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THE RESULTS OF POSTERIOR COMPLETE HEMIVERTEBRECTOMY FOR CONGENITAL SCOLIOSIS PATIENTS WITH HEMIVERTEBRAE

O.OZEL, T.BENLİ

Baskent University Medical School, Orthopedics and Traumatology Department, Istanbul.

ANADANGƏLMƏ SKOLİOZU OLAN XƏSTƏLƏRDƏ TAM HEMIREBREBREKTOMİYANIN NƏTİCƏLƏRİ.
O.OZEL, T. BENLİ.

Başkənd Universiteti Tibb fakültəsi, Ortopediya və Travmatologiya kafedrası, İstanbul

РЕЗУЛЬТАТЫ ЗАДНЕЙ ПОЛНОЙ ГЕМИВЕРТЕБРЕКТОМИИ У БОЛЬНЫХ С ВРОЖДЕННЫМ СКОЛИОЗОМ
О.ОЗЕЛ, Т.БЕНЛИ

Медицинский факультет Башкентского Университета, кафедра ортопедии и травматологии, Стамбул.

ABSRACT 

Objective: To evaluate the results of surgical treatment of patients with an unincarcerated fully-segmented hemivertebra treated with hemivertebrectomy by a posterior approach alone, circumferential fusion and posterior segmental pedicular screw instrumentation.

Study Design: Thirty patients with a mean age of 9.7 ± 5.4 (2–14) years were included in the study (14 girls and 16 boys). The mean duration of follow-up was 68.4 ± 49.6 (24–132) months. Diagnosis of a Type-IA hemivertebra was established by clinical, radiological, CT and MRI evaluation. For all patients, hemivertebrectomy with a posterior approach alone, circumferential fusion and posterior segmental pedicular screw instrumentation were applied. Analysis of the frontal and sagittal planes using radiograms obtained preoperatively, postoperatively, and after a minimum period of two years was performed. The balance was analyzed clinically and radiologically by measurement of the lateral trunk shift (LT).

Results: The mean preoperative Cobb angle was 9.5 ± 24.4°, and postoperatively a mean correction rate of 89.7 ± 17.4 % was obtained for the main curves (p=0.00). The mean preoperative Cobb angle of the secondary curves was 48.9 ± 16.1°, and postoperatively a mean correction rate of 89.9 ± 21.4% was obtained for the secondary curves (p=0.00). In the final follow-up, the mean loss of correction was 3.3 ± 3.3°. The local segmented kyphosis decreased from 26.4 ± 11.9° to 6.7 ± 4.7°. The trunk shift (LT) of the patients was corrected for all patients (preoperative mean LT: 3.6 ± 2.3 cm; postoperative mean LT: 0.7 ± 0.5 cm). Circumferential fusion was achieved in all cases. No neurological complications developed, the only complication seen was delayed wound healing.

Conclusion: In the light of these data, we conclude that hemivertebrectomy by a posterior approach alone, circumferential fusion and posterior segmental pedicular screw instrumentation is an effective and safe technique for the treatment of unincarcerated fully-segmented hemivertebrae in all vertebral regions.

Key words: Congenital scoliosis, surgical treatment, and hemivertebra excision.

Introduction

Hemivertebrae are the most common type of deformity and cause serious deformation and balance disturbances. Hemivertebrae at the lumbosacral joint, in particular, can cause pelvic tilting19. The growth pattern of hemivertebrae is unknown, and there have not been many studies. Generally, a crosspositioned hemivertebra results in a balanced deformity, but a single-sided fully-segregated and unincarcerated hemivertebra can result in progressive deformity. For patients with this type of deformity, progression peaks at the age of 2 and in the pre-adolescent period19,20. As for most cases of congenital scoliosis, the gold standard for treatment is in situ fusion.

Hemivertebrectomy was first implemented in 1928 by Royle, and has become popular again in the last few decades. Surgery must be performed before the development of compensatory thoracolumbar and thoracic deformities and pelvic tilt, especially in cases of lumbosacral and lumbar hemivertebrae1, 3, 17, 19, 29-32. Hemivertebrectomy is performed by total removal of the ‘Y’-shaped discs from the anterior and consecutive removal of the half vertebra from the posterior. Initially, correction of defects in young children after the removal of hemivertebrae was hard, as no suitable implants were available and so correction of the defect was attempted using positioning with body casts. Recently, by using the appropriate instrumentation for the appropriate ages, residual defects can be closed by instrumentation and high degrees of deformity correction can be achieved4,17,27. Initially, these processes were performed in two separate surgeries, but recently both interventions have been performed in the same session, either in two steps or together1-3,7,8,9,16,28.

