Degree Of Inclination Research Articles

Estudio experimental de las consecuencias de la sección del retináculo flexor sobre la estabilidad del escafoides

Objective To analyze the consequences of flexor retinaculum (FR) section on the kinetic behavior of the scaphoid, triquetrum and capitate bones under axial load. Material and method A 6 degree-of-freedom electromagnetic motion tracking device with sensors attached to the scaphoid, triquetrumcapitate and radius was used to monitor spatial changes in carpal bone alignment as a result of isometrically loading the main motor writs muscles. Six wrists from fresh cadavers were used, in which the principal motor tendons were subjected to loads proportional to physiological cross sectional area of each muscle. The experiment was carried out with the wrist in the neutral position, before and after the FR section. Results After FR section, the scaphoid showed less flexion ( P = .05) and a higher degree of radial inclination ( P = .03) compared to the same experiment with the FR intact. The kinetic behavior of the triquetrum did not change significantly. Discussion According to the results of this study, the isolated section of the FR did not produce greater instability of the scaphoid. If so, the scaphoid should have a higher degree of flexion, but exactly the opposite movement happens. Conclusion Resection of the FR alters the kinetic behavior of the scaphoid under axial load, but does not produce greater instability in the carpus. Pillar syndrome may not be as a result of scaphoid instability, but due to another type of dysfunction that needs to be determined in future studies.

ENGINEERING STUDIES ON THE FACTORS AFFECTING THE PERFORMANCE OF SHELLING AND GRADING CORN MACHINE

The performance of an Italian made combined machine was tested and evaluated for shelling and grading two different Egyptian corn crop varieties. Whereas, the optimum design, and operating parameters were determined in order to increase the mechanical shelling and grading efficiency and machine productivity. The crop was feed at a constant rate of 25 kg and at the grains recommended moisture content range of 12-14% (d.b). The shelling unit of the machine was deduced at four different drum speed levels (from 370 up to 820 rpm, those corresponding drum linear speeds from 4.84, up to 10.74 m/s). Also, shelling unit was tested under three concave clearance levels (32, 42 and 52mm). While, the grading unit deduced at different cylindrical screen speed levels (from 55, up to 95 rpm corresponding to linear cylinder speeds from 1.38, up to 2.39 m/s). The grading unit was also tested versus different cylindrical screen inclination angle up to 9 degrees. The tested machine performances were evaluated in terms of the grading and cleaning efficiency. In addition, costs per unit weight of production and energy unit requirements were estimated and compared with the traditional shelling and grading methods of corn crop. The obtained results revealed the following important points: The optimum parameter levels for the mechanical shelling operation were drum speed of 670 rpm (8.77 m/s) and concave clearance of 42 mm. These parameters levels were recommended to match the performance of the grading unit. The promising parameters levels for operating the grading both tested crop varieties were 80rpm (2.00 m/s) for cylindrical screen speed and 3 degrees for inclination angle.As operating at the optimum parameter levels the highest values of grading efficiency (83.68 and 82.84 %), grading cleanliness (77.78 and 77.18 %), and machine capacity (0.51 and 0.47 ton/h) were achieved. for both tested corn varieties, SC10 and TC310 respectively. Also, the lowest values of specific energy consumption (25.94 and 29.29 kW.h/Mg) and cost (76.12 and 78.28 LE/ton) for both tested corn varieties, SC10 and TC310, respectively.

Experimental study of the consequences of resection of the flexor retinaculum on the stability of the scaphoids

Objective To analyze the consequences of flexor retinaculum (FR) section on the kinetic behavior of the scaphoid, triquetrum and capitate bones under axial load. Material and method A 6 degree-of-freedom electromagnetic motion tracking device with sensors attached to the scaphoid, triquetrumcapitate and radius was used to monitor spatial changes in carpal bone alignment as a result of isometrically loading the main motor writs muscles. Six wrists from fresh cadavers were used, in which the principal motor tendons were subjected to loads proportional to physiological cross sectional area of each muscle. The experiment was carried out with the wrist in the neutral position, before and after the FR section. Results After FR section, the scaphoid showed less flexion (P = .05) and a higher degree of radial inclination (P = .03) compared to the same experiment with the FR intact. The kinetic behavior of the triquetrum did not change significantly. Discussion According to the results of this study, the isolated section of the FR did not produce greater instability of the scaphoid. If so, the scaphoid should have a higher degree of flexion, but exactly the opposite movement happens. Conclusion Resection of the FR alters the kinetic behavior of the scaphoid under axial load, but does not produce greater instability in the carpus. Pillar syndrome may not be as a result of scaphoid instability, but due to another type of dysfunction that needs to be determined in future studies.

