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1.
Eur J Orthop Surg Traumatol ; 33(6): 2435-2443, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-36534368

RESUMO

INTRODUCTION: There is a growing body of literature separately linking lumbar spinal stenosis (LSS) with various factors such as paravertebral muscle (PVM) impaired function/morphology, lordosis or BMI. However, their interplay is yet to be known. The present study aims to investigate the relationship between PVM morphology, BMI and lumbar lordosis in a population with a surgical indication for LSS. MATERIALS AND METHODS: A cross-sectional retrospective study was conducted on a group of 122 patients diagnosed with LSS in a hospital setting and scheduled for spine surgery. Epidemiological data and body mass index (BMI) were gathered. The cross-sectional area of the psoas muscle (rCSA) at the L4-L5 disc level on preoperative axial T2 MRI was measured. Fat infiltration of the anterior (APVM) and posterior paravertebral muscles (PPVM) was evaluated according to Goutallier classification while the severity of lumbar stenosis was staged according to Schizas criteria. Lumbar lordosis was measured on sagittal MRI using Cobb's angle method. The presence of the "rising psoas" sign was also noted. Statistical analysis of the data was performed using Pearson and Spearman correlations. RESULTS: Statistical analysis revealed a moderate correlation between the severity of LSS and BMI (p = 0.001), and fatty infiltration of paravertebral muscles (p = 0.000, p = 0.000). Adjusting for age, gender, and BMI resulted in a low correlation (p = 0.003, p = 0.045), rCSA correlated negatively with age, gender, and lordosis. BMI had a low positive correlation with lumbar lordosis (p = 0.006), severity (p = 0.001), number of levels (p = 0.005) and PPVM (p = 0.031). CONCLUSIONS: This study highlighted the relationship between PVM morphology and the severity of radiological signs in patients with LSS undergoing spine surgery and found a correlation independent of age, gender, and BMI. BMI was also shown to correlate with the severity after controlling for age and gender. rCSA has limited use in evaluating the severity of LSS.


Assuntos
Lordose , Estenose Espinal , Humanos , Constrição Patológica , Lordose/diagnóstico por imagem , Estudos Retrospectivos , Índice de Massa Corporal , Estudos de Coortes , Imageamento por Ressonância Magnética , Estenose Espinal/diagnóstico por imagem , Estenose Espinal/cirurgia , Músculos Psoas/diagnóstico por imagem , Vértebras Lombares/diagnóstico por imagem , Vértebras Lombares/cirurgia , Músculos Paraespinais
2.
Int Orthop ; 45(4): 997-1001, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33394077

RESUMO

PURPOSE: Long time recognized as a cause of lumbar stenosis, degenerative spondylolisthesis has an evolution in interrelation with sagittal balance. This study aimed to assess the role of ALIF in correcting the sagittal balance in patients with degenerative spondylolisthesis. MATERIAL AND METHODS: Twenty patients aged between 47 and 70 years were operated between July 2011 and September 2014 for degenerative spondylolisthesis by ALIF. The pre-operative and post-operative valid standing full spine radiographs were reviewed retrospectively. Clinical and radiological evaluations were conducted pre-operatively and postoperatively at one year and five years. RESULTS: Lumbar lordosis (LL) was measured to 41.16 ± 14.25° pre-operatively and 47.27 ± 11.25° post-operatively (p > 0.05). At one year was 49.76 ± 13.31° and at five years 46.93 ± 9.26° (p > 0.05). Mean gain of lordosis after ALIF at index level was calculated to 8 ± 1.6° [4-12°]. CONCLUSIONS: ALIF offers a good reduction of the slipped vertebra providing good conditions for fusion and is an efficient surgical technique to recreate the sagittal spine balance.


