Pelvic Anteversion Research Articles

Progressive restoration of spinal sagittal balance after surgical correction of lumbosacral spondylolisthesis before skeletal maturity.

Spinopelvic alignment is crucial in assessing an energy-efficient posture in both normal and disease states, such as high-displacement developmental spondylolisthesis (HDDS). The overall effect in patients with HDDS who have undergone local surgical correction of lumbosacral imbalance for the global correction of spinal balance remains unclear. This paper reports the progressive spontaneous improvement of global sagittal balance following surgical correction of lumbosacral imbalance in patients with HDDS. The records of 15 patients with HDDS who underwent surgery between 2005 and 2010 were reviewed. The treatment consisted of L4-sacrum reduction and fusion via a posterior approach, resulting in complete correction of lumbosacral kyphosis. Preoperative, 6-month postoperative, and final follow-up postoperative angular measurements were taken from full-spine lateral radiographs obtained with the patient in a standard standing position. Radiographic measurements included pelvic incidence, sacral slope, lumbar lordosis, and thoracic kyphosis. The degree of lumbosacral kyphosis was evaluated by the lumbosacral angle. Because of the small number of patients, nonparametric tests were considered for data analysis. Preoperative lumbosacral kyphosis and L-5 anterior slip were corrected by instrumentation. Transient neurological complications were noted in 5 patients. Statistical analysis showed a significant increase of thoracic kyphosis on 6-month postoperative and final follow-up radiographs (p < 0.001). A statistically significant decrease of lumbar lordosis was noted between preoperative and 6-month control radiographs (p < 0.001) and between preoperative and final follow-up radiographs (p < 0.001). Based on the authors' observations, this technique resulted in an effective reduction of L-5 anterior slip and significant reduction of lumbosacral kyphosis (from 69.8° to 105.13°). Due to complete reduction of lumbosacral kyphosis and anterior trunk displacement associated with L-5 anterior slipping, lumbar lordosis progressively decreased and thoracic kyphosis progressively increased postoperatively. Adjusting the sagittal trunk balance produced not only pelvic anteversion, but also reciprocal adjustment of lumbar lordosis and thoracic kyphosis, creating a satisfactory level of compensated global sagittal balance.

Relationship between the ability to perform the sit-to-stand movement and the maximum pelvic anteversion and retroversion angles in patients with stroke.

[Purpose] The purpose of this study was to investigate the relationship between the ability to perform the sit-to-stand movement and the maximum pelvic anteversion and retroversion angles of patients. [Subjects] Thirty-two stroke patients (66.7±7.6 years) (>3 months post-stroke) who were able to sit unsupported and 50 age-matched healthy subjects participated in this study. The stroke patients were classified into two groups according to the sit-to-stand movement test: the group that was able to stand up (the stand-able group) (18 persons) and the group that was unable to stand up (the stand-unable group) (14 persons). [Methods] Pelvic anteversion and retroversion maximum angles were measured by a manual goniometer attached to an inclinometer. [Results] The maximum pelvic anteversion angles were −1.6 ± 5.0°, 1.2 ± 2.8°, and −12.4 ± 6.1° in the control group, the stand-able stroke group, and the stand-unable stroke group, respectively. A significant main effect of group was found. An angle discriminating between the two stroke groups was found: the maximum anteversion angles in the stand-able group were distributed above −5°. [Conclusion] The maximum pelvic anteversion angle was significantly smaller in the stand-unable group than in the stand-able and control groups.

Postural characterization in visually impaired young adults: preliminary study.

