Ebook: Research into Spinal Deformities 4

On the 24-27 May 2002, the International Research Society of Spinal Deformities (IRSSD) held its fourth biannual scientific meeting at the Astir Palace Resort, Vouliagmenis, in Athens, by the beautiful and serene setting of the Aegean Sea.

The extended essays of the papers and posters presented at the meeting are included in this book unmodified. Presentations where the authors failed to submit the extended texts have not been included.

The scientific seeds planted at the previous meetings of the IRSSD gave this 4^th Meeting a wide variety and a rich collection of 132 papers on research and related clinical practice, which were presented by delegates from 23 countries, from all the continents.

Information about the history of the IRSSD, the previous forms of the society and its transformation, which led to the foundation of the IRSSD in Pescara in 1994 can be found in the previous books of “Research into Spinal Deformities, Volume 1-3”, and will not be repeated here.

The meeting comprised 17 Scientific Sessions on Spinal Deformities: Aetiology, Incidence, Natural History and Prognosis, Genetics and Growth, Anatomy, Pathology and Basic Science, Assessment, Biomechanics, Gait, Surface Topography, Imaging, Morphological Aspects (3-D) of Spinal Deformity, Technology, Cervical Spine, Spondylolisthesis – Low Back Pain, Conservative Treatment – (Physiotherapy – Brace), Surgical Treatment and Outcome. The programme was completed with three keynote lectures, the presidential address and three round table discussions.

Particular emphasis was given to the scientific programme, in order to have a well-balanced amount of research and clinical papers on Spinal Deformities. The scope of this policy was not only to disseminate the latest trends of research in spinal deformities to the clinical environment, but also for researchers to have analogous input from the problems of recent clinical practice, so that the consequent interaction could be productive in a collegial, international atmosphere, with approximately 200 registered delegates.

The objectives of the Society, to fuse together different trends of research in spine deformities, was thus fulfilled during the meeting, as Prof. Sevastik also highlighted in a previous meeting of the IRSSD.

As chairman of the 2002 Athens meeting I wish to express sincere thanks to the members of the International Scientific Committee:

Mark Asher (USA), Carl-Eric Aubin (Canada), Alexandras Chatzipavlos (Greece), Peter Dangerfield (England), Panagiotis Korovesis (Greece), Hubert Labelle (Canada), Morey Moreland (USA), George Sapkas (Greece), John Sevastik (Sweden), Panagiotis Soucacos (Greece), Ian Stokes (USA), Nobumasa Suzuki (Japan), Dirk Uyttendaele (Belgium), who during their busy schedule took the time to evaluate the number of abstracts that were submitted. To our great satisfaction this meeting exceeded our common expectations. This was indeed very satisfying, as more colleagues are starting to take an interest in the research field of spinal deformities.

I would like to thank the President of the IRSSD, Professor Nobumasa Suzuki, for raising the sum of $10,000, in order to contribute to the meeting. Also the sponsoring companies, Biomet Merck Hellas, Depuy Medec, Ebedent, Iamex, Mathys Medical, Medical Plus, Ortholand, Plus Endoprothetic Hellas, Unimed, who supported this meeting with their generous contributions. The Congress Organisers and Secretariat “Aktina – City Congress SA” for their faultless organization at the meeting, and last but not least, I would like to thank all the participants, without whom the Meeting would not have been possible. I hope that all participants found this meeting rewarding. Athens, May 2002 Dr. Theodoros B. GRIVAS, MD

The aetiology of adolescent 5coliosis remains unknown and hindering research is the absence of an appropriate animal model. It is now well-established that pinealectomy in young chickens results in the development of scoliosis that has many of the characteristics seen in patients with adolescent idiopathic scoliosis but the mechanism underlying this phenomenon remains elusive. The principle product of the pineal gland is melatonin and so many studies have focused on studying the effects of reduced levels of this hormone. The results have been mixed and the role of melatonin remains un~ear. As melatonin production is inhibited by light, it was hypothesised that providing the chickens with an environment consisting of intense, continuous light would reduce serum melatonin levels and avoid any of the potential artifacts involved with the pinealectomy surgery. Consequently, pinealectomised and normal chickens were exposed to very intense light for complete 24 h in each day. At the end of 22 days in this environment serum melatonin levels had been reduced to very low levels in all chickens. Most importantly, 15% of the normal chickens had developed scoliosis and the number of pinealectomised chickens that developed scoliosis increased from 50% to 80%. The results showed that a method for reducing serum melatonin without pinealectomy has been established and which can be used in further experiments. Furthermore, the results also showed that reduced levels of serum melatonin has significant effects on the development of scoliosis. The indication is that there is a threshold level of serum melatonin below which scoliosis may develop probably in conjunction with some other factor which has yet to be identified.