Assuntos
Fusão Vertebral , Espondilolistese , Idoso , Humanos , Vértebras Lombares/diagnóstico por imagem , Vértebras Lombares/cirurgia , Região Lombossacral , Pessoa de Meia-Idade , Estudos Retrospectivos , Fusão Vertebral/efeitos adversos , Espondilolistese/diagnóstico por imagem , Espondilolistese/cirurgia
4.
Int Orthop ; 41(5): 963-968, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28161853

RESUMO

INTRODUCTION: Osteoporotic vertebral fractures (OVF) can lead to late collapse which often causes kyphotic spinal deformity, persistent back pain, decreased lung capacity, increased fracture risk and increased mortality. The purpose of our study is to compare the efficacy and safety of vertebroplasty against conservative management of osteoporotic vertebral fractures without neurologic symptoms. MATERIAL AND METHODS: A total of 66 patients with recent OVF on MRI examination were included in the study. All patients were admitted from September 2009 to September 2012. The cohort was divided into two groups. The first study group consisted of 33 prospectively followed consecutive patients who suffered 40 vertebral osteoporotic fractures treated by percutaneous vertebroplasty (group 1), and the control group consisted of 33 patients who suffered 41 vertebral osteoporotic fractures treated conservatively because they refused vertebroplasty (group 2). The data collection has been conducted in a prospective registration manner. The inclusion criteria consisted of painful OVF matched with imagistic findings. We assessed the results of pain relief and minimal sagittal area of the vertebral body on the axial CT scan at presentation, after the intervention, at six and 12 months after initial presentation. RESULTS: Vertebroplasty with poly(methyl methacrylate) (PMMA) was performed in 30 patients on 39 VBs, including four thoracic vertebras, 27 vertebras of the thoracolumbar jonction and eight lumbar vertebras. Group 2 included 30 patients with 39 OVFs (four thoracic vertebras, 23 vertebras of the thoracolumbar junction and 11 lumbar vertebras). There was no significant difference in VAS scores before treatment (p = 0.229). The mean VAS was 5.90 in Group 1 and 6.28 in Group 2 before the treatment. Mean VAS after vertebroplasty was 0.85 in Group 1. The mean VAS at six months was 0.92 in Group 1 and 3.00 in Group 2 (p < 0.05). The mean VAS at 12 months was 0.92 in Group 1 and 2.36 in Group 2. The mean improvement rate in VAS scores was 84.40% and 62.42%, respectively (p < 0.05). For Group 1, mean area of the VBs measured on sagital CT images was 8.288 at the initial presentation, 8.554 postoperatively, 8.541 at five months and 8.508 at 12 months, respectively, and 8.388 at the initial presentation, 7.976 at six months and 7.585 at 12 months for Group 2 (Fig. 4). DISCUSSIONS: Although conservative treatment is fundamental and achieves good symptom control, in patients who suffer osteoporotic compression fractures (OCF), the incidence of late collapse is high and the prognosis is poor. In order to relieve the pain and avoid VB collapse, vertebroplasty is the recommended treatment in OCFs. Considering the above findings, the dilemma is whether vertebroplasty can change the natural history (pain and deformity) of OCFs. CONCLUSION: In our study on OVF, vertebroplasty delivered superior clinical and radiological outcomes over the first year from intervention when compared to conservative treatment of patients with osteoporotic compression fractures without neurological deficit. We believe that the possibility of evolution towards progressive kyphosis is sufficient to justify prophylactic and therapeutic intervention such as vertebroplasty, a minor gesture compared with extensive correction surgery and stabilization.


Assuntos
Dor nas Costas/cirurgia , Tratamento Conservador/métodos , Fraturas por Osteoporose/cirurgia , Vertebroplastia/métodos , Idoso , Tratamento Conservador/efeitos adversos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Manejo da Dor , Medição da Dor , Estudos Prospectivos , Coluna Vertebral/diagnóstico por imagem , Coluna Vertebral/cirurgia , Tomografia Computadorizada por Raios X , Vertebroplastia/efeitos adversos
5.
Eur J Orthop Surg Traumatol ; 26(7): 735-43, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27562589

