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1.  Painful rib hump: a new clinical sign for detecting intraspinal rib displacement in scoliosis due to neurofibromatosis 
Scoliosis  2006;1:10.
Spinal cord compression and associate neurological impairment is rare in patients with scoliosis and neurofibromatosis. Common reasons are vertebral subluxation, dislocation, angulation and tumorous lesions around the spinal canal. Only twelve cases of intraspinal rib dislocation have been reported in the literature. The aim of this report is to present a case of rib penetration through neural foramen at the apex of a scoliotic curve in neurofibromatosis and to introduce a new clinical sign for its detection.
A 13-year-old girl was evaluated for progressive left thoracic kyphoscoliotic curve due to a type I neurofibromatosis. Clinical examination revealed multiple large thoracic and abdominal "cafe-au-lait" spots, neurological impairment of the lower limbs and the presence of a thoracic gibbous that was painful to pressure at the level of the left eighth rib (Painful Rib Hump). CT-scan showed detachment and translocation of the cephalic end of the left eighth rib into the adjacent enlarged neural foramen. The M.R.I. examination of the spine showed neither cord abnormality nor neurogenic tumor.
The patient underwent resection of the intraspinal mobile eighth rib head and posterior spinal instrumentation and was neurologically fully recovered six months postoperatively.
Spine surgeons should be aware of intraspinal rib displacement in scoliotic curves in neurofibromatosis. Painful rib hump is a valuable diagnostic tool for this rare clinical entity.
PMCID: PMC1508157  PMID: 16774682
2.  Colour Doppler ultrasonography for evaluation of anterior chest blood supply: the possible role of arterial blood supply to the costosternal junction in the aetiology of idiopathic scoliosis in female adolescents 
European Spine Journal  2003;13(1):44-48.
This prospective comparative study was carried out to investigate the blood supply to the anterior chest wall by measurement of several anatomical and haemodynamic flow parameters of the internal mammary artery, with the use of colour Doppler ultrasonography, in female scoliotics with idiopathic right convex scoliosis in adolescence. Previous investigations have postulated that asymmetry of the breasts in female adolescents may be linked with the development of right convex thoracic scoliosis. This breast asymmetry is supposed to be linked with anatomical and functional asymmetry of the internal mammary artery that is the main supplier to the mammary gland. However, no measurements of anatomical and haemodynamic parameters of the internal mammary artery have been made to justify or reject the hypothesis of asymmetric blood flow volume to the breasts and costosternal junction in female adolescent scoliotics. Twenty female adolescents with right convex thoracic scoliosis and 16 comparable female individuals without spine deformity were examined with roentgenograms (scoliotics only) to measure scoliosis curve, vertebral rotation and concave and convex rib–vertebra angle at three vertebrae (the apical, one level above and one below the apical vertebra). Doppler ultrasonography was used to measure, at the origin of the internal mammary artery, its lumen diameter, cross-sectional area, time average mean flow and flow volume per minute in scoliotics and controls, which were compared with each other. The roentgenographic parameters were compared with the ultrasonographic parameters in the scoliotics to disclose any relationship. The reliability of colour Doppler ultrasonography was high and the intra-observer variability low (ANOVA, P=0.92–0.94). There was no statistically significant difference in the ultrasonographic parameters of the internal mammary artery between right and left side in each individual as well as between scoliotics and controls. In scoliotics the right mammary artery time average mean velocity increases with the convex (P<0.05) and concave (P<0.01) rib–vertebra angle one level above the apical vertebrae and with the apical convex rib–vertebra angle (P<0.05). The right internal mammary artery flow volume per minute increases with convex (P<0.01) and concave (P<0.01) rib–vertebra angle one level above the apical vertebrae and with the apical convex rib–vertebra angle (P<0.05). Left internal mammary artery cross-sectional area increases with convex apical rib–vertebra angle (P<0.01) and concave rib–vertebra angle one level above the apical vertebra (P<0.01). Conclusively, this investigation showed that haemodynamic flow parameters of the right internal mammary artery and anatomical parameters of the left internal mammary artery are significantly correlated with the magnitude of rib–vertebra angles close to the apex of right thoracic scoliosis in female adolescents. This study did not find any evidence for side-difference in vascularity of the anterior thorax wall and, thus, it could not clearly justify previous theories for development of right thoracic scoliosis in female adolescents.
PMCID: PMC3468036  PMID: 14648305
Aetiology; Thoracic idiopathic scoliosis; Internal mammary artery
3.  Burnei’s anterior transthoracic retropleural approach of the thoracic spine: a new operative technique in the treatment of spinal disorders  
Journal of Medicine and Life  2015;8(2):160-165.
Background: Up to the middle of the last century, the thoracic spine, especially in its upper part, has been considered an unapproachable site, a no-man’s land, but the constant evolution of medicine imposed techniques of the spine at these levels in order to solve a large area of pathology (infectious, tumoral, traumatic, and last but not least, deformative). This way, a series of anterior approaches allowed surgeons to gain access to the anterior part of the spine and the posterior mediastinum. The approaches described by Hodgson, Mirbaha or transthoracic transpleural approach (T4-T11), are enumerated. The idea to allow a more visible and extensive approach, but to avoid respiratory issues due to the lesion of the pleura, led to the description of a new anterior approach by Burnei in 2000.
Material and method: Burnei’s approach represents an anterior approach to the thoracic spine, being a transthoracic and retropleural one. This approach allows a large area of spinal pathology due to infectious, traumatic, tumoral and degenerative (idiopathic or congenital scoliosis) causes. Statistically, this approach has been performed more frequently in cases of spinal instrumentation after diskectomy, in order to perform a partial correction of severe, rigid idiopathic scoliosis with more than 70 degrees Cobb and in cases of congenital scoliosis for hemivertebra resection and somatic synthesis to correct the scoliotic curve.
Results: This kind of anterior approach allows the surgeon a large visibility of the anterior thoracic spine, diskectomies of up to 5 levels to tender the curve of the deformity and to ensure somatic or/ and transpedicular synthesis of up to 6 thoracic vertebrae. By performing a thoracotomy involving the resection of the posterior arches of the ribs, a thoracoplasty is also ensured with functional and aesthetic effects, by ameliorating the thoracic hump due to the scoliotic deformity.
Conclusions: Burnei’s approach joins all the other anterior approaches of the spine, addressing a large area of pathology of the thoracic spine. Even if difficult to be performed, requiring a thorough and perfect technique in the hands of a skilled surgeon, it will ensure satisfaction due to the detailed and visible exposure of the thoracic spine.