Improving the Accuracy of Acetabular Cup Implantation Using a Bulls-Eye Spirit Level

Acetabular introducers have a built-in inclination of 45 degrees to the handle shaft. With patients in the lateral position, surgeons aim to align the introducer shaft vertical to the floor to implant the acetabulum at 45 degrees. We aimed to determine if a bulls-eye spirit level attached to an introducer improved the accuracy of implantation. A small circular bulls-eye spirit level was attached to the handle of an acetabular introducer. A saw bone hemipelvis was fixed to a horizontal, flat surface. A cement substitute was placed in the acetabulum and subjects were asked to implant a polyethylene cup, aiming to obtain an angle of inclination of 45 degrees. Two attempts were made with the spirit level masked and two with it unmasked. The distance of the air bubble from the spirit level's center was recorded by a single assessor. The angle of inclination of the acetabular component was then calculated. Subjects included both orthopedic consultants and trainees. Twenty-five subjects completed the study. Accuracy of acetabular implantation when using the unmasked spirit level improved significantly in all grades of surgeon. With the spirit level masked, 12 out of 50 attempts were accurate at 45 degrees inclination; 11 out of 50 attempts were "open," with greater than 45 degrees of inclination, and 27 were "closed," with less than 45 degrees. With the spirit level visible, all subjects achieved an inclination angle of exactly 45 degrees. A simple device attached to the handle of an acetabular introducer can significantly improve the accuracy of implantation of a cemented cup into a saw bone pelvis in the lateral position.

120302 三次元有限要素法を用いた歯の移動様式の違いにおける応力分布の観察(OS03 実験力学的手法とその応用3,オーガナイズド・セッション)

The aim of this study was to examine the stress distribution in the maxilla on differences in the inclination degree of the maxillary anterior. We prepared a 3-dimensional finite element model (the normal model) with a total of 140,029 nodes and 762,375 elements, which included the suture palatine median, teeth, and periodontal ligament, according to cranial CT images taken from an adult dried skull. We made another model by inclining the maxillary anterior tooth of the normal model. And, we experimented by using these two models. We obtained the following results. When we compared the stress distribution of the normal model with that of the model with inclined upper incisor, the concentration of stress of 0.35 MPa or more was observed more widely in the normal model than in the inclined model. The results suggested that the tooth axis of the upper incisor influences the shape of the palate during orthodontic treatment.

Direct comparison of polyethylene wear in cemented and uncemented acetabular cups

BackgroundIt has been indicated that, in the long term, the rate of wear and the degree of osteolysis observed with uncemented acetabular components are greater than those associated with cemented cups, but most studies which compare the wear characteristics of cementless with cemented cups have used historical controls. We report a direct comparison of wear of a cemented and an uncemented cup with similar design, polyethylene, and sterilization method.Materials and methodsThe study cohort includes 92 patients who were operated in 1997 with primary total hip replacement and have been followed for a period of 9–10 years. All patients were operated by posterolateral approach. In patients 70 years or older we used a cemented cup, in those 60 years or younger we used an uncemented cup, and in patients between 60 and 70 years we used either a cemented or uncemented cup as decided by the surgeon. At follow-up, radiographic imaging was obtained as standard anterioposterior view of the pelvis, and mean wear was determined as described by Livermore et al.ResultsThe overall wear of the cemented acetabular components was 1.07 ± 0.78 mm, and that of the uncemented cups was 1.18 ± 0.61 mm (P = 0.529). Wear was significantly associated with male sex (P = 0.003), younger age (P = 0.003), and degree of inclination (P < 0.001), but wear was not significantly associated with cemented versus uncemented cup (P = 0.437).ConclusionOur findings in this 9–10-year follow-up study suggest that cementless cups wear no more than cemented cups of similar design.