RESUMO

PURPOSE: Spinopelvic parameters can be useful in identifying risk factors for lumbar degenerative disc disease, but few studies assess patients with single-level disc herniation and most do not evaluate symptoms. This comparative retrospective study was aimed to analyse spinopelvic parameters, symptoms and MRI changes in patients with single-level lumbar disc herniation undergoing conservative or surgical treatment. METHODS: Patients with clinical and radiological assessment (Japanese Orthopaedic Association Score) and an MRI evaluation of the lumbar spine were identified and divided into two groups: surgically treated (group A) and not requiring surgery (group B). Spinopelvic parameters were determined on standing profile radiographs of the lumbar spine and pelvis, and mean values were compared to those reported in the literature for normal subjects. MRI findings were graded according to the system described by Pfirrmann et al. RESULTS: The study included 71 patients with single-level lumbar disc herniation: 26 in group A (39.4 ± 12.1 years) and 45 in group B (51.4 ± 17.2 years). The notable differences in spinopelvic parameter means between the two groups did not reach statistical significance. A positive correlations of age with pelvic tilt and Pfirrmann changes with pelvic incidence was only found in group A, while both groups showed highly significant positive correlations of pelvic incidence with the spine's conformational type (p = 0.001). CONCLUSIONS: Characteristic changes in spinopelvic parameters identified in patients with lumbar degenerative disc disease were a reduction in pelvic incidence, sacral slope and lumbar lordosis, with an increased pelvic tilt. These were found to correlate with MRI changes in surgically treated patients.


Assuntos
Degeneração do Disco Intervertebral/fisiopatologia , Deslocamento do Disco Intervertebral/fisiopatologia , Vértebras Lombares/patologia , Equilíbrio Postural/fisiologia , Adulto , Feminino , Humanos , Degeneração do Disco Intervertebral/patologia , Deslocamento do Disco Intervertebral/patologia , Cifose/patologia , Cifose/fisiopatologia , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Radiografia , Estudos Retrospectivos
6.
Int Orthop ; 40(6): 1219-25, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26907875

RESUMO

INTRODUCTION: Pedicle substraction osteotomy (PSO) in the lumbar spine is indicated in the treatment of large sagittal deformities of the lumbar spine. Substantial complications associated with PSOs include pseudarthrosis and mechanical failure. The purpose of the present study was to assess the complications of this procedure and the causes of mechanical complications. MATERIAL AND METHODS: Fifteen patients aged between 38 and 79 years (mean age 63.8±12.82) were operated on between June 2011 and September 2014 for sagittal imbalance by means of one-level PSO. Pre-operative and post-operative values of radiological spino-pelvic sagittal parameters were measured. Clinical and radiological evaluations were conducted pre-operatively and post-operatively at six months and one year. Clinical evaluation included intra- and post-operative complications. RESULTS: Mean pelvic incidence was 54.86 ± 11.82°. Lumbar lordosis (LL) was measured to be 12.26 ± 18.48° pre-operatively and increased to 42.73 ± 14.05° post-operatively (p< 0.05). Mean gain of lordosis after PSO at index level was calculated to be 28 ± 11° (range, 14-41). SVA decreased post-operatively from 93.46 ± 36.69 mm to 61.73 ±38.68 mm (p< 0.05). Several complications (n = 8), including two minor (one dural tear with no clinical consequences and one transient radicular deficit) and six major with re-intervention, were observed in our series. DISCUSSIONS: Optimal post-operative correction in the sagittal plane: SVA <50 mm, LL= -(PI+10°) is an important parameter to reduce the risk of developing sagittal decompensation which is a common condition after PSO. Rate of complications after PSO is not negligible in the literature up to 45%. CONCLUSIONS: The main cause of mechanical complications was insufficient sagittal correction. To limit the risk of mechanical complications and to achieve a good sagittal balance, PSO must be associated with additional SPOs or a second corrective surgery to obtain a solid anterior fusion.


Assuntos
Vértebras Lombares/cirurgia , Osteotomia/métodos , Curvaturas da Coluna Vertebral/cirurgia , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Osteotomia/efeitos adversos , Complicações Pós-Operatórias/etiologia , Estudos Retrospectivos
7.
Int Orthop ; 39(5): 961-5, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25772278