PMCID: PMC4392095  PMID: 25866572
anterior approach; thoracotomy; thoracoplasty; retropleural; diskectomy
4.  Late-onset spinal deformities in children treated by laminectomy and radiation therapy for malignant tumours 
European Spine Journal  2005;14(8):765-771.
This is a retrospective study of 76 children who had had malignant tumours treated with laminectomy or laminoplasty and/or radiation therapy affecting the spine. Spinal tumours in children are extremely rare. However, their treatment can result in progressive spinal deformity. Radiation therapy affecting the growing spine can lead to asymmetric vertebral growth, causing kyphosis and/or scoliosis. These spinal deformities pose one of the most challenging problems for the spine surgeon. The aim of this article is to describe late-onset post-laminectomy/post-radiation spinal deformities and to evaluate the results of their treatment. Seventy-six children, with a mean age of 4 years and 7 months (range, 2 months to 16 years), underwent surgical removal of malignant tumours, between 1961 and 1995. Sixty-seven of them developed post-laminectomy/post-radiation spinal deformity. Conservative treatment consisted of bracing and corrective plaster casts. In 46 cases the deformity was treated surgically. A distraction plaster cast was used as preoperative preparation in the more severe and rigid curves, with or without neurological impairment. Surgery consisted of combined anterior and posterior fusion in 39 cases and posterior fusion in seven cases. Posterior instrumentation was used in 38 cases. The mean follow-up period was 6 years and 7 months (range, 9 months to 20 years and 2 months). Nine children did not develop deformity following the primary tumour treatment. One of them underwent laminectomy with posterolateral fusion and eight had laminoplasty combined with external immobilisation. Forty-six children developed iatrogenic kyphosis and underwent surgical correction from a mean of 75° pre-correction to a mean of 32°. The mean scoliotic angle correction was 66° preoperatively to 34° postoperatively. At follow-up, the mean correction loss was 7° in the sagittal plane and 5° in the coronal plane. Preoperative distraction plaster cast treatment resulted in a correction of 39% in kyphosis and of 58% in scoliosis, and in a partial or complete recovery of neurological deficits in all but one patient. In severe and rigid curves that develop following treatment of paediatric spinal tumours, preoperative application of a distraction plaster cast can reduce deformity and facilitate surgical correction. Furthermore, in the case of pure bony compression of the spinal cord due to the apical vertebra of the deformity, treatment with the distraction plaster can result in recovery from the neurological impairment. The prevention of post-laminectomy/post-radiation spine deformities is emphasised. Rigid external immobilisation for a period of 4 months in the cervical spine and of 6 months in the thoracic spine is recommended after both laminoplasty and laminectomy with posterolateral fusion.
PMCID: PMC3489260  PMID: 16012842
Laminectomy; Laminoplasty; Radiation therapy; Spinal deformity; Spine fusion; Distraction plaster
5.  Myelopathy and Quadriparesis due to Spinal Cord Compression of C1 Laminar Osteochondroma 
Asian Spine Journal  2012;6(1):66-70.
The aim of this paper is to show that osteochondromas of the cervical vertebrae can cause myelopathy and neck pain.The reported etiology, diagnosis, treatment and differential diagnosis were reviewed. Osteochondromas may present as a solitary lesion with no genetic component or as multiple lesions as a part of a genetic disorder known as hereditary multiple exostosis. Osteochondromas of the spine are rarely encountered in clinical practice. These lesions are reported more commonly with neural compression in cases associated with hereditary multiple exostosis. The authors describe a unusual clinical manifestation of a solitary osteochondroma located in the right posterior arch of the atlas. Complete removal of the tumor was performed resulting in the relief of neck pain and spastic quadriparesis. Although unusual, osteochondromas of the cervical spine must be considered in patients with persistent neck pain and progressive symptoms of myelopathy. Computed tomography and magnetic resonance imaging in conjunction with plain radiograms is the neuroradiological modality of choice. The diagnosis and surgical excision of these tumors are important because they can cause spinal stenosis resulting in neural tissue compression and myelopathy.
PMCID: PMC3302919  PMID: 22439091
Atlas; C1; Cervical vertebrae; Spinal cord diseases; Quadriparesis; Solitary osteochondroma
6.  Treatment of Costal Osteochondroma Causing Spinal Cord Compression by Costotransversectomy: Case Report and Review of the Literature 
Clinics and Practice  2015;5(2):734.
In laminectomies for costal osteochondroma causing spinal cord compression, visualization of the extraforaminal part of the tumor is limited. The authors describe using a costotransversectomy to resolve spinal cord compression by a costal osteochondroma invading through the neural foramen. A 21-year-old woman with hereditary multiple exostoses presented with hand numbness and progressive neck and upper back pain. Plain radiographs identified a large lesion of the T2 and T3 pedicles, with encroachment on the T2-3 neural foramen causing ~50% spinal canal stenosis. Costotransversectomy was performed to resect the cartilaginous portions of the osteochondroma, debulk the mass, and decompress the spinal canal. A mass of mature bone was left, but no appreciable cartilaginous tumor. At five-year follow-up, the patient had improvement of neck pain, no new neurological deficits. a stable residual mass, and no new osteochondromas, indicating that appropriate surgical management can yield good results and no evidence of recurrence.
PMCID: PMC4500873
Costal osteochondroma; spinal cord compression; costotransversectomy; hereditary multiple exostoses
7.  The rib index is not practically affected by the distance between the radiation source and the examined child 
Scoliosis  2015;10(Suppl 2):S8.
All lateral spinal radiographs in idiopathic scoliosis (IS) show a Double Rib Contour Sign (DRCS) of the thoracic cage, a radiographic expression of the rib hump. The outline of the convex overlies the contour of the concave ribs. The rib index (RI) method was extracted from the DRCS to evaluate rib hump deformity in IS patients. The RI was calculated by the ratio of spine distances d1/d2 where d1 is the distance between the most extended point of the most extending rib contour and the posterior margin of the corresponding vertebra on the lateral scoliosis films, while d2 is the distance from the least projection rib contour and the posterior margin of the same vertebra, (Grivas et al 2002). In a symmetric thorax the “rib index” is 1.
This report is the validity study of DRCS, ie how the rib index is affected by the distance between the radiation source and the irradiated child.
The American College of Radiology's (2009) guidelines for obtaining radiographs for scoliosis in children recommends for the scoliotic - films distance to be 1,80 meters.