Endurance exercise training promotes angiogenesis in the brain of chronic/progressive mouse model of Parkinson's Disease

The main goal of this study is to evaluate the effect of treadmill exercise on the angiogenesis markers in the striatum (ST) of chronic/progressive parkinsonian mice. Forty 57BL/6 albino mice were randomly divided into four groups. Sedentary control (SC, n=10), exercise control (ExC, n=10), sedentary Parkinson's (SPD, n=10), and exercised Parkinson's (ExPD, n=10). Parkinsonism was induced by the injection with 10 doses of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, (25 mg/kg) and probenecid (250 mg/kg) over 5 weeks, three days and half a part. Following the induction of parkinsonism, ExPD and ExC animal groups were trained on a modified human treadmill at a speed of 18 m/min, 0 degrees of inclination, 40 min/day, 5 days/week for 4~weeks. The remaining two groups (SPD and SC) were housed in cages for the same period. At the end of the experiment, the angiogenesis markers; Vascular Endothelial Growth Factor (VEGF) and CD34 were examined in the striatum in the four animal groups. PD resulted in a significant decrease in blood vessel density with the comparison between the sedentary control and PD model animals (p < 0.005). Four weeks of treadmill exercise training significantly increased angiogenesis in the striatum in ExPD groups (p < 0.05). Exercise also induced an increase in blood vessel density in the striatum of the control animals, but the change was not significant (P < 0.3). These data suggest that 4 weeks of treadmill exercise promoted angiogenesis in the brain of chronic Parkinsonian mice, which can partially explain the beneficial role exercise in patients with PD. Further studies are required to determine the mechanism of exercise-induced angiogenesis in PD.

Long-term outcome of distal ulna resection–stabilisation procedures in post-traumatic radio-ulnar joint disorders

Distal radius fractures represent 20% of fractures in adults. Although good results are usually obtained with treatment, functional sequelae are not uncommon, with injury of the distal radio-ulnar joint (DRUJ) being the most frequent. Various treatments have been described to address these disorders. Distal ulna resection-stabilisation (DURS) is our technique of choice when preservation of the DRUJ is impossible. Twenty patients operated between 1985 and 1996 were reviewed with minimum 6-year follow-up. Nine of them were men and 11 were women, with an average age 45 years. The initial trauma was a distal radius fracture in all cases. The main complaint was ulnar pain with no limitation of mobility in five patients, painful limitation of prono-supination in 14, and palmar subluxation of the ulna in one case. Radiographic evaluation and CT scan showed DRUJ incongruence in 14 patients with ulna head instability, and ulno-carpal abutment with degenerative changes at the DRUJ in six cases. In three patients, malunion of the distal radius was associated with degenerative DRUJ lesions. The satisfaction rate was 95% at an average follow-up of 11 years (range 6.7 to 18.6 years). Pain scores decreased progressively from 2.2 to 0.5 post-operatively. Range of motion improved in supination from 37 degrees to 80 degrees , and in pronation from 66 degrees to 84 degrees . Improvements were 15 degrees in ulnar inclination, 9 degrees in radial inclination, 16 degrees in flexion, and 23 degrees in extension. Distal ulna palpation was not painful, and no instability was observed on movement. Wrist strength was equivalent to 80.8% of the healthy contra-lateral side. Radiographic results showed no anomaly of the resected ulna, no sign of abutment on the radius and no ulnar translation of the carpus at follow-up. Only one patient, who presented algoneurodystrophic syndrome after the initial trauma, had a recurrence after DURS. DRUJ injuries are frequent in the context of wrist trauma. If not well-treated, they could lead to significant functional sequelae of the wrist. Radiographic evaluation should clarify the status of the DRUJ to choose between conservative or radical surgical treatment. If the DRUJ surfaces are preserved, conservative treatment, which consists of correcting the distal radius malunion and stabilising or shortening the ulna, is the treatment of choice. When the DRUJ surfaces are injured, DURS is our treatment of choice. This approach presents a low complication rate and more than 90% of satisfactory results, often with a pain-free wrist, functional range of motion and good strength. However, a rigorous technique, with limited ulna head resection, dorsal capsuloplasty, reconstruction of the extensor retinaculum and dorsal placement of the extensor carpi ulnaris tendon, is a prerequisite for success. Level IV retrospective therapeutic study.

