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1.
Zhonghua Yi Xue Za Zhi ; 99(34): 2706-2710, 2019 Sep 10.
Artigo em Chinês | MEDLINE | ID: mdl-31505724

RESUMO

Objective: To observe the biomechanical characteristics of bridge-link type combined internal fixation system (BCFS) with mixed-rod in the treatment of long segmental comminuted fracture of femoral shaft. Methods: A total of 16 models of long comminuted segment fracture of femoral shaft with mixed-rod and double-rod were made (8 each structure), and divided into the mixed-rod group and the double-rod group. The axial compression experiment and the radial torsion experiment were carried out on each of the mixed rod group and the double rod group. Four models were randomly selected from the two groups for axial compression experiment and radial torsion experiment, respectively. The changes of axial compression yield load and displacement, and also radial torsional yield load and angle were observed in two groups. At the same time, the maximum load was recorded when the curve had a break point or in a horizontal state, and then calculated the yield load. The data of normal distribution were compared with one-sample t test. Results: When the two groups were compressed axially at the same speed, as the axial compression yield load increased gradually, the longitudinal compression displacement of the mixed-rod group was obviously smaller than that in the double-rod group; and the maximum axial compression yield load of the mixed-rod group was greater than that in the double-rod group ((7 517±4)N vs (2 290±4) N, t=1 848.071, P=0.000). When the two groups were twisted radially at the same speed,as radial torsional yield load increased gradually, the radial torsion angle of the mixed-rod group was smaller than that in the double-rod group; and the maximum radial torsional yield load of the mixed-rod group was greater than that in the double-rod group ((61.3±2.0) Nm vs (24.4±2.2)Nm, t=25.201, P=0.000). Conclusions: For the long segment comminuted fracture of femoral shaft, the mixed-rod of BCFS can fix fracture more strongly than double-rod in longitudinal direction and maintain the stability of fracture end. The transverse torsion resistance is better than that of the double-rod, and the fatigue resistance is strong.


Assuntos
Fixação Interna de Fraturas , Fraturas Cominutivas , Fenômenos Biomecânicos , Placas Ósseas , Fêmur , Humanos
2.
Am J Orthod Dentofacial Orthop ; 156(3): 326-336, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31474262

RESUMO

INTRODUCTION: Orthodontic mini-implants aid in the correction of distocclusions via direct anchorage (pull from mini-implant to teeth) and indirect anchorage (teeth pulled against other teeth anchored by the mini-implant). The aim of this study was to compare stress levels on the periodontal ligament (PDL) of maxillary buccal teeth in direct and indirect distalization against orthodontic mini-implants and accounting for individual variation in maxillary anatomy and biomechanical characteristics of the compact bone. METHODS: A 3D model of the maxilla containing the different components (teeth, PDL, trabecular and cortical bones) was generated from a computed tomographic scan. Cortical bone was divided into several areas according to previously defined zones. Bone stiffness and thickness data, obtained from 11 and 12 cadavers, respectively, were incorporated into the initial model to simulate the individual cortical bone variation at the different locations. Subsequently, a finite element analysis was used to simulate the distalization modalities. RESULTS: Stresses at the buccal, palatal, mesial, and distal surfaces were significantly different between adjacent teeth under stiffness but not thickness variation. In both distalization modalities, low or no significant correlations were found between stress values and corresponding cortical bone thicknesses. High significant and inverted correlations were observed at the first molar between stress amounts and cortical bone stiffness (direct modality: -0.68 < r < -0.72; indirect modality: -0.80 < r < -0.82; P <0.05). CONCLUSIONS: With the use of a novel finite element approach that integrated human data on variations in bone properties, findings suggested that cortical bone stiffness may influence tooth movement more than bone thickness. Significant clinical implications could be related to these findings.


Assuntos
Análise do Estresse Dentário/métodos , Análise de Elementos Finitos , Técnicas de Movimentação Dentária/métodos , Fenômenos Biomecânicos , Parafusos Ósseos , Simulação por Computador , Implantes Dentários , Humanos , Imagem Tridimensional/métodos , Maxila/anatomia & histologia , Maxila/diagnóstico por imagem , Modelos Anatômicos , Dente Molar , Procedimentos de Ancoragem Ortodôntica/instrumentação , Procedimentos de Ancoragem Ortodôntica/métodos , Desenho de Aparelho Ortodôntico , Ligamento Periodontal , Estresse Mecânico , Técnicas de Movimentação Dentária/instrumentação , Torção Mecânica
3.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi ; 36(4): 590-595, 2019 Aug 25.
Artigo em Chinês | MEDLINE | ID: mdl-31441259

RESUMO

In order to study the mechanical behavior of degeneration and nucleotomy of lumbar intervertebral disc, compression experiments with porcine lumbar intervertebral discs were carried out. The lumbar intervertebral discs with trypsin-treated and nucleus nucleotomy served as the experimental group and the normal discs as the control group. Considering the effects of load magnitude and loading rate, the relationship between stress and strain, instantaneous elastic modulus and creep property of intervertebral disc were obtained. The creep constitutive model was established. The results show that the strain and creep strain of the experimental group increase significantly with the increase of compression load and loading rate, whereas the instantaneous elastic modulus decreases obviously, compared with the control group. It indicates that the effect of load magnitude and loading rate on load-bearing capacity of intervertebral disc after nucleotomy is larger obviously than that of normal disc. The creep behavior of the experimental group can be still predicted by the Kelvin three-parameter solid model. The results will provide theoretical foundation for clinical treatment and postoperative rehabilitation of intervertebral disc disease.


