Spine bone mineral density and vertebral body height are altered by alcohol consumption in growing male and female rats

Alcohol, consumed for extended periods by growing male and female rats, impairs osteogenesis and reduces bone size and mass. The skeletal sites of experimental animals commonly chosen for an evaluation of bone mechanical characteristics and architectural properties, bone matrix gene expression, tissue concentrations of growth factors, and bone mineral density (BMD) have been the tibiae and femora. Far less attention has been focused on the spine and the effects of alcohol on vertebral BMD and vertebral body height. Fifteen male and 15 female Sprague-Dawley rats (aged 30 days) were divided into three groups: an alcohol-fed group, matched to a pair-fed non-alcohol isocaloric-fed control group with animals of the same sex, and an ad libitum-fed control group. Alcohol-fed animals received a Lieber-DeCarli liquid diet containing 36% of caloric intake as alcohol; isocaloric pair-fed rats received the same diet without alcohol. After 45 days of feeding, the lumbar spine was removed. The fourth lumbar vertebra from each spine was dissected, and the vertebral body height was measured. Lumbar vertebral body height was significantly reduced by alcohol consumption in both male and female rats compared with findings for either control group. Cancellous and cortical BMD of the vertebral body was determined by peripheral quantitative computed tomography (pQCT). Male and female rats (aged 75 days) in the ad libitum-fed group had similar vertebral body cortical and cancellous BMD, with cortical BMD being greater than cancellous BMD. Lumbar vertebral body cancellous and cortical BMD declined for both male and female rats in response to alcohol consumption for 45 days compared with findings for either control group. More BMD loss occurred from cancellous than from cortical bone in both sexes after chronic alcohol consumption. Chronic alcohol consumption by growing rats results in vertebral growth reduction and vertebral osteopenia.

Spontaneous muscle twitches during sleep guide spinal self-organization

During development, information about the three-dimensional shape and mechanical properties of the body is laid down in the synaptic connectivity of sensorimotor systems through unknown adaptive mechanisms. In spinal reflex systems, this enables the fast transformation of complex sensory information into adequate correction of movements. Here we use a computer simulation to show that an unsupervised correlation-based learning mechanism, using spontaneous muscle twitches, can account for the functional adaptation of the withdrawal reflex system. We also show that tactile feedback resulting from spontaneous muscle twitches during sleep does indeed modify sensorimotor transformation in young rats in a predictable manner. The results indicate that these twitches, corresponding to human fetal movements, are important in spinal self-organization.

Discharge pattern of the sympathetic vertebral nerve activity in kittens in postnatal ontogenesis

Electrical activity of the sympathetic vertebral nerve (VN) was studied in kittens (0-180 days) using frequency domain analyzes. Rhythmical discharges in the studied nerve were observed from the moment of birth and correlated with cardiac (1.2-3 Hz) and respiratory frequency (0.15-0.7 Hz). Amplitude of discharges was minimal in newborn kittens and increased during ontogenesis. Relative spectral power was maximal at cardiac and respiratory frequencies in animals in all age groups. '10-Hz discharges' (8-12 Hz band) in the VN oscillations appeared only in animals older than 20 days of life. In accordance to their sympathetic nerve discharge, kittens become mature at 2 month of their life.

Height of girls with adolescent idiopathic scoliosis

In a Finnish population, the standing height of 1500 consecutive female patients aged 9-24 years (mean 13.9 years) with untreated idiopathic scoliosis of at least 10 degrees in their lateral curves was compared with the standing height of average girls. The mean magnitude of the major curves was 29.4 degrees (range 10 degrees-80 degrees), and that of the minor curves 20.3 degrees (range 0 degrees-66 degrees). A formula for the height loss caused by the lateral curves, and that caused by thoracic kyphosis, was derived. The corrected height of the girls with idiopathic scoliosis was highly significantly (P<0.001) greater than the height of average girls at the age of 11-15, and this high level of significance was present at the age of 11-13, even without correcting for the height loss caused by scoliosis. After maturation, the girls with idiopathic scoliosis were not significantly taller than average girls. On average, the magnitude of thoracic kyphosis did not affect the height of patients with scoliosis as compared with the height of normal girls of the same age.