RESUMO

INTRODUCTION: Unstable pelvic ring disruptions have been associated with high rates of morbidity. Accurate reduction with fixation diminishes pain, permits early patient mobility, and allows the pelvic ring to improve functional outcome. MATERIAL AND METHODS: This was a retrospective study, whereby 30 polytrauma hospitalized patients were included, with unstable pelvic lesions stabilized with an external fixator as a mean of temporary or definitive fixation. Data collected for these sample were: age, sex, cause of trauma, type of pelvic lesion, associated lesions (ISS score), pelvic stabilization methods, and functional outcome. There were 17 male subjects (57%) and 13 female subjects (43%), with a mean age of 42.5 years (range 18-62 years). According to Tile classification, the unstable pelvic ring lesions prevailed; 60 % of patients were type C while three patients with type C instability had associated acetabular fractures, and 40% had type B rotational instability. Stabilization was achieved using an external fixator in 16 patients; in 14 patients the anterior ring fixation was used with an external fixator combined with posterior stabilization using percutaneous sacroiliac screws. The pelvic stabilization using the external fixator was later replaced with plates and screws (ORIF) in four patients. Follow-up at one, three, six and 12 months postoperatively was based on the Majeed functional score and radiographic assessment. RESULTS: Eighteen patients (78%) had an excellent Majeed functional score, four patients had a good score, and only one patient had a fair functional outcome. Malunions were recorded in four patients with Tile C that were stabilized only by external fixation, and superficial pin track infection occurred in three patients. Within the studied group seven deaths have been recorded (23%) in patients with extremely severe associated injuries (ISS over 50), this being the decisive factor that determined the unfavourable evolution in six patients. CONCLUSIONS: The external fixation stabilizes the anterior pelvic ring lesions and it can be combined with the posterior stabilization using percutaneous sacro-iliac screws in case of associated lesions of the posterior ring. The external fixator is very useful especially in the acute phase, acquiring an acceptable reduction and an adequate stability in the partially unstable lesions (Tile B) and also reduces the pelvic volume and bleeding, being considered essential within the resuscitation protocols. The external fixator can be used as a permanent stabilization method when it guarantees a satisfying reduction.


Assuntos
Fixadores Externos , Fraturas Ósseas/cirurgia , Instabilidade Articular/cirurgia , Ossos Pélvicos/lesões , Adolescente , Adulto , Serviços Médicos de Emergência , Feminino , Fixação de Fratura/métodos , Humanos , Escala de Gravidade do Ferimento , Masculino , Pessoa de Meia-Idade , Traumatismo Múltiplo/cirurgia , Ossos Pélvicos/diagnóstico por imagem , Radiografia , Estudos Retrospectivos , Adulto Jovem
8.
Int Orthop ; 39(7): 1411-5, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25673510

RESUMO

PURPOSE: The reporting of gait analysis data on operated fractures of the tibial plateau, while extensive for studies of knee osteoarthritis of mostly undisclosed aetiology and ACL deficient knees, is rather limited in literature. METHODS: In the present study we investigated 25 tibial plateau fractures classified as Schatzker II, IV, V and VI that underwent operative reduction and lateral plate osteosynthesis. Apart from routine radiographic exploration and patient completed (KOOS) scores at three (mean of 3.2 months), six (mean of 5.6 months) and 12 months (mean of 11.3 months) postoperatively, gait analysis was performed at these intervals as well. Cadence, step time and knee flexion were the gait parameters that were selected for the comparison at six and 12 months postoperatively. RESULTS: The analysed gait parameters were significantly improved between the six and the 12-month session and statistically significant differences were found between the two groups of values. Cadence had a mean value of 41 steps/minute at six months and 45 steps/minute at 12 months (p = 0.99). Step time was a mean of 0.74 seconds at six months while at 12 months the median value was 0.66 seconds (p = 0.94). Knee flexion angles evolved in a similar manner with mean values of 58° at six months and 69° at 12 months (p = 0.95). The mean KOOS scores were 42.4, 56.3 and 67.99 at three, six and 12 months postoperatively, respectively. CONCLUSION: Complex intra-articular fractures, classified as Schatzker IV, V and VI, had a higher impact on joint function than Schatzker II fractures treated with similar techniques and implants. There were statistically significant improvements in the recovery status at 12 months postoperatively compared to six months with extended chances for improvement.


