Complex tibial plateau fractures can seriously affect quality of life and physical and mental health of patients.The anatomical relationship between the proximal tibial bone and soft tissue is complex,resulting in dif...Complex tibial plateau fractures can seriously affect quality of life and physical and mental health of patients.The anatomical relationship between the proximal tibial bone and soft tissue is complex,resulting in different types of tibial plateau fractures.Violent trauma can lead to displaced fracture,serious soft tissue injury,and potentially,dislocation of the knee joint.Therefore,tibial plateau fractures are extremely unstable.AIM To assess the use of locking compression plate(LCP)+T-type steel plate for postoperative weight bearing and functional recovery of complex tibial plateau fractures.METHODS Ninety-seven patients with complex tibial plateau fractures who underwent surgery at our hospital were selected for retrospective study.Forty-nine patients had been treated with LCP+T-type steel plate limited internal fixation(study group),and 48 patients with bilateral ordinary steel plate support(control group).The operation process index,postoperative rehabilitation related index,Rasmussen score of the knee joint,tibial plateau varus angle(TPA),tibial plateau retroversion angle(PA),and surgical complications of the two groups were compared.RESULTS The operation time and intraoperative bone graft volume in the study group were lower than those in the control group(P<0.05).There were no significant differences in surgical bleeding,anterior external incision length,postoperative drainage,hospital stay duration,and fracture healing time between the groups(P>0.05).There was no significant difference in the TPA and PA angle between the groups immediately and 18 mo after surgery(P>0.05).At 12 mo after surgery,the Rasmussen scale score was higher in the study group than in the control group(P<0.05).There was no significant difference in the Rasmussen scale score at 18 mo after surgery,and the radiology score at 12 and 18 mo after surgery,between the two groups(P>0.05).The postoperative complication rate in the study group(3.77%)was lower than that in the control group(15.09%;P<0.05).CONCLUSION LCP+T-type steel plate internal fixation has advantages in terms of minimizing trauma and enabling early postoperative functional exercise,promoting functional recovery and lower limb weight-bearing,and reducing postoperative complications.展开更多
Objective: To investigate the value of 3D printing techniques in the treatment of complex tibial plateau fractures. Methods: From September 2016 to September 2018, 28 patients with complex tibial plateau fractures wer...Objective: To investigate the value of 3D printing techniques in the treatment of complex tibial plateau fractures. Methods: From September 2016 to September 2018, 28 patients with complex tibial plateau fractures were treated in our hospital. According to the odevity of hospitalized order, the patients were divided into two groups. Group A used 3D reconstruction, virtually reduction, 3D printing and demonstration of individual fracture model before operation while group B only received conventional process by use X-rays or CT image. Comparison between the two groups was made in operation time, operative blood loss, radiation frequency, surgery instrument cost and knee function score. Results: The follow-up was 14.4 months on average (ranged 6 to 22 months). There was no statistical difference of the surgery instrument cost between the 2 groups (P > 0.05). The operation time of group A was significantly shorter than that of group B (P χ2 = 0.373, P = 0.54). Conclusion: 3D printing techniques can improve surgery effect in complex tibial plateau fractures.展开更多
Mechanical traction and percutaneous reduction by leverage and fixation by a bilateral groove externalfixator were performed on 23 patients with complex tibial plateau fractures involving a depressed and splitfragment...Mechanical traction and percutaneous reduction by leverage and fixation by a bilateral groove externalfixator were performed on 23 patients with complex tibial plateau fractures involving a depressed and splitfragments. The fixator is composed of two long groove frames, three to five nuts, hooked bolts and Stein-manns pins.All fractures united in good position in three months with no incision (only pinpricks), llttle operativetrauma and no significant complications but pintract infection, and the flexion-extension range of kneemovement was excllent in all patients, so that this technique is particularly advisable for complex tibialplateau fractures.展开更多
Purpose: To evaluate the clinico-radiological outcome of complex tibial plateau fractures treated with Ilizarov external fixation with or without minimal internal fixation. Methods: This retrospective review was condu...Purpose: To evaluate the clinico-radiological outcome of complex tibial plateau fractures treated with Ilizarov external fixation with or without minimal internal fixation. Methods: This retrospective review was conducted on all the cases of Schatzker types V and VI tibial plateau fractures treated by Ilizarov external fixation between July 2006 and December 2015 with the minimum follow-up duration of one year. There were 30 patients: 24 males and 6 females, mean age 43.33 years, and mean follow-up 3.6 years. Three of them were open fractures;15 cases were Schatzkertype V fractures and the other 15 type VI. According to AO/OTA classification, there were 11 type C1, 12 C2 and 7 type C3 fractures. Outcome assessment was made with American Knee Society Score (AKSS) and Rasmussen's Radiological Score (RRS) at final follow-up. Results: Out of the 30 cases, mini-open reduction was performed in 7, bone graft in 4, minimal internal fixation in 10 and knee temporary immobilisation in 11 patients. Mean duration of external fixation was 11.8 weeks. All fractures united. Pin tract infections in 7 and common peroneal neuropathy in 2 patients were self-limiting. Two patients had axial misalignment of less than 10°. At final follow-up, the mean knee range of motion was 114.7, mean AKSS 81.5 and mean RRS 16.7. On statistical analysis, Schatzker type of fractures, use of minimal internal fixation and knee-spanning did not influence the final outcome. Conclusion: Ilizarov external fixator with or without minimal internal fixation provides acceptable outcome for complex tibial plateau fractures. Care must be taken to look for minor loss of alignment, especially in Type VI Schatzker fractures after removal of the fixator. However small sample size precludes firm conclusions.展开更多
The management of a combination of fracture and multiligament knee injury(MKI) in traumatic knee injury remains controversial, and there are evolving treatment recommendations. Currently, there are no studies focusing...The management of a combination of fracture and multiligament knee injury(MKI) in traumatic knee injury remains controversial, and there are evolving treatment recommendations. Currently, there are no studies focusing on older adult patients with MKI's in combination with tibia fractures. As a result, there is no well-established treatment algorithm for older adult patients with these complex injuries. We report two cases of MKI's with concomitant fractures in patients fifty years of age or older. Both patients were treated surgically for their associated tibial plateau fractures, but were managed with conservative treatment of the multiligamentous knee injuries. We also provide a review of the literature and guidelines for older adult patients with these types of complex traumatic injuries. Early to mid term acceptable outcomes were achieved for both patients through surgical fixation of the tibial plateau fracture and conservative treatment of the ligament injuries. We propose a comprehensive treatment algorithm for management of these complex injuries.展开更多
