Proximal Plate Research Articles

Stress analysis of mandibular Kennedy class I partial overdenture submitted to different implant length and clasp designs - An in vitro study.

To analyze the distribution of stresses for mandibular Kennedy class I removable partial overdentures submitted to different implant lengths and clasp designs. Twenty-seven heat-cured acrylic resin casts with a uniform soft acrylic layer were constructed from models representing the mandibular Kennedy class I removable partial denture with the first premolars terminal abutment on both sides. The casts were grouped into a control group, group I, and group II with three casts of each for designing a different clasp on the last abutment with Rest, Proximal plate, Aker circumferential (RPA), Rest, Proximal plate, I-bar (RPI), and wrought wire (WW). All casts were submitted to vertical load for stress analysis after preparing channels at the buccal/distal surface of abutments, the crest of the ridge, and the buccal/lingual of the implant for placement of uniaxial strain gauges that can convert the electro-signals to micro-strain by using the software. Kolmogorov-Smirnov normality test, independent t-test, and one-way anlysis of Variance (ANOVA) test followed by Tukey`s Post Hoc for multiple comparisons test were used for statistical analysis. The control group results revealed more significant stresses on the ridge with RPA and RPI clasps but on the abutment with WW clasp as P < 0.05. In group I, the ridge was significantly stressed more than the implant followed by the abutment when the RPA clasp was used while there was insignificance on the implant with RPA and RPI as p > 0.05. In group II, the stresses were more on the abutment with RPA, RPI, and WW clasps followed by lower on the implant and lowest on the ridge. Proper implant and clasp type selection are critical for stress distribution on the ridge, abutment, and implant when using removable partial overdenture. The stresses on longer implants are tolerated and more widely distributed than shorter ones.

Treatment of Periprosthetic Hip Fractures Vancouver B1 and C: The Significance of Bicortical Fixation. A Bicentric Study Comparing Two Osteosynthesis Systems.

INTRODUCTION The incidence of periprosthetic fractures (PFFs) is estimated to range from 0.1% to 4.1%1, due to the increasing prevalence of joint arthroplasties, coupled with an aging population. Numerous risk factors, including advanced age (>80 years), female gender, implant type, prior diagnoses of osteonecrosis and rheumatoid arthritis, revision surgery, aseptic stem mobilization, and the use of non-cemented stems, have been identified. Survivors of periprosthetic fractures often experience functional deterioration, facing a fourfold higher risk of hospitalization for postoperative complications compared to patients undergoing primary implantation, especially in the first postoperative year. MATERIALS AND METHODS Between 2018 and 2022, at the Maggiore Hospitals in Bologna and the San Matteo Policlinic in Pavia, we performed osteosynthesis on 84 patients with periprosthetic fractures of Vancouver type B1 or C. In 38 patients, we employed angular stable plates with the Zimmer Biomet NCB-PP® system. In 46 patients, we utilized INTRAUMA plates: DF distal femur and PFF proximal. Relevant postoperative follow-up outcomes considered included reintervention, infectious complications, radiographic healing, and functional recovery, with reference to changes in the Glasgow Outcome Scale (GOS) and the Harris Hip Score (HHS). All patients underwent clinical and radiographic evaluations during the follow-up period, averaging 28 months (range: 12-48 months), with a minimum follow-up duration of 12 months. RESULTS At the 4-month postoperative assessment, 71% of patients maintained their preoperative functional level, 19% experienced a 1-point GOS scale drop, and 10% died (GOS 5). The average HHS at 4 months was 80.2 points (range: 65-90). At the 6-month follow-up, 98.2% of patients achieved complete healing on radiographic examination. Only 1 patient (1.2%) developed a pseudoarthrosis site with synthesis device rupture. Only 1 patient (1.2%) required additional surgical treatment 2 years later due to the development of un aseptic perisynthetic fluid collection, while the remaining 5 patients (6%) who developed complications benefited from conservative treatment: 4 patients (3.6%) with infectious complications were treated with intravenous antibiotics. In the 2 patients (2.3%) with mobilization or rupture of synthesis devices, clinical and radiographic monitoring was opted for. 8 patients (10.7%) died: one 48 hours after the surgery, and the other 7 more than one month after the surgery. CONCLUSION Our clinical findings align with to existing scientific literature on periprosthetic fractures (B1 and C according to Vancouver classification). Moreover, good stability has been guaranteed at the radiological follow up by Zimmer Biomet NCB-PP® and INTRAUMA DF distal femur and PFF proximal plates. The locking construct allows for improved stability especially in osteoporotic bone.