The cause of idiopathic scoliosis remains unknown, although research has possibly eliminated some hypothetical causes. Recent reports associating scoliosis convexity with equilibrium control central processing and motor lateralization have suggested that idiopathic scoliosis is connected causally with the motor cortex. In order to analyze these factors a study of labyrinthine function was carried out. This study included seventeen female patients 12 to 14 years old (mean age= 13.36y) with right thoracic idiopathic scoliosis and twelve normal control females 12 to 14 years old (mean age =13.1y).An electro-nystagmographic study of labyrinthine function (potential nystagmus) was performed in all the patients of the study with caloric tests. The nystagmus was recorded with the electronystagmographic technique (ENG) using Hartmann device. We evaluate these parameters: Slow phase velocity (SPV), Total amplitude (Tamp), Frequency of nystagmus (Freq). No children of the study presented spontaneous nystagmus. No correlation was found between the convexity of the curvature and the direction of nystagmus in posture tests. There were no significant differences between left- and right- beating nystagmus. The results are discussed with special reference to aetiology in idiopathic scoliosis.

The present study was designed to investigate the involvement of central nervous system (CNS) in the pathogenesis of idiopathic scoliosis.Seventeen female patients with right thoracic idiopathic scoliosis (mean age = 13.36y) and ten normal controls (mean age =12.6y) entered the study. Magnetic stimulation of the brain was performed. Threshold measurements included upper (UT) and lower threshold (LT). Cortical latencies of MEPs during muscle activation were also measured.

Nachemson [3] suggested that there are more girls than boys with progressive adolescent idiopathic because of a different timing between skeletal maturation and postural maturation in the sexes during adolescence. We termed Nachemson’s concept the neuro-osseous timing of maturation (NOTOM) hypothesis and used it to propose a possible medical treatment for idiopathic scoliosis by delaying puberty through the pituitary using gonadorelin analogues as in idiopathic precocious puberty [1,2].

The prevalence of scoliosis is reported to be increased in rhythmic gymnasts (RGs) in Bulgaria [4] and in ballet dancers (BDs) in the USA [5]. Both groups exhibit delayed puberty, which, at first sight, nullifies the NOTOM hypothesis for idiopathic scoliosis. While constitutional and environmental factors may determine these scolioses, the different curve types in RGs and BDs suggest that the exercise pattern over many years determines which type of scoliosis develops, although not the curve severity.

We support the view that scoliotic RGs should be included in a group of sports-associated scoliosis separate from idiopathic scoliosis [4]. Hence the delayed puberty of RGs and BDs with scoliosis does not nullify the NOTOM hypothesis as their scolioses are not idiopathic. There is a need to focus research on such subjects who have defined constitutional and environmental factors related to their scolioses

There is increasing interest in the concept that neuromuscular mechanisms and the central nervous system (CNS) are somehow involved in the etiology and pathogenesis of idiopathic scoliosis (IS). Yet in the extensive neuroscience research of idiopathic scoliosis certain neurodevelopmental concepts have been neglected. These include: (1) a CNS body schema for posture and movement control generated during development and growth by establishing a long-lasting memory; (2) pruning of cortical synapses at puberty; and (3) neuromorphic engineering. Memory of developing posture and movement might be established in neurons of the CNS body schema in the form of novel proteins; these could be coded by modified genes obtained by the recombination (crossing over) of DNA in a similar way to that in the production of immunological antibodies and during meiosis [11,27]. These concepts need evaluation in relation to (1) the etiopathogenesis of IS and (2) a possible new treatment approach to idiopathic scoliosis involving a neuromorphic device to control the output for muscle stimulators that are inserted and driven with telemetry.

The aim of the study is to compare the rib-vertebra angles (RVAs) between children with 10° - 20° of Cobb angle late onset idiopathic scoliosis (LOIS) and non-scoliotic children.

Materials and Method: The RVAs of 47 children, with mean age 12.4 years, who presented LOIS with a Cobb angle 10° - 20°, were studied. The children were classified into three groups according to the site of the scoliotic curve: 17 children had thoracic (T), 14 children had thoracolumbar (TL) and 16 children had lumbar (L) curves. The RVAs of the scoliotic children were compared to the RVAs of 60 non-scoliotic children of a similar age group, who were studied in the past.