AIM To systemically review all studies reporting return to sport following tibial plateau fracture, in order to provide information on return rates and times to sport, and to assess variations in sporting outcome for ...AIM To systemically review all studies reporting return to sport following tibial plateau fracture, in order to provide information on return rates and times to sport, and to assess variations in sporting outcome for different treatment methods.METHODS A systematic search of CINAHAL, Cochrane, EMBASE, Google Scholar, MEDLINE, PEDro, Scopus, SPORTDiscus and Web of Science was performed in January 2017 using the keywords "tibial", "plateau", "fractures", "knee", "athletes", "sports", "non-operative", "conservative", "operative", "return to sport". All studies which recorded return rates and times to sport following tibial plateau fractures were included. RESULTS Twenty-seven studies were included: 1 was a randomised controlled trial, 7 were prospective cohort studies, 16 were retrospective cohort studies, 3 were case series. One study reported on the outcome of conservative management(n = 3); 27 reported on the outcome of surgical management(n = 917). Nine studies reported on Open Reduction Internal Fixation(ORIF)(n = 193), 11 on Arthroscopic-Assisted Reduction Internal Fixation(ARIF)(n = 253) and 7 on Frame-Assisted Fixation(FRAME)(n = 262). All studies recorded "return to sport"rates. Only one study recorded a "return to sport" time. The return rate to sport for the total cohort was 70%. For the conservatively-managed fractures, the return rate was 100%. For the surgically-managed fractures, the return rate was 70%. For fractures managed with ORIF, the return rate was 60%. For fractures managed with ARIF, the return rate was 83%. For fractures managed with FRAME was 52%. The return rate for ARIF was found to be significantly greater than that for ORIF(OR 3.22, 95%CI: 2.09-4.97, P < 0.001) and for FRAME(OR 4.33, 95%CI: 2.89-6.50, P < 0.001). No difference was found between the return rates for ORIF and FRAME(OR 1.35, 95%CI: 0.92-1.96, P = 0.122). The recorded return time was 6.9 mo(median), from a study reporting on ORIF.CONCLUSION Return rates to sport for tibial plateau fractures remain limited compared to other fractures. ARIF provides the best return rates. There is limited data regarding return times to sport. Further research is required to determine return times to sport, and to improve return rates to sport, through treatment and rehabilitation optimisation.展开更多
AIM To determine the location of medial tibial plateau stress fractures and its relationship with tibial plateau morphology using magnetic resonance imaging(MRI).METHODS A retrospective review of patients with a diagn...AIM To determine the location of medial tibial plateau stress fractures and its relationship with tibial plateau morphology using magnetic resonance imaging(MRI).METHODS A retrospective review of patients with a diagnosis of stress fracture of the medial tibial plateau was performed for a 5-year period. Fourteen patients [three female and 11 male, with an average age of 36.4 years(range, 15-50 years)], who underwent knee MRI, were included. The appearance of the tibial plateau stress fracture and the geometry of the tibial plateau were reviewed and measured on MRI.RESULTS Thirteen of 14 stress fractures were linear, and one of them stellated on MRI images. The location of fractures was classified into three types. Three fractures were located anteromedially(AM type), six posteromedially(PM type), and five posteriorly(P type) at the medial tibial plateau. In addition, tibial posterior slope at the medial tibial plateau tended to be larger when the fracture was located more posteriorly on MRI.CONCLUSION We found that MRI showed three different localizations of medial tibial plateau stress fractures, which were associated with tibial posterior slope at the medial tibial plateau.展开更多
The non-hydrostatic global variable resolution model(MPAS-atmosphere)is used to conduct the simulations for the South Asian Summer monsoon season(June,July,and August)in 2015 with a refinement over the Tibetan Plateau...The non-hydrostatic global variable resolution model(MPAS-atmosphere)is used to conduct the simulations for the South Asian Summer monsoon season(June,July,and August)in 2015 with a refinement over the Tibetan Plateau(TP)at the convection-permitting scale(4 km).Two experiments with different topographical datasets,complex(4-km)and smooth(60-km)topography,are designed to investigate the impacts of topographical complexity on moisture transport and precipitation.Compared with the observations and reanalysis data,the simulation can successfully capture the general features of key meteorological fields over the TP despite slightly underestimating the inflow through the southern TP.The results indicate that the complex topography can decrease the inward and outward moisture transport,ultimately increasing the total net moisture transport into the TP by~11%.The impacts of complex topography on precipitation are negligible over the TP,but the spatial distributions of precipitation over the Himalayas are significantly modulated.With the inclusion of complex topography,the sharper southern slopes of the Himalayas shift the lifted airflow and hence precipitation northward compared to the smooth topography.In addition,more small-scale valleys are resolved by the inclusion of complex topography,which serve as channels for moisture transport across the Himalayas,further favoring a northward shift of precipitation.Overall,the difference between the two experiments with different topography datasets is mainly attributed to their differing representation of the degree of the southern slopes of the Himalayas and the extent to which the valleys are resolved.展开更多
The classic way of treatment of tibial plateau fractures with an extensive approach, opening of the knee and compressive internal fixation can lead to major complications such as infection, skin necrosis and knee stif...The classic way of treatment of tibial plateau fractures with an extensive approach, opening of the knee and compressive internal fixation can lead to major complications such as infection, skin necrosis and knee stiffness. Here we present a less invasive and thus safer surgical technique, and its indications and results. Twenty patients with various types of fractures according to Schatzker’s classification (mainly V and VI) were treated during a time period of seven years. Surgical treatment usually consisted of a combination of percutaneous canulated screws with a hybrid external fixator. In three cases canulated screws were combined with a laterally applied anatomic locking plate. Patients were followed up for six months to three years postoperatively. Indications as well as intra and postoperative parameters such as surgical time, stability of fixation, blood loss, wound healing, infection, fracture healing and final result were studied. No major complications were recorded either early or later. The use of external οr less invasive internal fixation in combination with percutaneous canulated screws appears to be an adequate method for the treatment of most types of these fractures.展开更多
Objective:To explore a new artificial intelligence(AI)-aided method to assist the clinical diagnosis of tibial plateau fractures(TPFs)and further measure its validity and feasibility.Methods:A total of 542 X-rays of T...Objective:To explore a new artificial intelligence(AI)-aided method to assist the clinical diagnosis of tibial plateau fractures(TPFs)and further measure its validity and feasibility.Methods:A total of 542 X-rays of TPFs were collected as a reference database.An AI algorithm(RetinaNet)was trained to analyze and detect TPF on the X-rays.The ability of the AI algorithm was determined by indexes such as detection accuracy and time taken for analysis.The algorithm performance was also compared with orthopedic physicians.Results:The AI algorithm showed a detection accuracy of 0.91 for the identification of TPF,which was similar to the performance of orthopedic physicians(0.92±0.03).The average time spent for analysis of the AI was 0.56 s,which was 16 times faster than human performance(8.44±3.26 s).Conclusion:The AI algorithm is a valid and efficient method for the clinical diagnosis of TPF.It can be a useful assistant for orthopedic physicians,which largely promotes clinical workflow and further guarantees the health and security of patients.展开更多