Fluid–structure–surface interaction of a flexibly mounted pitching and plunging flat plate in proximity to the free surface

This experimental study investigates the fluid–structure–surface interactions of a flexibly mounted rigid plate in axial flow, focusing on flow-induced vibration (FIV) response and vortex dynamics of the system within a reduced velocity range of $U^*=0.29\unicode{x2013}8.73$ , corresponding to a Reynolds number range of $Re=518\unicode{x2013}15\,331$ . The plate, with one and two degrees of freedom (DoFs) for pitching and plunging oscillations, is examined at various submerged heights near the free surface. Results show that the plate exhibits divergence instability at low reduced velocities in both 1DoF and 2DoF systems. As the flow velocity surpasses a critical reduced velocity, periodic limit-cycle oscillations (LCOs) occur, increasing in amplitude until a second critical reduced velocity is reached. Beyond this point, LCOs are suppressed, and the plate experiences an increased static divergence angle with further flow velocity increase. The proximity to the free surface significantly influences the FIV response, with decreasing submerged heights leading to reduced LCO amplitudes and a shift of instabilities to higher reduced velocities. Vortex dynamics are analysed using time-resolved volumetric particle tracking velocimetry and hydrogen bubble flow visualisation. The analysis reveals disruptions in the symmetric flow field near the free surface, causing elongation and fragmentation of vortices in the wake of the plate, as well as vortex coupling. Proper orthogonal decomposition (POD) identifies dominant coherent structures, including leading-edge and trailing-edge vortices, captured in the first and second paired modes. On the other hand, higher POD modes capture the interaction of vortices in the wake and near the free surface.

The importance of the thickness of femoral lateral wall for treating intertrochanteric fractures: a finite elements analysis

To explore how the thickness of the femoral lateral wall influences the effectiveness of internal fixation systems used to treat intertrochanteric fractures. CT images of the pelvis and femur of a male adult were used to construct an intertrochanteric fracture model (AO/OTA 31-A2) with various thicknesses of the femoral lateral wall (FLW). Four finite element (FE) models were created with the lateral femoral walls being 10 mm, 20 mm, 30 mm, and 40 mm thick. The fracture models were fixed with a dynamic hip screw (DHS), a proximal femoral nail anti-rotation (PFNA), and a proximal femoral locking compression plate (P-FLCP). A simulated vertical load was applied to the femoral head. The stress and displacement of the implant and femur in each model were recorded for comparison. The FE analysis of the intertrochanteric fracture models showed that the PFNA system could provide better stability than the DHS and P-FLCP with the same thickness of FLW. The FLW provided buttress support to the femoral head and neck when using a DHS and PFNA, and the buttress strength was proportional to the thickness of FLW. The maximum stress in the DHS model was recorded on the DHS plate which accommodated the lag screw. For the PFNA model, the maximum stress appeared at the connection between the nail and blade. In the P-FLCP model, the maximum stresses were highly concentrated at the connection between the cephalic nails and the proximal plate. The thickness of the femoral lateral wall should be considered an important factor when selecting a suitable internal fixation system for intertrochanteric fractures. Based on the FE analysis, intramedullary fixation, such as PFNA, experiences lower stress levels and a moderate displacement in comparison to DHS and P-FCLP when used to treat intertrochanteric fractures.

Biomechanical evaluation of an anatomical bone plate assembly for thin patella fracture fixation fabricated by titanium alloy 3D printing

This study established and evaluated the feasibility of a three-dimensional (3D)- printed titanium anatomical surface with adjustable thin bone plate assembly (AATBP) for patella fracture fixation. The AATBP was 1.6 mm in thickness and divided into a proximal plate (PP) with locking screw holes and a distal plate (DP) (0.4 mm in thickness) with compressive screw holes for assembly using a ratchet mechanism to adjust the total fixation height according to the patella size. Two pairs of hooks were designed on the proximal/distal edges to allow passage through the tendon to grip the fractured fragments. 3D printing combined with Computer Numerical Control (CNC) drilling was performed to manufacture the AATBP. Four-point bending and surface roughness tests were performed to evaluate the AATBP mechanical behavior. A cyclic (300 times) load test with 15-kg weights was adopted to compare the biomechanical stability between the AATBP and conventional tension band wiring (TBW) fixations. A parallel finite element (FE) analysis was achieved to understand the fracture gap and bone stress in the two different fixations on a transverse patella fracture. The result showed that the maximum AATBP manufacturing error was 3.75%. The average fracture gaps on the medial/lateral sides after cyclic loads were 2.38 &amp;plusmn; 0.57 mm/2.30 &amp;plusmn; 0.30 mm for TBW and 0.03 &amp;plusmn; 0.01 mm/0.06 &amp;plusmn; 0.03 mm for AATBP fixations. The same trend occurred in the FE simulation. This study confirmed that a complicated thin bone plate, including the anatomical surface, hooks, and ratchet with size-adjustable characteristics, can be fabricated using metal 3D printing with acceptable manufacturing error and reasonable anatomical surface/ thin bone plate assembly fitness. Biomechanical cyclic tests and FE simulation showed that the AATBP fixation is superior to the conventional TBW for patella transverse fractures.