Introduction: The postural control system, responsible for maintaining the erect posture, it is strongly influenced by the visual system. Posture is the state of balance between muscles and bones, capable of protecting other structures of the human body from possible injuries. The visual system plays an important role in stabilizing the posture by continuously provide, with respect to the current position and the segments of the body in relation to themselves and the environment information nervous system. Objective: Characterize postural profile of young adults with visual impairment using computerized photogrammetry. Method: A postural analysis was performed in thirteen subjects 8 female and 5 male (30.85 ± 6.85 years), by recording images of the anterior, posterior and lateral views. All data were analyzed using the SAPO postural assessment software and the results tabulated in Microsoft Office Excel 2007 program. Descriptive statistics were performed. Results: It was shown that the subjects in this study had the following changes in postural profile: forward head, torso leaning back, pelvic anteversion and valgus hindfoot. Conclusion: The findings of this study showed that the attitude of these individuals is characterized by forward head, posterior tilt of the trunk, anterior pelvic tilt, knees flexed and valgus hindfoot. Additionally, it appears that this quantitative and qualitative method, low cost, can easily be incorporated into the clinical setting, it is useful to health professionals in the identification of postural changes and consequently the most appropriate treatment for these individuals.

Características posturais de idosos praticantes de atividade física

AIMS: The purposes of this study were to characterize and to describe the posture of elderly who practice physical activities. METHODS: Elderly participants of the Third Age Study Group at the Santa Catarina State University, between 60 and 80 years old, who practiced physical activity for at least two days a week, were studied. Data were obtained through computerized photogrammetry using the Postural Assessment Software (PAS/SAPO) in anterior, posterior and side views. Descriptive statistics were performed by using the mean and standard deviation. RESULTS: The sample consisted of 40 subjects, 34 women and six men. Postural characteristics in the anterior view were head rotation, lifting shoulders, scapula and pelvis, and internal rotation of the lower limbs; in the posterior view were right and left valgus hindfoot; and, in the side view, were the head forward, backward inclination of the trunk, hip extension, pelvic anteversion and flexed knees. CONCLUSIONS: Some postural features observed in seniors engaged in physical activity were similar to those found in normal aging. However, inclination of trunk backward and extension of the hip differed from the typical flexor posture of the elderly. We believe that these features are a consequence of physical exercises that promote the strengthening of the extensor muscles, important for maintaining the correct posture.

Age-related Changes in Maximum Pelvic Anteversion and Retroversion Angles Measured in the Sitting Position.

[Purpose] The purpose of this study was to investigate the relationship between age and the maximum pelvic anteversion and retroversion angles, as well as the associated pelvic range of motion, measured in a sitting position with free knee movement. [Subjects] A total of 132 healthy volunteers (74 women, 58 men; age range, 20–79 years) were divided into six groups based on age (20–29, 30–39, 40–49, 50–59, 60–69, and 70–79 years). [Methods] The maximum pelvic anteversion and retroversion angles were measured manually five times by a goniometer in a sitting position that allowed free movement of the knee joints. [Results] There was a significant effect of age group on the maximum pelvic anteversion and retroversion angles and pelvic range of motion (the difference between these angles). There was a significant correlation between age and the maximum pelvic anteversion angle, maximum pelvic retroversion angle, and pelvic range of motion. [Conclusion] The maximum pelvic anteversion and retroversion angles and pelvic range of motion were significantly correlated with age. The maximum pelvic anteversion angle and pelvic range of motion were most affected by age.

Kinematic gait analysis in children with valgus deformity of the hindfoot.

Deformities of the feet in children can influence not only optimal foot development but also the development of other body segments. The aim of the study was to compare the hip and pelvis kinematics in groups of children with and without valgus deformity of the hindfoot. Three groups of children participated in the study: bilateral hindfoot valgosity (11 children, age 5.4 ± 1.4 years), unilateral hindfoot valgosity (14 children, age 5.6 ± 1.6 years) and the control group (8 children, 4.8 ± 1.2). Hindfoot valgus angle was measured clinically during standing. Hindfoot valgosity was considered in the range of 6 to 20 degrees. Kinematic data from five trials for each child was obtained using the Vicon MX system (six infrared cameras, frequency 200 Hz, Vicon Motion Systems, Oxford, UK). The results of our study showed significantly higher pelvic anteversion during the whole gait cycle for both unilateral and bilateral hindfoot valgosity children and significantly higher hip external rotation during the first half of the stance phase in bilateral deformity. The differences in the hip and pelvis kinematics, when compared to the control group, are higher for the group with bilateral deformity than in the group with unilateral deformity.