The purpose of this study was to evaluate factors that affect initiation of early postoperative range of motion (ROM) rehabilitation and to investigate whether the postoperative ROM and clinical outcomes were affected...The purpose of this study was to evaluate factors that affect initiation of early postoperative range of motion (ROM) rehabilitation and to investigate whether the postoperative ROM and clinical outcomes were affected by initiation of early ROM, immobilization and other factors. We conducted a retrospective analysis of tibial plateau fractures treated using stable internal fixation between December 2003 and June 2007. The resulting degree of flexion and Rasmussen Clinical and Radiographic Scores were evaluated. Thirty-nine patients were included, and 23 patients underwent a lateral submeniscal arthrotomy for evaluation of joint surface reduction, with 6 lateral meniscus lesions identified via arthrotomy. Three lateral collateral ligament lesions, 3 medial collateral ligament lesions and 1 anterior cruciate ligament lesion were found. Meniscus and ligament lesions significantly and negatively affected the initiation of knee joint ROM. Early ROM was achieved in 26 cases and 13 patients underwent immobilization for 4 weeks. At the final evaluation, the early ROM group had 130.42° ± 5.50° of flexion, compared with 122.92° ± 5.28° in the immobilization group. Moreover, the final Rasmussen score was 25.69 ± 2.92 in the early motion group, compared with 22.61 ± 3.5 in the immobilization group. There was no difference between radiographic scores of the groups. Although the initiation of early ROM improved the clinical results, soft tissue lesions influenced initiation of early knee joint motion. Therefore, meniscus and ligament injuries should be considered as prognostic factors in similar cases.展开更多
The Chayu area is located at the southeastern margin of the Qinghai-Tibet Plateau.This region was considered to be in the southeastward extension of the Lhasa Block,bounded by Nujiang suture zone in the north and Yarl...The Chayu area is located at the southeastern margin of the Qinghai-Tibet Plateau.This region was considered to be in the southeastward extension of the Lhasa Block,bounded by Nujiang suture zone in the north and Yarlung Zangbo suture zone in the south.The Demala Group complex,a set of high-grade metamorphic gneisses widely distributed in the Chayu area,is known as the Precambrian metamorphic basement of the Lhasa Block in the area.According to field-based investigations and microstructure analysis,the Demala Group complex is considered to mainly consist of banded biotite plagiogneisses,biotite quartzofeldspathic gneiss,granitic gneiss,amphibolite,mica schist,and quartz schist,with many leucogranite veins.The zircon U-Pb ages of two granitic gneiss samples are 205±1 Ma and 218±1 Ma,respectively,representing the ages of their protoliths.The zircons from two biotite plagiogneisses samples show core-rim structures.The U-Pb ages of the cores are mainly 644–446 Ma,1213–865 Ma,and 1780–1400 Ma,reflecting the age characteristics of clastic zircons during sedimentation of the original rocks.The U-Pb ages of the rims are from 203±2 Ma to 190±1 Ma,which represent the age of metamorphism.The zircon U-Pb ages of one sample taken from the leucogranite veins that cut through granitic gneiss foliation range from 24 Ma to 22 Ma,interpreted as the age of the anatexis in the Demala Group complex.Biotite and muscovite separates were selected from the granitic gneiss,banded gneiss,and leucogranite veins for 40Ar/39Ar dating.The plateau ages of three muscovite samples are 16.56±0.21 Ma,16.90±0.21 Ma,and 23.40±0.31 Ma,and the plateau ages of four biotite samples are 16.70±0.24 Ma,16.14±0.19 Ma,15.88±0.20 Ma,and 14.39±0.20 Ma.The mica Ar-Ar ages can reveal the exhumation and cooling history of the Demala Group complex.Combined with the previous research results of the Demala Group complex,the authors refer that the Demala Group complex should be a set of metamorphic complex.The complex includes not only Precambrian basement metamorphic rock series,but also Paleozoic sedimentary rock and Mesozoic granitic rock.Based on the deformation characteristics,the authors concluded that two stages of the metamorphism and deformation can be revealed in the Demala Group complex since the Mesozoic,namely Late Triassic-Early Jurassic(203–190 Ma)and Oligocene–Miocene(24–14 Ma).The early stage of metamorphism(ranging from 203–190 Ma)was related to the Late Triassic tectono-magmatism in the area.The anatexis and uplifting-exhumation of the later stage(24–14 Ma)were related to the shearing of the Jiali strike-slip fault zone.The Miocene structures are response to the large-scale southeastward escape of crustal materials and block rotation in Southeast Tibet after India-Eurasia collision.展开更多
Objective This study aimed to investigate the correlation between the surface area ratio of medial tibial plateau(MTP)to lateral tibial plateau(LTP)and the mechanical tibiofemoral angle(mTFA).Methods Lower limb comput...Objective This study aimed to investigate the correlation between the surface area ratio of medial tibial plateau(MTP)to lateral tibial plateau(LTP)and the mechanical tibiofemoral angle(mTFA).Methods Lower limb computed tomography(CT)images were collected at our hospital.Then,the original CT data were analyzed and reconstructed using medical image processing software.The proximal and distal centres of the femur and tibia were marked.The surface areas of MTP and LTP were identified using image processing software.GraphPad Prism 8.0.2 was used to perform the statistical analysis.Results The surface area ratio of MTP to LTP was significantly correlated with the mTFA in all patients(P<0.0001),male group(P<0.0001),female group(P<0.0001),varus group(P<0.0001),and valgus group(P=0.002).Furthermore,the surface area of MTP and LTP was significantly greater in the male group than in the female group(P<0.0001).There was significant difference in the surface area of the MTP between the varus and valgus groups(P<0.0001).Significant difference was also observed in the surface area ratio of MTP to LTP between the varus and valgus groups(P<0.0001).Conclusion The surface area ratio of MTP to LTP was correlated with the mTFA.Within a certain range,the smaller the mTFA,the greater the surface area ratio of MTP to LTP.For patients undergoing total knee arthroplasty,of whom the surface area of the MTP was basically equal to that of the LTP,it is recommended that the osteotomy should be performed in accordance with mechanical alignment standards,and that a symmetrical tibial plateau prosthesis should be used.For patients whose surface area of MTP is significantly greater than that of the LTP,it is recommended that the osteotomy should be performed in accordance with kinematic alignment standards,and that an anatomical tibial plateau prosthesis should be used.展开更多
Cenozoic potassic-ultrapotassic igneous rocks are widespread in the southeastern Tibetan Plateau.Their petrogenesis and magmatic processes remain subject to debate in spite of numerous publications.Almost all of the C...Cenozoic potassic-ultrapotassic igneous rocks are widespread in the southeastern Tibetan Plateau.Their petrogenesis and magmatic processes remain subject to debate in spite of numerous publications.Almost all of the Cenozoic extrusive and intrusive rocks in the Yao’an area,western Yunnan Province,SW China,are geochemically shoshonitic,collectively termed here the Yao’an Shoshonitic Complex(YSC).The YSC is located in the(south)easternmost part of the ENE-WSW-trending,~550 km-long and~250 km-wide Cenozoic magmatic zone;the latter separates the orthogonal and oblique collision belts of the India-Eurasia collision orogen.Previously published geochronological and thermochronological data revealed that the rocks of the YSC were emplaced over a short timespan of 34-32 Ma.This and our new data suggest that the primary magma of the YSC likely was formed by partial melting of ancient continental lithospheric mantle beneath the Yangtze Block.This part of the continental lithospheric mantle had likely not been modified by any oceanic subduction.Fractionation crystallization of an Mg-and Ca-bearing mineral and TiFe oxides during the magmatic evolution probably account for the variable lithologies of the YSC.展开更多
