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•论著•文章编号：1009-4237(2020)03-0181-04験上入路、験下入路胫骨髓内钉治疗胫骨干骨折的对比研究魏新程，杨凌云，刘军，王国栋$摘要】目的比较離上入路和離下入路胫骨髓内钉治疗胫骨干骨折的疗效，为胫骨髓内钉置入路径的选择提供依据。
方法回顾性分析南京医科大学第二附属医院2015年9月一2017年12月收治的58例胫骨干骨折患者，男性42例，女性16例;年龄19-73岁，平均50.3岁。
均采用髓内钉内固定手术，按手术入路分为離上入路"SPN)组和離下入路(IPN)组，各29例，统计并比较两组手术时间、出血量、骨折愈合、膝前疼痛、膝关节功能评分。
结果定期电话及门诊随访13~20个月，平均15.6个月。
SPN组手术时间(100.66±6.78)min短于IPN组(110.07±8.92)min；SPN组与IPN组相比，膝前疼痛程度较轻(VAS评分1.07±1.00k1.66±1.40)，膝关节功能评分较高(Lysholm评分96.28±4.08vs.93.93±4.62,Oxford评分53.28±3.96vs.51.17±3.55)，P<0.05。
SPN组与IPN组在出血量[(79.31±11.00)mL k(83.10±11.37)mL]、骨折愈合方面(RUST评分27.03±2.34k26.72±2.20)，差异无统计学意义，P>0.05。
结论与離下入路组相比，離上入路髓内钉治疗胫骨干骨折，操作简便，手术时间短，术后膝关节功能评分高，值得临床推广。
$关键词】胫骨干骨折；髓内钉；入路$中图分类号】R683.42$文献标识码】A$DOI】10.3969j.issn.1009-4237.2020.03.005Comparison of suprapatellar and infrapatellar intramedullary nailingfor tibial shaft fracturesWEI Xin-cheng，YANG Ling-yun，LIU Jun，WANG Guo-dong(Department of Orthopedics，the Second Affiliated Hospital or Nanjing Medical University，Nanjing210000，China %Abstract]Objectivs To compare the effect of suprapatellar and infrapatellar inmameduHay nailing for tibiai shaft fractures，with the purpose of providing evidence for choosing internai fixation routines of tibiai intramed-uiay nailing.Mettodu From Sep.2015te Dec.2017，58tibii shaft fracture patients were treated in Departmentof Orthopedics，the Second Afiliated Hospitai of Nanjing Medicai University.There were42males and16females，with an average are of50.3years(range，from19te73years).Thee were divided inte suprapatellar intrameduiaynailing(SPN)group and infrapatellar intrameduiay nailing(UN)group，with29patients in each group.Ali patients were treated with internai fixation of tibiai intrameduiay nailing.Operative time，blood loss，fracture heding，anterior knee pain and knee function score were recorded and compared between the two groups.Results A tele-phonefo i ow-up suaeeywasta a ied ouefoaeath paeiene，and ehefo i ow-up peaiod was15.6(13-20)monehson ae-erage.In contrast te the IN group，the SPN group had shorter operation time,(100.66±6.78)minutes ss.(110.07±8.92)minutes-，lower VAS pain score(1.07± 1.00vs. 1.66±1.40)，and higher knee functionai score(Ly-shOm score96.28±4.08vs.93.93±4.62，Oxford score53.28±3.96vs.51.17±3.55)，P<0.05.There wasno swtisecalla significant dmerencc in blood loss and fracture healing(P>0.05).Conclusion Compared withUN，SPN for tibiai shaft fractures is much better in terms of shorter operation1^X1，and higher postoperative kneefunction score.As a sirnple and convenient method，it is worth te be popularized.%Key wordt]tibiai shaft fracture；intrameduiae nailing；approach胫骨干骨折是下肢常见的骨折。
合成孔径光学成像系统与图像复原技术刘立涛,聂亮(西安工业大学光电工程学院，陕西西安710021)摘要:结合信息光学理论知识与合成孔径系统的基本成像原理，得出了三种类型子孔径排布方式下的光学调制传递函数(MTF)分布，分析其成像特性；利用MATLAB 软件在不同孔径排布情况下模拟其成像退化结果；采用最大似然的R--L 复原方法对成像结果分别进行复原。
根据计算机理论模拟的结果，该方法有较好的复原效果，图像的清晰度有所改善，一些细节系信息也有所完善；其中三臂型的清晰度最好，复原结果最佳。
关键词:合成孔径；点扩散函数；光学调制传递函数；退化；复原中图分类号：TP391.41文献标识码:A文章编号:1003-7241(2021)003-0096-06Synthetic Aperture Optical Imaging System and Image Restoration TechnologyLIU Li -tao,NIE Liang(School of Optoelectronic Engineering,Xi'an Technological University,Xi'an 710021China )Abstract:Based on the theoretical knowledge of information optics and the basic imaging principle of synthetic aperture system,theoptical modulation transfer function (MTF)distribution of three types of subaperture distribution is obtained,and its imag-ing characteristics are analyzed.MATLAB software was used to simulate the image degradation results under different ap-erture arrangement.The maximum likelihood R-L restoration method was used to recover the imaging results.According to the results of computer simulation,the method has a good recovery effect,the image clarity is improved,and some de-tails are also improved.The three -arm model has the best definition and recovery results.Key words:synthetic aperture;PSF;MTF;degradation;restoration收稿日期:2019-12-181引言随着现代科技技术的不断发展，人们对光学系统的成像分辨率要求也日益增高，特别是像航天观测，遥感监测，对光学系统的分辨率要求非常高。
ConnectionsTeaching ToolkitA Teaching Guide for Structural Steel ConnectionsPerry S.Green,Ph.D.Thomas Sputo,Ph.D.,P.E.Patrick VeltriThis connection design tool kit for students is based on the original steel sculpture designed by Duane S. Ellifritt, P.E., Ph.D., Professor Emeritus of Civil Engineering at the Uni-versity of Florida. The tool kit includes this teaching guide, a 3D CAD file of the steel sculpture, and a shear connection calculator tool. The teaching guide contains drawings and photographs of each connection depicted on the steel sculp-ture, the CAD file is a 3D AutoCAD® model of the steel sculpture with complete dimensions and details, and the cal-culator tool is a series of MathCAD® worksheets that enables the user to perform a comprehensive check of all required limit states.The tool kit is intended as a supplement to, not a replace-ment for, the information and data presented in the Ameri-can Institute of Steel Construction’s Manual of Steel Construction, Load & Resistance Factor Design, Third Edi-tion, hereafter, referred to as the AISC Manual. The goal of the tool kit is to assist students and educators in both learn-ing and teaching basic structural steel connection design by visualization tools and software application.All information and data presented in any and all parts of the teaching tool kit are for educational purposes only. Although the steel sculpture depicts numerous connections, it is by no means all-inclusive. There are many ways to connect structural steel members together.In teaching engineering students in an introductory course in steel design, often the topic of connections is put off until the end of the course if covered at all. Then with the crush of all the other pressures leading up to the end of the semes-ter, even these few weeks get squeezed until connections are lucky to be addressed for two or three lectures. One reason for slighting connections in beginning steel design, other than time constraints, is that they are sometimes viewed as a “detailing problem” best left to the fabricator. Or, the mis-taken view is taken that connections get standardized, espe-cially shear connections, so there is little creativity needed in their design and engineers view it as a poor use of their time. The AISC Manual has tables and detailing informa-tion on many standard types of connections, so the process is simplified to selecting a tabulated connection that will carry the design load. Many times, the engineer will simply indicate the load to be transmitted on the design drawings and the fabricator will select an appropriate connection. Yet connections are the glue that holds the structure together and, standardized and routine as many of them may seem, it is very important for a structural engineer to under-stand their behavior and design. Historically, most major structural failures have been due to some kind of connection failure. Connections are always designed as planar, two-dimensional elements, even though they have definite three-dimensional behavior. Students who have never been around construction sites to see steel being erected have a difficult time visualizing this three-dimensional character. Try explaining to a student the behavior of a shop-welded, field-bolted double-angle shear connection, where the out-standing legs are made purposely to flex under load and approximate a true pinned connection. Textbooks generally show orthogonal views of such connections, but still many students have trouble in “seeing” the real connection.In the summer of 1985, after seeing the inability of many students to visualize even simple connections, Dr. Ellifritt began to search for a way to make connections more real for them. Field trips were one alternative, but the availability of these is intermittent and with all the problems of liability, some construction managers are not too anxious to have a group of students around the jobsite. Thought was given to building some scale models of connections and bringing them into the classroom, but these would be heavy to move around and one would have the additional problem storing them all when they were not in use.The eventual solution