In 2006, Benli et al., one of the authors of this paper, performed two-step surgery in the same session for 14 of 26 patients. During this surgical procedure, they first removed the anterior hemivertebral body by an anterior approach and the posterior hemivertebral body by a posterior approach, and then they performed circumferential fusion and correction using posterior instrumentation.

30 patients received surgery using a unique technique that had not before been published, in which first the posterior parts of the hemivertebra were removed using a posterior approach, and then the anterior parts of the hemivertebrae were removed by an anterior approach, followed by correction with anterior instrumentation and circumferential fusion1 . After pedicular segmented screws became available for all spinal deformities, it has recently become possible to remove the hemivertebra by a posterior approach alone, and to achieve better filling of the residual defect cavity and better correction rates without any neurological deficit27. Nakamura et al. compared the results of hemivertebrectomy by anterior and posterior intervention in a single session and total hemivertebrectomy with a posterior approach alone, and reported that correction rates and clinical results are statistically similar21.

In this study, the most commonly used technique, hemivertebrectomy by a posterior approach, circumferential fusion and short segmental instrumentation using posterior pedicular screws, was employed in the treatment of 30 patients with fully-segmented locked hemivertebrae, the clinical results were evaluated retrospectively, and the effectiveness and safety of the method was estimated.

Patients and methods

30 patients with a fully-segmented unincarcerated hemivertebra who were operated on by two of the authors of this article (T.B. and M.A.) were included in this study. The average age of the patients was 9.7 ± 5.4 (2–14) years, and six patients were male and six were female. The patients were clinically evaluated, and standing postero-anterior, lateral, bending, and traction X-rays, and 3D computerized tomography of the affected region were performed. To detect the presence of additional vertebral abnormalities, a whole vertebral MRI was performed. To detect any cardiac and urinary system abnormalities, the appropriate studies and consultations were also demanded. For patients with a pure fully-segmented and unincarcerated hemivertebra, a total hemivertebrectomy from the posterior with circumferential fusion and posterior instrumentation was planned. Surgery was performed in prone position by making an incision from the previously marked hemivertebral site, and neural monitorization was employed during surgery. First, pedicular screws were placed freehand to the consecutive upper and lower vertebrae bilaterally, and then the posterior parts were removed using a Kerrison rongueur, the roots were separated to reach the anterior, and the discs were completely excised until the adjacent vertebral spongious bones were reached. In five of the cases, where accompanying kyphotic deformities were present, supportive grafts were placed at the anterior part of the body. After that, the temporary screw below the hemivertebra was removed, and a screw one size larger was placed. Rods were placed, compression from the concave side and distraction from the convex side were performed gradually, and the defect at the hemivertebral site was slowly and gradually corrected. After the final correction, rods were placed and a rigid window was created with two cross bridges. After decortication, posterior fusion was performed using local autografts and circumferential fusion was established. On the second day postoperatively the patients were mobilized and no external support was used. Complications were only observed in a single patient, and there was no neurological deficit development. The patients were followed up for a minimum of two years, for an average of  68.4 ± 49.6 (24–132) months. The final follow-ups were performed in June 2019. The Cobb angles of the compensatory deformation and the local kyphosis angles were measured, preoperatively, postoperatively, and at the last follow-up. The lateral body shift (LT) at the apex of the deformity at the hemivertebral site was also calculated from X-rays taken preoperatively, postoperatively, and at the final follow-up. The averages of these values were analyzed using the SPSS 11.0 for Windows program, using a paired sample correlation test and a student t-test with p=0.05. 90 The Journal of Turkish Spinal Surgery Figure-1. Patient Ş.A., a 10-year-old male, had an upper thoracic hemivertebra and a resulting upper thoracic 45° major deformity. a) Posterior view of the patient and planning, b) PA X-ray of the patient standing, c) lateral X-ray, d) 3D computerized tomography, e,f ) computerized tomography images, g) frontal MRI, j,k) postoperative PA and lateral X-rays.