A gabbro-diorite plutonic complex from the Southeast Obudu Plateau, representing limited volumes of magma, was studied for its trace and rare-earth element characteristics, in an attempt to document its genetic and ge...A gabbro-diorite plutonic complex from the Southeast Obudu Plateau, representing limited volumes of magma, was studied for its trace and rare-earth element characteristics, in an attempt to document its genetic and geodynamic history. Geochemical studies indicate that the gabbro samples are characterized by variable concentrations and low averages of such index elements as Cr (40×10-6–200×10-6; av. 80×10-6), Ni (40×10-6–170×10-6; 53.33×10-6) and Zr (110×10-6–240×10-6; 116.67×10-6); variable and high averages of Rb (3×10-6–270×10-6; 80.67×10-6), Sr (181×10-6–1610×10-6; 628.17×10-6) and U (0.14×10-6–3.46×10-6; 1.51×10-6), and fairly uniform Co (34×10-6–49×10-6; 36.33×10-6) and Sc (23×10-6–39×10-6; 34.5×10-6), while the diorite samples exhibit higher trace element compositions. The range of REE contents and distinctive chondrite-normalized patterns indicate moderate fractionation with slight positive Eu anomaly in the diorites to very low fractionation with flat patterns and slight positive Eu anomaly in the gabbros. However, the general element systematics of the samples, especially LILE (Ba, Rb, Sr, Cs and Pb), HFSE (Zr, Th, U, Hf, Mo, W, Nb and Sn), relatively immobile elements (Zr, Ni, Cr) and REE, suggests a differentiation model, involving fractional crystallization of olivine and clinopyroxene from a partial melt generated beneath an island arc complex. A possible model for the complex is therefore an island arc setting, the development of which was dominated by calc-alkaline magmatism across the Obudu Plateau.展开更多
Introduction: Tibial plateau fractures are solutions of continuity of the epiphyseal-metaphyseal block of the upper end of the tibia of which at least one line enters the joint. They threaten the stability and mobilit...Introduction: Tibial plateau fractures are solutions of continuity of the epiphyseal-metaphyseal block of the upper end of the tibia of which at least one line enters the joint. They threaten the stability and mobility of the knee and can compromise walking and standing. These fractures are on the increase, especially affecting young and active subjects. Orthopedic treatment is a rare indication apart from non-displaced or slightly displaced forms. Surgical treatment is required in displaced forms, particularly in depression fractures. The aim of this work was to report the lesional and therapeutic aspects of tibial plateau fractures in our department. Patients and Method: Patients and method: This was a retrospective study over 36 months from January 2019 to December 2021. Included in this study were patients treated for a tibial plateau fracture in our department and followed up for at least 10 months. The epidemiological and clinical data analyzed were age, sex, affected side, etiology, mechanism of injury, pathological anatomy and associated lesions. The fractures were classified according to the classification of Duparc and Ficat. The slightly or non-displaced forms were treated orthopedically while the displaced forms were treated surgically. The minimum follow-up was 10 months. The results were evaluated by the anatomical criteria according to Mazas and Duparc and functional according to Merle d’Aubigné. Results: The authors collected 71 cases of tibial plateau fractures. They accounted for 4.0% of all limb fractures, 5.8% of lower limb fractures and 33.8% of knee fractures in our service. The male sex was the most represented at 78.9% with a sex ratio of 3.7. The age group of [20 - 40] years was the most affected, i.e., 53.5%. The average age was 41 years with extremes of 17 and 82 years. The left side was affected (n = 47) and the right side (n = 24). Road traffic accident was the main cause. The mechanism of injury was mainly represented by lateral and sagittal compressions. Lateral unituberosity and bi-tuberosity fractures were the most frequent pathological types in our series, respectively 42.2% and 28.2%. The associated lesions were mainly represented by bone, ligament, skin and neurological lesions. The treatment was orthopedic in 52.1% and surgical in 47.9%. According to the functional criteria of PMA, our results were very good and good at 77.4%, Average at 14.1% and poor at 8.5%. Conclusion: It appears in this study that fractures of the tibial plateaus are frequent and serious because of their articular nature. Lateral and sagittal compressions are the most evoked injury mechanisms. Lateral unituberosity and bituberosity fractures are the most frequent pathological types. Functional and anatomical results are significantly better with surgical treatment.展开更多
There is a general consensus that most ophiolites formed above subduction zones(Pearce,2003),particularly during forearc extension at subduction initiation(Shervais,2001;Stern,2004;Whattam and Stern,2011)."Supra-...There is a general consensus that most ophiolites formed above subduction zones(Pearce,2003),particularly during forearc extension at subduction initiation(Shervais,2001;Stern,2004;Whattam and Stern,2011)."Supra-Subduction zone"(SSZ)ophiolites such as the well-studied Tethyan ophiolites,generally display a characteristic sequential evolution from mid-oceanic ridge basalts(MORBs)to island arc tholeiities(IATs)or bonites(BONs)(Pearce,2003;Dilek and Furnes,2009,2011),which were generated in sequence from the decompression melting of asthenospheric mantle and partial melting of subduction-metasomatized depleted mantle(Stern and Bloomer,1992;Dilek and Furnes,2009;Whattam and Stern,2011).However,ophiolites with MORB and/or oceanic-island basalt(OIB)affinities are rare,and their origin and tectonic nature are poorly understood(Boedo et al.,2013;Saccani et al.,2013).It is interesting that the composition of these ophiolites from the central Tibetan Plateau(CTP)is dominated by MORBs and minor OIBs and a distinct lack of IATs and BONs,which is inconsistent with most ophiolites worldwide(Robinson and Zhou,2008;Zhang et al.,2008).But the generation and tectonic nature of these ophiolites are still controversial.*In this study,we present new geochronological,mineralogical and Sr-Nd isotopic data for the Chayong and Xiewu mafic complexes in the western Garzê-Litang suture zone(GLS),a typical Paleo-Tethyan suture crossing the CTP(Fig.1).The Triassic ophiolite in the western GLS has been described by Li et al.(2009),who foundthat it mainly consists of gabbros,diabases,pillow basalts and a few metamorphic peridotites.The ophiolite has been tectonically dismembered and crops out in Triassic clastic rocks and limestones as tectonic blocks.The Chayong and Xiewu mafic complexes are generally regarded as important fragments of the Triassic ophiolites(e.g.,Jin,2006;Li et al.,2009).Zircon LA-ICP-MS U-Pb ages of234±3 Ma and 236±2 Ma can be interpreted as formation times of the Chayong and Xiewu mafic complexes,respectively.The basalts and gabbros of the Chayong complexexhibitenrichedMORB(E-MORB)compositional affinities except for a weak depletion of Nb,Ta and Ti relative to the primitive mantle,whereas the basalts and gabbros of the Xiewu complex display distinct E-MORB and OIB affinities.The geochemical features suggest a probable fractionation of olivine±clinopyroxene±plagioclase as well as insignificant crustal contamination.The geochemical and Sr-Nd isotopic data reveal that the Chayong mafic rocks may have been derived from depleted MORB-type mantle metasomatized by crustal components and Xiewu mafic rocks from enriched lithosphericmantlemetasomatizedbyOIB-like components.The ratios of Zn/Fet,La/Yb and Sm/Yb indicate that these mafic melts were produced by the partial melting of garnet+minor spinel-bearing peridotite or spinel±minor garnet-bearing peridotite.We propose thatback-arcbasinspreadingassociated with OIB/seamount recycling had occurred in the western GLS at least since the Middle Triassic times,and the decompression melting of the depleted MORB-type asthenospheremantleandpartialmeltingof sub-continental lithosphere were metasomatized by plume-related melts,such as OIBs,which led to the generation of the Chayong and Xiewu mafic melts.展开更多