Effect of various printing parameters on the accuracy (trueness and precision) of 3D-printed partial denture framework

ObjectivesTo measure and compare the accuracy of 3D-printed materials used for RPD production to improve workflow and eliminate errors in manufacturing. MethodsA partially edentulous maxilla (Kennedy Class III, modification 1) was prepared and designed with proximal plates, rest seats and clasps in one first premolar, one canine and two second molars. A total of 540 3D printed RPD frameworks were 3D printed with three different types of resin (DentaCAST (Asiga, Australia), SuperCAST (Asiga, Australia) and NextDent (3D Systems, Netherlands)). To evaluate the trueness of the printing materials, they were printed with three types of layer thickness: 50 μm, 75 μm and 100 μm, using two types of build angles: 0° and 45° and three types of plate locations: side, middle and corner. After production, all specimens were scanned and superimposed with a control sample that was digitally designed. Using the initial alignment and best-fit alignment method, the root mean square error (RMSE) was calculated. To capture region specific discrepancy, 10 points of XYZ internal discrepancy within RPDs were measured and Euclidean error was calculated. Data was statistically analysed using Shapiro-Wilk and Kruskal-Wallis tests, one-way ANOVA and T-test (SPSS Version 29) and MATLAB (R2022b). ResultsOptimal results were found using 45°, middle of the build plate and layer thicknesses of 100 μm (115 ± 19 μm, DentaCAST), 75 μm (143 ± 14 μm, NextDent), 50 μm (98 ± 35 μm, SuperCAST), which were clinically acceptable. Results were statistically significant when comparing layer thickness in each testing group (p < 0.001). Layer thickness was a primary parameter in the determination of print accuracy among all materials (p < 0.001). Higher discrepancies and failures were observed in 0° prints. No statistically significant difference was found in material usage between build angles or layer thickness (p > 0.005). ConclusionsAll three 3D printing materials exhibited clinically acceptable RMSE results with a build angle of 45° with a printing layer thickness of 50 μm for SuperCAST, 75 μm NextDent and 100 μm for DentaCAST. The highest discrepancies were mostly found in posterior clasps, while the lowest discrepancy was found in palatal straps. Despite unoptimized spacing of prints, frameworks configured to print in the middle of the build plate result in the least printing failures.

Defocused calibration for large field-of-view binocular cameras

In tunnel boring machine construction sites, on-site calibration of large field-of-view binocular cameras is still a challenging task due to factors such as the narrow spaces of the machines' mechanical structures, high pressure, or falling rocks. Therefore, a calibration method using a small plate in proximity to the camera (a defocused position safe for workers) is proposed in this paper to deal with the above challenges. First, a defocus-insensitive feature point encoding pattern is developed. Then feature points are extracted through a phase recovery network based on the Swin Transformer, and finally camera parameters are optimized based on virtual symmetric transfer errors. The relevant simulation and experimental data show that the relative error between the proposed method and the phase-shift method in feature extraction is 0.15 pixels, while the relative error between the proposed method and a high-precision laser tracker in three-dimensional measurement is 1.3%. The results demonstrate the feasibility of the method in a large field-of-view binocular camera for tunnel boring machine construction sites. Increasing the diversity of data sets and lightweight models will be the focus of future research.

Does the anteromedial plate position affect proximal screw length and worsen the clinical outcomes in medial opening wedge high tibial osteotomy?