Assuntos
Disco Intervertebral/fisiologia , Disco Intervertebral/cirurgia , Estresse Mecânico , Animais , Fenômenos Biomecânicos , Vértebras Lombares , Suínos , Suporte de Carga
4.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi ; 36(4): 596-603, 2019 Aug 25.
Artigo em Chinês | MEDLINE | ID: mdl-31441260

RESUMO

The mechanical properties of the aorta tissue is not only important for maintaining the cardiovascular health, but also is closely related to the development of cardiovascular diseases. There are obvious differences between the ventral and dorsal tissues of the descending aorta. However, the cause of the difference is still unclear. In this study, a biaxial tensile approach was used to determine the parameters of porcine descending aorta by analyzing the stress-strain curves. The strain energy functions Gasser-Ogden-Holzapfel was adopted to characterize the orthotropic parameters of mechanical properties. Elastic Van Gieson (EVG) and Sirius red stain were used to observe the microarchitecture of elastic and collagen fibers, respectively. Our results showed that the tissue of descending aorta had more orthotropic and higher elastic modulus in the dorsal region compared to the ventral region in the circumferential direction. No significant difference was found in hyperelastic constitutive parameters between the dorsal and ventral regions, but the angle of collagen fiber was smaller than 0.785 rad (45°) in both dorsal and ventral regions. The arrangement of fiber was inclined to be circumferential. EVG and Sirius red stain showed that in outer-middle membrane of the descending aorta, the density of elastic fibrous layer of the ventral region was higher than that of the dorsal region; the amount of collagen fibers in dorsal region was more than that of the ventral region. The results suggested that the difference of mechanical properties between the dorsal and ventral tissues in the descending aorta was related to the microstructure of the outer membrane of the aorta. In the relatively small strain range, the difference in mechanical properties between the ventral and dorsal tissues of the descending aorta can be ignored; when the strain is higher, it needs to be treated differently. The results of this study provide data for the etiology of arterial disease (such as arterial dissection) and the design of artificial blood vessel.


Assuntos
Aorta Torácica/fisiologia , Animais , Fenômenos Biomecânicos , Colágeno , Módulo de Elasticidade , Estresse Mecânico , Suínos
5.
Orthop Clin North Am ; 50(4): 529-537, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31466668

RESUMO

Ankle osteoarthritis affects a significant portion of the global adult population. Unlike other joints, arthritis of the ankle often develops as a response to traumatic injury (intra-articular fracture) of the ankle joints. The full mechanism leading to posttraumatic osteoarthritis of the ankle (PTOAA) is poorly understood. These deficits in knowledge pose challenges in the management of the disease. Adequate surgical reduction of fractured ankle joints remains the gold standard in prevention. The purpose of this review is to thoroughly delineate the known pathogenesis of PTOAA, and provide critical updates on this pathology and new avenues to provide therapeutic management of the disease.


Assuntos
Fraturas do Tornozelo/complicações , Fraturas do Tornozelo/cirurgia , Osteoartrite/patologia , Fraturas do Tornozelo/metabolismo , Fenômenos Biomecânicos , Gerenciamento Clínico , Fixação Interna de Fraturas/instrumentação , Humanos , Metabolismo dos Lipídeos , Osteoartrite/metabolismo , Resultado do Tratamento
6.
Beijing Da Xue Xue Bao Yi Xue Ban ; 51(4): 728-732, 2019 Aug 18.
Artigo em Chinês | MEDLINE | ID: mdl-31420630

RESUMO

OBJECTIVE: To establish animal models and investigate the impact of unilateral hemilaminectomy (ULHL) and different degrees of facetectomy (FT) on the cervical spinal biomechanics. METHODS: Twenty sheep were randomly and evenly divided into 4 groups. No operation was performed for group A, right C4-C6 ULHL was performed for group B, right C4-C6 ULHL and 50% ipsilateral C4-C5 FT was performed for group C, right C4-C6 ULHL and 100% ipsilateral C4-C5 FT was performed for group D. Animals of group A, B, C and D were sacrificed 24 weeks after operating and fresh cervical spine specimens were acquired, biomechanically tested and these data were compared to determine whether ULHL and different degrees of FT led to long-term differences in range of motion. RESULTS: (1) Changes of the total range of motion of cervical spine 24 weeks after surgery: the total range of motion of group D (60.2°±8.6°) was significantly greater than group A (40.7°±6.4°) and group B (41.2°±13.1°) under flexion-extension station, the total range of motion of group D (81.5°±15.7°) was significantly greater than that of group A (56.7°±12.2°) and group B (57.7°±12.8°) under lateral bending station, and the total range of motion of group D (38.5°±17.5°) had no obvious increase compared with group A (26.4°±9.9°) and group B (27.1°±10.9°) under axial rotation station. The total range of motion of group C had no obvious increase compared with group A and group B under flexion-extension station (44.1°±11.7°), lateral bending station (73.6°±11.4°) and axial rotation station (31.3°±11.5°). (2) Changes of the intersegmental motion 24 weeks after surgery: the intersegmental motion of group D (20.3°±4.6°) at C4-C5 was significantly greater than that of group A (11.7°±3.4°) and group B (11.9°±2.1°) under flexion-extension station, the intersegmental motion of group D (26.8°±3.5°) at C4-C5 was significantly greater than that of group A (15.2°±3.1°) and group B (16.2°±3.2°) under lateral bending station, the intersegmental motion of group D (15.2°±3.5°) at C4-C5 was significantly greater than that of group A (6.6°±2.3°) and group B (7.1°±1.9°) under axial rotation station. The intersegmental motion of group C (21.2°±4.1°) at C4-C5 was significantly greater than that of group A and group B under lateral bending station, the intersegmental motion of group C at C4-C5 had no obvious increase compared with group A and group B under flexion-extension station (15.7°±3.7°) and axial rotation station (10.3°±3.1°). CONCLUSION: ULHL does not affect cervical stability, ULHL and 50% ipsilateral FT does not affect the long-term cervical stability, ULHL and 100% ipsilateral FT can lead to long-term instability under lateral bending and flexion-extension station.