was to create a steel sculpture that would be an attractive addition to the public art already on campus, something that would symbolize engineering in general, and that could also function as a teaching aid. It was completed and erected in October 1986, and is used every semester to show students real connections and real steel members in full scale.Since that time, many other universities have requested a copy of the plans from the University of Florida and have built similar structures on their campuses.PREFACEConnections Teaching Toolkit • iConnection design in an introductory steel course is often difficult to effectively communicate. Time constraints and priority of certain other topics over connection design also tend to inhibit sufficient treatment of connection design. The Steel Connections Teaching tool kit is an attempt to effectively incorporate the fundamentals of steel connection design into a first course in steel design. The tool kit addresses three broad issues that arise when teaching stu-dents steel connection design: visualization, load paths, and limit states.In structural analysis classes, students are shown ideal-ized structures. Simple lines represent beams and columns, while pins, hinges, and fixed supports characterize connec-tions. However, real structures are composed of beams, girders, and columns, all joined together through bolting or welding of plates and angles. It is no wonder that students have trouble visualizing and understanding the true three-dimensional nature of connections!The steel sculpture provides a convenient means by which full-scale steel connections may be shown to stu-dents. The steel sculpture exhibits over 20 different connec-tions commonly used in steel construction today. It is an exceptional teaching instrument to illustrate structural steel connections. The steel sculpture’s merit is nationally recog-nized as more than 90 university campuses now have a steel sculpture modeled after Dr. Ellifritt’s original design.In addition to the steel sculpture, this booklet provides illustrations, and each connection has a short description associated with it.The steel sculpture and the booklet “show” steel connec-tions, but both are qualitative in nature. The steel sculpture’s connections are simply illustrative examples. The connec-tions on the steel sculpture were not designed to satisfy any particular strength or serviceability limit state of the AISC Specification. Also, the narratives in the guide give only cursory descriptions, with limited practical engineering information.The main goals of this Guide are to address the issues of visualization, load paths, and limit states associated with steel connections. The guide is intended to be a teaching tool and supplement the AISC Manual of Steel Construction LRFD 3rd Edition. It is intended to demonstrate to the stu-dent the intricacies of analysis and design for steel connec-tions.Chapters in this guide are arranged based on the types of connections. Each connection is described discussing vari-ous issues and concerns regarding the design, erectability, and performance of the specific connection. Furthermore,every connection that is illustrated by the steel sculpture has multiple photos and a data figure. The data figure has tables of information and CAD-based illustrations and views. Each figure has two tables, the first table lists the applicable limit states for the particular connection, and the second table provides a list of notes that are informative statements or address issues about the connection. The views typically include a large isometric view that highlights the particular location of the connection relative to the steel sculpture as well as a few orthogonal elevations of the connection itself. In addition to the simple views of the connections provided in the figures, also included are fully detailed and dimen-sioned drawings. These views were produced from the full 3D CAD model developed from the original, manually drafted shop drawings of the steel sculpture.The guide covers the most common types of steel con-nections used in practice, however more emphasis has been placed on shear connections. There are more shear connec-tions on the steel sculpture than all other types combined. In addition to the shear connection descriptions, drawings, and photos, MathCAD® worksheets are used to present some design and analysis examples of the shear connections found on the steel sculpture.The illustrations, photos, and particularly the detail draw-ings that are in the teaching guide tend to aid visualization by students. However, the 3D CAD model is the primary means by which the student can learn to properly visualize connections. The 3D model has been developed in the com-monly used AutoCAD “dwg” format. The model can be loaded in AutoCAD or any Autodesk or other compatible 3D visualization application. The student can rotate, pan and zoom to a view of preference.The issue of limit states and load paths as they apply to steel connections is addressed by the illustrations and narra-tive text in the guide. To facilitate a more inclusive under-standing of shear connections, a series of MathCAD®worksheets has been developed to perform complete analy-sis for six different types of shear connections. As an analy-sis application, the worksheets require load and the connection properties as input. Returned as output are two tables. The first table lists potential limit states and returns either the strength of the connection based on a particular limit state or “NA” denoting the limit state is not applicable to that connection type. The second table lists connection specific and general design checks and returns the condition “OK” meaning a satisfactory value, “NA” meaning the check is not applicable to that connection type, or a phrase describing the reason for an unsatisfactory check (e.g.INTRODUCTIONii• Connections Teaching Toolkit“Beam web encroaches fillet of tee”). The student is encouraged to explore the programming inside these work-sheets. Without such exploration, the worksheets represent “black boxes.” The programming must be explored and understood for the benefits of these worksheets to be real-ized.A complete user’s guide for these worksheets can be found in Appendix A. Contained in the guide is one exam-ple for each type of shear connection illustrated by the steel sculpture. Each example presents a simple design problem and provides a demonstration of the use of the worksheet. AppendixB provides a list of references that includes manuals and specifications, textbooks, and AISC engineer-ing journal papers for students interested in further informa-tion regarding structural steel connections.Many Thanks to the following people who aided in the development of this teaching aid and the steel sculpture Steel Teaching Steel Sculpture CreatorDuane Ellifritt, Ph.D., P.E.Original Fabrication DrawingsKun-Young Chiu, Kun-Young Chiu & AssociatesSteel Sculpture Fabrication and ErectionSteel Fabricators, Inc.Steel Sculpture Funding Steel Fabricators, Inc.Teaching tool kit Production StaffPerry S. Green, Ph.D.Thomas Sputo, Ph.D., P.E.Patrick VeltriShear Connection MathCAD® WorksheetsPatrick VeltriAutoCAD Drawings & 3D ModelPatrick VeltriPhotographsPatrick VeltriPerry S. Green, Ph.D.Proofreading and TypesettingAshley ByrneTeaching tool kit FundingAmerican Institute of Steel ConstructionConnections Teaching Toolkit • iiiPreface...............................................................................i. Introduction.....................................................................ii. Chapter 1.The Steel SculptureDesign DrawingsGeneral Notes........................................................1-2 North Elevation.....................................................1-3 South Elevation.....................................................1-4 East Elevation........................................................1-5 West Elevation.......................................................1-6 Chapter 2. Limit StatesBlock Shear Rupture.............................................2-1 Bolt Bearing..........................................................2-2 