Results: The comparison of the right and left RVAs within each group showed that the children who had: T curves differ at the level T4, T5, T6, T7 and T8, TL curves differ at the level T3, and L curves differ at the level T7 and T12.

The comparison of the ipsilateral RVA’s between the scoliotic groups showed that between: T and TL curves there are no differences at any thoracic level, between T and L curves the RVAs differ at the T7 level on the right side, whereas there are no differences between the RVAs on the left side, between TL and L curves the RVAs differ at the level T5, T6, and T7 on the right and at the level T5 on the left side. Comparing the RVAs between the scoliotic and nonscoliotic children, it was apparent that the scoliotic children rib cage had lower RVAs (p<0.0l) at almost all thoracic levels.

Discussion: It has been reported that RVAs is an expression of the resultant muscle forces, which act on each rib. It was also suggested that RVA asymmetries by weakening the spinal rotation-defending system are aetiological for idiopathic scoliosis, (Burwell et al 1992). This study shows that scoliotic children with small curves have underdeveloped thoracic cage compared to nonscoliotic counterparts. The differences are more apparent in the scoliotic children with thoracic curves. It is suggested that the differences of the RVAs between right and left side in this group are an expression of asymmetric muscle forces acting on the thoracic cage. It is concluded that asymmetric muscle forces participate in the pathogenesis of idiopathic scoliosis on the thoracic cage, which deforms early.

Introduction. The aim of this report is a) to study the lateral spinal profile, (LSP), in school-screening referrals with and without late onset idiopathic scoliosis of small curves 10° -20° Cobb angle and b) to validate LSP's aetiological importance in idiopathic scoliosis pathobiomechanics.

Methods and Material. The spinal radiographs of 133 children, 47 boys and 86 girls with a mean age of 13.28 and 13.39 years respectively and Axial Trunk Inclination (ATI) ≥ 7°, were examined. The Cobb angle was appraised from the anteroposterior standing radiographs and the segmental spinal profile was assessed. A line was drawn down the posterior surface of each vertebral body from T l to L5 on lateral standing radiographs, and the angle of this line from the vertical was recorded. Intervertebral values for LSP, (ILSP), that is the result of the subtraction of two consecutive spinal levels LSP, were also calculated. The data were then statistically analyzed.

Results. The statistical descriptives of LSP and intervertebral LSP are presented for several groups of children, namely in those: 1) with straight spines, 2) with spinal curvature having a Cobb angle less than 10°, and 3) in scoliotic children with a) thoracic, b) thoracolumbar and c) lumbar curves of 10°-20°. A correlation of the LSP with Cobb angle for the various types of curves for boys and girls is also presented. It is shown that the kyphotic segmental angulation is slightly less and the lordotic one almost normal in scoliotics, compared with the values of normal children. It is interesting to note that the LSP correlated with Cobb angle shows: a) a positive correlation pattern at T6, T7, T8 and T9 for thoracic curves of scoliotic boys and b) a negative correlation pattern at T3, T4 and T5 spinal levels of lumbar curves for scoliotic girls.

Discussion. The observed differences of the LSP are mainly located at the lumbar spine, suggesting that factors acting on the lumbar spine in sagittal plane contribute to the development of AIS. The minor hypokyphosis of the thoracic spine and its minimal differences observed in the studied small curves with nonscoliotics in this report add to the view that the reduced kyphosis, by facilitating axial rotation, could be viewed as being permissive, rather than as aetiological, in the pathogenesis of idiopathic scoliosis.

The current successful management of idiopathic scoliosis is an orthopaedic and not a paediatric responsibility. Hence the immediate aim of etiologic research is to improve surgical treatments based on a better understanding of the causation of the deformity. This focuses attention on the pathomechanisms of the spinal and ribcage deformities. The mechanisms of spinal deformity about the apex are unresolved but may be caused by forces created in the anterior spinal column [28]. Some current theories with practical application involve (1) front-back spinal growth mechanisms, (2) rib growth asymmetry and (3) muscles. Conclusions. The application of theory to surgical practice is advanced for concepts of front-back spinal growth asymmetry but rib hump reassertion occurs after surgery and these concepts ignore the ribcage as a possible factor in scoliosis pathogenesis. A theory of ribcage asymmetry involving concave rib overgrowth is beginning to be evaluated surgically. After surgery for IIS and AIS reassertion of the deformity has been shown to involve preoperative spinal and concave rib factors; the larger the concave rib-spinal angle the better results at 2-5 year. Muscular factors that may trigger/exacerbate the apical spinal deformity of scoliosis need more research. The concept that AIS pathogenesis involves putative neuromuscular dysfunction that deforms an immature spine is considered likely by several workers.