Postural alignment in children with Duchenne muscular dystrophy and its relationship with balance.

BackgroundIn Duchenne muscular dystrophy, functional deficits seem to arise from body misalignment, deconditioning, and obesity secondary to weakness and immobility. The question remains about the effects of postural deviations on the functional balance of these children. ObjectivesTo identify and quantify postural deviations in children with DMD in comparison to non-affected children (eutrophic and overweight/obese), exploring relationships between posture and function.MethodThis case-control study evaluated 29 participants aged 6 to 11 years: 10 DMD (DG), 10 eutrophic (EG), and 9 overweight/obese (OG). Digital photogrammetry and SAPo program were used to measure postural alignment and the Pediatric Balance Scale (PBS) was used to measure balance. The Kruskall-Wallis and Dunn post-hoc tests were used for inter-group comparison of posture and balance. Spearman's coefficient tested the correlation between postural and balance variables. ResultsThe horizontal pelvic alignment data indicated that the anteversion of the DG was similar to that of the OG and twice that of the EG (p<0.05). Compared to the EG, the DG and OG showed an increased forward position of the center of mass (p<0.05). There was a moderate and weak correlation between the PBS score and horizontal pelvic alignment (0.58 and 0.47-left/right). The PBS showed a weak correlation with asymmetries in the sagittal plane (-0.39). The PBS scores for the OG and EG suggest that obesity did not have a deleterious effect on balance. ConclusionsThe balance deficit in children with DMD was accompanied by an increased forward position of the center of mass and significant pelvic anteversion that constitutes a compensatory strategy to guarantee similar performance to the children not affected by the disease.

Postural Characterization of Adolescent Federation Basketball Players

The adolescent players federated to basketball have a high-level of endurance demand, often overloading the biological tissues and causing biomechanical compensations. Due to the immaturity of their musculoskeletal structures those consequences may influence the growing process and lead to the development of various postural patterns. We aimed to evaluate the postural alignment of the trunk in players. Participants, 74 healthy adolescents: 36 basketball players (BG) and 38 adolescents in control group (CG). First, adolescents were marked with spheres over specific anatomical landmarks. Postural photographs were taken in the sagittal and frontal planes, and analyzed using the free internet Postural Analysis Software to obtain quantitative measures of the head, shoulders, and trunk. ANCOVA has revealed significant group effects: players demonstrated greater lateral spinal inclination (P < .008). In the right sagittal plane, the BG had lower angular values of forward head position (P < .02), pelvic ante version (P < .02), vertical alignment of the trunk (P < .02), and thoracic kyphosis (P < .005). The covariate analysis has indicated that age influences the alignments of both the shoulders and the left scapula; and height influences the scapular alignment. This study has demonstrated that basketball training within federations influences the musculoskeletal system of adolescents and reflects a process of postural adaptations.

Orthopedics management of acromicric dysplasia: Follow up of nine patients

Acromicric dysplasia (AD) is an autosomal dominant disorder characterized by short stature, short extremities, stiff joint and skeleton features including brachymetacarpia, cone-shaped epiphyses, internal notch of the femoral head, and delayed bone age. Recently, we identified fibrillin 1 (FBN1) as the disease gene of AD. The aim of our study was to further describe the long-term follow up of AD patients with an emphasis on orthopedic management. Nine patients with FBN1 mutations were included in the study ranging in age from 5.5 to 64 years. For all, detailed clinical and radiological data were available. Birth parameters were always normal and patients progressively developed short stature <-3 SD. Carpal tunnel syndrome was observed in four patients. We found discrepancy between the carpal bone age and the radius and ulna epiphysis bone ages, a variable severity of hip dysplasia with acetabular dysplasia, epiphyseal and metaphyseal femoral dysplasia resembling Legg-Perthes-Calvé disease and variable pelvic anteversion and hyperlordosis. Orthopedic surgery was required in two patients for hip dysplasia, in one for limb lengthening and in three for carpal tunnel syndrome. Our observations expand the AD phenotype and emphasize the importance of regular orthopedic survey.