Accretionary complex study provides important knowledge on the subduction and the geodynamic processes of the oceanic plate,which represents the ancient ocean basin extinction location.Nevertheless,there exist many di...Accretionary complex study provides important knowledge on the subduction and the geodynamic processes of the oceanic plate,which represents the ancient ocean basin extinction location.Nevertheless,there exist many disputes on the age,material source,and tectonic attribute of the Lancang Group,located in Southwest Yunnan,China.In this paper,the LA-ICP-MS detrital zircon U‒Pb chronology of nine metamorphic rocks in the Lancang Group was carried out.The U‒Pb ages of the three detrital zircons mainly range from 590-550 Ma,980-910 Ma,and 1150-1490 Ma,with the youngest detrital zircons having a peak age of about 560 Ma.The U‒Pb ages of the six detrital zircons mainly range from 440-460 Ma and 980-910 Ma,and the youngest detrital zircon has a peak age of about 445 Ma.In the Lancang Group,metamorphic acidic volcanic rocks,basic volcanic rocks,intermediate-acid intrusive rocks,and high-pressure metamorphic rocks are exposed in the form of tectonic lens in schist,rendering typical melange structural characteristics of“block+matrix”.Considering regional deformation and chronology,material composition characteristics,and the previous data,this study thinks the Lancang Group may be an early Paleozoic tectonic accretionary complex formed by the eastward subduction of the Changning-Menglian Proto-Tethys Ocean,which provides an important constraint for the Tethys evolution.展开更多
目的:通过Meta分析系统评价自体骨移植和骨替代物治疗胫骨平台骨折的临床疗效。方法:计算机检索2005年1月至2022年8月PubMed、Web of Science、中国知网、万方等数据库已发表的关于自体骨移植和骨替代物治疗胫骨平台骨折的病例对照研究...目的:通过Meta分析系统评价自体骨移植和骨替代物治疗胫骨平台骨折的临床疗效。方法:计算机检索2005年1月至2022年8月PubMed、Web of Science、中国知网、万方等数据库已发表的关于自体骨移植和骨替代物治疗胫骨平台骨折的病例对照研究文献。根据纳排标准进行文献筛选及数据提取,对入选的随机对照研究(randomized controlled trial,RCT)采用Cochrane手册中的干预性Meta分析标准进行质量评价。采用RevMan 5.3软件对两种方法的关节凹陷、关节面二次塌陷率、失血量、手术时间和感染率进行Meta分析。结果:共纳入7项RCT研究,424例患者,其中骨替代物组296例,自体骨移植组128例。两组手术时间[MD=-16.79,95%CI(-25.72,-7.85),P=0.0002],出血量[MD=-70.49,95%CI(-79.34,-61.65),P<0.00001]比较,差异有统计学意义。而关节凹陷[MD=-0.17,95%CI(-0.91,0.58),P=0.66],关节面二次塌陷率[RR=-0.74,95%CI(0.35,1.57),P=0.43],感染率[RR=1.21,95%CI(0.31,4.70),P=0.78]比较,差异无统计学意义。结论:骨替代物与自体骨移植治疗胫骨平台骨折在关节凹陷、关节面二次塌陷率和感染率方面疗效相近。但骨替代物较自体骨移植,能减少失血量,缩短手术时间。展开更多
文摘Complex tibial plateau fractures can seriously affect quality of life and physical and mental health of patients.The anatomical relationship between the proximal tibial bone and soft tissue is complex,resulting in different types of tibial plateau fractures.Violent trauma can lead to displaced fracture,serious soft tissue injury,and potentially,dislocation of the knee joint.Therefore,tibial plateau fractures are extremely unstable.AIM To assess the use of locking compression plate(LCP)+T-type steel plate for postoperative weight bearing and functional recovery of complex tibial plateau fractures.METHODS Ninety-seven patients with complex tibial plateau fractures who underwent surgery at our hospital were selected for retrospective study.Forty-nine patients had been treated with LCP+T-type steel plate limited internal fixation(study group),and 48 patients with bilateral ordinary steel plate support(control group).The operation process index,postoperative rehabilitation related index,Rasmussen score of the knee joint,tibial plateau varus angle(TPA),tibial plateau retroversion angle(PA),and surgical complications of the two groups were compared.RESULTS The operation time and intraoperative bone graft volume in the study group were lower than those in the control group(P<0.05).There were no significant differences in surgical bleeding,anterior external incision length,postoperative drainage,hospital stay duration,and fracture healing time between the groups(P>0.05).There was no significant difference in the TPA and PA angle between the groups immediately and 18 mo after surgery(P>0.05).At 12 mo after surgery,the Rasmussen scale score was higher in the study group than in the control group(P<0.05).There was no significant difference in the Rasmussen scale score at 18 mo after surgery,and the radiology score at 12 and 18 mo after surgery,between the two groups(P>0.05).The postoperative complication rate in the study group(3.77%)was lower than that in the control group(15.09%;P<0.05).CONCLUSION LCP+T-type steel plate internal fixation has advantages in terms of minimizing trauma and enabling early postoperative functional exercise,promoting functional recovery and lower limb weight-bearing,and reducing postoperative complications.
文摘Objective: To investigate the value of 3D printing techniques in the treatment of complex tibial plateau fractures. Methods: From September 2016 to September 2018, 28 patients with complex tibial plateau fractures were treated in our hospital. According to the odevity of hospitalized order, the patients were divided into two groups. Group A used 3D reconstruction, virtually reduction, 3D printing and demonstration of individual fracture model before operation while group B only received conventional process by use X-rays or CT image. Comparison between the two groups was made in operation time, operative blood loss, radiation frequency, surgery instrument cost and knee function score. Results: The follow-up was 14.4 months on average (ranged 6 to 22 months). There was no statistical difference of the surgery instrument cost between the 2 groups (P > 0.05). The operation time of group A was significantly shorter than that of group B (P χ2 = 0.373, P = 0.54). Conclusion: 3D printing techniques can improve surgery effect in complex tibial plateau fractures.
文摘Mechanical traction and percutaneous reduction by leverage and fixation by a bilateral groove externalfixator were performed on 23 patients with complex tibial plateau fractures involving a depressed and splitfragments. The fixator is composed of two long groove frames, three to five nuts, hooked bolts and Stein-manns pins.All fractures united in good position in three months with no incision (only pinpricks), llttle operativetrauma and no significant complications but pintract infection, and the flexion-extension range of kneemovement was excllent in all patients, so that this technique is particularly advisable for complex tibialplateau fractures.
文摘Purpose: To evaluate the clinico-radiological outcome of complex tibial plateau fractures treated with Ilizarov external fixation with or without minimal internal fixation. Methods: This retrospective review was conducted on all the cases of Schatzker types V and VI tibial plateau fractures treated by Ilizarov external fixation between July 2006 and December 2015 with the minimum follow-up duration of one year. There were 30 patients: 24 males and 6 females, mean age 43.33 years, and mean follow-up 3.6 years. Three of them were open fractures;15 cases were Schatzkertype V fractures and the other 15 type VI. According to AO/OTA classification, there were 11 type C1, 12 C2 and 7 type C3 fractures. Outcome assessment was made with American Knee Society Score (AKSS) and Rasmussen's Radiological Score (RRS) at final follow-up. Results: Out of the 30 cases, mini-open reduction was performed in 7, bone graft in 4, minimal internal fixation in 10 and knee temporary immobilisation in 11 patients. Mean duration of external fixation was 11.8 weeks. All fractures united. Pin tract infections in 7 and common peroneal neuropathy in 2 patients were self-limiting. Two patients had axial misalignment of less than 10°. At final follow-up, the mean knee range of motion was 114.7, mean AKSS 81.5 and mean RRS 16.7. On statistical analysis, Schatzker type of fractures, use of minimal internal fixation and knee-spanning did not influence the final outcome. Conclusion: Ilizarov external fixator with or without minimal internal fixation provides acceptable outcome for complex tibial plateau fractures. Care must be taken to look for minor loss of alignment, especially in Type VI Schatzker fractures after removal of the fixator. However small sample size precludes firm conclusions.
文摘The management of a combination of fracture and multiligament knee injury(MKI) in traumatic knee injury remains controversial, and there are evolving treatment recommendations. Currently, there are no studies focusing on older adult patients with MKI's in combination with tibia fractures. As a result, there is no well-established treatment algorithm for older adult patients with these complex injuries. We report two cases of MKI's with concomitant fractures in patients fifty years of age or older. Both patients were treated surgically for their associated tibial plateau fractures, but were managed with conservative treatment of the multiligamentous knee injuries. We also provide a review of the literature and guidelines for older adult patients with these types of complex traumatic injuries. Early to mid term acceptable outcomes were achieved for both patients through surgical fixation of the tibial plateau fracture and conservative treatment of the ligament injuries. We propose a comprehensive treatment algorithm for management of these complex injuries.