Thoracolumbar spinal deformity in achondroplasia

The authors review the management of thoracolumbar kyphotic deformity in cases of achondroplasia. The presence of angular thoracolumbar kyphosis in achondroplasia is well recognized. In children this is initially a nonfixed deformity that persists, however, in more than 10% of individuals and becomes a fixed thoracolumbar kyphotic deformity. Additionally, with the coexistent spinal canal stenosis, neurological damage can occur and manifest as spinal cord or cauda equina compression. The nature of this condition, the natural history, and management options are discussed. Anatomical and biomechanical factors relevant to the condition are specifically highlighted. Avoidance of pitfalls in the management of these patients is discussed for both pediatric and adult patients.

Pediatric spinal deformities

Pediatric spinal deformity results from multiple conditions including congenital anomalies, neuromuscular disorders, skeletal dysplasia, and developmental disorders (idiopathic). Pediatric spinal deformities can be progressive and cause pulmonary compromise, neurological deficits, and cardiovascular compromise. The classification and treatment of these disorders have evolved since surgical treatment was popularized when Harrington distraction instrumentation was introduced.

The advent of anterior-spine instrumentation systems has challenged the concepts of length of fusion needed to arrest curvature progression. Segmental fixation revolutionized the surgical treatment of these deformities. More recently, pedicle screw–augmented segmental fixation has been introduced and promises once again to shift the standard of surgical therapy. Recent advances in thoracoscopic surgery have made this technique applicable to scoliosis surgery.

Not only has surgical treatment progressed but also the classification of different forms of pediatric deformity continues to evolve. Recently, Lenke and associates proposed a new classification for adolescent idiopathic scoliosis. This classification attempts to address some of the shortcomings of the King classification system.

In this article the authors review the literature on pediatric spinal deformities and highlight recent insights into classification, treatment, and surgery-related complications.

Association between estrogen receptor gene polymorphisms and curve severity of idiopathic scoliosis

STUDY DESIGN

Analysis of the estrogen receptor gene of girls with idiopathic scoliosis.

OBJECTIVES

To determine whether estrogen receptor gene polymorphisms correlate with curve severity of adolescent idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA

Studies suggest that idiopathic scoliosis is a familial condition and that curve progression is related to genetically determined factors, such as skeletal and sexual growth.

METHODS

A total of 304 girls with idiopathic scoliosis were followed until growth maturation. Height, arm span, menarcheal age, and age at growth maturation were recorded, and curve severity was measured using Cobb's method. The estrogen receptor gene, which contains polymorphic PvuII and XbaI sites, was amplified from lymphocyte deoxyribonucleic acid by polymerase chain reaction.

RESULTS

The mean maximum Cobb measurements for patients with genotypes XX and Xx were greater than for those with genotype xx (P = 0.002). The risk of curve progression, defined as progression of >5 degrees from initial evaluation, was higher with genotype Xx than with xx (P = 0.03). Patients with genotypes XX and Xx had a significantly higher risk for operative treatment than those with genotype xx (21.4%, 24.7% vs. 7.6%, P< 0.001). Growth examination around the time of the growth spurt revealed that the XbaI site polymorphism was also related to the age of growth maturation. The frequency of patients with growth maturation at >or=16 years was higher for genotypes XX and Xx than for genotype xx (33.3%, 29.9% vs. 16.8%, P= 0.013).

CONCLUSION

Our results suggest that the XbaI site polymorphism is associated with curve severity. DNA analysis may predict curve progression.

Pedicle screws in 1- and 2-year-old children: technique, complications, and effect on further growth

STUDY DESIGN

A retrospective study of 19 consecutive cases (1991-2001) where 91 thoracic and lumbar pedicle screws were used in the treatment of various pediatric spinal disorders in 1- and 2-year-old children.

OBJECTIVES

To determine the effectiveness and safety of pedicle screw fixation in very young children and to evaluate the effect of pedicle screw insertion on further growth of the vertebra.

SUMMARY OF BACKGROUND DATA

Although many studies exist about the use of pedicle screws and its advantages in spinal fixation in adults and older children, no study has been published about the use of pedicle screws in 1- and 2-year-old children.

METHODS

A retrospective review of 19 consecutive operations in 16 patients with insertion of 91 pedicle screws for various spinal disorders in 1- and 2-year-old children was performed. The technique of screw insertion was described. Complications were divided into those directly related to screw placement and general complications and short- and long-term complications. In three cases with more than 6 years follow-up, the effect of pedicle screw insertion on further growth was evaluated by radiographic measurements.