Assuntos
Vértebras Cervicais , Laminectomia , Animais , Fenômenos Biomecânicos , Amplitude de Movimento Articular , Rotação , Ovinos
7.
Curr Sports Med Rep ; 18(6): 210-216, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31385836

RESUMO

Musculoskeletal simulation and dynamic modeling programs have been used to gain insight into lower-limb musculoskeletal injury mechanisms. In addition to the temporospatial, kinematic, and kinetic data obtained from motion analysis systems, musculoskeletal simulation programs also can provide information on joint contact and muscle forces, musculotendinous lengths and velocities, and muscle activation levels. Musculoskeletal simulation platforms may help in the assessment of risk factors for sports-related injuries. Using musculoskeletal simulations for injury prevention programs may help lower the incidence of sports injuries, and may allow for fast recovery from injury. In this review, injury mechanisms and risk factors of some of the most common lower-limb musculoskeletal injuries, including anterior cruciate ligament, patellofemoral, and hamstring injuries were summarized from a biomechanical perspective. Also, the efficacy of musculoskeletal modeling and dynamic simulation tools in helping our understanding of these injury mechanisms was discussed.


Assuntos
Traumatismos em Atletas/etiologia , Traumatismos da Perna/etiologia , Modelos Biológicos , Sistema Musculoesquelético/lesões , Lesões do Ligamento Cruzado Anterior/etiologia , Fenômenos Biomecânicos , Músculos Isquiotibiais/lesões , Humanos , Articulação Patelofemoral/lesões
8.
Medicine (Baltimore) ; 98(34): e16898, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31441868

RESUMO

Both spiral plate and Herbert screw fixations have been clinically adopted for treating midshaft displaced clavicle fractures. However, the biomechanical properties of the 2 implant fixations have not yet been thoroughly evaluated. Here we report the results of a finite element analysis of the biomechanical properties of midshaft clavicle fractures treated with Herbert screw and spiral plate fixation. Hebert screw fixation showed stress distribution similar to intact clavicle under all loading conditions, but provided less stability than did spiral plate fixation. Postoperatively, excessive shoulder activities and weight-bearing should be avoided. Spiral plate fixation provides greater stability, but is associated with stress shielding. These results demonstrate that Herbert screw fixation is suitable for the treatment of simple displaced clavicluar fractures, but excessive shoulder activity and weight-bearing should be avoided after the operation. Therefore, spiral plate fixation may be preferred for patients requiring an early return to activity.


Assuntos
Clavícula/lesões , Fixação Interna de Fraturas/métodos , Fraturas Ósseas/cirurgia , Adulto , Fenômenos Biomecânicos , Placas Ósseas , Parafusos Ósseos , Clavícula/anatomia & histologia , Clavícula/diagnóstico por imagem , Feminino , Humanos , Imagem Tridimensional , Modelos Anatômicos , Melhoria de Qualidade , Adulto Jovem
9.
Anticancer Res ; 39(8): 4191-4197, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31366505

RESUMO

BACKGROUND/AIM: Biopsy hole for bone tumour biopsy may cause pathological fractures. This study aimed to identify the optimal shape of bone tumour biopsy hole using the rabbit femoral head compression test to avoid pathological fracture. MATERIALS AND METHODS: A compression test with no defect was performed to identify bone fracture location. Three shapes of biopsy holes (same size) were made artificially. Sixty rabbit femurs were randomly divided (n=15 each) into control (no defect), Shape 1 (round), Shape 2 (square), and Shape 3 (rectangular) groups. RESULTS: Twelve out of fifteen femurs were fractured on the femoral shaft; the femoral shaft was targeted for the compression test. Compressive maximum load and fracture energy were significantly higher for Shape 3 than for the other Shapes. CONCLUSION: A rectangular biopsy hole helps minimise reduction in bone strength. The defect width may be related to fragility of the affected bone.