文摘AIM To systemically review all studies reporting return to sport following tibial plateau fracture, in order to provide information on return rates and times to sport, and to assess variations in sporting outcome for different treatment methods.METHODS A systematic search of CINAHAL, Cochrane, EMBASE, Google Scholar, MEDLINE, PEDro, Scopus, SPORTDiscus and Web of Science was performed in January 2017 using the keywords "tibial", "plateau", "fractures", "knee", "athletes", "sports", "non-operative", "conservative", "operative", "return to sport". All studies which recorded return rates and times to sport following tibial plateau fractures were included. RESULTS Twenty-seven studies were included: 1 was a randomised controlled trial, 7 were prospective cohort studies, 16 were retrospective cohort studies, 3 were case series. One study reported on the outcome of conservative management(n = 3); 27 reported on the outcome of surgical management(n = 917). Nine studies reported on Open Reduction Internal Fixation(ORIF)(n = 193), 11 on Arthroscopic-Assisted Reduction Internal Fixation(ARIF)(n = 253) and 7 on Frame-Assisted Fixation(FRAME)(n = 262). All studies recorded "return to sport"rates. Only one study recorded a "return to sport" time. The return rate to sport for the total cohort was 70%. For the conservatively-managed fractures, the return rate was 100%. For the surgically-managed fractures, the return rate was 70%. For fractures managed with ORIF, the return rate was 60%. For fractures managed with ARIF, the return rate was 83%. For fractures managed with FRAME was 52%. The return rate for ARIF was found to be significantly greater than that for ORIF(OR 3.22, 95%CI: 2.09-4.97, P < 0.001) and for FRAME(OR 4.33, 95%CI: 2.89-6.50, P < 0.001). No difference was found between the return rates for ORIF and FRAME(OR 1.35, 95%CI: 0.92-1.96, P = 0.122). The recorded return time was 6.9 mo(median), from a study reporting on ORIF.CONCLUSION Return rates to sport for tibial plateau fractures remain limited compared to other fractures. ARIF provides the best return rates. There is limited data regarding return times to sport. Further research is required to determine return times to sport, and to improve return rates to sport, through treatment and rehabilitation optimisation.
文摘AIM To determine the location of medial tibial plateau stress fractures and its relationship with tibial plateau morphology using magnetic resonance imaging(MRI).METHODS A retrospective review of patients with a diagnosis of stress fracture of the medial tibial plateau was performed for a 5-year period. Fourteen patients [three female and 11 male, with an average age of 36.4 years(range, 15-50 years)], who underwent knee MRI, were included. The appearance of the tibial plateau stress fracture and the geometry of the tibial plateau were reviewed and measured on MRI.RESULTS Thirteen of 14 stress fractures were linear, and one of them stellated on MRI images. The location of fractures was classified into three types. Three fractures were located anteromedially(AM type), six posteromedially(PM type), and five posteriorly(P type) at the medial tibial plateau. In addition, tibial posterior slope at the medial tibial plateau tended to be larger when the fracture was located more posteriorly on MRI.CONCLUSION We found that MRI showed three different localizations of medial tibial plateau stress fractures, which were associated with tibial posterior slope at the medial tibial plateau.
基金supported by the National Natural Science Foundation of China NSFC (Grant Nos.91837310,42061134009,41775146)the USTC Research Funds of the Double First-Class Initiative (YD2080002007)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB41000000)
文摘The non-hydrostatic global variable resolution model(MPAS-atmosphere)is used to conduct the simulations for the South Asian Summer monsoon season(June,July,and August)in 2015 with a refinement over the Tibetan Plateau(TP)at the convection-permitting scale(4 km).Two experiments with different topographical datasets,complex(4-km)and smooth(60-km)topography,are designed to investigate the impacts of topographical complexity on moisture transport and precipitation.Compared with the observations and reanalysis data,the simulation can successfully capture the general features of key meteorological fields over the TP despite slightly underestimating the inflow through the southern TP.The results indicate that the complex topography can decrease the inward and outward moisture transport,ultimately increasing the total net moisture transport into the TP by~11%.The impacts of complex topography on precipitation are negligible over the TP,but the spatial distributions of precipitation over the Himalayas are significantly modulated.With the inclusion of complex topography,the sharper southern slopes of the Himalayas shift the lifted airflow and hence precipitation northward compared to the smooth topography.In addition,more small-scale valleys are resolved by the inclusion of complex topography,which serve as channels for moisture transport across the Himalayas,further favoring a northward shift of precipitation.Overall,the difference between the two experiments with different topography datasets is mainly attributed to their differing representation of the degree of the southern slopes of the Himalayas and the extent to which the valleys are resolved.
文摘The classic way of treatment of tibial plateau fractures with an extensive approach, opening of the knee and compressive internal fixation can lead to major complications such as infection, skin necrosis and knee stiffness. Here we present a less invasive and thus safer surgical technique, and its indications and results. Twenty patients with various types of fractures according to Schatzker’s classification (mainly V and VI) were treated during a time period of seven years. Surgical treatment usually consisted of a combination of percutaneous canulated screws with a hybrid external fixator. In three cases canulated screws were combined with a laterally applied anatomic locking plate. Patients were followed up for six months to three years postoperatively. Indications as well as intra and postoperative parameters such as surgical time, stability of fixation, blood loss, wound healing, infection, fracture healing and final result were studied. No major complications were recorded either early or later. The use of external οr less invasive internal fixation in combination with percutaneous canulated screws appears to be an adequate method for the treatment of most types of these fractures.
基金supported by the National Natural Science Foundation of China(No.81974355 and No.82172525).
文摘Objective:To explore a new artificial intelligence(AI)-aided method to assist the clinical diagnosis of tibial plateau fractures(TPFs)and further measure its validity and feasibility.Methods:A total of 542 X-rays of TPFs were collected as a reference database.An AI algorithm(RetinaNet)was trained to analyze and detect TPF on the X-rays.The ability of the AI algorithm was determined by indexes such as detection accuracy and time taken for analysis.The algorithm performance was also compared with orthopedic physicians.Results:The AI algorithm showed a detection accuracy of 0.91 for the identification of TPF,which was similar to the performance of orthopedic physicians(0.92±0.03).The average time spent for analysis of the AI was 0.56 s,which was 16 times faster than human performance(8.44±3.26 s).Conclusion:The AI algorithm is a valid and efficient method for the clinical diagnosis of TPF.It can be a useful assistant for orthopedic physicians,which largely promotes clinical workflow and further guarantees the health and security of patients.
文摘The purpose of this study was to evaluate factors that affect initiation of early postoperative range of motion (ROM) rehabilitation and to investigate whether the postoperative ROM and clinical outcomes were affected by initiation of early ROM, immobilization and other factors. We conducted a retrospective analysis of tibial plateau fractures treated using stable internal fixation between December 2003 and June 2007. The resulting degree of flexion and Rasmussen Clinical and Radiographic Scores were evaluated. Thirty-nine patients were included, and 23 patients underwent a lateral submeniscal arthrotomy for evaluation of joint surface reduction, with 6 lateral meniscus lesions identified via arthrotomy. Three lateral collateral ligament lesions, 3 medial collateral ligament lesions and 1 anterior cruciate ligament lesion were found. Meniscus and ligament lesions significantly and negatively affected the initiation of knee joint ROM. Early ROM was achieved in 26 cases and 13 patients underwent immobilization for 4 weeks. At the final evaluation, the early ROM group had 130.42° ± 5.50° of flexion, compared with 122.92° ± 5.28° in the immobilization group. Moreover, the final Rasmussen score was 25.69 ± 2.92 in the early motion group, compared with 22.61 ± 3.5 in the immobilization group. There was no difference between radiographic scores of the groups. Although the initiation of early ROM improved the clinical results, soft tissue lesions influenced initiation of early knee joint motion. Therefore, meniscus and ligament injuries should be considered as prognostic factors in similar cases.