Results

Four of the hemivertebra patients (13.3 %) had an upper thoracic, forteen (46.7 %) had a lower thoracic, and twelve (40.0 %) had a lumbar location. Major deformities were seen in the thoracic, thoracolumbar and lumbar regions with the given rates. The average preoperative Cobb angle of the major deformity of the patients was 63.5 ± 23.7°, and postoperatively the average Cobb angle reduced to 13.5 ± 13.1°, showing that a correction of 89.7 ± 17.4 % was obtained, which had statistical significance (p=0.00, t=7.3). The preoperative average angle of compensatory deformity was 48.9 ± 15.3°, and this reduced to 9.0 ± 7.7°, showing 89.9 ± 14.2% correction. Both the compensatory deformity and local kyphosis angle reductions were statistically significant (p0.05, t=3.2). The average preoperative LT value was 3.6 ± 2.3 cm, which reduced postoperatively to 0.7 ± 0.5 cm (p=0.00), and balance was obtained for all patients postoperatively. At the final follow-up, it was determined that the body shift values had not changed and the balance was preserved for all patients. None of the patients developed neurological deficits, and no postoperative early or late complications were observed. It was observed that circumferential fusion developed in all of the patients.

Discussion

One of the surgical treatment options for scoliosis resulting from a hemivertebra is hemivertebrectomy. This was first described by Royle in 192819. Compere published the first results of hemivertebrectomy in 1932 5 . This method was abandoned for a long time due to high morbidity rates, the development of neurological deficits, and an inability to correct defects that occurred after hemivertebrectomy and non-fusion8,29-32. A few decades ago, Leatherman and Dickson re-popularized the method17, and many studies have subsequently reported good results of anterior and posterior hemivertebra excision, in either a single or two separate sessions3,10,15,21.

Holte et al. reported the application of posterior instrumentation to 28 of the 38 patients that they operated on, and for the patients who received instrumentation, the deformities were reduced to an average of 33° from 54°, and all patients attained body balance10. In a tenpatient series by Deviren et al., a 59% correction rate was published,7 , and Callahan et al. showed 45% reduction with a single-step and 55% reduction with a two-step procedure4 . Klemme et al. reported the follow-up of six children treated with combined hemivertebrectomy with an anterior and posterior approach in a single session, and showed that there was a 70° reduction in the major deformity, and with the use of appropriate instrumentation this technique can be used for small children15.

Bradford and Boachie-Adjei showed that with combined anterior-posterior hemivertebrectomy, an average correction of 70 % can be obtained, and during an average of 45.6 months follow-up, an average of 1° of correction was lost3 . King and Lowery, in a seven-patient series, reported that a preoperative major deformity of 29.7° was reduced to an average of 18° at the last follow-up14. Lazar and Hall, in an 11-patient series, reduced an average preoperative major deformity of 47° to 14° postoperatively using a combined anteriorposterior hemivertebrectomy approach; Hall et al. also used the same method and observed the reduction of deformity from 54° to 33° 8,16.

Benli et al., one of the authors of this paper, performed combined anterior and posterior hemivertebrectomy in the same session for 26 patients. Nearly half of these patients were treated with anterior instrumentation with the Cotrel-Dubousset-Hopf (CDH) double rod technique after hemivertebrectomy instead of posterior instrumentation, for the first time in the literature. The remaining patients were treated with regular posterior instrumentation. For the groups receiving anterior and posterior instrumentation, 60.7% and 67.5% correction was obtained, respectively, with statistical significance, and less segments were instrumented during the anterior approach. After surgery, 80.8% of the patients were totally balanced and had clinically balanced vertebrae1 . Recently, after segmental pedicular systems have become available, total hemivertebrectomy with a posterior approach, circumferential fusion and posterior pedicular fixation have become popular. Shono et al. published the first posterior hemivertebrectomy27. In 2001, Shono et al. reported a series of 12 patients who received hemivertebrectomy with a posterior approach, and they reported 64 % correction without neurological deficits or pseudoarthrosis, and at the final follow-up an average loss of correction of 2° was observed. They proposed that this method was an efficient and safe method. They also pointed out that the preoperative average body shift was reduced from 23 mm to 3 mm postoperatively, and that all patients had balanced vertebrae27.