Bolt Shear..............................................................2-2 Bolt Tension Fracture............................................2-2 Concentrated Forces..............................................2-3 Flexural Yielding...................................................2-4 Prying Action.........................................................2-4 Shear Yielding and Shear Rupture........................2-4 Tension Yielding and Tension Rupture.................2-5 Weld Shear............................................................2-6 Whitmore Section Yielding / Buckling.................2-6 Chapter 3. Joining Steel MembersStructural Bolting..................................................3-1 Welding..................................................................3-2 Chapter 4. Simple Shear ConnectionsShear Connection Examplesand MathCAD worksheets....................................4-1 Double-Angle Connection.....................................4-3 Shear End-Plate Connection...............................4-12 Unstiffened Seated Connection...........................4-12 Single-Plate (Shear Tab) Connection..................4-18 Single-Angle Connection....................................4-18 Tee Shear Connection..........................................4-20Chapter 5: Moment ConnectionsFlange Plated Connections....................................5-1 Directly Welded Flange Connections....................5-5 Extended End Plate Connections..........................5-5 Moment Splice Connections.................................5-7 Chapter 6: Column ConnectionsColumn Splice.......................................................6-1 Base Plates.............................................................6-3 Chapter 7: Miscellaneous ConnectionsClevises.................................................................7-1 Skewed Connection (Bent Plate)..........................7-3 Open Web Steel Joist.............................................7-6 Cold Formed Roof Purlin......................................7-6 Shear Stud Connectors..........................................7-6 Truss Connections.................................................7-6 Chapter 8. Closing RemarksAppendix A. MathCAD WorksheetsUser’s GuideAppendix B. Sources for Additional SteelConnection InformationTABLE OF CONTENTSiv• Connections Teaching ToolkitAs a structure, the steel sculpture consists of 25 steel mem-bers, 43 connection elements, over 26 weld groups, and more than 144 individual bolts. As a piece of art, the steel sculpture is an innovative aesthetic composition of multi-form steel members, united by an assortment of steel ele-ments demonstrating popular attachment methods.At first glance, the arrangement of members and connec-tions on the steel sculpture may seem complex and unorgan-ized. However, upon closer inspection it becomes apparent that the position of the members and connections were methodically designed to illustrate several specific framing and connection issues. The drawings, photos, and illustra-tions best describe the position of the members and connec-tions on the steel sculpture on subsequent pages. The drawings are based on a 3D model of the sculpture. There are four complete elevations of the sculpture followed by thirteen layout drawings showing each connection on the sculpture. Each member and component is fully detailed and dimensioned. A bill of material is included for each lay-out drawing.In general terms, the steel sculpture is a tree-like structure in both the physical and hierarchical sense. A central col-umn, roughly 13 ft tall is comprised of two shafts spliced together 7 ft -6in. from the base. Both shafts are W12-series cross-sections. The upper, lighter section is a W12×106 and the lower, heavier section is a W12×170. Each shaft of the column has four faces (two flanges and two sides of the web) and each face is labeled according to its orientation (North, South, East, or West). A major connection is made to each face of the upper and lower shafts. Seven of the eight faces have a girder-to-column connection while the eighth face supports a truss (partial). Two short beams frame to the web of each girder near their cantilevered end. Thus, the steel sculpture does indeed resemble a tree “branching” out to lighter and shorter members.The upper shaft girder-to-column connections and all of the beam-to-girder connections are simple shear connec-tions. The simply supported girder-to-column connections on the upper shaft are all propped cantilevers of some form. The east-end upper girder, (Girder B8)* is supported by the pipe column that acts as a compression strut, transferring load to the lower girder (Girder B4). A tension rod and cle-vis support the upper west girder (Girder B6). The channel shaped brace (Beam B5A) spans diagonally across two girders (Girder B5 and Girder B8). This channel is sup-ported by the south girder (Girder B5) and also provides support for the east girder (Girder B8).The enclosed CD contains 18 CAD drawings of the steel connections sculpture which may serve as a useful graphi-cal teaching aid.*The identification/labeling scheme for beams, columns, and girders with respect to the drawings included in this document is as follows:CHAPTER 1The Steel Sculpture•Columns have two character labels. The first characteris a “C” and the second character is a number.•Girders have two character labels. The first character isa “B” and the second character is a number.•Beams have three character labels. Like girders, thefirst character is a “B” and the second character is anumber. Since two beams frame into the web of eachgirder, the third character is either an “A” or “B” iden-tifying that the beam frames into either the “A” or “B”side of the girder.•Plates have two character labels that are both arelower-case letters. The first character is a “p”.•Angles have two character labels that are both lower-case letters. The first character is an “a”.Connections Teaching Toolkit • 1-1GENERAL NOTES (U.N.0.)ABBREVIATIONS1-2• Connections Teaching ToolkitFigure 2-1. Block Shear Rupture Limit State (Photo by J.A. Swanson and R. Leon, courtesy ofGeorgia Institute of Technology)Connections Teaching Toolkit • 2-1BSFigure 2-2. Bolt Bearing Limit State(Photo by J.A. Swanson and R. Leon, courtesy of Georgia Institute of Technology)Figure 2-3. Bolt Shear Limit StateFigure 2-4.Bolt Tension Fracture Limit State (Photo by J.A. Swanson and R. Leon, courtesy of Georgia Institute of Technology)2-2• Connections Teaching ToolkitConnections Teaching Toolkit • 2-3Figure 2-5. Flange Local Bending Limit StateFigure 2-6. Web Crippling Limit State Figure 2-7. Web Local Buckling Limit State(SAC Project)2-4• Connections Teaching ToolkitFigure 2-9 Tee Stem Deformation (Astaneh, A., Nader, M.N., 1989)Figure 2-10 Seat Angle Deformation(Yang, W.H. et al., 1997)Figure 2-8 Web Local Yielding Limit State(SAC Project)Figure 2-12.Shear Yielding Limit StateFigure 2-11.Prying Action Limit StateConnections Teaching Toolkit • 2-5Figure 2-14.Tension Fracture Limit StateFigure 2-15.Weld Shear Limit State2-6• Connections Teaching ToolkitFigure 2-16. Whitmore Section Yielding/Buckling Limit StateConnections Teaching Toolkit • 2-7In current construction practice, steel members are joined by either bolting or welding. When fabricating steel for erection, most connections have the connecting material attached to one member in the fabrication shop and the other member(s) attached in the field during erection. This helps simplify shipping and makes erection faster. Welding that may be required on a connection is preferably performed in the more-easily controlled environment of the fabrication shop. If a connection is bolted on one side and welded on the other, the welded side will usually be the shop connec-tion and the bolted connection will be the field connection. The use of either bolting or welding has certain advan-tages and disadvantages. Bolting requires either the punch-ing or drilling of holes in all the plies of material that are to be joined. These holes may be a standard size, oversized, short-slotted, or long-slotted depending on the type of con-nection. It