Assuntos
Marcha , Fraturas Intra-Articulares/cirurgia , Articulação do Joelho/fisiopatologia , Amplitude de Movimento Articular , Fraturas da Tíbia/cirurgia , Remoção de Dispositivo , Feminino , Fixação Interna de Fraturas/métodos , Humanos , Fraturas Intra-Articulares/classificação , Fraturas Intra-Articulares/diagnóstico por imagem , Articulação do Joelho/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Período Pós-Operatório , Radiografia , Fraturas da Tíbia/classificação , Fraturas da Tíbia/diagnóstico por imagem
9.
In Vivo ; 29(1): 95-102, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25600536

RESUMO

AIM: To investigate a possible correlation between the histological and morphometric properties of herniated intervertebral disc, clinical and magnetic resonance imaging (MRI) characteristics of patients with lumbar disc degeneration (LDD). MATERIALS AND METHODS: Thirty six patients with LDD were clinically evaluated using Japanese Orthopaedic Association Score (JOAS), visual analogue scale (VAS) for pain in the lower back or in the pelvic limb; MRI-based classification according to Pfirrmann and Modic criteria. All patients underwent decompressive surgery and herniated intervertebral disc samples were histologically and morphometrically analyzed. Data obtained were statistically analyzed for bivariate and partial correlations. RESULTS: The mean area size of chondron clusters correlated with age, JOAS (r=-0.385, p=0.032, tau=-0.279, rho=-0.380), Pfirrmann (r=0.505, p=0.002, tau=0.289, rho=0.365) and Modic (r=0.500, p=0.002, tau=0.331, rho=0.419) grading. There was a strong correlation between maximum area size of chondrons and JOAS (r=-0.427, p=0.009, tau=-0.299, rho=-0.430), Pfirrmann changes (r=0.432, p=0.008, tau=0.309, rho=0.388) and Modic endplate changes (r=0.444, p=0.007, tau=0.343, rho=0.434). JOAS correlated with both MRI classifications used for LDD. CONCLUSION: The intervertebral disc cells tend to aggregate in clusters and the size of the chondrons from LDD correlated with JOAS, Pfirrmann and Modic. JOAS correlates with the imagistic evaluation systems Pfirrmann and Modic.


Assuntos
Degeneração do Disco Intervertebral/patologia , Disco Intervertebral/patologia , Microscopia/métodos , Adulto , Biópsia , Feminino , Humanos , Degeneração do Disco Intervertebral/diagnóstico , Degeneração do Disco Intervertebral/terapia , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Adulto Jovem
10.
Eur J Orthop Surg Traumatol ; 24(5): 685-92, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24297373

RESUMO

Haemophilia is a hereditary disease due to a defect of the X chromosome, which determines a faulty production of coagulation factor VIII in haemophilia A (85% of cases) and factor IX in haemophilia B. Three degrees of severity can be distinguished: low, with a deficient factor concentration greater than 5% of normal values, medium, with a concentration between 1 and 5%, and severe, comprising more than half of haemophilia cases, with a concentration of factor VIII or factor IX under 1% of normal. The evolution of haemophilic arthropathy is almost always from haemarthrosis to chronic synovitis and extended erosions of the articular surface, culminating in the final stage of articular destruction-chronic haemophilic arthropathy. This paper analyses the results of the treatment applied to a lot of one hundred and ten patients operated inside the our country's sole Compartment of Osteo-Articular Surgery of haemophiliac patients within the Clinic No. 2 of Orthopaedics and Traumatology between 2001 and 2013. This compartment was founded in 2001, being included in the Romanian Health Ministry's programme for financing the treatment for haemophilia. Within the aforementioned time period, a total of 158 patients from the entire country were consulted. From these, 110 patients underwent a series of surgical procedures, 112 in total. The age interval of the studied lot was between 9 and 45 years, with a maximum between 11 and 20 years. With replacement therapy and correct surgical indication, osteoarticular surgery in haemophiliacs, performed in a specialized centre by a multidisciplinary team, can give good results with acceptable risks.


Assuntos
Hemofilia A/complicações , Hemofilia B/complicações , Procedimentos Ortopédicos/estatística & dados numéricos , Adolescente , Adulto , Doenças Ósseas Metabólicas/complicações , Criança , Estudos de Coortes , Humanos , Pessoa de Meia-Idade , Osteoporose/complicações , Complicações Pós-Operatórias/etiologia , Adulto Jovem
11.
Eur J Orthop Surg Traumatol ; 23 Suppl 1: S115-9, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23412326

RESUMO

Lumbosacral nerve roots anomalies may produce low back pain. These anomalies are reported to be a cause for failed back surgery. They are usually left undiagnosed, especially in endoscopic discectomy techniques. Any surgery for entrapment disorders, performed on a patient with undiagnosed lumbosacral nerve roots anomaly, may lead to serious neural injuries because of an improper surgical technique or decompression. In this report, we describe our experience with a case of L5-S1 spondylolisthesis and associated congenital lumbosacral nerve root anomalies discovered during the surgical intervention, and the difficulties raised by such a discovery. Careful examination of coronal and axial views obtained through high-quality Magnetic Resonance Imaging may lead to a proper diagnosis of this condition leading to an adequate surgical planning, minimizing the intraoperatory complications.