Normal values used for the transverse diameter of the ribcage in children aged 6-12 years were those reported by Grivas in 1988.
Using the Euclidean geometry, it is shown that in a normal 12-year old child d1/d2 = 1.073 provided that the distance ΔZ ≈ 12cm (11,84) and EA = 180cm, with transverse ribcage diameter of the child 22 cm.
This validity study demonstrates that the DRCS is substantially true and the RI is not practically affected by the distance between the radiation source and the irradiated child. The RI is valid and may be used to evaluate the effect of surgical or conservative treatment on the rib cage deformity (hump) in children with IS. It is noted that RI is a simple method and a safe reproducible way to assess the rib hump deformity based on lateral radiographs, without the need for any other special radiographs and exposure to additional radiation.
PMCID: PMC4331768  PMID: 25810757
8.  Surgical treatment of multiple spine metastases from gastrinoma 
Study design: Case report.
Clinical question: To report successful surgical therapy for spinal cord compression in a patient with spinal metastases from a pancreatic gastrinoma.
Methods: A 43-year-old man presented three times within 4 years with cervical and upper thoracic spinal cord compression because of metastatic gastrinoma. He had two previous spine metastases to the lower thoracic and lumbar spine, a T11 compressive lesion which required a T9L1 fusion, and an L4 lesion that was treated with chemotherapy and stereotactic radiation. The compression was relieved each time by surgery.
Results: The patient underwent three surgeries in 4 years: (1) debulking and removal of the rib head on the left at T3, and debulking of the tumor at T3 with hemilaminectomy and spinal cord decompression with internal fixation from T1–T5 using posterolateral instrumented fusion and allograft; (2) anterior C7 corpectomy with placement of a cage from C7–T1 with both anterior and posterior fusion of C2C7; and (3) T1–T3 laminectomy, T1–T3 exploration of wound, revision of hardware, T1–T3 removal of spinal tumor, and T3 bilateral transpedicular circumferential decompression. The patient is alive and regained the ability to walk 8 years after initial diagnosis, despite the appearance of spinal metastases 1 year after the diagnosis of liver metastases.
Conclusion: Surgery for spinal cord compression in patients with metastatic neuroendocrine tumors can be effective in relieving radicular pain, weakness and numbness, and while not curative can greatly improve quality of life.
PMCID: PMC3506145  PMID: 23230405
9.  The effect of growth on the correlation between the spinal and rib cage deformity: implications on idiopathic scoliosis pathogenesis 
Scoliosis  2007;2:11.
Numerous studies have attempted to quantify the correlation between the surface deformity and the Cobb angle without considering growth as an important factor that may influence this correlation. In our series, we noticed that in some younger referred children from the school-screening program there is a discrepancy between the thoracic scoliometer readings and the morphology of their spine. Namely there is a rib hump but no spinal curve and consequently no Cobb angle reading in radiographs, discrepancy which fades away in older children. Based on this observation, we hypothesized that in scoliotics the correlation between the rib cage deformity and this of the spine is weak in younger children and vice versa.
Eighty three girls referred on the basis of their hump reading on the scoliometer, with a mean age of 13.4 years old (range 7–18), were included in the study. The spinal deformity was assessed by measuring the thoracic Cobb angle from the postero-anterior spinal radiographs. The rib cage deformity was quantified by measuring the rib-index at the apex of the thoracic curve from the lateral spinal radiographs. The rib-index is defined as the ratio between the distance of the posterior margin of the vertebral body and the most extended point of the most projecting rib contour, divided by the distance between the posterior margin of the same vertebral body and the most protruding point of the least projecting rib contour. Statistical analysis included linear regression models with and without the effect of the variable age. We divided our sample in two subgroups, namely the younger (7–13 years old) and the older (14–18 years old) than the mean age participants. A univariate linear regression analysis was performed for each age group in order to assess the effect of age on Cobb angle and rib index correlation.
Twenty five per cent of patients with an ATI more than or equal 7 degrees had a spinal curve under 10 degrees or had a straight spine. Linear regressions between the dependent variable "Thoracic Cobb angle" with the independent variable "rib-index" without the effect of the variable "age" is not statistical significant. After sample split, the linear relationship is statistically significant in the age group 14–18 years old (p < 0.03).
Growth has a significant effect in the correlation between the thoracic and the spinal deformity in girls with idiopathic scoliosis. Therefore it should be taken into consideration when trying to assess the spinal deformity from surface measurements. The findings of the present study implicate the role of the thorax, as it shows that the rib cage deformity precedes the spinal deformity in the pathogenesis of idiopathic scoliosis.
PMCID: PMC2040132  PMID: 17868459
10.  Spinal Exostosis in a Boy with Multiple Hereditary Exostoses 
Case Reports in Orthopedics  2013;2013:758168.
We report on a 13-year-old boy who presented with multiple hereditary exostosis and had development of back pain, associated with neurological deficits, and was found to have exostoses in the spinal canal. Spine radiograph showed a cauliflower-like abnormality of multiple exostoses of the posterior arch (pedicle) of the thoracic vertebrae (T3–5). Reformatted CT scanning revealed the simultaneous development of intra- and extraspinal osteochondromatosis of T3–5. The spinal cord was compressed by the intraspinal exostosis. Our patient was surgically treated for intraspinal exostoses and showed cessation of neurological deficits. We report what might be a rare association of spinal cord compression in a patient with multiple hereditary exostoses.
PMCID: PMC3844191  PMID: 24324905
11.  The anatomical relationship between the aorta and the thoracic vertebral bodies and its importance in the placement of the screw in thoracoscopic correction of Scoliosis 
European Spine Journal  2007;16(9):1367-1372.
Thoracoscopically-assisted anterior spinal instrumentation is being used widely to treat adolescent idiopathic scoliosis (AIS). Recent studies have showed that screws placed thoracoscopically could counter the aorta or entrance into the spinal canal. There are a few studies defining the anatomic landmarks to identify the relationship between the aorta and the thoracic vertebral body using quantitative measurement for the sake of safe placement of thoracoscopic vertebral screw in anterior correction for AIS. The CT scanning from T4 to T12 in 64 control subjects and 30 AIS patients from mainland China were analyzed manually. Parameters to be measured included the angle for safety screw placement (α), the angle of the aorta relative to the vertebral body (β), the distance from the line between the left and the right rib heads to the anterior wall of the vertebral canal (a), the distance from the left rib head to posterior wall of the aorta (b), the vertebral body transverse diameter (c) and vertebral rotation (γ). No significant differences were found between the groups with respect to age or sex. Compared with the control group, α angle from T7 to T10, β angle from T5 to T10 and b value at T9, T10 were significantly lower in the scoliotic group. The a value was significantly lower in the scoliotic group. The c value showed no significant difference between the two groups. In conclusion, to place the thoracoscopic vertebral screw safely, at the cephalad thoracic spine (T4–T6), the maximum ventral excursion angle should decrease gradually from 20° to 5°, the entry-point of the screw should be close to the rib head. For apical vertebrae (T7–T9), the maximum ventral excursion angle increased gradually from 5° to 12°. At the caudal thoracic spine (T10–T12), the maximum ventral excursion angle increased, the entry-point should shift 3∼5 mm ventrally.