is not unusual to have one ply of material pre-pared with a standard hole while another ply of the connection is prepared with a slotted hole. This practice is common in buildings having all bolted connections since it allows for easier and faster erection of the structural fram-ing.Welding will eliminate the need for punching or drilling the plies of material that will make up the connection, how-ever the labor associated with welding requires a greater level of skill than installing the bolts. Welding requires a highly skilled tradesman who is trained and qualified to make the particular welds called for in a given connection configuration. He or she needs to be trained to make the varying degrees of surface preparation required depending on the type of weld specified, the position that is needed to properly make the weld, the material thickness of the parts to be joined, the preheat temperature of the parts (if neces-sary), and many other variables.STRUCTURAL BOLTINGStructural bolting was the logical engineering evolution from riveting. Riveting became obsolete as the cost of installed high-strength structural bolts became competitive with the cost associated with the four or five skilled trades-men needed for a riveting crew. The Specification for Structural Joints Using ASTM A325 or A490 Bolts, pub-lished by the Research Council on Structural Connections (RCSC, 2000) has been incorporated by reference into the AISC Load and Resistance Factor Design Specification for Structural Steel Buildings. Many of the bolting standards are based on work reported by in the Guide to Design Cri-teria for Bolted and Riveted Joints, (Kulak, Fisher and Struik, 1987).High strength bolts can be either snug tightened or pre-tensioned. When bolts are installed in a snug-tightened con-dition the joint is said to be in bearing as the plies of joined material bear directly on the bolts. This assumes that the shank of the bolt provides load transfer from one ply to the next through direct contact. Bearing connections can be specified with either the threads included (N) or excluded (X) from the shear plane. Allowing threads to be included in the shear planes results in a shear strength about 25% less than if the threads are specified as excluded from the shear plane(s). However, appropriate care must be taken to spec-ify bolt lengths such that the threads are excluded in the as-built condition if the bolts are indeed specified as threads excluded.In pretensioned connections, the bolts act like clamps holding the plies of material together. The clamping force is due to the pretension in the bolts created by properly tightening of the nuts on the bolts. However, the load trans-fer is still in bearing like for snug-tightened joints.The initial load transfer is achieved by friction between the faying or contact surfaces of the plies of material being joined, due to the clamping force of the bolts being normal to the direction of the load. For slip-critical joints, the bolts are pretensioned and the faying surfaces are prepared to achieve a minimum slip resistance. The reliance on friction between the plies for load transfer means that the surface condition of the parts has an impact on the initial strength of slip-critical connections. The strength of slip-critical con-nections is directly proportional to the mean slip coefficient. Coatings such as paint and galvanizing tend to reduce the mean slip coefficient.The two most common grades of bolts available for struc-tural steel connections are designated ASTM A325 and ASTM A490. The use of A307 bolts is no longer that com-mon except for the ½-in. diameter size where they are still sometimes used in connections not requiring a pretensioned installation or for low levels of load. A307 bolts have a 60 ksi minimum tensile strength. A325 and A490 bolts are des-ignated high-strength bolts. A325 bolts have a 120 ksi min-imum tensile strength and are permitted to be galvanized, while A490 bolts have a 150 ksi minimum tensile strength, but are not permitted to be galvanized due to hydrogen embrittlement concerns. High strength bolts are available in sizes from ½- to 1½-in. diameters in 1/8in. increments and can be ordered in lengths from 1½ to 8 inches in ¼ in. incre-ments.CHAPTER 3Joining Steel MembersConnections Teaching Toolkit • 3-1When a pretensioned installation is required, four instal-lation methods are available: turn-of-the-nut, calibrated wrench, twist off bolt, and direct tension indicator methods. The turn-of-the-nut method involves first tightening the nut to the snug tight condition, then subsequently turning the nut a specific amount based on the size and grade of the bolt to develop the required pretension. The calibrated wrench method involves using a torque applied to the bolt to obtain the required level pretension. A torque wrench is calibrated to stall at the required tension for the bolt. Twist-off bolts have a splined end that twists off when the torque corre-sponding to the proper pretension is achieved. ASTM F1852 is the equivalent specification for A325 “twist-off”bolts. Currently, there is no ASTM specification equivalent for A490 tension control bolts. Direct tension indicators (DTIs) are special washers with raised divots on one face. When the bolt is installed, the divots compress to a certain level. The amount of compression must then be checked with a feeler gage.WELDINGWelding is the process of fusing multiple pieces of metal together by heating the metal to a liquid state. Welding can often simplify an otherwise complicated joint, when com-pared to bolting. However, welds are subject to size and length limitations depending on the thickness of the materi-als and the geometry of the pieces being joined. Further-more, welding should be preferably performed on bare metal. Paint and galvanizing should be absent from the area on the metal that is to be welded.Guidelines for welded construction are published by the American Welding Society (AWS) in AWS D1.1 Structural Welding Code-Steel. These provisions have been adopted by the AISC in the Load and Resistance Factor Design Specification for Structural Steel Buildings.Several welding processes are available for joining struc-tural steel. The selection of a process is due largely to suit-ability and economic issues rather than strength. The most common weld processes are Shielded Metal Arc Welding (SMAW), Gas Metal Arc Welding (GMAW), Flux Core Arc Welding (FCAW), and Submerged Arc Welding (SAW). SMAW uses an electrode coated with a material that vaporizes and shields the weld metal to prevent oxidation. The coated electrode is consumable and can be deposited in any position. SMAW is commonly referred to as stick welding.GMAW and FCAW are similar weld processes that use a wire electrode that is fed by a coil to a gun-shaped electrode holder. The main difference between the processes is in the method of weld shielding. GMAW uses an externally sup-plied gas mixture while FCAW has a hollow electrode with flux material in the core that generates a gas shield or a flux shield when the weld is made. GMAW and FCAW can be deposited in all positions and have a relatively fast deposit rate compared to other processes.Figure 3-1. Structural Fastener - Bolt, Nut and Washer Figure 3-2. Direct Tension Indicators and Feeler Gages Figure 3-3. Structural Fastener - Twist-off Bolt3-2• Connections Teaching Toolkit。