Thermal Stress Induced by Inclined Impinging Heating Jet on a Flat Plate

J ETS impinging normally on a flat plate have been extensively studied in terms of flow characteristics, wall temperature, and pressure distribution [1,2]. In some cases, a jet impinges on the plate with a certain degree of inclination with respect to the plate, resulting in the oblique impinging jet. In the case of a jet removing heat from the target plate (cooling jet), it has been established that the location ofmaximumheat transfer shifts increasingly toward the uphill side of the plate, and the maximum Nusselt number decreases as the inclination angle is decreased from the normal impinging position [3,4]. On the contrary, for a heating jet, such an inclination increases the maximum temperature (or heat transfer rate), leading to a significant temperature jump at all the points along the plate [5]. The upward shift of the maximum temperature is attributed to the reduction in effective entrainment of air on both the uphill and downhill sides of the target plate. Although a multitude of studies have been conducted to characterize theflowand heat transfer characteristics of an impinging jet [1– 7], there has not yet been a study devoted to the thermal stresses induced on the target plate by an inclined impinging heating jet. Several systems, including welding, laser heating, and electric discharge machining (EDM), are similar to the impinging heating jet in terms of heat transfer to the target plate and consequently have akin temperature profiles. Yadav et al. [8] used the Galerkin finite element formulation to simulate the EDM-induced temperature and thermal stresses on a target plate. High temperature gradient zones were found to correspond to regions of large stresses that may exceed the material yield strength. Sunar et al. [9] analyzed the temperature and thermal stresses developed in a sheet metal due to welding. The thermal stresses were found to be compressive in nature and follow a trend similar to the temperature distribution due to the high gradients near the center. The present study is concerned with the thermal stresses developed on a flat plate, due to an impinging heating slot jet, and their variation with jet inclination. For fixed separation distance and Reynolds number, and selected jet inclination angles, the measured temperature data are used as input for thermal stress modeling, using the sequential coupling finite element method (FEM). For a given set of thermal boundary conditions, thermal stresses are calculated for various inclination angles and physical boundary conditions of the plate. The study is limited to the steady-state responses of temperature and thermal stresses.

Effects of Prone and Reverse Trendelenburg Positioning on Ocular Parameters

: In a pilot study of awake volunteers, intraocular pressure (IOP), choroid layer thickness, and optic nerve diameter were shown to increase in the prone position over 5 h with a nonsignificant trend of attenuation using a 4-degree increase of table inclination. These effects have previously not been isolated from anesthetic and fluid administration over a prolonged period, using an adequate sample size. : After institutional review board approval, 10 healthy volunteers underwent IOP measurement (Tono-Pen XL, Medtronic Solan, Jacksonville, FL) as well as choroidal thickness and optic nerve diameter assessment (Sonomed B-1000, Sonomed, Inc., Lake Success, NY, or the I System-ABD, Innovative Imaging, Inc., Sacramento, CA) on a Jackson table (Orthopedic Systems, Inc., Union City, CA), during 5 h horizontal prone and 5 h 4-degree reverse Trendelenburg positioning. Measurements were assessed as initial supine, initial prone, and hourly thereafter. Vital signs were recorded at each position and time point. : IOP, choroidal thickness, and optic nerve diameter were observed to increase with time in the prone position. A small degree of reverse Trendelenburg attenuated the increase in choroidal thickness but not IOP or optic nerve diameter. : Prolonged prone positioning increases IOP, choroid layer thickness, and optic nerve diameter independent of anesthetics and intravenous fluid infusion and 4 degrees of table inclination (15 cm of head to foot vertical disparity) may not attenuate these effects.

O tratamento da Classe III: revisão sistemática - Parte I. Magnitude, direção e duração das forças na protração maxilar

INTRODUÇÃO: para o tratamento da Classe III durante o crescimento, a protração maxilar é a terapia mais relatada na literatura. Durante o tratamento, é requerida especial atenção à mecânica utilizada para a correção do problema. OBJETIVO: sintetizar as informações relativas à magnitude, direção e tempo diário da aplicação das forças, por meio de uma revisão sistemática. MÉTODOS: estudos foram identificados a partir de uma pesquisa eletrônica no Medline database - Entrez PubMed (178 artigos) e Bireme (550 artigos), no período de janeiro de 1983 a dezembro de 2008. Após um criterioso processo de inclusão e exclusão, 56 estudos primários foram selecionados e submetidos a um segundo processo de seleção, restando 39 artigos. Foram calculados a média e o desvio-padrão, bem como os valores mínimos e máximos para a magnitude, a direção e a quantidade de horas de uso das forças de protração maxilar. RESULTADOS E CONCLUSÃO: as médias de magnitude, direção e duração das forças de protração maxilar foram de, respectivamente, 447,8 gramas, 27,5 graus de inclinação em relação ao Plano Oclusal, e 15,2 horas por dia.

