and superior to that of the pVCR (posterior Vertebral Column Resection) with no presence of infection and permanent neurological deficit. New studies are needed to validate this promising technique.


INTRODUCTION
The treatment of severe stiff scoliosis is a challenge for spine surgeons. 1The literature brings us two main classic correction techniques used in the treatment of these deformities.The traditional combined approach 2,3 (anterior + posterior), in which discectomy, anterior longitudinal ligament release, posterior longitudinal ligament release, resection of intervertebral discs, resection of the rib head, and osteotomy of the vertebral body are performed via anterior approach, and subsequently, on the same day or in a second surgery, correction is performed via posterior approach with resection of the facet joints, laminas, and yellow ligament, and arthrodesis with instrumentation.If the two-step procedure is chosen, the patient may be kept in halo-gravitational traction during the period between the two procedures. 4This procedure requires longer surgical time and has higher morbidity as compared to other techniques, especially when applied to patients with compromised respiratory function, starting in the preoperative period, due to the nature of the restrictive lung disease secondary to the spinal deformity.
The second technique disseminated in the literature in recent years is the posterior vertebral column resection (pVCR), published by Suk et al. 5 This technique has lower morbidity because of its use of a single access, through which Schwab grade V or VI 6 vertebral body osteotomies at the apex of the curve can be performed, which permits good correction of the deformity through this region, but generates at this point an area of high instability that increases the risk of accidental spinal cord lesion during the execution of the correction maneuvers.Scoliosis is corrected mostly through this region, with two rigid blocks remaining proximal and distal to the apical region.
In order to improve the correction of rigid scolioses, attempting to minimize the problems identified in the Suk technique, in 2012, the group of Li et al., 7 presented their posterior extrapleural interbody intervertebral space release (PEISR) technique, using an exclusively posterior approach aimed at flexibilizing the spinal deformity in a harmonic manner in the regions both proximal and distal to the apex of the curve.Associated with this approach, the group performed a posterior wedge osteotomy in the apical region of the deformity, introduced by Shimode et al., 8 and widely reported in the literature.
We also used the posterior extrapleural interbody intervertebral space release technique in our case series, performing multiple osteotomies of the inferior plateau of the vertebrae adjacent to the apex of the deformity, two to three levels proximal and distal to the apex vertebra, removing the intervertebral discs at the same time, instead of performing the posterior wedge osteotomy of the apical vertebra according to the Li et al. 7 technique.
The objective of this study was to describe a modification to the posterior extrapleural interbody intervertebral space release technique for correction of spinal deformities associated with transcorporal osteotomies of the inferior plateau (LIEPO -Liberação Interssomática ExtraPleural com Osteotomia); as well as to evaluate the degree of correction and the complications that occurred in both the early and late postoperative periods in patients submitted to this new LIEPO technique.

METHODS
The study was a retrospective analysis of a case series of patients who underwent surgery to correct severe rigid surgery during the period from 2012 and 2016 at the Instituto Nacional de Traumatologia e Ortopedia Jamil Haddad (INTO).The information was obtained from the work database approved by the CAAE Ethics Commitee: 41659215.0.0000.5273.The authors signed the Statement of Investigator, in which they ethically committed to the confidentiality and professional use of the data obtained from the medical records.Six patients who underwent the modified posterior extrapleural interbody intervertebral space release technique (PEISR), 7 associated with osteotomies of the inferior vertebral plateau of the vertebrae adjacent to the apex of the deformity, as shown in Figure 1, resection of the intervertebral discs, the anterior longitudinal ligament, the posterior longitudinal ligament, and the rib head section of the concave side of the curve (LIEPO).The inclusion criteria were patients with coronal deformity greater than 90 Cobb degrees and with less than 25% flexibility confirmed by lateral inclination radiographic tests.
Six patients, two men and four women, were included in this study.The average age was 18 years (13 -23 years).The diagnosis was idiopathic scoliosis in five cases and syndromic scoliosis in one case.In all cases, the apex of the curve was located in the thoracic spine.All the patients participated in follow-up for a minimum of 12 months, with clinical evaluations and imaging exams.
We evaluated the clinical history, demographic data, surgical time, estimated blood loss, functional improvement, and complications by analyzing the medical records.Calibration of the magnitude of the curves and the study of sagittal balance were conducted using anterior-posterior and lateral panoramic radiographs obtained both pre-and postoperatively.Atypical vertebral translation (AVT) was measured by the interval between a plumb line passing through the center of C7 and the center of the apical vertebra or disc.Coronal deformity was measured using the Cobb method.Thoracic kyphosis was measured using the Cobb method between the superior terminal plate of T5 and the inferior terminal plate of T12.Sagittal alignment was measured by the distance between the plumb line from C7 and the posterior-superior portion of S1.All the measurements were taken by a researcher not directly involved in the surgical procedure, using the Surgimap® computer program.