Key featuresn15, 50 and 100 psia ranges n225 mV full scalen Absolute reference DescriptionModel 8530C is a miniature, high sensitivity piezoresistive pressure transducer for measuring absolute pressure. The volume behind the diaphragm is evacuated and glass sealed to provide an absolute pressure reference. Full scale output is 225 mV with high overload capability and high frequency response. It is available in ranges from 15 psia to 100 psia. 8530B is available for higher pressure ranges.Endevco pressure transducers feature a four-arm strain gage bridge ion implanted into a unique sculptured silicon diaphragm for maximum sensitivity and wideband frequency response. Self-contained hybrid temperature compensation provides stable performance over the temperature range of 0°F to 200°F (-18°C to +93°C). Endevco transducers also feature excellent linearity (even to 3X range), high shock resistance, and high stability during temperature transients.8530C has been used successfully in many blast test situations. For this application, a protective coating is recommended to eliminate photoflash sensitivity and provide particle impingement protection. This coating does not degrade the superior dynamic response characteristics of the sensor.8530C is available with metric M5 mounting thread as 8530C-XXM5 on special order. See “other options.”Recommended electronics for signal conditioning and power supply are model 126 and 136 general purpose three channel conditioners, ultra low noise 4430A conditioner, or the 4990A-X (Oasis) multi-channel rack mount system.Piezoresistive pressure transducer Model 8530C -15, -50, -100The following performance specifications conform to ISA-RP-37.2 (1964) and are typical values, referenced at +75˚F (+24˚C) and 100 Hz, unless otherwise noted. Calibration data, traceable to National Institute of Standards and Technology (NIST), is supplied.Notes1. 1 psi = 6.895 kPa = 0.069 bar.2. FSO (Full Scale Output) is defined as transducer output change from 0 psia to + full scale pressure.3. Zero Measurand Output (ZMO) is the transducer output with 0 psia applied.4. Significantly higher thermal transient errors occur if the excitation voltage exceeds 10 Vdc. For sensitive phase change studies, manyusers reduce the excitation to 5 Vdc or even 1 Vdc.5. Per ISA-S37.10, Para.6.7, Proc. II. The metal screen partially shields the silicon diaphragm from incident radiation. Accordingly, lightincident at acute angles to the screen generally increases the error by a factor of 2 or 3.6. Warm-up time is defined as elapsed time from excitation voltage “turn on” until the transducer output is within ±1% of reading accuracy.7. Case pressure identifies media containment pressure in the event of diaphragm rupture.8. For best results when using excitation voltages other than 10.0 Vdc, it is recommended that the transducer be calibrated at the desiredexcitation during manufacture. Otherwise larger thermal errors may occur, especially at voltages above 10 Vdc.9. O-ring, EHR93 Parker 5-125, compound V747-75 (Viton®) is supplied unless otherwise specified on purchase order. FluorosiliconeO-ring, EHR96 Parker material L677-70, for leak tight operation below 0°F is available on special order.10. Maintain high levels of precision and accuracy using Endevco’s factory calibration services. Call Endevco’s inside sales force at866-ENDEVCO for recommended intervals, pricing and turn-around time for these services as well as for quotations on our standard products.Other optionsM1 “A” screen, black greaseM2 “B” screen, black greaseM5 Metric threadM37Integral connectorM58 “B” screenM57No screen, gelM59 No screen8530C − XXX − YYY − EExcitation voltage (if no voltage is specified the default is 10 Vdc)A=2 Vdc, B=2.5 Vdc, C=3.3 Vdc, D=5 Vdc, E=7, F=7.5Cable length in inches (ie 8530C-100-200 has a length of 200 inches)If no dash number is specified the default is 30 inches.For lengths ≤ 10 ft specify 1 ft increments (12”, 24”...120”)For lengths ≤ 10 ft specify 5 ft increments (180”, 240”...etc)Pressure range (psia)-15, -50, -100Basic model number10869 NC Highway 903, Halifax, NC 27839 USA |*****************| 866 363 3826© 2022 PCB Piezotronics - all rights reserved. PCB Piezotronics is a wholly-owned subsidiary of Amphenol Corporation. Endevco is an assumed name of PCB Piezotronics of North Carolina, Inc., which is a wholly-owned subsidiary of PCB Piezotronics, Inc. Accumetrics, Inc. and The Modal Shop, Inc. are wholly-owned subsidiaries of PCB Piezotronics, Inc. IMI Sensors and Larson Davis are Divisions of PCB Piezotronics, Inc. Except for any third party marks for which attribution is provided herein, the。
O RIGINAL A RTICLEThree-Column Fixation for ComplexTibial Plateau FracturesCong-Feng Luo,MD,PhD,Hui Sun,MD,Bo Zhang,MD,and Bing-Fang Zeng,MDObjectives:1)To introduce a computed tomography-based‘‘three-columnfixation’’concept;and2)to evaluate clinical outcomes(by using a column-specificfixation technique)for complex tibial plateau fractures(Schatzker classification Types V and VI).Design:Prospective cohort study.Setting:Level1trauma center.Patients:Twenty-nine cases of complex tibial plateau fractures were included.Based on routine x-ray and computed tomography images, all the fractures were classified as a‘‘three-column fracture,’’which means at least one separate fragment was found in lateral,medial,and posterior columns in the proximal tibia(Schatzker classification Types V and VI).Intervention:The patients were operated on in a‘‘floating position’’with a combined approach,an inverted L-shaped posterior approach combined with an anterior–lateral approach.All three columns of fractures werefixed.Outcome Measures:Operative time,blood loss,quality of reduction and alignment,fracture healing,complications,and functional outcomes based on Hospital for Special Surgery score and lower-extremity measure were recorded.Results:All the cases were followed for average27.3months (range,24–36months).All the cases had satisfactory reduction except one case,which had a4-mm stepoff at the anterior ridge of the tibial plateau postoperatively.No case of secondary articular depres-sion was found.One case had secondary varus deformity,one case had secondary valgus deformity,and two cases of screw loosening occurred postoperatively.No revision surgery was performed.Two cases had culture-negative wound drainage.No infection was noted. The average radiographic bony union time and full weightbearing time were13.1weeks(range,11–16weeks)and16.7weeks(range, 12–24weeks),respectively.The mean Short Form36,Hospital for Special Surgery score,and lower-extremity measure at24months postoperatively were89(range,80–98),90(range,84–98),and87 (range,80–95),respectively.The average range of motion of the affected knee was2.7°to123.4°at2years after the operation. Conclusion:Three-columnfixation is a newfixation concept in treating complex tibial plateau fractures,which is especially useful for multiplanar fractures involving the posterior column.The combination of posterior and anterior–lateral approaches is a safe and effective way to have direct reduction and satisfactoryfixation for such difficult tibial plateau fractures.Key Words:tibial plateau fracture,three-columnfixation,combined approach,floating position(J Orthop Trauma2010;24:683–692)INTRODUCTIONComplex tibial plateau fracture management remains clinically challenging.These fractures are usually described as Schatzker Type V and VI or as a C type injury when using the AO/Orthopaedic Trauma Association classification.1,2Bilat-eral dual plating is usually recommended as the definite fixation for this kind of fracture.3–6However,this technique sometimes is not applicable to work in fractures with multi-planar articular comminution.This is especially true when there is posterior shearing or a coronal fracture.7,8Tradition-ally,the treatment for tibial plateau fractures is based on two-dimensional classification systems.Several authors have noted computed tomography(CT)-based three-dimensional consideration of the fracture pattern was important in the treatment of tibial plateau fractures.9–11In recent years,we developed a‘‘three-columnfixation’’technique to treat the multiplanar complex tibial plateau fractures,which is based on three-dimensional understanding of the fractures.In this article,we report on the clinical results of using a‘‘three-columnfixation’’technique through combined approaches:the anterolateral and the posterior approaches.A special‘‘floating position’’was designed to perform the surgery,which was based on a lateral decubitus,and the lower leg was rotated to a prone position when the posterior approach to the tibial plateau was performed.PATIENTS AND METHODSThe patients’data were collected prospectively.Patient demographics and the preinjury status were recorded atAccepted for publication January14,2010.From the Department of Orthopaedic Surgery,Shanghai Sixth