The Effect of Varus and Valgus Osteotomies on Femoral Version

Although seldom described, varus and valgus osteotomies of the proximal femur can affect femoral version. The magnitude of the effect can be predicted with an understanding of the distinction between femoral version and femoral neck inclination. The purpose of this study was to elucidate this relationship. Version, inclination, apparent neck-shaft angle, and true neck-shaft angle were defined and measured in 72 preserved femora. Average values were 19.8+/-11.8 degrees for version versus 14.5+/-10.1 degrees for inclination (P=0.004), giving a mean difference of 27% between version and inclination, with greater discrepancy with increasing neck-shaft angle. There were high correlations between measured inclination and inclination calculated using version and apparent neck-shaft angle (r=0.96) and true neck-shaft angle (r=0.97), validating our formulaic relationship between these variables. We present and validate the concept of inclination, and its relationship with version and neck-shaft angle. This explains the mechanism for a varus osteotomy decreasing anteversion, and a valgus osteotomy increasing anteversion. With an understanding of these concepts, a surgeon can incline the femoral neck axis to achieve a desired amount of version, for any given neck-shaft angle. Without this understanding, precise control of the version and neck-shaft angle is difficult.

Rotator cuff tears in proximal humeral fractures: an MRI cohort study in 76 patients

The aim was to evaluate if concomitant injury to the rotator cuff is important for functional outcome in proximal humerus fractures, and to relate loss of function to malunion of the fractures. A total of 76 patients treated conservatively for proximal humerus fracture were included in this cohort study. Performing an MRI: examination at the time of injury and after 12 months, tears of the rotator cuffs were classified as partial- or full thickness. The fractures were classified, according to the AO classification, and the degree of tubercle displacement and humeral head inclination evaluated at 12 months. Constant score was used as outcome measure. Magnetic resonance imaging (MRI) examinations confirmed 22 rotator cuff tears (four full thicknesses) diagnosed at the time of injury, and 10 additional tears (three full thicknesses) at one year. Functional loss at one year significantly corresponded to the tears at the time of injury (P = 0.004), varus malunion of the head and displacement of tubercles (P < 0.001). Partial- as well as full thickness tears of the rotator cuff are important for functional outcome. Skeletal deterioration seems even more important.

Accuracy of Computer Navigation for Acetabular Component Placement in THA

The accuracy and precision of any computer-aided surgical device is critical to its utility. We asked the following question: how accurate and precise are the values measured by an imageless computer navigation system as compared with those measured using postoperative CT scans? Twenty-five patients (26 hips) underwent primary THA using an imageless computer navigation system for placement of the acetabular component. Inclination and anteversion were measured in the operative coordinate system as defined by Murray. Accuracy, precision, and bias were computed, and Bland-Altman analysis was used to assess levels of agreement. The accuracy (mean +/- standard deviation of the absolute difference between computer-assisted navigation and CT) was 1.8 degrees +/- 1.2 degrees for inclination and 2.0 degrees +/- 2.0 degrees for anteversion. Precision was 3.4 degrees for inclination and 5.5 degrees for anteversion. Bias was 0.52 degrees for inclination and 0.35 degrees for anteversion. Limits of agreement were 4.26 degrees for inclination and 5.58 degrees for anteversion. An imageless computer navigation system can precisely determine acetabular cup position.