BackgroundDuring medial opening wedge high tibial osteotomy (MOWHTO), sometimes the plate tends to be positioned anteromedially. The plate position can affect the length of the proximal screw, which significantly affects stability after osteotomy. Therefore, research on the correlation among plate position, screw length, and clinical outcomes is needed.MethodsThis retrospective review examines 196 knees in 175 patients who underwent MOWHTO from May 2012 to December 2018, for symptomatic medial compartment osteoarthritis with a varus alignment of > 5°. We evaluated the anteroposterior plate position, length of proximal screw, and postoperative computed tomography (CT). We reviewed patients’ clinical outcome scores, presence of lateral hinge fracture, neurovascular complications, and infection. The correlation among proximal plate position, proximal screw length, and clinical outcomes was evaluated using Pearson’s correlation analysis. A subgroup analysis by screw angle (> 48 ° or < 48 °) was also performed using chi-square test and Student t-test.ResultsThe mean proximal plate position was 16.28% (range, 5.17–44.74) of the proximal tibia’s anterior-to-posterior distance ratio, and the proximal screw length averaged 63.8 mm (range, 44–80 mm). Proximal posteromedial plate position and proximal screw length were significantly correlated (r2 = 0.667, P < .001), as were screw angle and length (r2 = 0.746, P < .001). Medial plating (< 48°) can use a longer proximal screw; nevertheless, no significant difference occurred in clinical outcomes between the two groups. Also, no differences occurred in complication rate, including hinge fracture.ConclusionWith more medially positioned plating during MOWHTO, we can use longer proximal screws. However, there was no significant difference in clinical outcomes and the incidence of lateral hinge fractures regardless of plate position and screw length.

Comparative Biomechanical Analysis of Ankle Arthrodesis Techniques: Experimental Study

Background. Despite the existing significant number of various techniques for ankle arthrodesis, a number of authors point to certain technical difficulties of these operations, the loss of the talus and tibia position during ankylosing, nonunion. The problem of the ankle arthrodesis technique improving requires new solutions.&#x0D; The aim of the study was to compare the stability of various fixation systems in ankle arthrodesis by the finite element method.&#x0D; Methods. The finite element method was used to evaluate the biomechanical characteristics of three variants of ankle arthrodesis systems: three cancellous screws, the originally designed plate combined with two cancellous screws, when the screw in the proximal plates hole is cortical, and the same plate combined with two cancellous screws, when the screw in the proximal plates hole with angular stability. The stresses and strains under the application of various types of loads are studied.&#x0D; Results. In the anterior plate ankle fixation model combined with two cancellous screws and a proximal cortical screw, the implants and the talus experienced the least stresses compared to the other two models. Thus, the maximum equivalent stress in implants in the second variant was 68-124 MPa, in the first variant 92-147 MPa, in the third variant 130-331 MPa. The equivalent stress in the talus in the second version of fixation ranged from 20 to 46 MPa, in the first and third versions 28-58 MPa and 47-65 MPa, respectively. The indicators of maximum contact pressure at the border of the tibia and talus turned out to be the highest in the first variant compared to the other two models (34 MPa, 31 MPa and 31 MPa, respectively).&#x0D; Conclusions. Among the studied ankle fixation systems for arthrodesis, an anterior plate combined with two cancellous screws and a proximal cortical screw is the most preferable in terms of biomechanics.

Distal 1/3 humerus shaft fracture - a lateral paratricipital approach with proximal split window

Patient is a 25yo F following a fall from a height. Closed distal 1/3 diaphyseal fracture with no neurological symptoms. Patient sought a rapid recovery without use of an orthosis so consented and proceeded with open reduction and locking plate fixation. Operation was performed prone with the arm resting on a small side support table, the forearm flexed 90deg towards the floor. Midline posterior approach to the humerus, elevation of a lateral paratricipital window from the lateral intermuscular septum - utilising the ascending course of the posterior antebrachial cutaneous nerve as a guide to find the perforation of the radial nerve through the septum. The fracture was reducible entirely through the lateral window distal to the radial nerve. A small medial paratricipital window anterior to the ulnar nerve was opened for lag screwing before positioning the plate. To facilitate proximal plate fixation without having to mobilise the lateral belly of triceps (and with it the radial nerve) we opened an additional proximal working window between long and lateral heads of triceps. Proximal to the aponeurosis it is a simple matter to identify and mobilise the descending course of the radial nerve bundle, protect it, and proceed with proximal instrumentation and plate fixation.