RESULTS

Short-term complications occurred in two patients (one pedicle fracture, one infection) and long-term complications in three patients (one screw breakage, two failures of screw connection). Three of 91 screws were misplaced without any neurologic symptoms. Measurements of the vertebral growth in long-term follow-up did not show any adverse effect related to pedicle screw insertion.

CONCLUSION

The results suggest that pedicle screw fixation can be performed safely in 1- and 2-year-old children without negative effects on vertebral growth. In various pediatric spinal disorders, transpedicular screw fixation is the only procedure that provides a secure anchorage in short-segment instrumentation.

A new technique for the surgical management of deformities in the growing spine

The Luque procedure was developed to correct the deformity without the need of bracing and maintaining that correction with growth. However many authors are disappointed by their results and the complications which appear in the management of infantile scoliosis with Luque trolley alone. Besides failed implants, pseudarthrosis, modest spinal growth and protuberant rods and wires, the major problem of the Luque systems is the high incidence of loss of correction by postoperative rotation. Therefore a new application technique is recommended. A standard posterior extraperiostal approach is chosen. Sublaminar titanium cables are passed at each level except the caudal lamina. Then the rods are precontoured in shape of the planed curve correction. We use a low profile titanium instrumentation with 5.0 mm diameter rods and 4.2 mm pedicle screws. In contrast to the conventional use of two antiparallel "L"-rods we recommend the use of one reversed "U"-rod securing the laminae with sublaminar titanium cables of the upper end vertebrae. For fixation of the lower spine a dual-opening pedicle screw system is used. Using a holding forceps the distal rods are introduced and fixed into the side opening of the screws then secured by sublaminar wires. In addition both single rods are stabilized by a low profile cross link bar. This technique allows to correct pelvic obliquity and a stable anchorage of two screws reduces risk of postoperatively rotation or caudal rod slippage due to gravity forces.

Responses of bone turnover markers and bone mineral density to growth hormone therapy in children with isolated growth hormone deficiency and multiple pituitary hormone deficiencies

Growth hormone deficiency (GHD) is an important cause of decreased bone mass in childhood and adolescence. The role of other pituitary hormone deficiencies on bone mass is still a query in children. Thirty-nine children (28 with isolated GHD [IGHD] and 11 with multiple pituitary hormone deficiency [MPHD]) were investigated to show the effects of IGHD vs MPHD on bone status. Bone turnover markers (calcium, phosphate, alkaline phosphatase [ALP] Bone ALP [BALP], osteocalcin [OSC], carboxyterminal propeptide of type-1 collagen [CPP-I], parathyroid hormone [PTH]) were measured before and every four months during growth hormone (GH) therapy; bone mineral density (BMD) of the lumbar spine was measured before and every six months during therapy. All bone turnover markers except calcium and PTH increased significantly during 1 year of GH therapy. There were no differences in the levels of bone turnover markers between children with IGHD and MPHD at baseline, and after 4, 8 and 12 months of therapy. Lumbar spine BMD SDS of all patients increased significantly during 1 year of therapy (p = 0.035 after 6 months and p <0.001 after 12 months compared with baseline). BMD SDS of both IGHD and MPHD groups were similar at baseline and after 6 and 12 months of therapy (p = 0.235, p = 0.295 and p = 0.384). Height SDS (HtSDS) at baseline was the most important predictor of baseline BMD SDS in children with GHD (t = 4.166, p <0.001). DeltaHtSDS was also positively related to deltaBMD SDS after 1 year of GH therapy. In conclusion, there was no difference in bone status of the patients with IGHD and MPHD at baseline. GH therapy yielded similar increases in bone mass in both groups. Increase in height contributed to increase in BMD during 1 year of GH therapy.

Transverse process fusion with bovine anorganic bone

A biodegradable collagen membrane and bovine anorganic bone were studied in a rabbit spine fusion model. The bovine, anorganic bone is a nonantigenic, acellular clinical product used as a bone substitute for dento-alveolar applications. We reasoned this product with a collagen membrane could be useful for spine fusions. Our hypothesis was that bovine, anorganic bone, and a collagen membrane would promote spine fusion equivalent to an autogenous bone graft. To test the hypothesis, the transverse processes of the fourth and fifth lumbar vertebrae were decorticated in 30 rabbits divided equally among five groups. In one group, following decortication, no treatment was administered, whereas in the remaining four groups, treatments consisted of either autograft, collagen membrane, anorganic bone, or anorganic bone plus collagen membrane. Rabbits were euthanized 6 weeks after surgery, and the lumbar vertebrae were removed, radiographed, and processed for histology. The radiographs and histological sections were subjected to quantitative morphometric analyses and post hoc statistical testing (p < or = 0.05). We determined anorganic bone without a collagen membrane migrated into the soft tissues contiguous to the transverse processes. However, with a collagen membrane, the anorganic bone remained at the implant site, causing an osseous fusion of the transverse processes. Although the autograft promoted the greatest amount of new bone formation, significant transverse process fusion was accomplished with the anorganic bone and collagen membrane. Additional longer term studies are contemplated to validate feasibility of this clinical option, including a biomechanical component.