Assuntos
Biópsia/efeitos adversos , Neoplasias Ósseas/fisiopatologia , Fraturas do Fêmur/fisiopatologia , Fêmur/fisiopatologia , Animais , Fenômenos Biomecânicos , Neoplasias Ósseas/complicações , Neoplasias Ósseas/diagnóstico , Modelos Animais de Doenças , Fraturas do Fêmur/diagnóstico , Humanos , Coelhos
10.
Zhongguo Gu Shang ; 32(7): 658-665, 2019 Jul 25.
Artigo em Chinês | MEDLINE | ID: mdl-31382726

RESUMO

OBJECTIVE: Using the CT three-dimensional reconstruction to measure the activity degree of atlanto-occipital joint and the atlantoaxial joint in different directions and its coupling movement in healthy volunteers, and three dimensional motion range of the maximum rotation position of the upper cervical spine of cervical spondylosis patients, and to analyze the differences, verifing the reliability of the method at the meantime. METHODS: From January 2014 to June 2015, 20 healthy adult subjects(healthy adult group), and 26 patients with cervieal spondylosis(cervical spondylosis group) were selected. In healthy adult group, there were 11 males and 9 females, aged from 22 to 26 years old with an average of (24.0±1.2) years, and in cervical spondylosis group, there were 24 males and 2 females, aged from 36 to 72 years old with an average of (52.8±8.6) years. Healthy adults underwent CT examination in neutral position, maximum right rotation, maximum right lateral bending, maximum flexion and extention, and cervical spondylosis patients underwent CT examination in neutral position, maximum right rotation. Then the software Mimics was used to reconstruct occiput (Oc), atlas(C1) and axial(C2) vertebral three-dimensional image. Three virtual non-collinear markers were positioned on prominent structures of foramen magnum, C1 and C2. The 3D spatial coordinates of these virtual anatomical markers entail the definition of an anatomical local coordinate system which represent the position and orientation of the bones. Segmental motions were calculated using Eulerian angle in three major planes, and the difference between cervical spondylosis group and healthy adult group were compared. Due to the inaccuracy in anatomical landmark idenrification, two groups were measured 3 times, and the reliability of the experimental metnod was verified by the intra-group correlation (intra-group ICC) and the inter-group correlation coefficient(inter-group ICC). RESULTS: Reliability verification results:the intra-group ICC and inter-group ICC results were all above 0.90, and the measurement method had high reliability. Three-dimensional activity of the upper cervical spine in healthy adults:the atlanto-occipital joint had(-6.8±1.5)° coupled left lateral bending and (8.9±2.0)° coupled extension in the maximum right rotation position, and the motion of atlanto-occipital joint had low activity[maximum was(5.3±2.6)°] in the remaining 3 positions; the rotation of atlanto-axial joint was(37.9±5.1)°, accounting for 52.34% of the total cervical spine activity[(72.4±5.0)°] in the maximum right rotation position, and rotational motion was still prominent in the remaining three positions. The relative translations of the upper cervical spine in all direction were small. The average axial rotation angle [(62.0±3.4)] ° of the total cervical spine in cervical spondylosis group was significantly lower than that in the healthy adult group, but the mean axial rotation angles of the atlanto-occipital and the atlantoaxial joint were not significantly different from those of the healthy adults(P>0.05). CONCLUSIONS: The three-dimensional CT reconstruction method has high reliability, which can be applied to measure the movement of spine. The upper cervical spine contributed the most to the direction of rotation, and the movement in all directions are accompanied by coupled motion in the other direction. There was no significant difference in the rotation of the upper cervical spine between cervical spondylosis patients and normal subjects.


Assuntos
Articulação Atlantoaxial , Imagem Tridimensional , Adulto , Idoso , Fenômenos Biomecânicos , Vértebras Cervicais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Amplitude de Movimento Articular , Reprodutibilidade dos Testes , Rotação , Coluna Vertebral , Tomografia Computadorizada por Raios X , Adulto Jovem
11.
Zhongguo Gu Shang ; 32(7): 677-682, 2019 Jul 25.
Artigo em Chinês | MEDLINE | ID: mdl-31382729

RESUMO

At present, artificial vertebral implants have proven to be effective in the treatment of spinal tumors, infections, fractures and other diseases. However, the fusion artificial vertebral body can cause adjacent intervertebral joint degeneration and loss of original physiological curvature and activity. The movable artificial vertebral body can, to some extent, restore the normal physiological movement and reduce biomechanical changes of the spine, reducing the occurrence of complication. The design of movable artificial vertebral body is to equip movable device when the basis of reliable stability is obtained. According to its principle it can be divided into ball socket joint or elastic deformation. However the overall design of movable artificial vertebral body needs further improvement. Traditional mechanical processing methods are difficult to process complex prostheses and the agreement rate between traditional produced prostheses and lesions was low. While the emerging 3D printing technology can achieve individualized improvement of prosthesis, its slow rate and high cost need to be improved. The materials of movable artificial vertebral body includes metal, ceramics, biomaterials, high polymer materials and so on. Titanium alloy is the main material in metal materials, which is widely used, but its modulus of elasticity is still far from that of human bone and it lacks ideal bone fusion. Ceramic materials are rich in variety but fragile and poor in wear resistance. Biomaterials include autogenous bone, allogeneic bone, etc., with limited source and complicated operation. There are many kinds of polymer and biodegradable materials which obtain excellent and ideal properties. But their properties and applications need to be further studied. The movable artificial vertebral body still needs to be promoted and developed. The clinical experimental data is still insufficient, and long-term curative effect needs to be further observed and studied. This paper reviews the development, advantages, design, processing and materials of movable artificial vertebral bodies and provides useful reference for optimization design, processing and clinical application of movable artificial vertebral bodies.