Introduction: Between various etiological factors of idiopathic scoliosis we also studied the biomechanical causes connected with the hip and pelvic regions. At all children with idiopathic scoliosis there is a real or functional abduction contracture of the right hip (sometimes plus flexions- and out-rotation contracture). The right hip abduction contracture is connected with “syndrome of contractures” at newborns and babies.

Material:629 children treated in University Pediatric Orthopaedic Department, Lublin/Poland were divided into two groups: ^*I group of development of scoliosis- 220 children aged from 4 to 10. Real abduction contracture of the right hip 4-6-8 degree, adduction of the left hip 35-40-45 degree. Rotation deformity, both scoliosis (Lumbar L and thoracic Th) at the same time. Progression. ^**II group of development of scoliosis - 409 children aged from 10-12 to 14. Adduction of the right hip 10-15 even 20 degrees, adduction of the left hip 35-40-45 degree. Lumbar left convex scoliosis, no rotation deformity or small, no thoracic scoliosis, or small, no progression or small.

Information about “syndrome of contractures” Clinical symptoms of _syndrome of contractures“ were described exactly by Mau and others. At scoliotic patients we see in the region of right hip the following tissues contracted and shortened: ^*tractus iliotibialis, ^*fascia lata, ^*fascias of m.gluteus medius and minimus, ^*m. sartorius, ^*m. rectus, ^*capsules of right hip joint.

Clinical research: Since 1980s we added the tests for the adduction of both hips in straight position of the joint to the standard examination of scoliotic patient. Depending on the value of adduction movements of both hips we divided all patients into two above mentioned groups (I and II).

Evaluation of present rehabilitation treatment in our material.ChMrm were divided into three groups depending on range of scoliosis:

A. Scoliosis L 5° – 10°, Th 5° – 10°. These children did not perform (wrong!) extension exercises 10 % B.

Scoliosis L 15° – 25°, Th 15° – 25°. These children performed (wrong!) extension exercises 30%

C. Scoliosis L 25° - 35° or more, Th 25° - 35° or more. Older children. Extension (wrong!) exercises long time (1-2-3 years!) 60 %

Conclusions:!.The so-called idiopathic scoliosis are connected with the right hip real or functional abduction contracture (sometimes plus flexion and out-rotation contracture). 2.There are two groups of development of idiopathic scoliosis. The first group - small children, early rotation deformity, both scoliosis (L and Th), progression. The second group is connected only with the habit of permanent standing “at ease” on the right leg. Older children. L scoliosis, sometimes Th scoliosis. 3. X-ray pictures of spine with pelvis are necessary for proper diagnosis.4. Abduction contracture of the right hip is connected with “syndrome of contractures” of new-borns and babies.5. We see necessity to introduce new stretching-flexion asymmetric exercises and a special sports program for the children endangered with scoliosis. 6. We proved that the “new prophylactics” through “new clinical test” and “new rehabilitation treatment” at school children (5-6-7-8 years old) gives positives results.

Aim: The creation of a database with somatometric parameters (body weight and eight) from school screening children and the comparison of nonscoliotic children with their counterparts suffering of scoliosis to Cobb angle >10° curves.

Material and Method: 3631 screened children where divided in 3 groups. The 1st group comprised normal children with 0° angle of trunk inclination, (ATI). The 2nd group comprised children with ATI >1° and < 6°. The third group comprised children with ATI >7° and Cobb angle >10°. The mean/median and standard deviation (± 1 SD) of body weight and height, the body mass index (BMI = weight/height²) and the corrected for the scoliotic curve height were calculated by age. Statistical analysis included descriptives (mean, ± 1 SD, median) and Mann - Whitney non-parametric test.

Results: In boys of the 1st and 2nd group 4,25% had obesity (BMI = 30-35), 2,9% severe obesity (BMI = 30-35) and 1,7% morbid obesity (BMI = 40-45)- while 6,4%, 1,9% and 1,3% in girls respectively. In the 3rd group girls, 27,2% were underweight (BMI = 16-20) and 11,3% severely underweight (BMI < 16), while among boys 42% were severely underweight. In the 3rd group there were no obese girls and only 5% obese boys. The comparison of body weight between scoliotic (3rd group) and nonscoliotic children (1st and 2nd group) fails to show any statistical difference.