Assuntos
Descompressão Cirúrgica/métodos , Discotomia/métodos , Vértebras Lombares , Plexo Lombossacral/anormalidades , Raízes Nervosas Espinhais/anormalidades , Espondilolistese/cirurgia , Adulto , Feminino , Humanos , Cuidados Intraoperatórios/métodos , Dor Lombar/etiologia , Vértebras Lombares/patologia , Vértebras Lombares/cirurgia , Região Lombossacral/diagnóstico por imagem , Região Lombossacral/inervação , Região Lombossacral/cirurgia , Imageamento por Ressonância Magnética , Espondilolistese/complicações , Espondilolistese/diagnóstico , Espondilolistese/fisiopatologia , Tomografia Computadorizada por Raios X , Resultado do Tratamento
12.
Eur J Orthop Surg Traumatol ; 23 Suppl 1: S67-70, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23412325

RESUMO

OBJECTIVE: The current study aims to find the neurological characteristic of thoracolumbar junction fractures as well as the impact of a proper initial neurological assessment onto the treatment management of patients admitted into Timisoara County Clinical Emergency Hospital's Emergency Unit. MATERIALS AND METHODS: This is a retrospective study based on patients with thoracolumbar fractures between 2004 and 2009. Age, sex, cause and level of injury, fracture pattern and distribution, and neurological presentation of patients were studied. RESULTS: There were 605 patients with predominance of men (59.17 %); the mean age was 32.4 years old. The main cause of the fractures was represented by car accidents (56.2 %), and associated trauma was found in 38.51 % of the patients. The majority of the patients presented with incomplete neurological deficit (45.62 %), whilst 20.66 % suffered from complete neurological deficit. CONCLUSION: We found a correlation between the fracture level and the neurological deficit, the grade of neurological motor deficit and anal sphincter disorder and stenosis grade in relation to neurological lesions.


Assuntos
Vértebras Lombares , Doenças do Sistema Nervoso , Traumatismos da Coluna Vertebral , Vértebras Torácicas , Adulto , Serviço Hospitalar de Emergência/estatística & dados numéricos , Feminino , Hospitais de Condado/estatística & dados numéricos , Humanos , Vértebras Lombares/lesões , Vértebras Lombares/cirurgia , Masculino , Doenças do Sistema Nervoso/diagnóstico , Doenças do Sistema Nervoso/epidemiologia , Doenças do Sistema Nervoso/etiologia , Doenças do Sistema Nervoso/fisiopatologia , Exame Neurológico/métodos , Estudos Retrospectivos , Romênia/epidemiologia , Traumatismos da Coluna Vertebral/complicações , Traumatismos da Coluna Vertebral/diagnóstico , Traumatismos da Coluna Vertebral/epidemiologia , Estenose Espinal/epidemiologia , Estenose Espinal/etiologia , Estenose Espinal/fisiopatologia , Estatística como Assunto , Vértebras Torácicas/lesões , Vértebras Torácicas/cirurgia , Índices de Gravidade do Trauma
13.
Chemphyschem ; 9(11): 1541-7, 2008 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-18613194

RESUMO

The formation of artificial opal films consists of wet opal deposition, drying, and possible transformations in the dry state. The processes after deposition, before the crystals lattice reaches its final equilibrium state, are studied herein. We follow the time evolution of the optical transmission spectra for polystyrene opals with different thicknesses. The evolution of the spectra shows pronounced changes in the Bragg peak position, width and height, as well as changes in the background and, in the beginning of the process, a band related to residual water in the sample. Therefore, a wet and a dry phase can be distinguished in the opal transformations. They are all connected to shrinkage and we associate one of them with a possible new sintering mechanism.

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