Gender differences in sagittal standing alignment before pubertal peak growth: the importance of subclassification and implications for spinopelvic loading

The aim of this study was to analyze gender differences in sagittal standing alignment at pre-peak height velocity age thereby applying a scientifically sound and practically oriented classification scheme for overall standing balance. The study population consisted of healthy boys (n=639) and girls (n=557) before pubertal peak growth. During subjects' habitual standing, sagittal plane measures of the spine, pelvis and lower limbs were collected using a clinical screening protocol. With each subject classified as one of three postural types (neutral, sway-back, or leaning-forward), differences in sagittal plane alignment were analyzed between sexes. The results revealed clear differences between genders in each of the postural types. Within the neutral and sway-back postural subgroups, boys presented more forward inclination of the trunk, more thoracic kyphosis and more pelvis backtilt compared with girls. Within the leaning-forward category, girls displayed more forward trunk lean, less thoracic kyphosis and more pelvic anteversion. A state of lumbar segmental hyperextension appeared to exist in female leaning-forward subjects. Our results reveal for the first time that sagittal standing alignment is different between prepubescent boys and girls when subjects are appropriately subclassified, and conversely represent a 'wash-out effect' when pooled. When the classification system is applied, gender-specificity in gravity line position is suggested, implying gender-related differences in lever arms and thus load. Present findings may add to our understanding of gender-specific biomechanical challenges posed by habitual posture, and may shed new light on sagittal standing alignment as a possible contributory factor in developmental spinal-pelvic disorders.

Manipulation and selective exercises decrease pelvic anteversion and low-back pain: A pilot study

To study the effect of a protocol involving joint manipulation and specific exercises for pelvic stability to influence proprioceptive input to the spinal tissues and to observe the effects on sensorimotor function. Seven patients with pelvic anteversion and low back pain participated in an eight-week protocol (three sessions per week/nonconsecutive days). At each session, a high-velocity, low-amplitude manipulative thrust was applied to the sacroiliac joint, followed by quadriceps eccentric and hamstring concentric contractions. The perceived pain symptoms, pelvic anteversion as determined by photogrammetry analysis, and the electromyographic activity of the rectus femoris and lateral and medial hamstrings during flexion and extension exercises were assessed before and after treatment. Non-parametric tests were used to compare the groups before and after treatment with α=0.05. Perceived pain symptoms decreased after treatment (p=0.0007). The differences in the pelvis angles (p=0.0130) suggested significant differences between the assessments, and the electromyographic activities of all the muscles during isometric voluntary contraction increased. The eight-week manipulation/exercise protocol was effective for these subjects' needs. Further research should include a greater sample size to confirm the results and to determine the lead factors of pelvic stability.

Postural Assessment of Lumbar Lordosis and Pelvic Alignment Angles in Adolescent Users and Nonusers of High-Heeled Shoes

Objective The aims of this study were (1) to analyze the influence of wearing high-heeled shoes on lumbar lordosis and pelvic inclinations among adolescents aged between 13 and 20 years were users and nonusers of high-heeled shoes and (2) to correlate these postural angles with age. Methods Fifty adolescents from the nonuser group (NUG) of high-heeled shoes and 50 from the user group (UG) were evaluated. Postural assessments were obtained by photogrammetry under 2 conditions—barefoot and with high-heeled shoes—and analyzed using the evaluation postural software. The measured angles included lumbar lordosis and the horizontal alignment of the pelvis. Descriptive analyses were carried out, with a significance level of 5%. Results With high-heeled use, the NUG demonstrated rectification of the lumbar spine and pelvic retroversion, whereas the UG demonstrated hyperlordosis and pelvic anteversion. When barefoot, smaller lumbar lordosis angles for both groups were observed. However, the pelvic angles were lower for the UG group and higher for the NUG. The studied angles showed high reliabilities. Age was correlated with lumbar lordosis angles for the NUG in the barefoot condition and with pelvic alignments in both conditions for the UG. Conclusion For the subjects in this study, the use of high-heeled shoes is correlated with increased lumbar lordosis and pelvic anteversions. Lumbar lordosis angles are correlated with age for the NUG when barefoot.