In the 1st and 2nd group, the girls’ mean height is greater than that of boys aged 9–12 years but less when boys are 13-18 years old. In the 3rd group a mean of 1,15 cm increase is observed after height correction for the scoliotic curve, in boys and 1,3 cm in girls respectively. The comparison of body height (both uncorrected and corrected) between scoliotic and nonscoliotic children fails to show any statistical difference.

Discussion-Conclusions: A variety of findings regarding the stature and weight of AIS children has been published. In this studied Mediterranean sample of the population, the somatometric parameters of height and weight in children with scoliosis, regardless of curve type and site, are not statistically different from their nonscoliotic counterparts.

The objective of this study was to conduct an intrasubject longitudinal study quantifying the evolution of two- and three-dimensional geometrical scoliotic descriptors. The evolution of regional and local scoliotic descriptors was analyzed between two scoliotic visits on a cohort of 28 adolescents with progressive idiopathic scoliosis. Mean age at the first visit was 12.7±1.7 years old and averaged time interval between two assessments reached 22.8±10.8 months. Scoliotic descriptors were obtained from three-dimensionally reconstructed spines. The initial thoracic Cobb angle was on average 35.3°± 8.4° (range, 14°-54°). The evolution of spinal curvatures and vertebral deformities was assessed statistically in terms of descriptor absolute variations, and of descriptor variations normalized with respect to time and to the increase in Cobb angle. At the thoracic level, vertebral wedging increased with curve severity in a relatively consistent pattern for most scoliotic patients and axial rotation mainly increased towards curve convexity with scoliosis severity. No consistent evolution was associated with the angular orientation of the maximum wedging. Thoracic kyphosis changes (increase and decrease) were observed in important proportions. Results of this study challenge the existence of a typical scoliotic evolution pattern and suggest that the scoliotic evolution is quite variable and patient-specific.

Retrospective review of the scoliosis database showed adolescent idiopathic scoliosis to be the most common but least significant variety of spinal deformity. Data from 112 girls diagnosed on repeat screening showed the importance of menarche as a date in the natural history. In the whole database, there were 514 aged at least 15 years at last review, 45 boys and 469 girls. Braces were prescribed for a total of 38, mostly during the early part of the period and gradually abandoned without an increase in surgical rate. Progression depended on the age and maturity of the patient as well as the initial Cobb angle. Surgery was recommended for 27% overall. A sub-group with more complete data diagnosed after bracing had been discontinued confirmed the findings.

The shape of a curved line that passes through thoracic and lumbar vertebrae is often used to study spinal deformity with -measurements in "auxiliary" planes that are not truly three-dimensional (3D). Here we propose a new index, the geometric torsion, which could uniquely describe the spinal deformity. In this study we assessed whether geometric torsion could be effectively used, to predict spinal deformity with the aid of multiple linear regression. Anatomical landmarks were obtained from multi-view radiographic reconstruction and used to generate 3D model of the spine and rib cage of 28 patients. Fourier series best fitted to the vertebral centroids approximated the spinal shape. For each patient, spinal deformity indices were computed. Torsion was calculated and 20 derived parameters were recorded. Torsion inputs were used in a multiple linear regression model for prediction of key spinal indices. The primary clinical Cobb angle (mainly thoracic) was predicted well, with r=0.89 using all 20 inputs of torsion or r=0.83 using just two. Torsion was also well related to the Orientation of plane of maximal deformity (r=0.87). Torsion was less accurate but still significant in predicting maximal vertebral axial rotation (r=0.77). This preliminary study showed promising results for the use of geometric torsion as an alternative 3D index of spinal deformity.

A retrospective analysis of the natural history and treatment outcome of scoliosis, both idiopathic and syndromic, presenting before age 10 years was undertaken. The pattern was generally one of relentless progression, with little discernible benefit from orthotic treatment and surgical correction as the outcome for the majority. This result makes imperative a properly constructed study on the evolution and long-term outcome of this less common but more significant type of spinal deformity.

Introduction. The aim of the study is the documentation of the national incidence of idiopathic scoliosis (IS) based on the School Screening programs performed at the various geographical departments of the country, and the estimation of the probable number of children who will need to be conservatively or surgically treated.