Assuntos
Coluna Vertebral , Materiais Biocompatíveis , Fenômenos Biomecânicos , Humanos , Próteses e Implantes , Neoplasias da Coluna Vertebral , Titânio
12.
Bone Joint J ; 101-B(8): 929-940, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31362561

RESUMO

AIMS: Patient-specific instrumentation of total knee arthroplasty (TKA) is a technique permitting the targeting of individual kinematic alignment, but deviation from a neutral mechanical axis may have implications on implant fixation and therefore survivorship. The primary objective of this randomized controlled study was to compare the fixation of tibial components implanted with patient-specific instrumentation targeting kinematic alignment (KA+PSI) versus components placed using computer-assisted surgery targeting neutral mechanical alignment (MA+CAS). Tibial component migration measured by radiostereometric analysis was the primary outcome measure (compared longitudinally between groups and to published acceptable thresholds). Secondary outcome measures were inducible displacement after one year and patient-reported outcome measures (PROMS) over two years. The secondary objective was to assess the relationship between alignment and both tibial component migration and inducible displacement. PATIENTS AND METHODS: A total of 47 patients due to undergo TKA were randomized to KA+PSI (n = 24) or MA+CAS (n = 23). In the KA+PSI group, there were 16 female and eight male patients with a mean age of 64 years (sd 8). In the MA+CAS group, there were 17 female and six male patients with a mean age of 63 years (sd 7). Surgery was performed using cemented, cruciate-retaining Triathlon total knees with patellar resurfacing, and patients were followed up for two years. The effect of alignment on tibial component migration and inducible displacement was analyzed irrespective of study group. RESULTS: There was no difference over two years in longitudinal migration of the tibial component between the KA+PSI and MA+CAS groups (reaching median maximum total point motion migration at two years of 0.40 mm for the KA+PSI group and 0.37 mm for the MA+CAS group, p = 0.82; p = 0.68 adjusted for age, sex, and body mass index (BMI) for all follow-ups). Both groups had mean migrations below acceptable thresholds. There was no difference in inducible displacement (p = 0.34) or PROMS (p = 0.61 for the Oxford Knee Score) between groups. There was no correlation between alignment and tibial component migration or alignment and inducible displacement. These findings support non-neutral alignment as a viable option with this component, with no evidence that it compromises fixation. CONCLUSION: Kinematic alignment using patient-specific instrumentation in TKA was associated with acceptable tibial component migration, indicating stable fixation. These results are supportive of future investigations of kinematic alignment. Cite this article: Bone Joint J 2019;101-B:929-940.


Assuntos
Artroplastia do Joelho/métodos , Prótese do Joelho , Osteoartrite do Joelho/cirurgia , Falha de Prótese/etiologia , Cirurgia Assistida por Computador , Idoso , Artroplastia do Joelho/instrumentação , Fenômenos Biomecânicos , Método Duplo-Cego , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Resultado do Tratamento
13.
BMC Ophthalmol ; 19(1): 167, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31370817

RESUMO

BACKGROUND: The aim of this study was to compare the postoperative corneal biomechanical properties between small incision lenticule extraction (SMILE) and other corneal refractive surgeries. METHODS: A systematic review and meta-analysis were conducted. Articles from January 2005, to April 2019, were identified searching PubMed, EMBASE, Web of Science, and International Clinical Trials Registry Platform. Studies that compared SMILE with other corneal refractive surgeries on adult myopia patients and evaluated corneal biomechanics were included. Multiple effect sizes in each study were combined. Random-effects model was conducted in the meta-analysis. RESULTS: Twenty-two studies were included: 5 randomized controlled trials (RCTs), 9 prospective and 6 retrospective cohort studies, and 2 cross-sectional studies. Using the combined effect of corneal hysteresis (CH) and corneal resistance factor (CRF), which were obtained from ocular response analyzer (ORA), the pooled Hedges' g of SMILE versus femtosecond laser-assisted in situ keratomileusis (FS-LASIK) was 0.41 (95% CI, 0.00 to 0.81; p = 0.049; I2 = 78%), versus LASIK was 1.31 (95% CI, 0.54 to 2.08; p < 0.001; I2 = 77%), versus femtosecond lenticule extraction (FLEX) was - 0.01 (95% CI, - 0.31 to 0.30; p = 0.972; I2 = 20%), and versus the group of photorefractive keratectomy (PRK) and laser-assisted sub-epithelial keratectomy (LASEK) was - 0.26 (95% CI, - 0.67 to 0.16; p = 0.230; I2 = 54%). The summary score of Corvis ST (CST) after SMILE was comparable to FS-LASIK/LASIK with the pooled Hedges' g = - 0.05 (95% CI, - 0.24 to 0.14; p = 0.612, I2 = 55%). CONCLUSIONS: In terms of preserving corneal biomechanical strength after surgeries, SMILE was superior to either FS-LASIK or LASIK, while comparable to FLEX or PRK/LASEK group based on the results from ORA. More studies are needed to apply CST on evaluating corneal biomechanics after refractive surgeries.