RESULTS
Six patients were included in the study.The etiology of the scoliosis was idiopathic in five cases and syndromic in one case, in which the patient had Treacher Collins syndrome.
The patient demographic data are presented in Table 1.The average number of discs excised per patient was 4.3 (3 -5), the average number of osteotomies of the inferior vertebral plateau for extrapleural access was 2.7 (2 -3), the average number of vertebrae involved in the area of the arthrodesis was 13.2 (11 -15), the average surgical time was 8.8h (8-10h), the average estimated bleeding was 1525 ml (900 -2300 ml), with an average variation in the hemoglobin count from the perioperative period to the first postoperative day of 4.3 points (2.6 -6.7), which corresponds to an estimated 34% loss of red blood cell volume in the first 24h after the surgical procedure.The average length of stay in an intensive care unit was 9.3 days (5 -18) and the average outpatient clinic follow-up was 30 months, ranging from 12 to 58 months.
As complications, we observed one patient who developed neurological deficit in the peri-and immediate postoperative periods, evolving with a neurogenic bladder and presenting total improvement of the deficit at the final outpatient consultation.One patient evolved with pneumonia and another with a postoperative urinary tract infection.Both were treated with intravenous antibiotic therapy and were discharged after clinical improvement.A chest drain with water seal was routinely placed in all patients immediately following the surgical procedure and remaining for less than 1 week in all cases, aimed at preventing the more serious complication of a possible hemopneumothorax.None of the patients had chylothorax.None of the patients required surgical revision and there were no cases of muscle necrosis, permanent neurological lesion, or infection of the surgical site.
Five patients were operated on in two stages.In the first surgery, we performed pedicle instrumentation, Ponte osteotomies, release of the yellow ligament, and placement of the cranial halo, which remained for two weeks in the patients under halo-gravitational traction at a weight corresponding to 20% to 30% of their body weight.
In the second surgery, two weeks after the first procedure, we performed extrapleural interbody release associated with transcorporal osteotomy of the inferior plateau of the periapical vertebrae (LIEPO), scoliosis correction, and system locking maneuvers, and the removal of the cranial halo, thus obtaining correction of the spinal deformity.

DISCUSSION
][10] The literature shows that historically patients with curves greater than 70°, or those who remain at magnitudes greater than 50° in lateral inclination tests, should be operated by combined approach in order to perform anterior ligament release associated with correction via posterior approach.Thus, Li et al. 2 achieved a correction rate of 48.6% in their series of 31 cases with an average preoperative Cobb of 98°.
Scoliosis with a high angular value can be treated by anterior approach alone according to Shen et al., 11 who described their study in which they performed anterior release associated with instrumentation and fusion in 12 patients with an average Cobb of 98.5°, obtaining 59.5% correction.
Anterior release via thoracoscopy prior to posterior arthrodesis has been described as being less invasive and optimizing clinical results, but the technical difficulty of this procedure in patients with severe deformity of the thoracic cage is a limiting factor.Moreover, Picetti et al. 12 demonstrated that this procedure should be reserved for patients with good pulmonary function.
Bradford described circumferential vertebral column resection (cVCR), via double approach, published together with Tribus, 13 a series of 24 patients with severe rigid scoliosis, with an average deformity of 103° Cobb in the coronal plane, obtaining 52% correction with their technique, requiring more than 12 h of surgical time, and with a loss of volume greater than observed in other techniques.Suk et al. 5 presented an exclusively posterior approach in which anterior release associated with posterior fixation is performed.In this series of 16 cases, they performed pVCR in patients with an average preoperative Cobb of 109° in the coronal plane, obtaining 59% correction.There were four serious complications and one patient evolved with permanent paralysis.
In 2002, Shimode et al. 8 described a wedge osteotomy technique at the apex of the deformity in patients with kyphoscoliosis, in which they obtained 54.9% correction in patients with an average Cobb of 85.3° in the coronal plane.Lemko achieved 51% correction 1 with pVCR in a series of 35 patients with an average preoperative Cobb of 115°.
The pVCR technique consists of a vertebral resection osteotomy at the apex of the deformity, allowing significant correction of the curve through this point, leaving two rigid blocks proximal and distal to the excised segment, generating instability in the apical region, which  causes the possibility of spinal cord injury occurring at this point, mostly due to the accumulation of tension in the rigid segments. 14i et al. 7 described the technique of posterior extrapleural interbody intervertebral space release (PEISR) associated with wedge osteotomy of the apex of the deformity, aimed at reducing the limitations encountered in the pVCR and at homogenizing gradual correction in the proximal and distal blocks through release at several interbody levels.
We obtained correction of 65%, a value close to the 71% of the Chao Li group and greater than the correction percentage achieved by other techniques such as Suk et al. 5 using the pVCR technique (59%), (Table 3) with low blood loss.None of our patients suffered permanent neurological damage or required a new surgical intervention.
Our average scoliosis value at diagnosis was 123° (97° -157°) Cobb, with 66% of the patients with curves greater than 120° Cobb.This value stands out because, in all the other studies, less than 40% of the patients had preoperative curves greater than 120°.

Figure 2 .
Figure 2. Pre-and postoperative clinical and radiographic images in the coronal plane.

Figure 3 .
Figure 3. Pre-and postoperative clinical and radiographic images in the sagittal plane.

Figure 4 .
Figure 4. Pre-and postoperative clinical and radiographic images in the coronal plane.

Figure 5 .
Figure 5. Pre-and postoperative clinical and radiographic images in the sagittal plane.

Figure 6 .
Figure 6.Per-and postoperative radiographs in the sagittal and coronal planes.

Table 1 .
Clinical results of patients submitted to correction of scoliosis using the LIEPO technique.

Table 2 .
Radiographic results of patients submitted to the correction of scoliosis using the LIEPO technique.

Table 3 .
Comparison of percent correction obtained with the respective surgical techniques.