University of Southern California Dissertations and Theses

Contact pressures in the distal radioulnar joint as a function of radial malunion

(USC Thesis Other)

Contact pressures in the distal radioulnar joint as a function of radial malunion

PDF

Download a page range

Download transcript

Copy asset link

Request this asset

Transcript (if available)

Content Contact Pressures in the Distal Radioulnar Joint as a Function of Radial Malunion by Cyrus Fram Buhari Thesis Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree MASTER OF SCIENCE (BIOMEDICAL ENGINEERING) August 2001 Copyright 2001 Cyrus Fram Buhari Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. UMI Number: 1406438 ___ ® UMI UMI Microform 1406438 Copyright 2001 by Bell & Howell Information and Learning Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. Bell & Howell Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, Ml 48106-1346 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. This thesis, written by Cyrus Fram Buhari under the guidance of his/her Faculty Committee and approved by all its members, has been presented to and accepted by the School of Engineering in partial fulfillm ent of the requirements for the degree of Master of Science, Biomedical Engineering Date' March 2 0 0 1 Faculty Committee Chairm/a Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Dedication: This Master’s Thesis is dedicated to Frances Elizabeth Sharpe, M.D. Her never- ending pursuit of excellence both as a brilliant orthopedic surgeon and as a scientist has been something that I have admired from the time this project began. Her dedication, and skill have given me something to strive for in my life and future career. This paper is also dedicated to my mentor and friend, Edward Ebramzadeh, Ph.D. He has educated me in the field of medical research by trying to instill in me the scientific integrity that he displays in his work on a daily basis. He has been much more than a committee advisor in my life and I thank him for being my friend. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. A cknow ledgem ents: I would like to acknowledge all the people who gave me support while working toward this thesis. All of my friends at Orthopaedic Hospital deserve some recognition in the completion of this study. Especially, Jim Alexander, who machined parts in exchange for beer, Julie Hamilton, who jumped at every opportunity to aid the laboratory with her wisdom, and Michael Liang, who worked with me until he quit and went to a dot-com company. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Table of Contents: List of Figures...........................................................................................................................v Abstract........................................................................................................................... vii Introduction:....... 1 Evolution of the Wrist Joint:...............................................................................................2 Anatomy:.............................. ...4 Purpose of Study:....................... ......................................................6 Materials and Methods:...................... 8 Specimen Preparation:....................... 8 Fuji film preparation:................. 9 Data Acquisition:............................... 9 Results:....................................................................................................................................20 Axial Load.................................................. 21 V olar Flexion........................ .................................................. ..........................................24 Dorsiflexion..................... 27 Pronation................................................................ 30 Supination................................... 33 Radial Deviation........................................................................... 36 Ulnar Deviation............... 39 Discussion:........................................................................................................... 42 Mean Pressure.....................................................................................................................43 Peak Pressure.............................................................. 45 Contact Area ........................................... 46 Overview and Current Understanding of DRUJ Contact Pressure................................ 47 Conclusion:.............................................................................................................................51 References:........ 53 Appendix:........ I iv Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. List of Figures: Figure 1: ............... 8 Figure 2 : ........................................................... 9 Figure 3 : ......................................................................... 9 Figure 4 : ......................................................... 11 Figure 5 : .................................................................................................................................. 12 Figure 6 : .................................................................................................................................. 12 Figure 7 : ............................................................... 12 Figure 8 : ................................ 12 Figure 9 : ......................... 13 Figure 10:................................................................... 13 Figure 11:.............. 14 Figure 1 2 :.................................................................................................................... 14 Figure 13:................................................... 15 Figure 14: ........................................................ 17 Figure 1 5 :................................................................................................................................21 Figure 16:................................... 22 Figure 17:............................................. 22 Figure 1 8 :...................................... .23 Figure 19: ........................................... 24 Figure 2 0 :.......................................... 25 Figure 21: ............ ....25 Figure 2 2 :................................... 26 Figure 2 3 :............................... 27 Figure 2 4 :................................................. , ................. — .............. 28 Figure 2 5 :................................................... -.................28 Figure 2 6 :.............................................. .29 Figure 27: ........................................ 30 Figure 2 8 :................................................................................................................................ 31 Figure 2 9 :............ 31 Figure 3 0 :.................................... 32 Figure 3 1 :................................................................................................................................ 33 Figure 3 2 :....................................................................................................................... 34 Figure 3 3 :..................................................... 34 Figure 3 4 :................................................................................................................ 35 Figure 3 5 :........................................... 36 Figure 3 6 :..................................................................................... 37 Figure 3 7 :................................................................................................................................ 