PMCID: PMC2200740  PMID: 17410383
Aorta; Thoracic vertebrae; Anatomy; Thoracoscopy; Scoliosis
12.  Anterior short correction in thoracic adolescent idiopathic scoliosis with mini-open thoracotomy approach: prospective clinical, radiological and pulmonary function results 
European Spine Journal  2012;21(Suppl 6):765-772.
This is a prospective study of adolescent patients in whom idiopathic thoracic scoliosis was corrected by short anterior fusion through a mini-open thoracotomy approach. Clinical, radiological and pulmonary function results of minimal 2-year (2–6) follow-up are presented.
Materials and methods
Consecutive 62 patients with Lenke 1 and 2 curves, having main thoracic scoliosis of up to 75°, were prospectively included. The shoulder imbalance in Lenke 2 patients was less than 20 mm. Thoracic scoliosis was corrected by short anterior fusion. The thoracic spine was exposed by an 8-cm mini-open thoracotomy incision. The operation technique and choosing of fusion levels are thoroughly described. Complete 360° discectomies and convex side vertebral endplates osteotomies are essential for deformity corrections with short fusions. Single-rod 5.5-mm titanium implants were used. The age at the time of operation was mean 15.2 years; 56 patients had a single thoracic curve and 6 patients had a double thoracic curve. There were almost equal numbers of patients with lumbar modifier A, B or C. The average length of fusion was 5.5 (4–7) vertebrae. The average length of fusion was 3.5 (2–6) vertebrae shorter than the average curve length.
The instrumented thoracic curves improved by 58.3% at 6 weeks and 56.3% at the last follow-up. Apex thoracic vertebral rotation improved by 73.78% at 6 weeks and 76.24% at the last follow-up. The non-instrumented upper thoracic curve improved by 25% in double thoracic scoliosis, where the mid-thoracic curve was selectively fused, and the non-instrumented lumbar curves improved by 33.9% at the last follow-up. The radiological changes from 6 weeks to the last follow-up were statistically not significant. The clinical rib hump improved by 54% at the last follow-up. There were no significant changes in the pulmonary function. FVC% was 81.04% preoperatively, 76.41% at 6 months and 80.38% at the 2-year follow-up. The results of SRS 24 questionnaire improved from a total of 61.40 points preoperatively to 100.50 points at 6 months and 98.62 points at the 2-year follow-up. There were no neurological or thoracotomy related complications, no pseudarthrosis, no implant pullout or breakage.
A good deformity correction without loss of correction or adding on, a good cosmetic result and good patient’s satisfaction were achieved through shorter than end-to-end thoracic fusions. The radiological residual deformity is acceptable. Anterior correction of thoracic scoliosis with a short spinal fusion is recommended to keep the large part of the spine mobile. A very short fusion, small thoracotomy incision, low-profile implants and complete closure of parietal pleura are keys to prevent reduction in postoperative lung function.
PMCID: PMC3535212  PMID: 22274321
Idiopathic thoracic scoliosis; Short anterior correction; Mini-thoracotomy; Pulmonary function; Single rod instrumentation
13.  Cotrel–Dubousset instrumentation in neuromuscular scoliosis 
European Spine Journal  2011;20(Suppl 1):75-84.
The study design is retrospective. The aim is to describe our experience about the treatment of patients with neuromuscular scoliosis (NMS) using Cotrel–Dubousset instrumentation. Neuromuscular scoliosis are difficult deformities to treat. A careful assessment and an understanding of the primary disease and its prognosis are essential for planning treatment which is aimed at maximizing function. These patients may have pelvic obliquity, dislocation of the hip, limited balance or ability to sit, back pain, and, in some cases, a serious decrease in pulmonary function. Spinal deformity is difficult to control with a brace, and it may progress even after skeletal maturity has been reached. Surgery is the main stay of treatment for selected patients. The goals of surgery are to correct the deformity producing a balanced spine with a level pelvis and a solid spinal fusion to prevent or delay secondary respiratory complications. The instrumented spinal fusion (ISF) with second-generation instrumentation (e.g., Luque–Galveston and unit rod constructs), are until 1990s considered the gold standard surgical technique for neuromuscular scoliosis (NMS). Still in 2008 Tsirikos et al. said that “the Unit rod instrumentation is a common standard technique and the primary instrumentation system for the treatment of pediatric patients with cerebral palsy and neuromuscular scoliosis because it is simple to use, it is considerably less expensive than most other systems, and can achieve good deformity correction with a low loss of correction, as well as a low prevalence of associated complications and a low reoperation rate.” In spite of the Cotrel–Dubousset (CD) surgical technique, used since the beginning of the mid 1980s, being already considered the highest level achieved in correction of scoliosis by a posterior approach, Teli et al., in 2006, said that reports are lacking on the results of third-generation instrumentation for the treatment of NMS. Patients with neuromuscular disease and spinal deformity treated between 1984 and 2008 consecutively by the senior author (G.D.G.) with Cotrel–Dubousset instrumentation and minimum 36 months follow-up were reviewed, evaluating correction of coronal deformity, sagittal balance and pelvic obliquity, and rate of complications. 24 patients (Friedreich’s ataxia, 1; cerebral palsy, 14; muscular dystrophy, 2; polio, 2; syringomyelia, 3; spinal atrophy, 2) were included. According the evidence that the study period is too long (1984–2008) and that in more than 20 years many things changed in surgical strategy and techniques, all patients were divided in two groups: only hooks (8 patients) or hybrid construct (16 patients). Mean age was 18.1 years at surgery (range 11 years 7 months–max 31 years; in 17 cases the age at surgery time was between 10 and 20 years old; in 6 cases it was between 20 and 30 and only in 1 case was over 30 years old). Mean follow-up was 142 months (range 36–279). The most frequent patterns of scoliosis were thoracic (10 cases) and thoracolumbar (9 cases). In 8 cases we had hypokyphosis, in 6 normal kyphosis and in 9 hyperkyphosis. In 8 cases we had a normal lordosis, in 11 a hypolordosis and in 4 a hyperlordosis. In 1 case we had global T4–L4 kyphosis. In 8 cases there were also a thoracolumbar kyphosis (mean value 24°, min 20°–max 35°). The mean fusion area included 13 vertebrae (range 6–19); in 17 cases the upper end vertebra was over T4 and in 11 cases the lower