Is Cobb angle progression a good indicator in adolescent idiopathic scoliosis?

STUDY DESIGN

A retrospective follow-up study of spine geometry after posterior instrumentation and fusion for adolescent idiopathic scoliosis (AIS).

OBJECTIVES

To evaluate 1) if Cobb angle progression is a reliable indicator of the crankshaft phenomenon; 2) if significant growth of the spine can occur after surgery without the development of a crankshaft phenomenon?

SUMMARY OF BACKGROUND DATA

Anterior fusion of the spine is often recommended for skeletally immature scoliotic patients to avoid the risk of a crankshaft phenomenon, a long-term loss of curve correction caused by residual growth of the spine combined with the constraints of a posterior fusion. The crankshaft phenomenon is usually assessed indirectly by documenting progression of the Cobb angle on frontal radiographs. Thus far, no study has directly measured the three-dimensional growth of the spine after surgery in AIS.

METHODS

Cobb angle, spine length and spine height were obtained from three-dimensional radiographic reconstructions of the spine in 48 adolescent scoliotic patients undergoing posterior instrumentation and fusion. Measurements were done before surgery, after surgery and at skeletal maturity. A significant growth of the spine was defined as a > or = 10 mm increase in spine length, while a significant curve progression was defined as a > or = 10 degrees increase in Cobb angle at skeletal maturity.

RESULTS

In the majority of patients (56%), there was no significant change in spinal length or in Cobb angle measurements at an average 2.4 years post surgery. A crankshaft phenomenon was detected in 6 patients (12%) for which significant increases both in spinal length and Cobb angle measurement were found. Significant curve progression without any change in spine length was noted in 9 patients (19%) while an increase in spine length with no evidence of curve progression was present in 6 patients at last follow-up.

CONCLUSION

Spinal growth as indicated by an increase in spinal length can be measured in a significant proportion of adolescents with idiopathic scoliosis after posterior instrumentation and fusion. Some of these study participants will develop a crankshaft phenomenon but Cobb angle progression is not a reliable indicator of this complication, since it may occur without any detectable growth of the spine.

Biomechanical modelling of spinal growth modulation for the study of adolescent scoliotic deformities: a feasibility study

A model of growth modulation was formulated with variables integrating a biomechanical stimulus of growth modulation, a sensitivity factor to the stimulus and time. It was integrated into a finite element model of the thoracic and lumbar spine using an iterative procedure. A simulation on the personalized geometry of a mild scoliotic patient allowed qualitative investigation of scoliotic deformities over 12 cycles (months) in response to a load variation due to an eccentricity of the patient's gravity line in the frontal plane. Resulting frontal, sagittal and transverse spinal views correspond to clinically observable scoliotic configurations. The simulation adequately reproduces a progressing thoracic scoliotic curve while the slight increasing kyphosis represents a possible condition although a thoracic hypokyphosis is frequently reported in the literature. At the thoracic apex, increased wedging as well as axial rotation evolving towards curve convexity are in agreement with clinical and experimental observations reported with curve progression. This study demonstrates the feasibility of the approach and, compared to other biomechanical models, it achieves a more complete representation of the scoliotic spine by incorporating vertebral growth modulation.

[Spinal growth under physiological and pathological conditions]

Spinal growth is developing analogously to extremity growth. As the vertebral spine is built by 25 "vertebral units" there are much more possibilities of compensatory growth in short parts of pathologic alterations than there are in cases of affected extremities that only show epiphyseal compensations in metaphyseal or diaphyseal deformities (such as juvenile fractures). The dynamics of growth is different in the spine. The neurocentral epiphysis, basis to seize of spinal channel, shows very strong dynamics in embryonal and early childhood growth corresponding to the development in central nerve system. Whereas, enchondral height growth of vertebral bodies does not end after puberty, in male sex even at about the age of eighteen. Enchondral growth of the spine is much more sensible to affections than periostal growth. This is analogous in the extremities. Spinal growth is determined genetically, but especially in puberty it can be influenced by the child's posture. This is a therapeutic hint especially for the period of fast vertebral growth in puberty. The strong straightening tendency of spine is fascinating. Thus, in the period of growth all spinal deformities are compensated by the vertebral segments below and above, so that the axis appears in horizontal line and the spine altogether in perpendicular position.