Material - Methods: During the years 1975 - 1999, 17 School Screening programs were performed in Greece and their results were analyzed and published in the book “School Screening in Greece”. These studies had in common the children age distribution, the clinical examination, the radiological definition of IS when the Cobb - angle was ≥ 5° or ≥ 10° after SRS. The standing forward bending test was used. An Orthopaedic surgeon always participated in the scientific screening team. 215899 children aged 5.5 -15 years were screened. When there was suspicion of scoliosis, the child was further assessed radiolographically (standing postero - anterior spinal radiographs), for Cobb angle appraisal.

Results: In 130689 screened children, scoliosis was considered when the consequent radiological assessment revealed Cobb angle of > 10°, (a), and in 85210 children when it revealed Cobb angle of ≥ 5° respectively, (b). In (a) studies the scoliosis incidence was 2.9% (range 1.1 - 5.7%), and (b) 4.9% (range 2.7 - 9.5%) respectively. The right thoracic curves dominated in both (a) and (b) studies and thoraco - lumbar, lumbar and double curves followed. Among 7965 scoliotics out of the total sample of 215899 children, 4.5% were conservatively treated with the use of a brace, and only 0.19% was treated surgically.

Conclusions: From data of 1998 national census, the population of children aged 8 to 14 years old was approximately 751000. With the above - mentioned datum and with a national mean scoliosis incidence of 2.9%, (Cobb angle ≥ 10°), 21781 children will be found with scoliosis. 980 will need conservative treatment using a brace while 41 children will need surgical treatment.

Introduction: School-screening programs contributed greatly to the study of idiopathic scoliosis (IS) prevalence. A similar program confined to a highly industrialized area is being performed in our Department. Thus the comparison of the findings of IS prevalence of this program with those of programs performed in non-industrialized areas of the same country could imply the significance of special industrial environmental factors on IS aetiology.

Materials and Methods: 3039 schoolchildren (1506 boys, 1533 girls), aged 5,5 to 17,5 years, have been screened for IS. These children comprise 20% of a total population of 20000 schoolchildren, who live in the region. The detection of the scoliotic children was attained utilizing the criterion of the angle of trunk inclination (ATI). The Prujis scoliometer was used to assess ATI. A cut off point of ≥ 7° ATI was used as a criterion for children’s referral to hospital. 262 (8,6%) were referred for further evaluation, whereas 118 (3,9%) among these children underwent radiological examination.

Results: 90 children were found to have a Cobb angle of ≥10° at their standing PA spinal radiographs (2,9 % of the screened population). A Cobb angle of 10° -20° was found in 74 (2,4%) children. Sixteen (0,5%) children, who had scoliotic curves with a Cobb angle of ≥20°, underwent conservative treatment by means of spinal orthosis. Relatively to their location on the vertebral column, 20% of the scoliotic curves were thoracic, 26,7% thoracolumbar, 20% lumbar, 24,4% double and 8,9% miscellaneous.

Discussion: The screened area represents a place of particular interest because it experienced considerable environmental pollution during the past decades without any improvement of the available Health Services. A quite diverse population in relation to its occupation and its origin inhabits this area as well. The scoliosis incidence found in this area is similar to the incidence observed (2,9%) at other non-industrialized geographical departments of this country (2,6%). This implies that industrial environmental factors probably do not significantly influence the prevalence of AIS.

The development of the spine is affected by both biological and mechanical factors. As the geometry of the motion segment changes throughout growth, so does the mechanical behaviour of the spine owing to changing vectors acting on a variable geometry system.

The biomechanical analysis of the growing spine enables the assessment of the role played by biological and mechanical factors in the pathogenesis of progressive scoliosis to be assessed and its comparison with factors acting on an adult scoliotic spine. The knowledge of these principles is instrumental to setting the right parameters for treatment and to design braces that may be capable of obtaining correction of the deformity.

The elastic behaviour of child and adult spine differs because of both physiologic and pathologic conditions. In child scoliosis an abnormal geometry causes a persistent stress concentration in crucial areas of the motion segment. This induces a progressive elasto-plastic strain which modifies the geometry of the motion segment, thus worsening the stress concentration and the excessive strain through a vicious cycle. In adult scoliosis, on the other hand, deformation primarily affects the viscous-elastic structures, namely the intervertebral disc and the capsulo-ligamentous structures. This produces instabilty of the motion segments and slow deformation of the vertebrae through remodelling.