Spinopelvic Alignment After Interspinous Soft Stabilization With a Tension Band System in Grade 1 Degenerative Lumbar Spondylolisthesis

Retrospective clinical study. The purpose of this study was to examine the changes in spinopelvic alignment after interspinous soft stabilization (ISS) with a tension band system and to identify the lumbosacral parameters related to those changes and to determine their impact on the clinical outcomes compared with posterior lumbar interbody fusion (PLIF) in patients with low-grade degenerative spondylolisthesis (DS). The sacropelvic morphometric changes after fusion surgery have received much research attention. However, few reports have addressed the issue after use of dynamic or soft stabilization systems. From April 2001 to November 2003, 45 patients presenting with grade 1 DS with stenosis underwent either ISS with a tension band system (ISS group) or PLIF with pedicle screw fixation (PLIF group). The mean follow-up period was 76.8 months. Three pelvic parameters, the sacral slope (SS), pelvic tilt (PT), and pelvic incidence, were investigated to address the sacropelvic morphometric change. Clinical outcomes were assessed using the visual analog scale score, the Oswestry Disability Index, and the patient's satisfaction index. Both groups showed significant improvements in all of the clinical outcomes, with no significant differences between groups. In the ISS group, the SS increased and PT decreased, whereas in the PLIF group, the SS decreased and PT increased, resulting in pelvic anteversion and retroversion, respectively, with significant intergroup differences in SS and PT (SS: P = 0.047; PT: P = 0.01). The positive association of lumbar lordosis with SS (r = 0.448) and its negative association with PT (r = -0.674) in the respective groups indicate the influence of changes in lumbar lordosis on pelvic positional changes. Significant correlations between follow-up segmental lumbar lordosis and the visual analog scale score for leg pain (r = -0.685) and Oswestry Disability Index score (r = -0.425) were found in the ISS group alone. Segmental lordotic change after ISS with a tension band system was the possible decisive factor in the development of pelvic anteversion while maintaining sagittal lumbar balance; lack of lumbar lordosis led to compensatory pelvic retroversion in the PLIF group. Considering the comparable clinical results with PLIF surgery and the achievement of physiologic sagittal spinopelvic balance, the ISS procedure can be a feasible alternative to fusion surgery in patients with grade 1 DS with stenosis.

Correlação entre padrão postural em jovens praticantes do atletismo

O estudo objetivou observar o alinhamento corporal de jovens atletas praticantes de atletismo e analisar a associação de tais padrões dentro e entre os grupos de provas desta modalidade. Participaram 63 atletas de ambos os sexos e o protocolo de coleta para análise postural baseou-se na observação e registro fotográfico com marcações nos principais acidentes ósseos visando à verificação do alinhamento dessas estruturas. Os segmentos considerados para análise foram: tronco, pelve, joelho e tornozelo. Foi utilizado para análise dos dados o teste de Goodman para contrastes entre e dentro de proporções binomiais. Os resultados mostraram que saltadores (58,33%) e arremessadores/lançadores (50,00%) apresentam o tronco em posição mais equilibrada que atletas de resistência (5,56%). Na região do quadril, arremessadores/lançadores apresentaram predomínio de pelve com rotação esquerda (66,67%), enquanto nos saltadores foi observada elevada frequência de anteversão pélvica (58,33%). A observação do joelho revelou altas taxas de normalidade e recurvatum em fundistas, valgo nos arremessadores/lançadores (50,00%) e varo para os demais grupos. Para a articulação do tornozelo, nota-se que, exceto os saltadores, os grupos apresentaram predominância de valgismo. Conclui-se que, para atender às características particulares de cada prova, níveis distintos de postura são estabelecidos.