end vertebra was over L4 or L5. In 7 cases the lower end vertebra was S1 to correct the pelvic obliquity. In 5 cases the severity of the deformity (mean Cobb’s angle 84.2°) imposed a preoperative halo traction treatment. There were 5 anteroposterior and 19 posterior-only procedures. In 10 cases, with low bone quality, the arthrodesis was performed using iliac grafting technique while in the other (14 cases) using autologous bone graft obtained in situ from vertebral arches and spinous processes (in all 7 cases with fusion extended until S1, it was augmented with calcium phosphate). The mean correction of coronal deformity and pelvic obliquity averaged, respectively, 57.2% (min 31.8%; max 84.8%) and 58.9% (mean value preoperative, 18.43°; mean value postoperative, 7.57°; mean value at last follow-up, 7.57°). The sagittal balance was always restored, reducing hypo or hyperkyphosis and hypo or hyperlordosis. Also in presence of a global kyphosis, we observed a very good restoration (preoperatory, 65°; postoperatory, 18° kyphosis and 30° lordosis, unmodified at last f.u.). The thoracolumbar kyphosis, when present (33.3% of our group) was always corrected to physiological values (mean 2°, min 0°–max 5°). The mean intraoperative blood lost were 2,100 cc (min 1,400, max 5,350). Major complications affected 8.3% of patients, and included 1 postoperative death and 1 deep infection. Minor complications affected none of patients. CD technique provides lasting correction of spinal deformity in patients with neuromuscular scoliosis, with a lower complications rate compared to reports on second-generation instrumented spinal fusion.
PMCID: PMC3087033  PMID: 21404030
Neuromuscular scoliosis; Cotrel–Dubousset; Spinal fusion
14.  A segmental radiological study of the spine and rib – cage in children with progressive Infantile Idiopathic Scoliosis 
Scoliosis  2006;1:17.
The role of rib cage in the development of progressive infantile idiopathic scoliosis (IIS) has not been studied previously. No report was found for rib growth in children with IIS. These findings caused us to undertake a segmental radiological study of the spine and rib-cage in children with progressive IIS. The aim of the present study is to present a new method for assessing the thoracic shape in scoliotics and in control subjects and to compare the findings between the two groups.
Materials and methods
In the posteroanterior (PA) spinal radiographs of 24 patients with progressive IIS, with a mean age of 4.1 years old, the Thoracic Ratios (TRs) (segmental convex and concave TRs), the Cobb angle, the segmental vertebral rotation and vertebral tilt were measured. In 233 subjects, with a mean age of 5.1 years old, who were used as a control group, the segmental left and right TRs and the total width of the chest (left plus right TRs) were measured in PA chest radiographs. Statistical analysis included Mann-Whitney, Spearman correlation coefficient, multiple linear regression analysis and ANOVA.
The comparison shows that the scoliotic thorax is significantly narrower than that of the controls at all spinal levels. The upper chest in IIS is funnel-shaped and the vertebral rotation at T4 early in management correlates significantly with the apical vertebral rotation at follow up.
The IIS thorax is narrower than that of the controls, the upper chest is funnel-shaped and there is a predictive value of vertebral rotation at the upper limit of the thoracic curve of IIS, which reflects, impaired rib control of spinal rotation possibly due to neuromuscular factors, which contribute also to the funnel-shaped chest.
PMCID: PMC1635062  PMID: 17049098
15.  A biomechanical analysis of the vertebral and rib deformities in structural scoliosis 
European Spine Journal  1999;8(4):252-260.
Although the structural changes occurring in the scoliotic spine have been reported as early as the 19th century, the descriptions and biomechanical explanations have not always been complete and consistent. In this study, three-dimensionally rendered CT images of two human skeletons with a scoliotic deformity and two patients with serious scoliosis were used to describe the intrinsic vertebral and rib deformities. The pattern of structural deformities was found to be consistent. Apart from the wedge deformation of the apical vertebrae, a rotation deformity was found in the transversal plane between the vertebral body and the posterior complex: the vertebral body was maximally rotated towards the convexity of the scoliotic curve, whereas the tip of the spinous process was pointed to posterior. The rib deformities at the convex side of the scoliotic curve showed an increased angulation of the rib at the posterior angle, whereas the rib curve on the concave side was flattened. The observed vertebral deformities suggest that these are caused by bone remodelling processes due to forces in the anterior spinal column, which drive the apical vertebral body out of the midline, whereas forces of the musculo-ligamentous structures at the posterior side of the spinal column attempt to minimize the deviations and rotations of the vertebrae. The demonstrated rib deformities suggest an adaptation to forces imposed by the scoliotic spine.
PMCID: PMC3611175  PMID: 10483825
Key words Scoliosis; Scoliosis; deformity; Scoliosis; vertebra; Scoliosis; rib; Scoliosis; biomechanics
16.  A shallow chest correlates with the aortic position in the normal spine: features resembling those observed in structural scoliosis 
Scoliosis  2014;9:14.
Right thoracic curvature, rib cage deformities and aortic left shift are features of adolescent idiopathic scoliosis that are correlated with each other. We recently reported that disturbance of ribcage development results in progressive thoracic scoliosis in mice. Recently, it has been confirmed that the normal spine exhibits right thoracic curvature and rib cage deformities and that these deformities worsen during the adolescent period. The purpose of this study was to examine whether rib cage deformities correlate with thoracic side curvature in the normal spine, as observed in scoliosis, which is important basic knowledge needed to elucidate the causative factors of adolescent idiopathic scoliosis.
To examine the relationship between rib cage deformities and thoracic side curvature in the normal spine, CT scans of 148 consecutive adult females were examined. The anteroposterior chest dimension, aortic location and rib cage rotation were measured on CT scans obtained at the T8 level. The thoracic side curvature (T5-T12) was also measured on chest radiographs.
The anteroposterior chest dimension exhibited a significant correlation with aortic left shift. The aortic location and rib cage rotation were correlated, and the rib cage rotation and thoracic side curvature were correlated.