基金a project of National Natural Science Foundation of China(41773026)two geological survey projects initiated by the China Geological Survey(DD20190053,DD20160021).
文摘The Chayu area is located at the southeastern margin of the Qinghai-Tibet Plateau.This region was considered to be in the southeastward extension of the Lhasa Block,bounded by Nujiang suture zone in the north and Yarlung Zangbo suture zone in the south.The Demala Group complex,a set of high-grade metamorphic gneisses widely distributed in the Chayu area,is known as the Precambrian metamorphic basement of the Lhasa Block in the area.According to field-based investigations and microstructure analysis,the Demala Group complex is considered to mainly consist of banded biotite plagiogneisses,biotite quartzofeldspathic gneiss,granitic gneiss,amphibolite,mica schist,and quartz schist,with many leucogranite veins.The zircon U-Pb ages of two granitic gneiss samples are 205±1 Ma and 218±1 Ma,respectively,representing the ages of their protoliths.The zircons from two biotite plagiogneisses samples show core-rim structures.The U-Pb ages of the cores are mainly 644–446 Ma,1213–865 Ma,and 1780–1400 Ma,reflecting the age characteristics of clastic zircons during sedimentation of the original rocks.The U-Pb ages of the rims are from 203±2 Ma to 190±1 Ma,which represent the age of metamorphism.The zircon U-Pb ages of one sample taken from the leucogranite veins that cut through granitic gneiss foliation range from 24 Ma to 22 Ma,interpreted as the age of the anatexis in the Demala Group complex.Biotite and muscovite separates were selected from the granitic gneiss,banded gneiss,and leucogranite veins for 40Ar/39Ar dating.The plateau ages of three muscovite samples are 16.56±0.21 Ma,16.90±0.21 Ma,and 23.40±0.31 Ma,and the plateau ages of four biotite samples are 16.70±0.24 Ma,16.14±0.19 Ma,15.88±0.20 Ma,and 14.39±0.20 Ma.The mica Ar-Ar ages can reveal the exhumation and cooling history of the Demala Group complex.Combined with the previous research results of the Demala Group complex,the authors refer that the Demala Group complex should be a set of metamorphic complex.The complex includes not only Precambrian basement metamorphic rock series,but also Paleozoic sedimentary rock and Mesozoic granitic rock.Based on the deformation characteristics,the authors concluded that two stages of the metamorphism and deformation can be revealed in the Demala Group complex since the Mesozoic,namely Late Triassic-Early Jurassic(203–190 Ma)and Oligocene–Miocene(24–14 Ma).The early stage of metamorphism(ranging from 203–190 Ma)was related to the Late Triassic tectono-magmatism in the area.The anatexis and uplifting-exhumation of the later stage(24–14 Ma)were related to the shearing of the Jiali strike-slip fault zone.The Miocene structures are response to the large-scale southeastward escape of crustal materials and block rotation in Southeast Tibet after India-Eurasia collision.
基金the National Natural Science Foundation of China(No.81672155).
文摘Objective This study aimed to investigate the correlation between the surface area ratio of medial tibial plateau(MTP)to lateral tibial plateau(LTP)and the mechanical tibiofemoral angle(mTFA).Methods Lower limb computed tomography(CT)images were collected at our hospital.Then,the original CT data were analyzed and reconstructed using medical image processing software.The proximal and distal centres of the femur and tibia were marked.The surface areas of MTP and LTP were identified using image processing software.GraphPad Prism 8.0.2 was used to perform the statistical analysis.Results The surface area ratio of MTP to LTP was significantly correlated with the mTFA in all patients(P<0.0001),male group(P<0.0001),female group(P<0.0001),varus group(P<0.0001),and valgus group(P=0.002).Furthermore,the surface area of MTP and LTP was significantly greater in the male group than in the female group(P<0.0001).There was significant difference in the surface area of the MTP between the varus and valgus groups(P<0.0001).Significant difference was also observed in the surface area ratio of MTP to LTP between the varus and valgus groups(P<0.0001).Conclusion The surface area ratio of MTP to LTP was correlated with the mTFA.Within a certain range,the smaller the mTFA,the greater the surface area ratio of MTP to LTP.For patients undergoing total knee arthroplasty,of whom the surface area of the MTP was basically equal to that of the LTP,it is recommended that the osteotomy should be performed in accordance with mechanical alignment standards,and that a symmetrical tibial plateau prosthesis should be used.For patients whose surface area of MTP is significantly greater than that of the LTP,it is recommended that the osteotomy should be performed in accordance with kinematic alignment standards,and that an anatomical tibial plateau prosthesis should be used.
基金financially supported by the Ministry of Sciences and Technology of China(Grant No.2022YFF0800901)the Natural Science Foundation of China(Grant Nos.92055206 and 42163007)。
文摘Cenozoic potassic-ultrapotassic igneous rocks are widespread in the southeastern Tibetan Plateau.Their petrogenesis and magmatic processes remain subject to debate in spite of numerous publications.Almost all of the Cenozoic extrusive and intrusive rocks in the Yao’an area,western Yunnan Province,SW China,are geochemically shoshonitic,collectively termed here the Yao’an Shoshonitic Complex(YSC).The YSC is located in the(south)easternmost part of the ENE-WSW-trending,~550 km-long and~250 km-wide Cenozoic magmatic zone;the latter separates the orthogonal and oblique collision belts of the India-Eurasia collision orogen.Previously published geochronological and thermochronological data revealed that the rocks of the YSC were emplaced over a short timespan of 34-32 Ma.This and our new data suggest that the primary magma of the YSC likely was formed by partial melting of ancient continental lithospheric mantle beneath the Yangtze Block.This part of the continental lithospheric mantle had likely not been modified by any oceanic subduction.Fractionation crystallization of an Mg-and Ca-bearing mineral and TiFe oxides during the magmatic evolution probably account for the variable lithologies of the YSC.
文摘A gabbro-diorite plutonic complex from the Southeast Obudu Plateau, representing limited volumes of magma, was studied for its trace and rare-earth element characteristics, in an attempt to document its genetic and geodynamic history. Geochemical studies indicate that the gabbro samples are characterized by variable concentrations and low averages of such index elements as Cr (40×10-6–200×10-6; av. 80×10-6), Ni (40×10-6–170×10-6; 53.33×10-6) and Zr (110×10-6–240×10-6; 116.67×10-6); variable and high averages of Rb (3×10-6–270×10-6; 80.67×10-6), Sr (181×10-6–1610×10-6; 628.17×10-6) and U (0.14×10-6–3.46×10-6; 1.51×10-6), and fairly uniform Co (34×10-6–49×10-6; 36.33×10-6) and Sc (23×10-6–39×10-6; 34.5×10-6), while the diorite samples exhibit higher trace element compositions. The range of REE contents and distinctive chondrite-normalized patterns indicate moderate fractionation with slight positive Eu anomaly in the diorites to very low fractionation with flat patterns and slight positive Eu anomaly in the gabbros. However, the general element systematics of the samples, especially LILE (Ba, Rb, Sr, Cs and Pb), HFSE (Zr, Th, U, Hf, Mo, W, Nb and Sn), relatively immobile elements (Zr, Ni, Cr) and REE, suggests a differentiation model, involving fractional crystallization of olivine and clinopyroxene from a partial melt generated beneath an island arc complex. A possible model for the complex is therefore an island arc setting, the development of which was dominated by calc-alkaline magmatism across the Obudu Plateau.