Menarche in scoliotic and nonscoliotic Mediterranean girls. Is there any relation between menarche and laterality of scoliotic curves?

There is a controversy in the current literature concerning the age at menarche between scoliotic and nonscoliotic girls. The aim of this study is to elucidate this issue in the Mediterranean school aged girls.

MATERIAL AND METHODS

The menarche of 1,305 nonscoliotic girls (mean age 12,3 years, range 7,41 to 18,41 years, SD 2,5 years) and of 105 scoliotic girls (mean age 14.15 years, range 7.47 to 18.97 years, SD=2.7 years) was studied. These two groups originate from a total population of 4,535 schoolchildren who were examined during school screening (2,245 girls, 2,290 boys). The Angle of Trunk Inclination (ATI) greater or equal to 7 degrees, measured with the Pruijis Scoliometer was used as a pass-fail criterion for radiological examination. The diagnosis of scoliosis was defined as the finding of a Cobb angle greater or equal to 10 degrees on a standing postero-anterior radiograph of the spine. Statistical analysis was performed using the SPSS statistical program.

RESULTS

476 girls out of 1,305 nonscoliotic girls (36,50%, mean age 14,04 years, range 9.04 to 18,21 years, SD=1.59 years) had menarche (mean age at menarche 12,07 years, SD 1,35 years, range from 7,63 to 14,59 years), while the remaining 829 girls (63,50%, mean age 11,09 years, SD 2,09 years, range 7,41 to 18,47 years) had not any. On the other hand, 77 out of the 105 scoliotic girls had menarche (73,33%, mean age 15,29 years, SD 1,54 years, range 11,35 to 18,97 years). The mean age at menarche of the scoliotic girls was 11,98 years, SD 1,49 years, range 7,7 to 16,72 years. Twenty-eight scoliotic girls had no menarche yet (mean age 10.99 years, range 7.41 to 17.24 years, SD=2.72). There was a predominance of right-sided primary curves in menarche positive scoliotic girls (61%), while menarche negative scoliotic girls showed mainly left sided primary curves (64,3%). This difference is statistically significant (p<0,05). The frequency of the various scoliotic curves in menarche positive scoliotic girls was as follows: right thoracic (32,5%), left lumbar (23,4%) and right thoracolumbar (15,6%) curves. The respective locations of scoliotic curves in girls without menarche were left lumbar (25%), left thoracolumbar (25%) and thoracic curves (14,3%) were equally distributed on both. Delayed onset of menarche or no menarche was observed in 4 scoliotic girls. Furthermore, 2 scoliotic girls mentioned that they had menarche after the age of 15 years and only after hormonal treatment. Despite of the apparent prevalence of the scoliotic girls in the menarche positive population, there is no statistically significant difference between scoliotic and nonscoliotic girls with menarche when the respective ages at menarche are compared.

CONCLUSION

In this study, there was not a statistically significant difference of the age at menarche between scoliotic and nonscoliotic girls. On the other hand, there was a significant difference between menarche positive and menarche negative scoliotic girls in relation to the laterality of scoliotic curves: the former showed predominantly right sided primary curves while the latter had mainly left sided primary curves.

[Pediatric spinal injuries]

Spine injuries during growth are rare, but in comparison to adults they are more often associated with neurologic impairment. They also may occur without visible injuries in X-rays. The problems of conventional radiologic diagnostics include before all the differential diagnosis between synchondrosis, apophysis and fracture lines. MRI is indicated in case of neurologic deficits without radiologic abnormalities. In principle the fracture types correspond to those seen in adults. In addition growth specific injuries of the end-plates (growth plates) or ring apophysis may occur. Stable compression fractures are treated conservatively. The spontaneous remodelling capacity for posttraumatic deformities decreases with age: in children below the age of ten years the remodelling capacity for posttraumatic kyphosis is excellent whereas deformities in the frontal plane show no or only incomplete remodelling. Unstable fractures and injuries with associated compression of neural structures should be treated conservatively.