Experimental investigation on flow-induced vibration control of flexible risers fitted with new configuration of splitter plates

Experimental investigations within the Reynolds number range of 2600–9100 were performed to examine the effectiveness of serrated splitter plates in controlling the flow-induced vibration (FIV) of flexible risers. Conventional splitter plates were arranged for contrast to highlight the unparalleled features of the new splitter plates. Bending strains of FIV responses were measured and converted into critical parameters of displacement, dominant frequency, oscillation orbit, suppression efficiency, and fatigue damage for analysis. Test results illustrate that for flexible risers with conventional or serrated splitter plates, a galloping phenomenon occurs at a low reduced velocity, and standing wave characteristics invariably dominate their FIV responses. As the reduced velocity varies increasingly, the conventional splitter plate triggers a continuous monotonous increase in the FIV amplitudes of controlled risers. However, owing to the phase difference in the interaction of the shear layers between proximal plates and distal plates, the FIV amplitudes of the risers fitted with serrated splitter plates start to stay constant virtually and then distinctly decline with appearing chaotic oscillation trajectories. Moreover, the control performance of serrated splitter plates with uniformly distributed serrations in alleviating FIV amplitudes is optimal at high reduced velocities; whereas excessively dense or sparse serrations can reduce FIV inhibition.

Dorsal minimally invasive plate osteosynthesis of the humerus: Feasibility and risk of nervous injury of a modified technique in an anatomical study

BackgroundThe aim of the study was to design a convenient technique for dorsal minimally invasive plate osteosynthesis (MIPO) of extra-articular fractures of both distal thirds of the humeral shaft as well as to characterise the course and proximity of the radial nerve (RN) and the axillary nerve (AN). MethodsThe collective consisted of 20 upper extremities of human adult body donors. A 3.5 mm Locking Compression Plate (LCP), an extra-articular distal humerus plate was inserted through a MIPO approach including two incisions. The primary incision was performed 5 cm in lenght on the dorsal side of the lateral epicondyle. An additional 5 cm incision was conducted distal to the humeral deltoid muscle insertion and the RN was depicted. The longest suitable plate was advanced under nerve protection starting distally and fixed by locking screws. A third incision with a length of 5 cm was made beginning at the distal border of the deltoid muscle, and a muscle split was performed to dissect the AN. The respective plate holes, where the AN and RN were located and the distances between the nerves were examined. ResultsThe RN was mostly (30%) localised on holes 6 and 7 (starting distally). The AN laid directly on the plate in 65% and on the most proximal plate hole in 12 cases, but was never situated underneath the plate. The distance between the AN and RN was at mean 93.5 mm. ConclusionsMIPO via a dorsal method proves to be a noteworthy technique and valuable option as indicated by our results. This 5–5-(5) concept may be performed as a two-incision or three-incision technique for extra-articular fractures of both distal thirds of the humerus.

Optimization of Locking Plate Screw Angle Used to Treat Two-Part Proximal Humerus Fractures to Maintain Fracture Stability

Proximal humerus fractures increase with the aging of the population. Due to the high failure rates of surgical treatments such as open reduction and internal fixation (ORIF), biomechanical studies seek to optimize the treatments and intervening factors to improve the quality of life of people undergoing these treatments. The aim of the present study was to determine the optimal insertion angle configuration of screws used in a two-part proximal humerus fracture-locking plate osteosynthesis treatment based on finite element analysis (FEA). A series of 3D models of PHILOS locking plates with different screw insertion angle configurations were designed using a matrix system for screw angulation. The locking plate models were evaluated in a two-part proximal humerus fracture with surgical neck fracture under bending and compressive loading conditions using FEA and statistically analyzed using a design of experiments (DOE). The optimal screw insertion angle setting showed an improvement in relation to the interfragmentary strain value of the fracture. Moreover, calcar screws were the most significant feature in fracture stability throughout the tests, followed by the divergence of the most proximal screws and the proximal–distal alignment of the locking plate.

Обґрунтування можливості використання одноплощинного шарнірного апарата зовнішньої фіксації для лікування контрактур пальців кисті

При стійких довготривалих контрактурах після травм, включаючи артрогенні, доцільне використання апаратів зовнішньої фіксації. Мета роботи: надати біомеханічне обґрунтування для використання одноплощинного шарнірного апарата зовнішньої фіксації для лікування контрактур у міжфалангових суглобах пальців кисті. Матеріали та методи. Шляхом математичного моделювання вивчалася біомеханічна робота пристрою для лікування контрактур суглобів пальців кисті однобічної одноплощинної конструкції. Результати й обговорення. У математичній моделі біомеханічну роботу даного апарата зовнішньої фіксації можна поділити на дві частини: активну механічну роботу накладної системи та пасивну роботу кістково-суглобного вузла. Суглоб у розрахунках може бути поданий у вигляді пружного шарніра. Сила, що необхідна для щоденного прикладання під час лікування, становить 21 Н, що відповідає 1 градусу повороту у хворому суглобі. Пристроєм необхідне активне зусилля розвивається й передається через два кісткові різьбові стрижні на середню чи дистальну фаланги. Аналітичні вирази дають змогу визначити поздовжні зусилля, що діють у дистальній, проксимальній пластині та поворотному механізмі в будь-який момент роботи апарата зовнішньої фіксації. Висновки. Проведене дослідження дає підстави вважати, що використання одноплощинного одностороннього апарата забезпечує умови для дозованого повороту в суглобі та подолання пружних характеристик різного ступеня вираженості.