People’sHospital,Shanghai Jiaotong University,Shanghai,China.The authors did not receive grants or outside funding in support of theirresearch or preparation of this manuscript.This study was presented in part as a poster presentation at the AnnualMeeting of the Orthopaedic Trauma Association,San Diego,CA,2009.Reprints:Cong-Feng Luo,MD,PhD,Department of Orthopaedic Surgery,Shanghai Sixth People’s Hospital,Shanghai Jiaotong University,600YiShan Road,Shanghai200233,China(e-mail:cong_fengl@yahoo.).CopyrightÓ2010by Lippincott Williams&WilkinsJ Orthop Trauma Volume24,Number11,|683admission.Preliminary management included distal bony skeletal traction or bridging externalfixation where reduction needed to be maintained preoperatively.The externalfixator was used in emergency situations in which there was high-energy injury to the soft tissues.Thefixation bridged across the knee and the pin(s)in the tibial shaft were placed to avoid the site of future operative incisions.All the patients had definitive operative procedures after the soft tissue condition was stable.The mean time from presentation to definitive fixation was8.5days(range,1–18days).On admission,all the patients underwent a standard radiologic protocol of x-rays and CT scans.The CT scans were performed after bony traction or bridging externalfixation had been applied;this was much more informative for decision-making.Besides Schatzker classification,all the fractures were also classified with a‘‘three-column’’concept(Fig.1);on the transverse view,the tibial plateau is divided into three areas, which are defined as the lateral column,the medial column, and the posterior column.These three columns are separated by three connecting lines,namely OA,OC,and OD.Point O is the center of the knee(midpoint of two tibial spines);Point A represents the anterior tibial tuberosity;Point D is the posteromedial ridge of proximal tibia;and Point C is the most anterior point of thefibular head.Point B is the posterior sulcus of the tibial plateau,which intersects the posterior column into the medial and lateral parts.Besides the transverse view,the accurate classification usually was done with the help of frontal view and three-dimensional reconstruction.A‘‘three-column classification’’was used for decision-making.According to this classification,one independent articular depression with a break of the column wall is defined as a fracture of the relevant column.Pure articular depression (Schatzker Type III)was defined as a‘‘zero-column fracture.’’Most of the simple lateral split and split depression fractures (Schatzker Types I and II)belong to a‘‘one-column(lateral column)fracture.’’However,when there is an anterolateral fracture and a separate posterior–lateral articular depression with a break of the posterior wall,the fracture is defined as a‘‘two-column(lateral and posterior column)fracture.’’Articular depression in the posterior column with a break of the posterior wall is also defined as a‘‘one-column(posterior column)fracture’’(not included in any type of the Schatzker classification).The other typical‘‘two-column fracture’’is the anteromedial fracture with a separate posteromedial fragment (medial and posterior column fracture),which traditionally belongs to Schatzker Type IV(medial condylar fracture).The ‘‘three-column fracture’’is defined as at least one independent articular fragment in each column.The most common three-column fracture is a traditional‘‘bicondylar fracture’’(Schatzker Type V or Type IV)combined with a separate posterolateral articular fragment.All the cases were assessed by different team leaders(we have seven trauma teams).If the case was considered to need the‘‘three-columnfixation’’technique,he or she was transferred to the authors’team.All of these29cases were operated on by the authors(C.F.L.and B.F.Z.).Postoperatively,anteroposterior x-rays of the knee were taken in the immediate postoperative period,6weeks,12 weeks,and every6to8weeks until bony union occurred and then2years after the index operation.Tibial plateau angle (TPA),the femorotibial angle,and the medial and lateral posterior slope angle(PA)were measured by one surgeon (B.Z.).Malreduction was defined as intra-articular stepoff of 2mm or more,a TP A$95°/TP A#80°,or P A$15°/P A#–5°.11 Secondary loss of reduction was defined as an increase of5°malalignment or an articular depression of2mm when compared with thefirst postoperative radiograph atfinal follow up.Bony union was defined as radiologicallyfinding at least three healed cortices.Full weightbearing was defined as the time that patients could have painless walking without any aids. Operative TechniqueAll patients were treated by open reduction and internal fixation with the same surgical team.After induction of general anesthesia and antibiotic prophylaxis,the procedure was performed in the‘‘floating position,’’which was based on a lateral decubitus,and the lower leg was rotated to a prone position when the posterior approach to the tibial plateau was performed(Fig.2).A combined approach was used for all the cases.The bridgingfixator was removed before surgery started.A posterior inverted L-shaped approach was indicated to deal with medial column and posterior column fractures (Fig.2).With the patient prone on a radiolucent table,the knee was slightlyflexed by a bump under the ankle.An inverted L-shaped incision begins at the center of popliteus parallel to Langers line superiorly and medial.Distally it turns at the medial corner of the popliteal fossa and is carried downto FIGURE1.Three-column classification.684| q2010Lippincott Williams&Wilkins Luo et al J Orthop Trauma Volume24,Number11,November2010deep fascia.Full-thickness fasciocutaneous flaps were raised paying attention to protecting the sural nerve and short saphenous vein.The tendon of the medial head of the gastrocnemius was then visualized with blunt dissection and then retracted laterally,protecting the neurovascular bundle and displaying the back of the knee capsule (Fig.3).To avoid injury to the neurovascular bundle in popliteal space,all the dissection from medial to lateral should be done beneath popliteus muscle in the proximal part.Overdissection laterally toward the tibial shaft should be avoided,because it is easy to injure the posterior tibial recurrent artery (a branch from the proximal part of the anterior tibial artery and bifurcation of the tibial arteries).The popliteus and soleus origin are then elevated off the posteromedial aspect of the proximal tibia from medial to lateral as needed to gain exposure of the fracture of posterior column.In most situations,under general anesthesia,the entire posterior aspect of the tibia can be exposed without cutting the medial head of the gastrocnemius.The articular surface was elevated by working through the ‘‘fracture window’’at the fracture site by using a periosteum elevator (Fig.4).The reduced articular surface was temporarily fixed with several subchondral Kirschner wires.From the posterior approach,it is not easy to manipulate the anterolateral part of the articular surface,which can only be reduced and fixed through the anterolateral approach in the later stage of the operation.Flexing the knee to relax the posterior soft tissue can help exposure;however,full reduction and buttress plate fixation of the articular surface in the posterior column can only be done with the knee in extension.Because there is no standardimplant for posterior column fractures,an undercontoured 3.5-mm LC-DCP ,3.5-mm T -plate,or a 3.5-mm cloverleaf plate (Synthes,Oberdorf,Switzerland)with the central tip cut off was used for posterior column fixation.For the posteromedial fragment (between Points D and B in Fig.1),the buttress plate was usually put in longitudinally (parallel to the medial ridge of the tibia).An oblique posterior plate (from proximal lateral to the distal medial)was usually used to buttress the postero-lateral fragment (between Points B and C in Fig.1)(Fig.5).To expose the anteromedial (medial column)fracture,anterior dissection can be done along the medial edge of this incision.The fascia was incised between the medial gastrocnemius and the pes