There was a significant correlation between a shallow chest and the aortic position, between the aortic position and the rib cage rotation and between the rib cage rotation and the thoracic side curvature in the normal spine. These findings suggest the possibility that rib cage development is one of the causative factors of adolescent idiopathic scoliosis.
PMCID: PMC4152277  PMID: 25183992
Scoliosis; Rib cage deformity; Aorta; Shallow chest
17.  Video-assisted thoracoscopic surgery (VATS) for the treatment of scolioticrib hump deformity 
European Spine Journal  2007;16(9):1373-1377.
A retrospective study of 21 patients with idiopathic scoliosis who underwent endoscopic thoracoplasty was done. The objective of the study was to report and assess the morbidity and mid term outcomes of video-assisted thoracoplasty in idiopathic scoliosis. Patients with idiopathic scoliosis often present cosmetic complaints due to their rib deformity. This deformity may still exist after surgical correction of the main scoliotic curve. Endoscopic thoracoplasty has been reported as a safe method in limited cases of idiopathic scoliosis. Between 2002 and 2004, 21 patients underwent endoscopic anterior release and thoracoplasty for significant rib hump deformity associated with idiopathic scoliosis. Patients were operated on lateral position, with two endoscopic ports. Anterior release and rib resection were performed during the first stage, and instrumented posterior fusion was performed in a second stage. Patients were evaluated preoperatively, 1 week after surgery, 6 months after surgery and at their most recent follow-up with clinical and radiological measurement of the rib deformity. The mean age at surgery was 14.9 years old (range 13–17 years). The average Cobb’s angle of the main scoliotic curve was 70° (range 60°–85°). Average follow-up was 25 months (range 23–32 months). The mean number of resected ribs was five ribs (range 4–7) and the mean length of the resected rib was 4.2 cm (range 2.2–7 cm). Average operating time of endoscopic thoracoplasty (including anterior release) was 65 min (range 45–108 min). The mean preoperative height of rib hump deformity was 3.6 cm (range 2.5–5.5 cm). It was reduced to 1.5 cm at most recent follow-up. There was no significant thoracic pain necessitating medication postoperatively. No complications related to endoscopic anterior release and rib hump resection occurred in the series. Endoscopic thoracoplasty is a safe and reliable technique in idiopathic scoliosis. If indicated, the anterior release can be performed with video-assistance and the thoracoplasty can be performed on the same stage.
PMCID: PMC2200748  PMID: 17356821
Scoliosis; Thoracoscopy; Thoracic deformity
18.  Osteochondroma Arising from the Thoracic Transverse Process 
SAS Journal  2009;3(1):12-16.
The incidence of osteochondroma is rare and only 2% of such tumors are found in the spine area. When they are found in the vertebral column, less than 1% of all osteochondromas and few tumors occur in the thoracic vertebrae. An osteochondroma arising from the transverse process of the vertebra is even rarer, especially following from the thoracic transverse process. Here we report a giant solitary osteochondroma arising from the thoracic transverse process of T8 vertebra and involving the corresponding transverse process and rib.
A 28-year-old man presented with a progressive thoracic node, and neuroradiological evaluation of the spine showed a giant mass lesion involving the transverse process of T8 vertebra and concomitant corresponding facet joint and rib on the left side. At surgery, a firm and cartilaginous tumor originating from the transverse process was radically excised and surgical curettage of the lesion was performed.
It is concluded that accurate and prompt diagnosis requires a high index of suspicion followed by surgical treatment to prevent severe morbidity in cases of primary spinal column tumors. The histological examination of this patient revealed the lesion was osteochondroma.
The best choice of treatment for spinal osteochondromas is surgical excision or curettage and spinal stabilization, if necessary.
PMCID: PMC4365589  PMID: 25802624
Osteochondroma; Spine tumor; Process; Appendix of vertebral
19.  Rib hump deformity assessment using the rib index in adolescent idiopathic scoliotics treated with full screw or hybrid constructs: aetiological implications 
Scoliosis  2015;10(Suppl 2):S10.
Review of literature reveals that in Idiopathic Scoliosis (IS) children, the post-operative rib hump (RH) correction using full transpedicular screw construct has never been compared to hybrid constructs, applying the Rib-Index (RI) method. Therefore the aim of this report is to study which of the above two constructs offers better postoperative Rib Hump Deformity (RHD) correction.
Twenty five patients with Adolescent Idiopathic Scoliosis (AIS) were operated using full pedicle screw construct or hybrid construct. Sixteen underwent full screw instrumentation (group A) and nine an hybrid one (group B). The median age for group A was 15 years and for group B 17.2 years. The RHD was assessed on the lateral spinal radiographs using the RI. The RI was calculated by the ratio of spine distances d1/d2, where d1 is the distance between the most extended point of the most extending rib contour and the posterior margin of the corresponding vertebra on the lateral scoliosis films and d2 is the distance from the least projected rib contour and the posterior margin of the same vertebra. Moreover the amount of RI correction was calculated by subtracting the post-operative RI from the pre-operative RI.
Although within group A the RI correction was statistical significant (the pre-op RI was 1.93 and the post-op 1.37; p<0.001) and similarly in group B (the mean pre-op RI was 2.06 while the mean post-op 1.51; p=0.008), between group A and B the post-operative RI correction mean values were found to be no statistically significant, (p=0.803).
Although the pre- and post-operative RI correction was statistically significant within each group, this did not happen post-operatively between the two groups. It appears that the RHD correction is not different, no matter what the spinal construct type was used. Provided that the full screw construct is powerful, the post-operative derotation and RHD correction was expected to be better than when an hybrid construct is applied, which is not the case in this study. It is therefore implied that the RHD results more likely from the asymmetric rib growth rather than from vertebral rotation, as it has been widely believed up to now. In 2013 Lykissas et al, reported that costoplasty combined with pedicle screws and vertebral derotation significantly improved RH deformity as opposed to pedicle screws and vertebral derotation alone. Another interesting implication is that the spinal deformity is the result of the thoracic asymmetry, implication in line with the late Prof. John Sevastikoglou’s (Sevastik’s) thoracospinal concept.
PMCID: PMC4331727  PMID: 25810758
20.  Rib-vertebral angle asymmetry in idiopathic, neuromuscular and experimentally induced scoliosis 
European Spine Journal  1997;6(2):84-88.