Аналіз оперативного лікування осіб літнього та старечого віку з переломами проксимального відділу стегнової кістки методом накісткового остеосинтезу пластиною

Актуальність. Переломи проксимального відділу стегнової кістки (ПВСК) в осіб похилого та старечого віку продовжують залишатися актуальною проблемою клінічної медицини. Мета: оцінити віддалені результати оперативного лікування методом накісткового остеосинтезу пластиною пацієнтів похилого та старечого віку з переломами проксимального відділу стегнової кістки. Матеріали та методи. Проаналізовано 744 історії хвороби пацієнтів, які знаходилися на стаціонарному лікуванні в травматологічному відділенні Харківської міської клінічної багатопрофільної лікарні № 17 у період 2008–2016 рр. До групи дослідження ввійшли пацієнти літнього та старечого віку з низькоенергетичними переломами ПВСК. Для подальшого дослідження за віковими критеріями та типом перелому сформована група з 24 пацієнтів, середній вік яких становив 71–74 роки: 10 пацієнтів чоловічої та 14 пацієнтів жіночої статі. У всіх пацієнтів виявлена супутня патологія з переважанням захворювань серцево-судинної системи. Усім хворим виконано остеосинтез проксимальною стегновою пластиною з кутовою стабільністю. Оцінка больового синдрому, статико-динамічної активності пацієнтів, деформації та амплітуди рухів оперованої нижньої кінцівки проводилася з використанням оцінної шкали Харріса. Результати. Віддалені результати лікування переломів ПВСК методом остеосинтезу накістковою пластиною вивчалися на прикладі 24 пацієнтів, термін спостереження становив від 9 років до 1 року. Залежність від сторонньої допомоги при виписці спостерігалася у 16 пацієнтів, 15 хворих використовували ходунки. У 14 випадках пацієнти частково навантажували оперовану нижню кінцівку, 3 пацієнта пересувалися з повним навантаженням, 7 пацієнтів — без опори на оперовану нижню кінцівку. Термін користування зовнішніми опорами становив від 4 місяців дотепер. При анкетуванні 91,6 % хворих суб’єктивно відзначили погіршення якості життя після хірургічного лікування перенесеної травми. Після остеосинтезу накістковою пластиною хороший результат (12,5 %) виявлено лише у однієї пацієнтки, задовільні результати у анкетованих пацієнтів не виявлено, незадовільні результати (87,5 %) відзначені у 7 анкетованих пацієнтів. Слід сказати, що хороший результат (88 балів за шкалою Харріса) відзначено у однієї пацієнтки з 2-м типом перелому, вік якої на момент операції становив 66 років. Причинами незадовільних результатів стало вторинне зміщення кісткових уламків (25 %), присутність помірного або слабкого болю (87,5 %). Висновки. Хірургічне лікування переломів проксимального відділу стегнової кістки у осіб похилого та старечого віку супроводжується високою летальністю (66,6 %). Віддалені результати після остеосинтезу переломів цієї ділянки у 87,5 % були поганими, причинами чого були вторинне зміщення кісткових уламків (25 %), присутність помірного або слабкого болю (87,5 %). Лікування хворих літнього та старечого віку накістковим остеосинтезом із переломами проксимального відділу стегнової кістки часто не дозволяє активізувати хворих у ранні терміни, що згодом призводить до загострення хронічних супутніх захворювань. Застосування накісткового остеосинтезу при лікуванні переломів проксимального відділу стегна в осіб похилого та старечого віку є малоефективним методом, який би дозволив досягти хороших і задовільних результатів. Потрібна розробка методів хірургічного лікування пацієнтів похилого та старечого віку з переломами проксимального відділу стегнової кістки, що дозволяють здійснити ранню активізацію хворого з повним навантаженням на оперовану нижню кінцівку.