anserinus anteriorly.The medial collateral ligament remains intact anteriorly and deep to the pes anserinus.The semimembranosus insertion was released off the bone.Both pes anserinus and semimembranosus can be reattached with nonabsorbable sutures after fracture fixation.A buttress plate (usually 3.5-mm LC-DCP)was put on the medial ridge of the proximal tibia to support the medial column.It is important to not put this plate too posteriorly or the buttress effect will decrease.A conventional anterior approach was used to reduce and fixate the fracture in the lateral column.The arthrotomy was performed through a submeniscal approach.The articular surface was elevated through the ‘‘fracture window’’and fixed with a lateral plate (L-plate or LISS-PT;Synthes).The quality of reduction,the location of the plates,and the length of the screws were confirmed under fluoroscopic guidance.The deep fascia was left open.Subcutaneous tissue and skin were closed over suctiondrainages.FIGURE bined approach:reversed L-shaped approach +anterior–lateral approach.q 2010Lippincott Williams &Wilkins |685J Orthop Trauma Volume 24,Number 11,November 2010Three-Column Fixation for Complex Tibial Plateau FracturesPostoperative Management and Follow UpA continuous passive motion machine was used in the hospital for 3days after the surgery.Partial weightbearing began at the fourth to sixth postoperative week.Fullweightbearing was delayed until the fracture was healed and callus appeared on radiographs.Standard anteroposterior and lateral radiographs were taken at follow up and were evaluated for fracture healing and joint congruity.Bony union time and full weightbearing time were recorded.Both TPA and PA on the radiographs immediately postoperatively and 24months postoperatively were measured and recorded.At 24-month follow up,patients were administered the Short Form 36general health survey,Hospital for Special Surgery,score and lower-extremity measure.Statistical MethodsAll data analysis was done using SPSS 11.0(SPSS Inc.,Chicago IL).Descriptive statistics were used to determine ranges,means,and standard deviations.One-way analysis of variance and Student t tests were used to determine the difference between two means.Correlations were analyzed by using the Pearson correlation coefficient.P ,0.05was considered statistically significant.RESULTSFrom December 2004to July 2006,266cases of tibial plateau fractures were operated on in our center.Among those,there were 32cases diagnosed as ‘‘three-column fractures,’’which needed ‘‘three-column fixation.’’Three patients were excluded because they could not be contacted during follow up,leaving 29cases for the study.The patient demographics and fracture types are shown in Table 1.There were six women and 23men with an average age of 46.8years (range,22–62years).Thirteen fractures were on the left side and 16on the right.All fractures in this series were closed fractures without any distal neurovascular injury or compartment syndromes.The total mean operation time was 140minutes (range,110–180minutes).The mean blood loss was 327mL (range,200–800mL).Two cases had blood transfusion (No.4andFIGURE 4.Intraoperative photograph.Depressed posterolat-eral articular surface (arrow)can be seen from the ‘‘fracture window.’’Direct reduction and fixation was performed through thiswindow.FIGURE 5.Intraoperative photograph.The posterior column was reconstructed and buttressed with two separateplates.FIGURE 3.Schematic diagram of the operative approach to the posterior aspect of the tibial plateau.686|q 2010Lippincott Williams &WilkinsLuo et al J Orthop Trauma Volume 24,Number 11,November 2010No.5).All the cases were followed up for at least24months; the mean follow-up time was months27.3(range,24–36 months).The average radiographic bony union time was13.1 weeks(range,11–16weeks)and the average full weightbear-ing time was16.7weeks(range,12–24weeks).One case(No.21)had secondary varus deformity,one case(No.26)had secondary valgus deformity,and two cases(No.15and No.17)had screw loosening postoperatively.No revision surgery was performed for these complications.There were two cases (No.10and No.12)of wound drainage with negative bacterial culture,and these healed with nonoperative wound manage-ment.No infection was noted.Patient scores for the Short Form36,Hospital for Spe-cial Surgery score,and lower-extremity measure at24months postoperatively were89(range,80–98),90(range,84–98), and87(range,80–95),respectively.The average range of motion of the affected knees was2.7°to123.4°.There were no significant differences in either TPA or PA on the radiographs immediately postoperatively and24months postoperatively (P=0.840for TPA,0.060for medial posterior-slope-angle, and0.061for lateral posterior-slope-angle)(Table2).DISCUSSIONMost of the current classification systems for tibial plateau fractures use two-dimensional images,which usually direct surgeons to pay attention to medial and lateralfixation without thinking of posteriorfixation.With careful review and application of the CT scan for the evaluation for these fractures,7,8,10–12some surgeons have realized the importance of considering posteriorfixation in tibial plateau fractures, especially for the posteromedial fragment.8,13In this article, we reported on a column specificfixation concept:three-columnfixation,which is dependent on the understanding of the fractures using CT scans.The authors believe thisfixation concept for tibial plateau fractures has been poorly reported on in the English literature.Multiplanar complex tibial plateau fractures,especially those involving the posteriorTABLE1.Patient and Immediate Postoperative DataPatient SexAge(years)Time toSurgery(days)SchatzkerClassificationDuration ofFollow Up(months)OperationTime(minutes)BloodLoss(mL)PostoperativeFTA(degree)PostoperativeTP A(degree)PostoperativeP AM(degree)PostoperativeP AL(degree)PostoperativeStepoff(mm)1F558VI24115200174.387.0 6.8 5.202F5918VI24135200173.283.313.810.113M4815VI26130200170.486.4 5.7 3.624M4511VI30175800170.291.77.8 4.105M6212VI27150800170.486.313.5 1.116M4112V26145200169.991.2 4.9 2.907M569V25160300170.392.010.28.518F5911VI24110300171.087.07.0 3.229M3613V27120200176.485.4 2.1 1.0010M559V25180200173.188.9 3.0 2.8411F498VI30140800173.186.6 6.8 5.1212M495VI29120200177.485.211.37.6013M398VI26170300178.388.3 3.3 1.8214M4419VI27130200175.585.87.6 6.4115M5811VI28120200170.188.4 3.2 2.6016M5914VI28110300174.788.213.49.6017M4915VI29130400172.387.410.28.1018M4512VI29160400177.289.311.47.8019M479V30145300172.587.410.67.9020M2612V24135200178.183.512.17.8121M467VI24120400177.487.29.48.2122M429V29150200172.686.512.112.9123M3911VI36140400177.586.68.1 6.7024M388VI27115500173.290.810.77.7025M2514VI32135300173.588.912.67.8126F6110VI27170300172.389.87.3 6.5227F449VI30120200175.086.3 6.0 4.6128M589V24160300174.787.910.68.1129M2211V25170200172.683.813.611.3030M3512VI0140300174.286.39.9 5.8031F4610V0120400175.085.212.07.8032M398V1135400172.388.811.68.91 FTA,femorotibial angle;TPA,tibial-plateau-angle;PAM,medial posterior-slope-angle;PAL,lateral posterior-slope-angle;F,female;M,male.q2010Lippincott Williams&Wilkins |687 J Orthop Trauma Volume24,Number11,November2010Three-Column Fixation for Complex Tibial Plateau Fracturescolumn,are quite difficult to manage clinically.With our technique,posterior columnfixation is stressed when the fractures involve the posterior aspect of the plateau.Instead of classic bilateral(medial and lateral)approaches,a new combination of posterior and anterolateral approaches using careful patient positioning(the‘‘floating position’’)is introduced to treat such a fracture.This new approach is safe and effective in managing complex Schatzker V and VI tibial plateau fractures.Most complex tibial plateau fractures are a result of high-energy injury.Resulting comminution makes interpreting of fracture patterns difficult.Fully understanding these fractures is the basis for successful treatment.Both the Schatzker and AO/Orthopaedic Trauma Association systems classify these fractures according to the appearance on anteroposterior radiographs.14Some of these fractures are easy to misunderstand,especially fractures