The concave and convex rib-vertebral angle (RVA) at levels T2–T12 was measured on AP radiographs of 19 patients with right convex idiopathic thoracic scoliosis and 10 patients with major thoracic right convex neuromuscular scoliosis. The difference between the angles on the concave and the convex sides, the RVAD, was calculated. The RVAs were also measured on radiographs from three animal groups in which spinal curves had been induced experimentally in a variety of ways. Group 1 comprised 16 rabbits that had been subjected to selective electrostimulation of the latissimus dorsi, the erector spinae and the intercostal muscles. Group 2 comprised four dead rabbits whose spines had been subjected to manual bending. Group 3 comprised eight rabbits that had undergone mechanical elongation of one rib. In both the idiopathic and the neuromuscular group, the convex RVA was smaller than the concave RVA between levels T2 and T8, with a maximal difference between T4 to T5. From T9 to T12 the concave RVA was smaller than the convex. The RVA in relation to the scoliotic segment, i.e. the apex level of the curve and the two neighbouring vertebrae above and below this level, showed similar results. With increasing Cobb angle the RVADs increased linearly with the greatest difference at the second vertebra above the apex. In the three experimental groups the pattern of the RVADs between T6 to T12 was basically similar to the findings of the clinical study. From the results of these clinical and experimental studies, it is concluded that the typical pattern of the RVAs on the concave and convex sides seems to be independent of the underlying cause of the spinal curvature. It is likely that the RVADs result from a passive mechanical adaptation of the ribs to the lateral curvature of the spine.
PMCID: PMC3454587  PMID: 9209873
Rib-vertebral angle difference; Idiopathic scoliosis; Neuromuscular scoliosis; Experimental scoliosis
21.  Surgical treatment of scoliosis: a review of techniques currently applied 
Scoliosis  2008;3:6.
In this review, basic knowledge and recent innovation of surgical treatment for scoliosis will be described. Surgical treatment for scoliosis is indicated, in general, for the curve exceeding 45 or 50 degrees by the Cobb's method on the ground that:
1) Curves larger than 50 degrees progress even after skeletal maturity.
2) Curves of greater magnitude cause loss of pulmonary function, and much larger curves cause respiratory failure.
3) Larger the curve progress, more difficult to treat with surgery.
Posterior fusion with instrumentation has been a standard of the surgical treatment for scoliosis. In modern instrumentation systems, more anchors are used to connect the rod and the spine, resulting in better correction and less frequent implant failures. Segmental pedicle screw constructs or hybrid constructs using pedicle screws, hooks, and wires are the trend of today.
Anterior instrumentation surgery had been a choice of treatment for the thoracolumbar and lumbar scoliosis because better correction can be obtained with shorter fusion levels. Recently, superiority of anterior surgery for the thoracolumbar and lumbar scoliosis has been lost. Initial enthusiasm for anterior instrumentation for the thoracic curve using video assisted thoracoscopic surgery technique has faded out.
Various attempts are being made with use of fusionless surgery. To control growth, epiphysiodesis on the convex side of the deformity with or without instrumentation is a technique to provide gradual progressive correction and to arrest the deterioration of the curves. To avoid fusion for skeletally immature children with spinal cord injury or myelodysplasia, vertebral wedge ostetomies are performed for the treatment of progressive paralytic scoliosis. For right thoracic curve with idiopathic scoliosis, multiple vertebral wedge osteotomies without fusion are performed. To provide correction and maintain it during the growing years while allowing spinal growth for early onset scoliosis, technique of instrumentation without fusion or with limited fusion using dual rod instrumentation has been developed. To increase the volume of the thorax in thoracic insufficiency syndrome associated with fused ribs and congenital scoliosis, vertical expandable prosthetic titanium ribs has been developed.
PMCID: PMC2346456  PMID: 18423027
22.  Pathogenesis of adolescent idiopathic scoliosis in girls - a double neuro-osseous theory involving disharmony between two nervous systems, somatic and autonomic expressed in the spine and trunk: possible dependency on sympathetic nervous system and hormones with implications for medical therapy 
Scoliosis  2009;4:24.
Anthropometric data from three groups of adolescent girls - preoperative adolescent idiopathic scoliosis (AIS), screened for scoliosis and normals were analysed by comparing skeletal data between higher and lower body mass index subsets. Unexpected findings for each of skeletal maturation, asymmetries and overgrowth are not explained by prevailing theories of AIS pathogenesis. A speculative pathogenetic theory for girls is formulated after surveying evidence including: (1) the thoracospinal concept for right thoracic AIS in girls; (2) the new neuroskeletal biology relating the sympathetic nervous system to bone formation/resorption and bone growth; (3) white adipose tissue storing triglycerides and the adiposity hormone leptin which functions as satiety hormone and sentinel of energy balance to the hypothalamus for long-term adiposity; and (4) central leptin resistance in obesity and possibly in healthy females. The new theory states that AIS in girls results from developmental disharmony expressed in spine and trunk between autonomic and somatic nervous systems. The autonomic component of this double neuro-osseous theory for AIS pathogenesis in girls involves selectively increased sensitivity of the hypothalamus to circulating leptin (genetically-determined up-regulation possibly involving inhibitory or sensitizing intracellular molecules, such as SOC3, PTP-1B and SH2B1 respectively), with asymmetry as an adverse response (hormesis); this asymmetry is routed bilaterally via the sympathetic nervous system to the growing axial skeleton where it may initiate the scoliosis deformity (leptin-hypothalamic-sympathetic nervous system concept = LHS concept). In some younger preoperative AIS girls, the hypothalamic up-regulation to circulating leptin also involves the somatotropic (growth hormone/IGF) axis which exaggerates the sympathetically-induced asymmetric skeletal effects and contributes to curve progression, a concept with therapeutic implications. In the somatic nervous system, dysfunction of a postural mechanism involving the CNS body schema fails to control, or may induce, the spinal deformity of AIS in girls (escalator concept). Biomechanical factors affecting ribs and/or vertebrae and spinal cord during growth may localize AIS to the thoracic spine and contribute to sagittal spinal shape alterations. The developmental disharmony in spine and trunk is compounded by any osteopenia, biomechanical spinal growth modulation, disc degeneration and platelet calmodulin dysfunction. Methods for testing the theory are outlined. Implications are discussed for neuroendocrine dysfunctions, osteopontin, sympathoactivation, medical therapy, Rett and Prader-Willi syndromes, infantile idiopathic scoliosis, and human evolution. AIS pathogenesis in girls is predicated on two putative normal mechanisms involved in trunk growth, each acquired in evolution and unique to humans.