Assuntos
Córnea/fisiopatologia , Ceratectomia Subepitelial Assistida por Laser/métodos , Ceratomileuse Assistida por Excimer Laser In Situ/métodos , Miopia/cirurgia , Ceratectomia Fotorrefrativa/métodos , Refração Ocular/fisiologia , Acuidade Visual , Fenômenos Biomecânicos , Córnea/cirurgia , Humanos , Miopia/fisiopatologia , Período Pós-Operatório
14.
Am J Orthod Dentofacial Orthop ; 156(2): 203-209, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31375230

RESUMO

INTRODUCTION: The objective of this clinical prospective study was to evaluate the effect of the 2 treatment strategies, translation or controlled tipping, followed by root correction on canine retraction efficiency, specifically canine movement rate. METHODS: Twenty-one patients who needed bilateral maxillary canine retraction to close extraction space as part of their treatment plan were selected for this study. Segmental T-loops designed for controlled tipping or for translation were applied randomly to each side. Two digital maxillary dental casts (taken before and after treatment) were used to measure the tooth displacements of each patient. The coordinate system located at the center of canine crown on the pretreatment model with the 3 axes defined in the mesial-distal (M-D), buccal-lingual, and occlusal-gingival directions was used to express the 6 tooth displacement components. The movement rates on the occlusal plane and in the M-D direction were computed. Movement rates were calculated by dividing the M-D displacements or the resultant displacement on the occlusal plane with the corresponding treatment time. RESULTS: T-Loops for controlled tipping moved canines faster (33.3% on occlusal plane and 38.5% in the M-D direction) than T-loops for translation. The differences were statistically significant (P = 0.041 on the occlusal plane and 0.020 in the M-D direction). CONCLUSIONS: Moment-to-force ratio (M/F) affects the canine movement rate in a maxillary canine retraction treatment with the use of a segmented T-loop mechanism. Within the neighborhood of the ratio for translation, lower M/F moves the canine faster than higher M/F both on the occlusal plane and in the M-D direction.


Assuntos
Dente Canino , Estresse Mecânico , Técnicas de Movimentação Dentária/métodos , Adolescente , Adulto , Fenômenos Biomecânicos , Dente Canino/anatomia & histologia , Feminino , Análise de Elementos Finitos , Humanos , Masculino , Maxila , Desenho de Aparelho Ortodôntico , Estudos Prospectivos , Coroa do Dente , Adulto Jovem
15.
Am J Orthod Dentofacial Orthop ; 156(2): 210-219, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31375231

RESUMO

INTRODUCTION: More patients are choosing customized orthodontic appliances because of their excellent esthetics. It is essential that clinicians understand the biomechanics of the tooth movement tendency in customized lingual orthodontics. This study aimed to evaluate the tooth movement tendency during space closure in maxillary anterior teeth with the use of miniscrew anchorage in customized lingual orthodontics with various power arm locations. METHODS: Three-dimensional finite element models of the maxilla were created with miniscrews and power arms; the positions were varied to change the force directions. A retraction force (1.5 N) was applied from the top of the miniscrews to the selected points on the power arm, and the initial displacements of the reference nodes of the maxillary teeth were analyzed. RESULTS: After applying force in different directions, power arms located at the distal side of the canines led to larger initial lingual crown tipping and occlusal crown extrusion of the maxillary incisors compared with power arms located at the midpoint between the lateral incisors and canines, and caused a decreasing trend of the intercanine width. CONCLUSIONS: In customized lingual orthodontic treatment, power arms located at the distal side of the canines are unfavorable for anterior teeth torque control and intercanine width control. Power arms located at the midpoint between the lateral incisors and canines can get better torque control, but still cannot achieve excepted torque without extra torque control methods, no matter whether its force application point is higher than, lower than, or equal to the level of the top of the miniscrews.


Assuntos
Parafusos Ósseos , Análise de Elementos Finitos , Procedimentos de Ancoragem Ortodôntica/instrumentação , Procedimentos de Ancoragem Ortodôntica/métodos , Fechamento de Espaço Ortodôntico , Técnicas de Movimentação Dentária/instrumentação , Técnicas de Movimentação Dentária/métodos , Adulto , Fenômenos Biomecânicos , Simulação por Computador , Dente Canino/patologia , Humanos , Imagem Tridimensional/métodos , Incisivo/patologia , Maxila , Modelos Biológicos , Desenho de Aparelho Ortodôntico , Aparelhos Ortodônticos , Braquetes Ortodônticos , Fechamento de Espaço Ortodôntico/instrumentação , Fechamento de Espaço Ortodôntico/métodos , Fios Ortodônticos , Planejamento de Assistência ao Paciente , Estresse Mecânico , Coroa do Dente , Torque , Resultado do Tratamento
16.
Am J Orthod Dentofacial Orthop ; 156(2): 275-282, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31375238

RESUMO

This case report describes the interdisciplinary treatment of an ectopic horizontally placed maxillary right central incisor with severe root dilaceration. The root was distally angulated and entrapped by the root of the maxillary right lateral incisor. The initial force system was aimed at an occlusal displacement and applied to the crown. During the second phase, a button was cemented onto the apex of the impacted tooth. A force from the apex to a temporary anchorage device in the palate moved the root toward the midline. Finally, a root canal and an apectomy were performed and the central incisor could be moved to its ideal position. The treatment generated a normal height of the alveolar bone and an ideal occlusion with a healthy periodontium.