Numerical investigation of the first bifurcation for natural convection of fluids enclosed in a 2D square cavity with Pr lower than 1.0

This article presents a numerical study of the effect of the Prandtl number on the first bifurcation of natural convection for fluids enclosed in a 2D square cavity subject to a horizontal temperature gradient. The natural convection equations are solved using a second-order Euler–Taylor–Galerkin (ETG) finite element method of fractional steps. Influence of the mesh resolution on the numerical investigation is analyzed first on ten sets of uniform square element meshes while the Rayleigh numbers are 10 4 and 10 5 keeping Pr = 0.71. Variations of the averaged Nusselt number and its relative error in the results provided by the benchmark computation of Davis with the grids are used to find the role of mesh resolution. As for Ra = 10 4 and 10 5, Nu AVER increases first with the increase in the number of grids used. And for each Ra, Nu AVER tends to be independent of the number of elements when it is higher than 80 × 80. Grids (101 × 101) are then used in the study to capture the first bifurcation of natural convection. The bisection method and the flow patterns are utilized to estimate the critical Rayleigh number for 11 different fluids for which Pr ⩽ 1.0. It can be deduced from the results presented that Ra Cr decreases with the increase in Pr. Variation of Ra Cr with Pr is also fitted to estimate Ra Cr for any fluids for which Pr ⩽ 1.0 directly. It is also observed that the global flow cores are inclined for each Pr and that the inclination degree increases in anticlockwise direction with Pr.

Radiographic and Clinical Outcomes After Instrumented Reduction and Transforaminal Lumbar Interbody Fusion of Mid and High-grade Isthmic Spondylolisthesis

Retrospective cohort study. The objective of this study is to document and review the surgical technique and the clinical and radiographic outcomes after instrumented reduction and transforaminal lumbar interbody fusion of mid and high-grade adult isthmic spondylolisthesis. Although high-grade slips make up a distinct minority of all patients afflicted with spondylolisthesis, approximately 2% in most series, the treatment of this small cohort of patients has been the topic of on going, and often heated debate. Recently, there has been a trend in the literature toward the combination of instrumented posterior spinal fusion (PSF) and interbody fusion with or without reduction. Although spine surgeons have used this procedure as a tool to treat patient's with spondylolisthesis of any cause, there is no report in the literature describing the results of neural element decompression, transforaminal interbody fusion (TLIF) reduction, and instrumented PSF of the listhetic vertebrae in the treatment of high and mid-grade isthmic spondylolisthesis. From 1999 to 2003, 13 patients with mid and high-grade isthmic spondylolisthesis (Meyerding grades II, III, or IV) who failed conservative treatment were treated by posterior lumbar decompression, TLIF at the disk space of the level of the slip, instrumented PSF, and reduction of the listhetic vertebrae. Standing lumbar radiographs were taken preoperatively, at the time of the initial postoperative visit and at regular intervals thereafter. Several radiographic parameters were noted including degree of anterolisthesis, slip angle, sacral inclination, and disk height. Statistical comparisons were made with 2-tailed paired t tests. The average anterolisthesis, normalized to the superior endplate diameter, was 51.0%+/-16.6% preoperatively, 13.2%+/-11.8% immediately postoperative, and 17.0%+/-12.6% at final follow-up (Table 1). Of the 10 patients with sufficient radiographic follow-up, all but one had radiographic evidence of solid bony union at the time of final radiographic examination. Follow-up averaged 21.5 months and ranged from 11 to 48 months. This study represents a unified approach to the solitary diagnosis of mid and high-grade adult isthmic spondylolisthesis, adding further information to the growing body of literature for the TLIF procedure.

Systematic evaluation of the features influencing the accuracy of third order measurements

The aims of this study were to evaluate the relationship of third order measurements on dental casts with those on lateral radiographs, and to identify those incisor features on radiographs which can best explain third order measurements on dental casts. Lateral cephalograms and corresponding dental casts were obtained from 39 untreated Caucasians (12 males, 27 females; mean age 19.5 years; standard deviation 3.7 years) with occlusal relationships considered to be 'normal'. The upper (U1) and lower (L1) incisors were assessed with reference to the occlusal plane perpendicular which was established on the lateral radiographs, including third order angles (U1TR, L1TR) which were also derived from direct dental cast measurements (U1TA, L1TA). Both single regression and multiple linear regression analysis with stepwise variable selection were performed using third order measurements on casts as the dependent variable and crown axis (U1C, L1C), root axis (U1R, L1R), tip-apex connecting line (U1E, L1E), and radiographic third order measurements as independent variables. Single regression analysis indicated an overall difference of 0.02 degrees between radiographic third order inclination and cast assessment in the maxilla (mandible: -2.83 degrees). A change of 1 degree in radiographic third order inclination would produce a change of 0.65 degrees for U1TA and 0.86 degrees for L1TA assessments. Third order measurements on dental casts can best be explained by a linear combination of U1TR and U1E (maxilla) and of L1TR and L1C (mandible) measurements. This study demonstrates the functional enmeshment between two different third order assessments and the most common incisor features on lateral radiographs. Both methods of third order evaluation show sufficient reliability and are appropriate for routine orthodontic practice.