involving the posterior aspect of the tibial plateau.Wicky et al11reported a cohort of42cases with tibial plateau fractures,which were assessed by plain radiographs and three-dimensional CT separately.As a result,43%(18of42)of the fractures were underevaluated by plain radiographs.On the other hand,such fractures can be difficult tofit into the classification systems currently used,which makes diagnosis and preoperative planning difficult.Macarini et al15studied25cases of tibial plateau fractures.After CT scan,only48%of the cases had the same classification as before the CT scan and60%of the cases had changes in the operative plan.Most authors agree that CT scanning adds invaluable information to the treatment of tibial plateau fractures.7,8,16We think the CT-based‘‘three-column concept’’can help surgeons analyze these fractures three dimensionally providing a better approach andfixation methods.Although Khan et al12had listed coronal splits at the posterior tibial plateau as a separate group in their classifica-tion system,this group of the fracture has been underappre-ciated in other commonly used classification systems.7,16This is partly because this type of fracture usually appears con-fusing on initial radiograph and only can be clearly identified on a CT scan.For example,when the fracture involves theTABLE2.24-Month Postoperative DataPatient No.*X-rayUnion(weeks)FWB(weeks)2-Y ear FTA(degree)2-Y earTP A(degree)2-Y earP AM(degree)2-Y earP AL(degree)2-Y earStepoff(mm)2-Y earExtension2-Y earFlexion2-Y earHSS2-Y earLEM2-Y earSF-3611317175.287.27.6 5.201132939092 21216173.684.713.610.116121908588 31517172.686.7 6.0 3.805120888586 41112171.889.67.8 4.302129949093 51416170.886.313.4 1.213119878593 61212170.091.0 5.0 3.002122939096 71524170.690.610.48.404120868589 81220172.286.67.0 3.313120869084 91112176.485.8 2.3 1.300128988598 101217174.888.5 3.0 2.545120848080 111624173.686.8 6.9 5.024********* 121417176.285.311.37.602126908580 131315178.388.3 3.2 2.010********* 141316175.686.57.6 6.413122848088 151417172.087.8 3.5 2.704110848592 161113174.988.213.29.606121868588 171518173.787.710.28.103124888588 181316177.289.111.27.802120908588 191317172.587.411.48.102120939090 201314178.384.612.17.910126929596 211422182.387.39.48.604121859088 221316174.286.512.112.902128908590 231116176.786.78.2 6.501125939090 241517173.990.311.67.702127908588 251113173.288.412.67.812130939086 261416167.888.67.2 6.826122888088 271315175.686.9 6.2 4.612128969090 281216173.987.910.68.413123949088 291424173.585.013.511.100134989596*Patients30–32were lost to followup.FWB,full weightbearing;FTA,femorotibial angle;TPA,tibial plateau angle;PAM,medial posterior-slope-angle;PAL,lateral posterior-slope-angle;HSS,Hospital for Special Surgery,LEM,lower-extremity measure;SF-36,Short Form36.688| q2010Lippincott Williams&Wilkins Luo et al J Orthop Trauma Volume24,Number11,November2010posterior–lateral aspect of the plateau,the fracture might be visible through an anterior approach,but the reduction and fixation are quite difficult,especially for those without an intact posterior cortex (disruption of the posterior column).Direct reduction through posterior approaches and posterior buttress plating have been recommended by several authors.16–19Other authors have also used this theory to produce better clinical results than older less safe approaches.18,19A bilateral dual plating technique using a posterior–medial approach combined with an anterior–lateral approach has been suggested by several authors.8,20This posteromedial approach,in the supine position,can deal with the poster-omedial fragment,21but it is impossible to obtain a direct reduction when there is an articular depression in the lateral part of the posterior column (between PointsB andC in Fig.1).Posterior–lateral depressed fracture fragments are impossible to deal with in the supine position and can only be reduced and buttressed posteriorly in the prone position.The amount of posterior dissection and the number of buttress plates can be determined from preoperative CT.Unilateral locking plates have also been used to treat complex tibial plateau fractures.Some of the proximal tibial locking plates have special design features with a ‘‘posterior–medial fragment screw’’aiming from anterolateral to poster-omedial.Clinically,they are not strong enough to hold these fragments and prevent secondary varus when compared with a direct posterior–medial buttress plate.7,9,22Barei et al 8investigated 57bicondylar fractures with CT scans and found the occurrence of the posteromedial fragment in approxi-mately one third of the cases.The different shapes and morphologic features of these fragments implicated supple-mentary fixation when managing such a fracture.A com-bination of the ‘‘reversed L-shaped’’posterior approachandFIGURE 6.Female,59years of age,the victim of a traffic accident,with a complex tibial plateau fracture of the rightleg.FIGURE puted tomography scan after emergent bridging exter-nal fixator.q 2010Lippincott Williams &Wilkins |689J Orthop Trauma Volume 24,Number 11,November 2010Three-Column Fixation for Complex Tibial Plateau Fracturesthe anterior–lateral approach is recommended by the authors for those fractures that have a bicondylar fracture,but also for those that have a separate fragment/articular depression in the posterior column.Such fractures will not reduce well withconventional bilateral dual plating techniques.It is important to note that only a small percentage of tibial plateau fractures need the ‘‘three-column fixation’’technique in our series (12%of fractures,or 33of 266of the cases).Without careful planning,these ‘‘three-column fractures’’usually proceed to failure of reduction and fixation.In our technique,through the ‘‘reversed L-shaped’’posterior approach,both posterior–lateral and posterior–medial fragments can be directly reduced and buttressed (reconstruction of posterior column)(Figs.6–9).In the authors’opinion,this approach also obviates the use of a secondposterolateralFIGURE 8.Coronal computed tomography scan indicating both medial and lateral column areinvolved.FIGURE 9.Sagittal computed tomography scan indicating a posterior columnfracture.FIGURE 10.Postoperative x-ray after a combined approach with three-column fixation.690|q 2010Lippincott Williams &WilkinsLuo et al J Orthop Trauma Volume 24,Number 11,November 2010incision as advocated by Carlson.23The posterolateral approach creates problems around the exposure of the common peroneal nerve and management of posterior tibial recurrent artery (a branch from the proximal part of the anterior tibial artery).Through the inverted L-shaped posterior approach,the re-duction of the posterolateral articular surface can be achieved with an elevator through a posterior ‘‘fracture window.’’We recommend application of a buttress plate to the posterolateralplateau and it can be placed in an oblique fashion (from proximal posterolateral to distal posteromedial)(Fig.10).As the last step,the anterior–lateral aspect of proximal tibia (the lateral column)is approached through an anterolateral incision,which can be performed on a patient in the ‘‘floating position’’without a second draping (Fig.2).The lateral column fracture is usually manipulated with minimal invasive techni-ques;the small proximal incision is used to reduce the articular surface and the metaphyseal area is plated percutaneously.Because ‘‘three-column fractures’’are usually quite commi-nuted and the fragments are small,3.5-/4.5-mm systems instead of the conventional 4.5-/6.5-mm systems are recommended for fixation.To the authors’understanding,this is the first time that this ‘‘floating position’’for the combined approach has been reported in the English literature.The weaknesses of this article include the fact that this is a small series of patients and it represents a single center’sFIGURE 11.One-year follow-upx-ray.FIGURE 12.One-year follow-upfunction.FIGURE 13.One-year follow-upfunction.FIGURE 14.Posterior ‘‘reversed L-shaped’’approach.q 2010Lippincott Williams &Wilkins |691J Orthop Trauma Volume 24,Number 11,November 2010Three-Column Fixation for Complex Tibial Plateau Fractures。