It therefore ensues that the aim of the treatment differs in both conditions. In the child spine the aim is to prevent the motion segment deformity by means of braces which adequately modifies the stress distribution acting on the spine, thus enabling the spine to grow according to a quasi-physiological model. In adult scoliosis a stable equilibrium is required in order to prevent further deformation of the motion segment.

Aim: Idiopathic scoliosis (IS) affects approximately 1-2% of the population and has a heritable component. It is clear that in general IS displays the features of a complex genetic disorder; however families displaying a Mendelian inheritance pattern have been described. Our aim is to identify families segregating rare, highly penetrant loci. In the case described here the disorder appears to cosegregate with a chromosomal rearrangement.

Methods and Materials: We have studied a family in which a pericentric inversion of chromosome 8 appears to cosegregate with idiopathic scoliosis in three generations. We have used fluorescent in situ hybridization (FISH) to identify cloned DNAs that span the breakpoints on the two arms of the chromosome. These clones allow the recovery of sequence information from the breakpoint region and identification of candidate genes. Results: We have identified a YAC of 1190kb that spans the p arm breakpoint and from this a cosmid of 35kb that also identifies the break. We have derived DNA sequence information on this region.

We have identified a BAC of 150kb that crosses the q arm breakpoint. The complete genomic DNA sequence of this BAC is being analyzed to identify candidate genes and to further localize the precise breakpoint. Conclusion: We have sublocalized within two small genomic regions the position of a possible locus for idiopathic scoliosis.

Three hundred and four girls with adolescent idiopathic scoliosis were investigated to determine if DNA polymorphisms in the vitamin D receptor (VDR), estrogen receptor (BR), and CYP17 gene were related to curve progression of idiopathic scoliosis. The results suggested that XbaJ site polymorphism in the ER gene was associated with curve progression. The Cobb's curve angle with genotype XX and Xx was statistically greater than that with genotype xx. The curve progression risk (∼5 degrees) was higher for genotype XX and Xx than for genotype xx. Furthermore, patients with genotype XX and Xx had a higher risk of receiving operative treatment than those with genotype xx. In conclusion, DNA analysis may predict curve progression, although other polymorphisms were not associated with curve severity.

The aim of this study was to determine whether the amount of growth response to mechanical compression and the underlying mechanism differed with night-time or day-time loading, relative to full time loading. Mechanical compression (nominally 0.1 MPa stress) was applied across tibial and tail vertebral growth plates of growing Sprague-Dawley rats. Four groups of animals were tested: 24/24 hour (full-time loading); 12/24 hour (day-loading); 12/24 hour (night-loading); and 0/24 hour (sham instrumented), 4 or 5 animals . per group. After 8 days animals were euthanized and the growth plates were processed for quantitative histology of loaded and within-animal control growth plates to measure 24-hour growth, total and BrdU-positive proliferative zone chondrocyte counts, and hypertrophic chondrocyte enlargement in the growth direction. Results: Growth as a percentage of within-animal control averaged 82% (full-time); 93% (day-loading); 90% (night-loading); 100% (sham) for vertebrae. For proximal tibiae it averaged 70% (full-time); 84% (day-loading); 86% (night-loading); 89% (sham). Reduced amount of hypertrophic chondrocytic enlargement explained about half of this effect in full-time compressed growth plates, but was not significantly altered in half-time loaded growth plates. The remaining variation in growth was apparently explained by reduced total numbers of proliferative zone chondrocytes. The BrdU labeling index demonstrated an opposite trend, which was not statistically significant. In half-time loaded growth plates the proliferative zone cell count change predominated.

Retrospective analysis of height and weight data recorded during routine clinic visits of children with congenital vertebral anomaly were related to decimal age and compared with national centiles. Individuals were dropped from the study at surgery. Growth followed a normal trajectory until puberty, although girls tended to be smaller than average. At puberty, they lagged behind their peers and at maturity were shorter than average. This does not appear to be a hormonal problem, and suggests a fundamental failure of growth.

Objectives: To measure the dimensions of the pedicles of Tl to L5 in the Greek population.

Methods:A total of 12 whole human cadaver spines were evaluated regarding pedicle dimensions (5 women and 7 men). The mean age at the time of death was 69,6 (range 62 to 84 years).

The transverse and sagittal out side pedicle isthmus widths, the internal transverse diameter and cortex width were measured with electronic calipers both on the right and left pedicles.

The data collected were statistically analyzed with the t- test.