Assuntos
Incisivo/cirurgia , Técnicas de Movimentação Dentária/métodos , Raiz Dentária/cirurgia , Dente Impactado/cirurgia , Dente Impactado/terapia , Fenômenos Biomecânicos , Criança , Tomografia Computadorizada de Feixe Cônico/métodos , Cavidade Pulpar , Feminino , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imagem Tridimensional , Má Oclusão de Angle Classe I/terapia , Maxila/anatomia & histologia , Maxila/diagnóstico por imagem , Maxila/cirurgia , Aparelhos Ortodônticos Fixos , Extrusão Ortodôntica/métodos , Planejamento de Assistência ao Paciente , Tratamento do Canal Radicular , Coroa do Dente , Dente Impactado/diagnóstico por imagem , Resultado do Tratamento
17.
Vasc Health Risk Manag ; 15: 229-251, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31413582

RESUMO

Purpose: Left ventricular (LV) mechanics by speckle-tracking echocardiography (STE) is prognostic in patients with cardiovascular diseases, but evidence related to community-dwelling individuals is uncertain. We therefore performed a systematic review and meta-analysis of STE as a predictor of adverse outcomes in the general population. Methods: PRISMA guidelines were followed and MEDLINE and EMBASE were searched to identify eligible studies. Primary outcome was all-cause mortality and secondary outcomes were composite cardiac and cardiovascular end-point. Random effects meta-analysis was performed, and a modified Newcastle-Ottawa Assessment Scale was used for quality assessment. Results: Eight papers matched the predefined criteria (total number of individuals studied=11,744). All publications assessed global longitudinal strain (GLS) by two-dimensional speckle-tracking echocardiography (2D-STE), one assessed circumferential, radial and transverse strains, and one assessed GLS-derived post-systolic shortening. None assessed LV rotational measures in association with outcomes. Two studies reported associations between GLS and all-cause mortality and composite cardiovascular end-point. Six papers reported an association between GLS and composite cardiac end-point, three of which were from the same study. Four papers were suitable for meta-analysis. GLS predicted all-cause mortality (pooled minimally adjusted HR per unit strain (%)=1.07 [95% CI 1.03-1.11], p=0.001), and composite cardiovascular (pooled maximally adjusted HR=1.18 [1.09-1.28], p<0.0001) and cardiac (HR=1.08 [1.02-1.14], p=0.006) end-points. GLS also predicted coronary heart disease (HR=1.15 [1.03-1.29], p=0.017) and heart failure (HR=1.07 [1.02-1.13], p=0.012). The quality of all studies was good. Conclusions: This study provides some evidence that STE may have utility as a measure of cardiac function and risk in the general population. 2D-STE-based GLS predicts total mortality, major adverse cardiac and cardiovascular end-points in community-dwelling individuals in a limited number of studies. Despite this, this systematic review also highlights important knowledge gaps in the current literature and further evidence is needed regarding the prognostic value of LV mechanics in unselected older populations.Registration number: CRD42018090302.


Assuntos
Doenças Cardiovasculares/diagnóstico por imagem , Ecocardiografia/métodos , Ventrículos do Coração/diagnóstico por imagem , Contração Miocárdica , Função Ventricular Esquerda , Adulto , Idoso , Idoso de 80 Anos ou mais , Fenômenos Biomecânicos , Doenças Cardiovasculares/mortalidade , Doenças Cardiovasculares/fisiopatologia , Feminino , Ventrículos do Coração/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Prognóstico , Medição de Risco , Fatores de Risco
18.
Medicine (Baltimore) ; 98(33): e16751, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31415372

RESUMO

BACKGROUND: Biomechanical studies have demonstrated that cortical bone trajectory (CBT) screw can provide a 30% increase in uniaxial yield pullout load than pedicle screw (PS). In addition, the insertion torque of CBT screw is 1.71 times higher than that of PS. A meta-analysis was conducted to evaluate clinical results between CBT screw technique and PS technique in lumbar fusion surgery. METHODS: An extensive search of literature was performed in PubMed, Embase, the Cochrane library. The following outcomes were extracted: visual analog scale (VAS), Oswestry disabilities index (ODI), Japanese Orthopaedic Association (JOA) score, complications, fusion rates, hospital stay, incision length, blood loss, and operation time. Data analysis was conducted with RevMan 5.3 and STATA 12.0. RESULTS: A total of 12 studies were included in the final analysis. The results indicated that CBT group with less blood loss [P < .01], less hospital stay [P < .01], and less incision length [P < .01] than PS group. There were no significant differences between 2 groups in other clinical parameters and outcomes. CONCLUSION: CBT technique provided similar clinical outcomes and fusion rates compared to PS technique in lumbar fusion surgery. However, CBT technique provided additional benefits of less blood loss, less hospital stay, and less incision length.