Ocorrência de desvios posturais em escolares do ensino público fundamental de Jaguariúna, São Paulo

OBJETIVO: Avaliar a postura de escolares do ensino público fundamental e diferenciar as alterações que fazem parte do crescimento normal das compensatórias. MÉTODOS: Trata-se de um estudo analítico, descritivo, de corte transversal, no qual se realizou avaliação postural em escolares de primeira a quarta série de uma escola pública da cidade de Jaguariúna, situada no interior do Estado de São Paulo. Cada aluno foi avaliado nos planos coronal-anterior, coronal-posterior e sagital, utilizando-se o método de Kendall como referência de alinhamento postural normal. RESULTADOS: A avaliação postural de 247 escolares (131 masculinos e 116 femininos) identificou a seguinte incidência de alterações: desnível (50,2%) e protrusão de ombro (39,7%), escápula alada (40,5%), aumento do ângulo valgo de joelho (29,6%), inclinação (21,5%) e anteroversão pélvica (19%), hiperextensão de joelho (19%), rotação de fêmur (12,9%), protrusão (11,7%) e inclinação cervical (15,4%), cifose torácica (9,7%) e hiperlordose lombar (26,3%). CONCLUSÕES: Houve elevada incidência de escápula alada, desnível e protrusão de ombro, aumento do ângulo valgo de joelho e hiperlordose lombar, consideradas normais durante o desenvolvimento da criança. As inclinações e a protrusão cervical, alterações que necessitam de intervenção precoce, também foram identificadas.

Bilateral and unilateral increases in calcaneal eversion affect pelvic alignment in standing position

Excessive foot pronation has been associated with the occurrence of low back pain, possibly for generating changes in the lumbopelvic alignment. However, the influence of foot pronation (measured as calcaneal eversion) on pelvic alignment during standing has not been well established. Fourteen young healthy subjects participated in the study. A Motion Analysis System was used to obtain pelvic positions in sagittal and frontal planes and calcaneal position in the frontal plane. Volunteers were filmed in relaxed standing position during three trials, in three conditions: control; unilateral experimental with increased right calcaneal eversion and bilateral experimental with increased bilateral calcaneal eversion. Increased calcaneal eversion was obtained using wedges tilted 10° medially, unilaterally and bilaterally. Repeated measures ANOVAs with Bonferroni corrections were used for statistical analysis. Unilateral and bilateral use of medially tilted wedges produced a significant increase of calcaneal eversion ( P⩽0.01), on the right and left sides. Bilateral and unilateral increases of the calcaneal eversion caused average pelvic anteversion of 1.57° ( P=0.003) and 1.41° ( P=0.021), respectively. Unilaterally increased everted position generated an average pelvic lateral tilt of 1.46° ( P<0.001). Excessive calcaneal eversion during standing changes pelvic alignment and should be considered, associated with other relevant factors, when assessing pelvic misalignments.

Evaluation of the effect of backpack load and position during standing and walking using biomechanical, physiological and subjective measures

Recommendations on backpack loading advice restricting the load to 10% of body weight and carrying the load high on the spine. The effects of increasing load (0%–5%–10%–15% of body weight) and changing the placement of the load on the spine, thoracic vs. lumbar placement, during standing and gait were analysed in 20 college-aged students by studying physiological, biomechanical and subjective data. Significant changes were: (1) increased thorax flexion; (2) reduced activity of M. erector spinae vs. increased activation of abdominals; (3) increased heart rate and Borg scores for the heaviest loads. A trend towards increased spinal flexion, reduced pelvic anteversion and rectus abdominis muscle activity was observed for the lumbar placement. The subjective scores indicate a preference for the lumbar placement. These findings suggest that carrying loads of 10% of body weight and above should be avoided, since these loads induce significant changes in electromyography, kinematics and subjective scores. Conclusions on the benefits of the thoracic placement for backpack loads could not be drawn based on the parameter set studied.