Results.The widest transverse diameter was at the L5 level with a mean of 11,3mm (range 7,55-15,46mm). The narrowest transverse diameter was at the T5 level with a mean of 5,37mm (range 4,10 – 6,88mm). The widest sagittal diameter was at the Tl 1 level with a mean of 17,23mm (range 14,84-19,57mm), while the narrowest one was at T l level with a mean of 9,1mm (range 7,18-11,37mm). The maximum internal transverse diameter was at the L4 level with a mean of 8,26 mm (range 7,10-9,23mm) while the minimum was at the T5 level with a mean of 3,9mm (range 3,14-4,78mm).

The maximum cortex width was at the L5 level with a mean of 2,55mm (range 2,15-3,02mm) and the minimum at the T5 level with a mean of 1,30mm (range 0,40-2,10mm).

Conclusions .From the statistic analysis of the above data it was found that regarding the internal diameter there was statistically significant difference between males and females especially at T3, T7, T8 and L3 levels (P<0,05), and almost in all levels regarding the cortex width. There was also statistically significant difference between right and left pedicles regarding the transverse and the sagittal widths (P<0,05). The narrowest pedicle was at the T5 level and the widest was at the L5.

Objectives. This study was conducted to investigate the course of incorporation of coralline hydroxyapatite in human spine.

Summary of Background data. Conventional techniques for surgical treatment of spine have a substantial failure rate and associated morbidity. Bone graft substitutes are an alternative technique to enhance fusion rates and limit the morbidity associated with spine fusion using autologous iliac crest bone graft. There are some experimental studies supporting the use of hydroxyapatite in spine surgery.

Material & Methods. During revision surgery specimens derived from the fusion mass from 15 operations in 13 patients, who received spinal instrumentation and fusion in cervical, thoracic, and lumbar spine and addition of coralline hydroxyapatite. The age of patients at the time of revision surgery was 46+20 years. The time lapsed from the implantation of coralline hydroxyapatite and revision surgery was 11+9 months. The indication for revision surgery was infection, pseudarthrosis, technical error, and pain related to bulky hardware. The diagnosis for the primary fusion was degenerative disease, trauma and scoliosis, and the material of instrumentation used was composed from titanium alloy. The coralline hydroxyapatite was applied on the decorticated posterior elements of the instrumented spine. Material from ten different places from the fusion mass was intraoperatively taken in all patients and was sent for histological evaluation using the Hematoxylin-eosin histological stain technique and photomicroscope.

Results: Under photomicroscope there was a remarkable concentration of foreign-body like giant cells & development of inflammatory granulation tissue around hydroxyapatite, which was gradually replaced by dense connective collagen tissue. Both inflammatory granulation and collagen tissue showed areas with foreign body reaction. In the cases, where bone has developed, the most initial finding was the presence of osteoblasts & apposition of osteoid in contact to hydroxyapatite granules. In a later phase, cancellous and lamellar bone has developed as a result of secondary ossification. Bone formation was observed in 11/15 cases and was related with the patient’s age in favor of young patients (R=0.56, PO.05), while there was no correlation with time lapsed from operation.

Conclusion: Coralline hydroxyapatite conducts bone formation in spine surgery because in the vast majority of the operated cases for different spinal disorders bone and osteoid has developed around the implanted coralline hydroxyapatite.

Bone growth is a complex process involving proliferation, maturation and hypertrophy of chondrocytes in the growth plates. Mechanical forces applied to growing bones alter their longitudinal growth. However, the mechanisms by which chondrocytes modulate longitudinal bone growth are not well understood. This in vitro study investigated the effects of mechanical loading on the mRNA expression pattern of key molecular components of the growth-plate. Short-term static loading was applied to rat proximal tibial growth-plate explants. Various age groups at specific developmental stages were investigated. In situ hybridization was used to assess the mRNA expression of the cells in different zones of the growth-plate. Four key components were investigated: 18s (basic cell metabolism), type II collagen (major extracellular matrix component), type X collagen (matrix component in hypertrophic zone) and PTH-PTHrP receptors (pre-hypertrophic chondrocytes). The spatial variation in the mRNA expression between loaded explants and their contralateral controls was compared to establish: - the sensitivity of the different growth-plate zones to mechanical loading; - the sensitivity of the different developmental stages to loading. Preliminary results indicated that static loading on the growth plate of 80 d.o. rats affects type II and X collagen gene expressions while PTH-PTHrP remains insensitive to static loading. Improved understanding of growth- plate mechanics and the underlying biology is required to provide a scientific basis for the treatment of progressive deformities.