Boosting quantum yields in two-dimensional semiconductors via proximal metal plates

Monolayer transition metal dichalcogenides (1L-TMDs) have tremendous potential as atomically thin, direct bandgap semiconductors that can be used as convenient building blocks for quantum photonic devices. However, the short exciton lifetime due to the defect traps and the strong exciton-exciton interaction in TMDs has significantly limited the efficiency of exciton emission from this class of materials. Here, we show that exciton-exciton interaction in 1L-WS2 can be effectively screened using an ultra-flat Au film substrate separated by multilayers of hexagonal boron nitride. Under this geometry, induced dipolar exciton-exciton interaction becomes quadrupole-quadrupole interaction because of effective image dipoles formed within the metal. The suppressed exciton-exciton interaction leads to a significantly improved quantum yield by an order of magnitude, which is also accompanied by a reduction in the exciton-exciton annihilation (EEA) rate, as confirmed by time-resolved optical measurements. A theoretical model accounting for the screening of the dipole-dipole interaction is in a good agreement with the dependence of EEA on exciton densities. Our results suggest that fundamental EEA processes in the TMD can be engineered through proximal metallic screening, which represents a practical approach towards high-efficiency 2D light emitters.

Pure titanium denture large-span frameworks additively manufactured with selective laser melting

Objective: To investigate the accuracy of pure titanium and cobalt-chromium alloy frameworks fabricated using the additive manufacturing (AM) of selective laser melting technology (SLM) for the mandibular implant-supported fixed prostheses and the maxillary removable partial denture (RPD), and to provide a reference for clinical application of SLM pure titanium frameworks. Methods: One edentulous mandibular model with implants and screw fixed abutments at bilateral canines and the first molars was selected and used as the mandibular full arch implant-supported model. At the same time, a Kennedy class Ⅰ maxillary dentition defect model was selected. The digital models were obtained by scanning the dental models, and the metal frameworks of the mandibular full arch implant-supported denture and the maxillary RPD (design model) were designed using the 3 Shape software. Meanwhile, 12 mandibular frameworks in the cobalt-chromium alloy and the pure titanium (6 in each group were treated with heat treatment, while the other 6 were not treated), and 7 maxillary frameworks in the cobalt-chromium alloy and the pure titanium were respectively made by SLM with the improved dual-laser metal printer. The axial direction of the printing powder accumulation was taken as the Z-axis. During the design process, the software (3Shape Dental System 2018) automatically generated the X-axis and Y-axis, X axis was the sagittal axis of the dental model and Y axis was the coronal axis of the dental model. The deviation of the interface center of the abutment of the digital model of the mandibular frameworks from the design model in the X, Y and Z axes was analyzed. As for the trueness of the mandibular framework, the larger the deviation data was, the worse the trueness was. The deviation of the whole maxillary framework and 7 measuring points (palatal plate center point and bilateral occlusal rests, I bars, proximal plates) were analyzed. The fitness of the whole maxillary framework to the design model was expressed by root mean square (RMS) of the deviation data, and the fitness of measuring points was expressed by the mean±standard deviation of the data. The trueness differences of each group before and after heat treatment of the mandibular framework and the fitness of the maxillary framework were compared. Results: The cobalt-chromium alloy frameworks showed lower trueness on the X, Y, Z-axes [(96.3±12.1), (86.3±11.4), (61.2±13.2) μm] than did the pure Ti frameworks [(82.3±11.2), (72.2±10.2), (51.2±11.6) μm] by SLM, and the heat treatment could reduce the discrepancy between the SLM frameworks and STL models, for pure titanium frameworks [(62.4±11.3), (55.2±13.2), (41.3±10.8) μm] and for cobalt-chromium alloy [(84.5±10.5), (72.3±11.2), (54.2±11.6) μm]. For the thin RPD major frameworks, pure titanium had better fitness [(121.3±17.0) μm] than cobalt-chromium alloy [(174.0±18.3) μm] by SLM, and the difference was statistically significant (P<0.05). Conclusions: Pure titanium frameworks fabricated by SLM additive manufacturing technology exhibited better fitness and trueness than did the Co-Cr frameworks after heat treatment respectively, and this satisfied the requirements of implant-supported fixed prostheses and RPD major metal frameworks.