Growth plate chondrocyte enlargement modulated by mechanical loading

Mechanical compression and distraction forces are known to modulate growth in vertebral growth plates, and are implicated in the progression of scoliosis. The amount of cellular enlargement is thought to be a key variable correlating with differing growth at different anatomical sites. This work tested the hypothesis that growth differences produced by mechanical loading are associated with alterations in the amount of cell height increase in the growth direction. Compression force (3 animals) or distraction force (4 animals) of 60% bodyweight was maintained on a caudal vertebra of growing rats with an external apparatus attached to vertebrae adjacent to the experimental level via transfixing pins. Growth of loaded and control vertebrae was measured from weekly radiographs. After four weeks, animals were euthanized and the loaded vertebrae and adjacent control vertebrae were excised for histological sections from which the following were measured: height of the hypertrophic zone (the average separation between boundaries of the zone); Mean Hypertrophic chondrocytic height; slope of the linear regression of cell height vs. position in the zone, (the amount of cell enlargement). Distracted and compressed vertebra growth averaged 110% and 53% of control levels. The percentage changes in the measures of chondrocyte dimensions, relative to control values, were smaller than the percentage changes in growth velocity. Also, the effects were of smaller magnitude for distracted vertebrae than for compressed vertebrae. Growth plate zonal height, slope and mean cell height all correlated significantly (p<0.05) with growth rate (expressed as a percentage of control) (Pearson r = 0.69, 0.37 and 0.41 respectively. Thus mechanical loading of tail vertebrae modulated their growth rate, that in turn correlated with changes in the amount of hypertrophic chondrocyte height increase. The effects for compression were greater than for distraction.

[Surgical treatment of idiopathic scoliosis and juvenile kyphosis]

Indication for operative treatment of idiopathic scoliosis and juvenile kyphosis is mainly cosmetic. There is also a higher incidence of pain in scoliosis patients, and reduced pulmonary function in severe deformity, especially in severe deformities present at the age of 5 years (early onset). Scoliotic curves of less than 30 degrees will not progress in adults, whereas curves of 50-75 degrees will further progress a mean of 25 degrees during 40 years. Progression in adults with juvenile kyphosis is not well documented. Operative treatment aims to stop progression, to control spinal growth, or to perform correction and fusion by spinal instrumentation and bone grafts. These goals can be achieved either by an anterior, a posterior, or a combined approach. Correction principles are compression, distraction, derotation and translation. The forces applied by correction are transferred by fixation devices (pedicle screws, anterior screws, hooks, sublaminar wires) to the spine. The higher correction forces are, the higher is the correction achieved, but also the risk of fracture and torn out implants. Mobilisation reduces rigidity and allows to achieve a better correction with equal forces. The best mobilisation techniques are disc excision, facet joint removal, and techniques to mobilise the thorax.

Spinal deformity in the adolescent athlete

Today more and more children with diagnoses of adolescent spinal deformity are participating in athletic competitions. Certain sports appear to have an increased association with spinal deformity, especially in the adolescent female population. Modern treatment techniques including bracing will allow participation in most athletic endeavors. Those treated with surgery need to have their postoperative care individualized. However, modern surgical techniques still allow continued participation in most activities.

Retrospective results in immature idiopathic scoliotic patients treated with a Chêneau brace

This paper reports a retrospective series which includes 105 idiopathic scoliotic patients treated with a Chêneau brace. With an average age of 12.5 years old and a mean Risser sign of 0.9, the initial major Cobb angle was 36.8 degrees corrected to 25.9 degrees in the brace (31.1% of the primary correction), and the major torsion angle was 16.8 degrees corrected to 12.9 degrees in the brace (22.2% of the primary correction). 37 patients have finished the treatment with a mean follow-up of 16.8 months. For this group, the initial Cobb and torsion angles were not significantly changed (36.4 degrees Cobb to 34.1 degrees Cobb at follow-up, and 16.9 degrees Perdriolle to 15.7 degrees Perdriolle at follow-up). The proportion of patients without progression greater than 5 degrees Cobb (n=20) and with an improved final Cobb angle (n=10) was greater than failures (n=7). However, due to the catastrophic nature of some progressions which generally coincide with a high Cobb angle right from the start, with low primary correction, and with non-compliance, the final Cobb angle showed a slight tendency to decrease but without reaching high significance. These preliminary results demonstrate that the Chêneau brace can effectively prevent the progression of Cobb and torsion angles, even in cases of bad prognosis.