PMCID: PMC2781798  PMID: 19878575
23.  Changes of concave and convex rib–vertebral angle, angle difference and angle ratio in patients with right thoracic adolescent idiopathic scoliosis 
European Spine Journal  2010;20(1):129-134.
The aim of this study is to describe the radiological changes in rib–vertebral angles (RVAs), rib–vertebral angle differences (RVADs), and rib–vertebral angle ratios (RVARas) in patients with untreated right thoracic adolescent idiopathic scoliosis and to compare with the normal subjects. The concave and convex RVA from T1 to T12, the RVADs and the RVARas were measured on AP digital radiographs of 44 female patients with right convex idiopathic scoliosis and 14 normal females. Patients were divided into three groups: normal subjects (group 1), scoliotic patients with Cobb’s angle equal or <30° (group 2) and scoliotic patients with Cobb’s angle over 30° (group 3). Overall values (mean ± SD) of the RVAs on the concave side were 90.5° ± 17° in group 1, 90.3° ± 15.8° in group 2 and 88.8° ± 15.4° in group 3. On the convex side, values were 90.0° ± 17.3° in group 1, 86.3° ± 13.7° in group 2 and 80.7° ± 14.4° in group 3. Overall values (mean ± SD) of the RVADs at all levels were 0.5° ± 0.7° in group 1, 4.0° ± 4.8° in group 2 and 8.0° ± 4.0° in group 3. The RVARa values (mean ± SD) at all levels was 1.008° ± 0.012° in group 1, 1.041° ± 0.061° in group 2 and 1.102° ± 0.151° in group 3. RVAD and RVARa values in the scoliotic segment were greater in patients with untreated scoliosis over 30° than in patients with an untreated deformity of <30° or normal subjects. A significant effect between groups was observed for the RVA, RVAD and RVARa variables. Measurement of RVA, RVAD and RVARa should not only be performed at and around the apex of a thoracic spinal deformity, but also extended to the whole thoracic spine.
PMCID: PMC3036015  PMID: 20811755
Rib–vertebral angle; Rib–vertebral angle difference; Rib–vertebral angle ratio; Adolescent idiopathic scoliosis
24.  One-stage and posterior approach for correction of moderate to severe scoliosis in adolescents associated with Chiari I malformation: is a prior suboccipital decompression always necessary? 
European Spine Journal  2011;20(7):1106-1113.
Priority of neurological decompression was regarded as necessary for scoliosis patients associated with Chiari I malformation in order to decrease the risk of spinal cord injury from scoliosis surgery. We report a retrospective series of scoliosis associated with Chiari I malformation in 13 adolescent patients and explore the effectiveness and safety of posterior scoliosis correction without suboccipital decompression. One-stage posterior approach total vertebral column resection was performed in seven patients with scoliosis or kyphosis curve >90° (average 100.1° scoliotic and 97.1° kyphotic curves) or presented with apparent neurological deficits, whereas the other six patients underwent posterior pedicle screw instrumentation for correction of spinal deformity alone (average 77.3° scoliotic and 44.0° kyphotic curves). The apex of the scoliosis curve was located at T7–T12. Mean operating time and intraoperative hemorrhage was 463 min and 5,190 ml in patients undergoing total vertebral column resection, with average correction rate of scoliosis and kyphosis being 63.3 and 71.1%, respectively. Mean operating time and intraoperative hemorrhage in patients undergoing instrumentation alone was 246 min and 1,450 ml, with the average correction rate of scoliosis and kyphosis being 60.8 and 53.4%, respectively. The mean follow-up duration was 32.2 months. No iatrogenic neurological deterioration had been encountered during the operation procedure and follow-up. After vertebral column resection, neurological dysfunctions such as relaxation of anal sphincter or hypermyotonia that occurred in three patients preoperatively improved gradually. In summary, suboccipital decompression prior to correction of spine deformity may not always be necessary for adolescent patients with scoliosis associated with Chiari I malformation. Particularly in patients with a severe and rigid curve or with significant neurological deficits, posterior approach total vertebral column resection is likely a good option, which could not only result in satisfactory correction of deformity, but also decrease the risk of neurological injury secondary to surgical intervention by shortening spine and reducing the tension of spinal cord.
PMCID: PMC3176690  PMID: 21399931
Scoliosis; Kyphosis; Chiari malformation; Adolescent; Corrective surgery
25.  Biomechanical simulations of the spine deformation process in adolescent idiopathic scoliosis from different pathogenesis hypotheses 
European Spine Journal  2004;13(1):83-90.
It is generally recognized that progressive adolescent idiopathic scoliosis (AIS) evolves within a self-sustaining biomechanical process involving asymmetrical growth modulation of vertebrae due to altered spinal load distribution. A biomechanical finite element model of normal thoracic and lumbar spine integrating vertebral growth was used to simulate the progression of spinal deformities over 24 months. Five pathogenesis hypotheses of AIS were represented, using an initial geometrical eccentricity (gravity line imbalance of 3 mm or 2° rotation) at the thoracic apex to trigger the self-sustaining deformation process. For each simulation, regional (thoracic Cobb angle, kyphosis) and local scoliotic descriptors (axial rotation and wedging of the thoracic apical vertebra) were evaluated at each growth cycle. The simulated AIS pathogeneses resulted in the development of different scoliotic deformities. Imbalance of 3 mm in the frontal plane, combined or not with the sagittal plane, resulted in the closest representation of typical scoliotic deformities, with the thoracic Cobb angle progressing up to 39° (26° when a sagittal offset was added). The apical vertebral rotation increased by 7° towards the convexity of the curve, while the apical wedging increased to 8.5° (7.3° with the sagittal eccentricity) and this deformity evolved towards the vertebral frontal plane. A sole eccentricity in the sagittal plane generated a non-significant frontal plane deformity. Simulations involving an initial rotational shift (2°) in the transverse plane globally produced relatively small and non-typical scoliotic deformations. Overall, the thoracic segment predominantly was sensitive to imbalances in the frontal plane, although unidirectional geometrical eccentricities in different planes produced three-dimensional deformities at the regional and vertebral levels, and their deformities did not cumulate when combined. These results support the hypothesis of a prime lesion involving the precarious balance in the frontal plane, which could concomitantly be associated with a hypokyphotic component. They also suggest that coupling mechanisms are involved in the deformation process.
PMCID: PMC3468030  PMID: 14730437
Idiopathic scoliosis; Pathogenesis; Biomechanical modeling; Growth modulation; Spine; Vertebra

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