Anterior positioning screw in proximal femoral plating restricts posterior tilt of retroverted femoral neck fractures: a retrospective cohort study

BackgroundPreoperative posterior tilt is a risk factor for fixation failure in femoral neck fractures. This study aimed to evaluate the configuration of anterior positioning screw in proximal femoral plating in the treatment of retroverted femoral neck fractures in terms of resisting posterior tilt.MethodsWe retrospectively analyzed patients with retroverted femoral neck fractures who were fixed by proximal femoral plating from January 2014 to August 2019. All patients were divided into two groups according to screw configuration: anterior long-threaded screw (ALTS, n = 36) and normally short-threaded screws (NTS, n = 46). Baseline characteristics were reviewed and radiological and clinical outcomes were analyzed. Logistic regression analysis was used to identify risk factors for developing posterior tilt.ResultsAge, gender, Garden classification, posterior comminution, and reduction quality showed no significant difference between the groups. Increased posterior tilt was lower in the ALTS group (3.2°, 2.1–4.3°) than that in the NTS group (5.3°, 4.2–8.3°) (p < 0.001), and the percentage of people with > 5° of posterior tilt was also lower in the ALTS group (5, 13.9% vs. 24, 52.2%; p < 0.001). Femoral neck shortening (FNS) was lower in the ALTS group (3.1 (2.1–4.7) mm vs. 4.3 (3.1–6.3) mm, p = 0.003), though not statistically significant when using 5 mm as the cut-off value. Harris Hip Score in the ALTS group was higher than that in the NTS group (87.0, 84.0–90.0 vs. 82.0, 76.0–84.5; p < 0.001). Postoperative complications including delayed union, nonunion, and avascular necrosis were comparable between the groups. Multivariable analysis identified posterior comminution (OR 15.9, 95% CI 3.6–70.3, p < 0.001), suboptimal reduction quality (OR 12.0, 95% CI 2.6–56.1, p = 0.002), and NTS configuration (reference: ALTS configuration) (OR 21.9, 95% CI 4.1–116.4, p < 0.001) as risk factors for developing posterior tilt.ConclusionsConfiguration of anterior positioning screw in proximal femoral plating provides better resistance against posterior tilt in the fixation of retroverted femoral neck fractures. Also, posterior comminution, suboptimal reduction, and NTS configuration (reference: ALTS) are risk factors for developing posterior tilt.Trial registrationThe trial registration number was ChiCTR2000039482.

Reabilitação implantossuportada de molar superior com implante cônico interno de diâmetro extra-largo – relato de caso

Tooth loss can occur due to several factors including dental caries. Immediate replacement of posterior teeth with dental implants facilitates to plan and to obtain consistent results with good prognosis. Factors such as minimally traumatic extraction, primary implant stability, maintenance of proximal bone ridges, buccal and lingual bone plates, in addition to a temporary or customizable component for tissue stabilization are important parameters to make the case predictable. The immediate technique for implants placement in the posterior regions has been described in the literature since the 1990s, presenting a high success rate and predictability of patients rehabilitation with shorter waiting times and maintenance of soft and bone tissue architecture. This study reports a clinical case of extraction of an upper molar tooth (26) with dental caries and placement of an extra-wide diameter implant, followed by filling of the surgical alveolar socket with bioactive calcium phosphate ceramic and placement of a customizable healing abutment. Clinical and radiographic control was performed after 8 months with success, with maintenance of soft tissue and marginal bone.

Internal Radioulnar Fixation for Treatment of Nonunion of Proximal Radius and Ulna Fractures in a Toy Breed Dog

AbstractIn this case report, we describe an alternative surgical procedure to treat proximal radius and ulnar nonunion in a toy breed dog. A 14-month-old, Maltese cross-breed dog was referred after previous treatment with external and internal fixation had failed, resulting in a nonunion of a fracture of the proximal radius and ulna with the proximal radius fragment too small and friable to be used for fixation. A craniomedial approach was made to debride the radius nonunion site and a second approach to the lateral aspect of the ulna was made. The fracture was realigned and a titanium locking plate was applied in bridging fashion, fixed to the proximal ulnar fragment with three locking screws in the most proximal plate holes, a fourth screw was inserted in the mid-shaft of the distal ulnar fragment and three locking screws were inserted in the distal most holes of the plate through the distal ulna to engage the distal radial fragment. A recombinant bone morphogenetic protein 2 graft was inserted into the radius and ulna fracture sites. The dog had a successful clinical and radiographic outcome with bridging of the defect 4 weeks postoperatively and complete callus formation 8 weeks postoperatively. Implants have undergone dynamization and then removal. Use of a locking plate as an internal fixator achieving fixation of the proximal ulna and distal radius can be considered an option for the treatment of proximal radioulnar nonunions with a small proximal radial fragment.