Assuntos
Parafusos Ósseos , Degeneração do Disco Intervertebral/cirurgia , Vértebras Lombares , Fusão Vertebral/métodos , Fenômenos Biomecânicos , Humanos , Resultado do Tratamento
19.
Bone Joint J ; 101-B(7_Supple_C): 33-39, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31256647

RESUMO

AIMS: There is insufficient evidence to recommend the use of alternative polyethylene bearings in modular, fixed-bearing total knee arthroplasty (TKA). The purpose of this study was to compare standard polyethylene (SP) and highly crosslinked polyethylene (XLP) tibial liners in posterior-stabilized TKA, with osteolysis as the primary outcome and clinical results and the rate of re-operation as the secondary outcomes. PATIENTS AND METHODS: This is a single-surgeon, prospective randomized study involving one design of modular posterior-stabilized TKA. An analysis of 122 TKAs with an SP compression moulded liner and 123 with an XLP liner was performed, with a mean follow-up of six years (2 to 11). Patients were evaluated clinically using the Knee Society score, Lower Extremity Activity Score (LEAS), and the presence of an effusion, and standard radiographs were assessed for radiolucent lines and osteolytic lesions. RESULTS: Osteolysis was present in four TKAs (3.3%) in the SP group, and no knees in the XLP group (p = 0.06). There were no significant differences between the Knee Society total score, change in total score, knee function score, change in function score, LEAS, and change in LEAS in the two groups. There was a significant difference in the presence of an effusion (10/122 with SP liners, 1/123 with XLP liners; p = 0.02). There was no significant difference in the rate of re-operation between the two groups (p = 0.36). There were no complications related to the XLP liner. CONCLUSION: At this length of follow-up, there were no advantages and no complications related to the use of this XLP tibial liner. The presence of effusion and small osteolytic lesions was more frequent with SP than XLP liners, but of unknown clinical significance. Cite this article: Bone Joint J 2019;101-B(7 Supple C):33-39.


Assuntos
Artroplastia do Joelho/métodos , Reagentes para Ligações Cruzadas , Previsões , Articulação do Joelho/cirurgia , Osteoartrite do Joelho/cirurgia , Polietileno , Tíbia/cirurgia , Idoso , Fenômenos Biomecânicos , Feminino , Seguimentos , Humanos , Articulação do Joelho/diagnóstico por imagem , Articulação do Joelho/fisiopatologia , Masculino , Osteoartrite do Joelho/diagnóstico , Osteoartrite do Joelho/fisiopatologia , Estudos Prospectivos , Desenho de Prótese , Falha de Prótese , Radiografia , Fatores de Risco , Resultado do Tratamento
20.
Bone Joint J ; 101-B(7): 779-786, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31256663

RESUMO

AIMS: The aim of this study was to estimate the 90-day risk of revision for periprosthetic femoral fracture associated with design features of cementless femoral stems, and to investigate the effect of a collar on this risk using a biomechanical in vitro model. MATERIALS AND METHODS: A total of 337 647 primary total hip arthroplasties (THAs) from the United Kingdom National Joint Registry (NJR) were included in a multivariable survival and regression analysis to identify the adjusted hazard of revision for periprosthetic fracture following primary THA using a cementless stem. The effect of a collar in cementless THA on this risk was evaluated in an in vitro model using paired fresh frozen cadaveric femora. RESULTS: The prevalence of early revision for periprosthetic fracture was 0.34% (1180/337 647) and 44.0% (520/1180) occurred within 90 days of surgery. Implant risk factors included: collarless stem, non-grit-blasted finish, and triple-tapered design. In the in vitro model, a medial calcar collar consistently improved the stability and resistance to fracture. CONCLUSION: Analysis of features of stem design in registry data is a useful method of identifying implant characteristics that affect the risk of early periprosthetic fracture around a cementless femoral stem. A collar on the calcar reduced the risk of an early periprosthetic fracture and this was confirmed by biomechanical testing. This approach may be useful in the analysis of other uncommon modes of failure after THA. Cite this article: Bone Joint J 2019;101-B:779-786.


Assuntos
Artroplastia de Quadril/instrumentação , Fraturas do Quadril/prevenção & controle , Prótese de Quadril/efeitos adversos , Fraturas Periprotéticas/prevenção & controle , Complicações Pós-Operatórias/prevenção & controle , Desenho de Prótese/efeitos adversos , Reoperação/estatística & dados numéricos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Artroplastia de Quadril/métodos , Fenômenos Biomecânicos , Criança , Feminino , Seguimentos , Fraturas do Quadril/etiologia , Fraturas do Quadril/cirurgia , Humanos , Técnicas In Vitro , Masculino , Pessoa de Meia-Idade , Fraturas Periprotéticas/etiologia , Fraturas Periprotéticas/cirurgia , Complicações Pós-Operatórias/etiologia , Complicações Pós-Operatórias/cirurgia , Sistema de Registros , Fatores de Risco , Resultado do Tratamento , Adulto Jovem
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