文摘Introduction: Tibial plateau fractures are solutions of continuity of the epiphyseal-metaphyseal block of the upper end of the tibia of which at least one line enters the joint. They threaten the stability and mobility of the knee and can compromise walking and standing. These fractures are on the increase, especially affecting young and active subjects. Orthopedic treatment is a rare indication apart from non-displaced or slightly displaced forms. Surgical treatment is required in displaced forms, particularly in depression fractures. The aim of this work was to report the lesional and therapeutic aspects of tibial plateau fractures in our department. Patients and Method: Patients and method: This was a retrospective study over 36 months from January 2019 to December 2021. Included in this study were patients treated for a tibial plateau fracture in our department and followed up for at least 10 months. The epidemiological and clinical data analyzed were age, sex, affected side, etiology, mechanism of injury, pathological anatomy and associated lesions. The fractures were classified according to the classification of Duparc and Ficat. The slightly or non-displaced forms were treated orthopedically while the displaced forms were treated surgically. The minimum follow-up was 10 months. The results were evaluated by the anatomical criteria according to Mazas and Duparc and functional according to Merle d’Aubigné. Results: The authors collected 71 cases of tibial plateau fractures. They accounted for 4.0% of all limb fractures, 5.8% of lower limb fractures and 33.8% of knee fractures in our service. The male sex was the most represented at 78.9% with a sex ratio of 3.7. The age group of [20 - 40] years was the most affected, i.e., 53.5%. The average age was 41 years with extremes of 17 and 82 years. The left side was affected (n = 47) and the right side (n = 24). Road traffic accident was the main cause. The mechanism of injury was mainly represented by lateral and sagittal compressions. Lateral unituberosity and bi-tuberosity fractures were the most frequent pathological types in our series, respectively 42.2% and 28.2%. The associated lesions were mainly represented by bone, ligament, skin and neurological lesions. The treatment was orthopedic in 52.1% and surgical in 47.9%. According to the functional criteria of PMA, our results were very good and good at 77.4%, Average at 14.1% and poor at 8.5%. Conclusion: It appears in this study that fractures of the tibial plateaus are frequent and serious because of their articular nature. Lateral and sagittal compressions are the most evoked injury mechanisms. Lateral unituberosity and bituberosity fractures are the most frequent pathological types. Functional and anatomical results are significantly better with surgical treatment.
基金financially supported by the National Nature Science Foundation of China (Grant 41272079)
文摘There is a general consensus that most ophiolites formed above subduction zones(Pearce,2003),particularly during forearc extension at subduction initiation(Shervais,2001;Stern,2004;Whattam and Stern,2011)."Supra-Subduction zone"(SSZ)ophiolites such as the well-studied Tethyan ophiolites,generally display a characteristic sequential evolution from mid-oceanic ridge basalts(MORBs)to island arc tholeiities(IATs)or bonites(BONs)(Pearce,2003;Dilek and Furnes,2009,2011),which were generated in sequence from the decompression melting of asthenospheric mantle and partial melting of subduction-metasomatized depleted mantle(Stern and Bloomer,1992;Dilek and Furnes,2009;Whattam and Stern,2011).However,ophiolites with MORB and/or oceanic-island basalt(OIB)affinities are rare,and their origin and tectonic nature are poorly understood(Boedo et al.,2013;Saccani et al.,2013).It is interesting that the composition of these ophiolites from the central Tibetan Plateau(CTP)is dominated by MORBs and minor OIBs and a distinct lack of IATs and BONs,which is inconsistent with most ophiolites worldwide(Robinson and Zhou,2008;Zhang et al.,2008).But the generation and tectonic nature of these ophiolites are still controversial.*In this study,we present new geochronological,mineralogical and Sr-Nd isotopic data for the Chayong and Xiewu mafic complexes in the western Garzê-Litang suture zone(GLS),a typical Paleo-Tethyan suture crossing the CTP(Fig.1).The Triassic ophiolite in the western GLS has been described by Li et al.(2009),who foundthat it mainly consists of gabbros,diabases,pillow basalts and a few metamorphic peridotites.The ophiolite has been tectonically dismembered and crops out in Triassic clastic rocks and limestones as tectonic blocks.The Chayong and Xiewu mafic complexes are generally regarded as important fragments of the Triassic ophiolites(e.g.,Jin,2006;Li et al.,2009).Zircon LA-ICP-MS U-Pb ages of234±3 Ma and 236±2 Ma can be interpreted as formation times of the Chayong and Xiewu mafic complexes,respectively.The basalts and gabbros of the Chayong complexexhibitenrichedMORB(E-MORB)compositional affinities except for a weak depletion of Nb,Ta and Ti relative to the primitive mantle,whereas the basalts and gabbros of the Xiewu complex display distinct E-MORB and OIB affinities.The geochemical features suggest a probable fractionation of olivine±clinopyroxene±plagioclase as well as insignificant crustal contamination.The geochemical and Sr-Nd isotopic data reveal that the Chayong mafic rocks may have been derived from depleted MORB-type mantle metasomatized by crustal components and Xiewu mafic rocks from enriched lithosphericmantlemetasomatizedbyOIB-like components.The ratios of Zn/Fet,La/Yb and Sm/Yb indicate that these mafic melts were produced by the partial melting of garnet+minor spinel-bearing peridotite or spinel±minor garnet-bearing peridotite.We propose thatback-arcbasinspreadingassociated with OIB/seamount recycling had occurred in the western GLS at least since the Middle Triassic times,and the decompression melting of the depleted MORB-type asthenospheremantleandpartialmeltingof sub-continental lithosphere were metasomatized by plume-related melts,such as OIBs,which led to the generation of the Chayong and Xiewu mafic melts.
基金supported by the Second Comprehensive Scientific Investigation and Research Program on the Qinghai-Tibet Plateau(2019QZKK0702)the China Geological Survey Program(DD20221715,DD20190053).
文摘Accretionary complex study provides important knowledge on the subduction and the geodynamic processes of the oceanic plate,which represents the ancient ocean basin extinction location.Nevertheless,there exist many disputes on the age,material source,and tectonic attribute of the Lancang Group,located in Southwest Yunnan,China.In this paper,the LA-ICP-MS detrital zircon U‒Pb chronology of nine metamorphic rocks in the Lancang Group was carried out.The U‒Pb ages of the three detrital zircons mainly range from 590-550 Ma,980-910 Ma,and 1150-1490 Ma,with the youngest detrital zircons having a peak age of about 560 Ma.The U‒Pb ages of the six detrital zircons mainly range from 440-460 Ma and 980-910 Ma,and the youngest detrital zircon has a peak age of about 445 Ma.In the Lancang Group,metamorphic acidic volcanic rocks,basic volcanic rocks,intermediate-acid intrusive rocks,and high-pressure metamorphic rocks are exposed in the form of tectonic lens in schist,rendering typical melange structural characteristics of“block+matrix”.Considering regional deformation and chronology,material composition characteristics,and the previous data,this study thinks the Lancang Group may be an early Paleozoic tectonic accretionary complex formed by the eastward subduction of the Changning-Menglian Proto-Tethys Ocean,which provides an important constraint for the Tethys evolution.