Clinical and radiological assessment of unicompartmental knee prostheses implanted with a minimally invasive technique

Purpose To assess the radiological position and the short-term clinical outcome of a series of unicompartmental knee prostheses implanted through a small incision. Materials and methods Retrospective review of the first 44 arthroplasties of this kind performed in our Department with a minimum 1-year follow-up. The study includes an analysis of the relationship between the result obtained in terms of the American Knee Society score and the patients’ age, gender, body mass index, diagnosis, number of previous surgeries and 25 radiological variables recorded on the basis of anteroposterior, lateral and axial views. Any errors in the positioning of each of the components on the different planes were also determined. Results The results obtained are significantly poorer the higher the body mass index (r=- 0.42; p=0.01) and the higher the degree of posterior inclination of the tibial component (r=-0.34; p=0.02); this difference is statistically significant from 8° (t=-2.15; p=0.04) onwards. The greatest variability in terms of prosthetic placement is found in the degree of rotation of the tibial component on the axial plane and in the flexion-extension of the femoral component on the sagittal plane. Surgical expertise is crucial when it comes to sound prosthetic placement, with significantly fewer errors being committed by surgeons who perform the procedure habitually (t=2,06; p=0,04). Conclusions Unidcondylar knee replacement is an attractive yet technically demanding therapeutic alternative for unicompartmental pathology, which is associated to a mandatory learning curve. In addition to appropriate patient selection, correct implant placement is crucial to obtain a satisfactory end result.

Valoración clínica y radiológica de las prótesis unicompartimentales de rodilla implantadas con técnica mínimamente invasiva

Purpose To assess the radiological position and the short-term clinical outcome of a series of unicompartmental knee prostheses implanted through a small incision. Materials and methods Retrospective review of the first 44 arthroplasties of this kind performed in our Department with a minimum 1-year follow-up. The study includes an analysis of the relationship between the result obtained in terms of the American Knee Society score and the patients’ age, gender, body mass index, diagnosis, number of previous surgeries and 25 radiological variables recorded on the basis of anteroposterior, lateral and axial views. Any errors in the positioning of each of the components on the different planes were also determined. Results The results obtained are significantly poorer the higher the body mass index (r=−0.42; P=.01) and the higher the degree of posterior inclination of the tibial component (r=−0.34; P=.02); this difference is statistically significant from 8° (t=−2.15; P=.04) onwards. The greatest variability in terms of prosthetic placement is found in the degree of rotation of the tibial component on the axial plane and in the flexion-extension of the femoral component on the sagittal plane. Surgical expertise is crucial when it comes to sound prosthetic placement, with significantly fewer errors being committed by surgeons who perform the procedure habitually (t=2.06; P=.04). Conclusions Unicondylar knee replacement is an attractive yet technically demanding therapeutic alternative for unicompartmental pathology, which is associated to a mandatory learning curve. In addition to appropriate patient selection, correct implant placement is crucial to obtain a satisfactory end result.

Development of High Performance Magnesium Alloys via Microstructure and Texture Control

The mechanical properties of extruded ZA (Mg-Zn-Al) alloys with different Al contents were examined. The effects of Al on deformation behaviour were examined by tensile and compressive tests. The changes in texture due to plastic deformation were examined using the X-ray diffraction method. It was found that the basal poles of the extruded ZA alloy were parallel to the normal direction with a slight tendency to incline toward the extrusion direction. The degree of inclination increased with increasing Al content. The inclination degree of the basal poles was found to be closely related to the change in the deformation behaviour of the ZA alloy. Computer simulations were also carried out using the VPSC (visco-plastic self-consistent) theory in order to predict the contributions of various deformation modes to the plastic deformation behaviour of the ZA alloy.