Ruf and Harms 24-25 and Nakamura et al.19 published their results with this technique in 2002. In 2008, Liu et al. performed posterior hemivertebrectomy for 24 patients with an average age of 9.4 years, and reported 61.5% correction without any neurological deficits18. In 2009, Hedequist et al. reported a decreased Cobb angle, from an average of 44° to 8°, for ten patients who received hemivertebrectomy with a posterior approach and double rod application to the concave side9 . In 2009, Ruf et al. reported a decrease in the major deformity from 69° to 23° in 41 congenital scoliosis patients, and also a spontaneous decrease in the caudal secondary deformity from 15° to 3° and a decrease in the local kyphosis angle from 22° to 8° 26. In 2011, Zhang et al., in a study including 59 hemivertebra patients aged from 1.5–1.7 years showed 72.9% correction, the local kyphosis angle decreased from 42° to 14.5°, and a residual defect was only observed in five patients34. In the same year, Peng et al. published the use of the same method for two patients, and reported correction of the major deformity, compensatory deformity and segmental kyphosis by 65.9%, 62.8%, and 78.1%, respectively23. In the same year, Yazsay et al. reported the results of 66 cases over two years in a multicentric study. When in situ fusion and convex epiphysiodesis were compared, they proposed that hemivertebra excision had a higher complication rate33. In 2012, Jerzenksy et al. reported very good results after 16 years of surveillance for a fusion-less hemivertebrectomy patient11. In the same year, Sun et al., in a study including 44 hemivertebra patients aged 2–17 years, compared hemivertebrectomy with posterior approach alone and stepwise anterior-posterior hemivertebrectomy with instrumentation, and showed that they have similar clinical results, although in rigid cases, in particular, hemivertebrectomy with an anterior-posterior approach must be preferred28. Karami et al. published a clinical series of ten patients from Iran in 2013. They performed hemivertebrectomy with a posterior approach, and in the major deformity and local kyphosis saw 72.5% and 90% correction, respectively12. Obeid et al. published a study in the same year stating that hemivertebrectomy with a posterior approach alone could be safely employed in the thoracic region22. In our study, this technique is safely and successfully implemented in the thoracic and cervicothoracic regions. Finally, at the beginning of 2014, Crostelli et al. published a series that included 15 children under the age of 10 who were surveyed for at least three years. They reported 75% correction of the major deformity with no major complications in any of the patients6 . In another study in 2014, Zhu et al. published the results of 60 hemivertebra patients treated with hemivertebrectomy with a posterior approach alone. They reported correction of 87.3%, a decrease in body tilt and 70.1% correction of segmental local kyphosis, with no neurological deficits35. In our study, the major deformity correction was 89.7 %, with statistical significance (p=0.00), and the compensatory deformity correction was 9.3°, which is 89.9 %. The local segmental kyphosis angle decreased from an average of 26.4° to 6.7°. The corrections of both the local kyphosis and compensatory deformity were statistically significant (p=0.05). The average postoperative LT values decreased to 0.7 cm from 3.3 cm (p=0.00), and for all patients balance was fully established postoperatively. At the final follow-up, the body tilt values had not changed and the balance was preserved. None of the patients developed neurological deficits, and no postoperative early or late complications were observed.

Crankshaft phenomenon are not observed on hemivertebrae excision, as this process allows circumferential fusion19,31. Kesling et al. and Winter reported pseudoarthrosis occurring in small children due to residual cavities that could not be filled13,29-32. However, after correction with instrumentation and use of segmental pedicular screws, in particular, there were cases of pseudoarthrosis in all of the studies3,4,7,8,10,15,16,21-27. In our study, in the final follow-up, solid fusion was observed in all of the 12 patients. In some studies, use of a concave single rod has been reported23. However, in this study, the development of a rigid window by connecting two rods crosswise was preferred. We also believe that distractive movements on the convex rod are helpful for filling the defect cavity left after hemivertebrectomy. Based on the results of this study, total 94 The Journal of Turkish Spinal Surgery hemivertebra excision with a posterior approach, together with posterior instrumentation using segmental pedicular screws, shows high rates of correction and circumferential fusion. We conclude that this method is efficient and safe.

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