Lumbar hyperlordosis of neuromuscular origin: pathophysiology and surgical strategy for correction

Lumbar hyperlordosis of neuromuscular origin is rare and requires surgical treatment in order to preserve a good sitting posture. We report twenty-seven cases of a preponderantly sagittal hyperlordosis deformity of the lumbar spine in patients with neuromuscular disorders and identify the indications and results of treatment. Seventeen males and ten females, aged 13 to 27 years, underwent operations for a lumbar hyperlordosis of neuromuscular origin responsible for major difficulties in sitting. In all patients, the sacrum was horizontal and associated in twenty-six cases with marked pelvic anteversion. Eleven patients were treated surgically by a posterior approach. The sixteen remaining patients had a preliminary discectomy, followed by posterior correction and fusion. Lumbar hyperlordosis was reduced from 8 degrees to 77 degrees between L1 and S1. The horizontal sacrum was partially reduced with an improvement from 8 degrees to 50 degrees . Consequently, patients recovered a comfortable sitting position. One patient died of respiratory complications six weeks after surgery. Surgical correction is a demanding procedure which can be performed by a posterior approach. It is mandatory to analyse the spino-pelvic balance to avoid iliac retroversion and the loss of the role of the ischia in the sitting position.

Lumbar hyperlodosis in cerebral palsy: anatomic analysis and surgical strategy for correction

We report our experience of five cases in adolescents with spastic quadriplegia who had primarily sagittal plane deformity with hyperlordosis of the lumbar spine, an uncommon condition in cerebral palsy spinal deformity. Three boys and two girls, 13 to 19 years old, were surgically treated for excessive lumbar lordosis which made sitting difficult. Bilateral hip flexion contractures were present in all cases with a very horizontal sacrum and, in four cases, associated with pelvic anteversion. Two patients were surgically treated by posterior spinal fusion and instrumentation, and three patients had anterior discectomy and fusion prior to posterior fusion and instrumentation. Hyperlordosis was reduced by 26 to 48 degrees , and the horizontal sacrum was corrected by 15 to 35 degrees , which enabled the patients to sit comfortably.

Conséquences défavorables sur l’équilibre sagittal du rachis du système de neutralisation dynamique

Purpose of the study The dynamic neutralization system (Dynesis™) has been proposed for the treatment of symptomatic lumbar discopathy. This system preserves the mobility of the instrumented vertebral segment and restores discal height by posterior distraction on pedicular screws, stabilization being ensured by compression on a spacer. The potential kyphosing effect of this system and the impact on sagittal morphology of the spine were analyzed. Material and methods Twenty-six patients were studied. Lateral x-rays of the lumbar spine in the upright position were obtained before and after the surgical procedure and at mean 9.5 ± 3.3 months follow- up.Comparisons were made between the pre- and postoperative presentation with measurement of the pelvic and spinal sagittal parameters described by Duval-Beaupère: inclination of the pelvic segement on the sacrum, lordosis, and disc wedge angles at each level (particularly the instrumented levels). Sagittal morphology was assessed pre- and postoperatively. Results Mean kyphosing effect was 6 ± 1.4°, induced by the posterior distraction system. This accentuated the initial lumbar hypolordosis related to the degenerative disease. Comparison of the pre- and postoperative films revealed four types of sagittal reaction of the lumbopelvic segment: no modification (type A), significant loss of lordosis without change at the pelvis level (type B) or with compensatory pelvic retroversion (type C), accentuation of the lordosis with pelvic anteversion (type D). Conclusion The dynamic neutralization system (Dynesis™) can stabilize degenerative discopathy and protect the adjacent levels. Posterior distraction perturbs the initial hypokyphosis and can lead to pelvic compensation to achieve better dynamic balance. This loss of lordosis is however a cause of excessive mechanical stress on the lumbar structures and can lead to long-term degradation. Future developments of this dynamic system should take into account the essential factor of sagittal balance.