37 Figure 3 8 :................................................................................................................................ 38 Figure 3 9 :....................................................................................................................... 39 Figure 4 0 :............................................................................................. 40 Figure 4 1 :................ 41 Figure 4 2 :........................................................................... 42 v Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Appendix: Figure 1 :............ I Appendix: Figure 2 : ............................................................................................ II Appendix: Figure 3 :........................................................................ Ill Appendix: Figure 4 : ........................................................ ...IV Appendix: Figure 5 :.............................................. V Appendix: Figure 6 :............................................................................................................. VI Appendix: Figure 7 :............................................................................................................ VII Appendix: Figure 8 :....................................................................................... VIII Appendix: Figure 9 : ........................................................................................... IX Appendix: Figure 10:................................. X Appendix: Figure 11:............................................................................................................XI vi Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Abstract: Contact Pressures in the Distal Radioulnar Joint as a Function of Radial Malunion Pressure sensitive Fuji film was used to measure contact areas and pressures in the distal radioulnar joints of cadaveric human arms. Joint pressure and contact areas varied as a function of simulated physiological loading under combinations of seven anatomical positions and four dorsal malunions (0°, 5°, 10°, 20°) of the distal radius. In 75% of the cases, mean pressure decreased 3-44% from intact to 0° malunion. During pronation, there was an increase of 5-28% in mean pressure with increasing dorsal malunion from 5° to 20°. Consistent increases in peak pressure were recorded with pronation (3-27%), ulnar deviation (6-35%), and dorsiflexion (9-28%). Increasing dorsal malunion had a nonlinear effect on contact pressures under all loading conditions. These results should be taken into consideration when evaluating acceptable thresholds for radial deformity in surgical practice. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Introduction: We use our hands and arms in almost every aspect of life. Many would say that in addition to the ability to think and communicate through spoken language, the use of hands makes humans what they are. The human hand is as intricate a device as seen among any other animal in nature. Evolution has given man a tool with which to control his environment. Six degrees of freedom are required to specify the location of a rigid object in three-dimensional space: three for position (x, y, z), and three for orientation (pitch, roll, yaw).4 5 The joints of the arm, however, allow seven degrees of freedom: flexion-extension, abduction-adduction, and humeral rotation at the shoulder; flexion at the elbow; flexion-extension, abduction-adduction, and pronation-supination at the wrist.4 5 It is at the human wrist join that man gains this extra degree of freedom. To imagine life without the functionality of a wrist joint is very difficult. However, there are books and journal articles totaling thousand upon thousands of pages written about injury, deformation, and disease affecting the wrist. These people either cannot use the tool that evolution has provided them, or they must endure significant amounts of pain while conducting everyday tasks that we would never give a second thought to. The reliance upon a functional wrist is what makes injury so devastating. Before beginning talk about the study itself, it is first necessary to gain some small understanding of the role of wrist and hand development through our existence on earth. Without piercing the surface of evolution too deeply, the anatomy of the human 1 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. wrist and how it relates to everyday function will be described in relation to physiologic ranges of motion and how they are affected by injury. Evolution of the W rist Joint: The ability to significantly supinate and pronate led to the development of a true synovial distal radioulnar joint (see Appendix: Figure 1). A rotational forearm is a necessity in using spears, axes, knives, and in carrying baskets, activities that allowed the evolution from food-gathering to food-producing.4 3 The ability to throw hammer and grasp requires supinating-pronating ability of the forearm, and this adaptive mechanism gave an evolutionary advantage to humans as they learned to control their environment and eventually use tools.4 3 There is some parallel developmental variation in the structure of the mammalian wrist with respect to distal radioulnar and radiocarpal joint morphology. For example, a gorilla’s distal radioulnar joint is most similar to human, while chimpanzee and orangutan are similar to man in many other ways.4 3 Supination and pronation was of no significance in the wrist of the earliest predecessors of man, the primitive amphibian Eryops. The upper extremity contained five phalanges, thirteen carpal bones, a radius, an ulna, and a humerus.4 3 The ulna was the primary weight bearing bone of this animal. In the change from amphibian to reptile, the pectoral girdle developed further allowing greater mobility and increased shock- absorbing effects. The upper extremity early reptile began to evolve by allowing internal rotation. This allowed more pronation of the forearm so as to have the upper extremity more underneath the animal.4 3 2 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. As millions of years passed and these primitive animals evolved to mammalian form, these animals began to take to the trees. Efficient swinging from branch to branch encouraged increased development of rotation at the wrist, and therefore the distal radioulnar joint developed more motion. The distal radioulnar joint began to distract from the triquetrum and pisiform to form a synovial joint. Brachiation developed as a means of propelling the body foreward by swinging from arm to arm. This required even more supination of the forearm. This ability allowed these primates to move effectively through trees and gain access to the smaller terminal branches of the trees where food was more abundant. There is controversy over whether ancestral apes had developed a true distal radioulnar joint. Some schools of thought believe that pronation-supination in these mammals was carried through the midcarpal joint, the ball-and-socket configuration allowing this rotational motion.4 3 As this evolution of the upper extremity continued, a bipedal mammal was believed to have had a relatively large brain, an opposable thumb, and a distal radioulnar joint that allowed pronation and supination (see Appendix: Figure l).4 3 Because this mammal ambulated on two feet, the upper extremity was freed from the requirements of locomotion and could therefore be used for more highly adaptive behaviors such as foraging for food, taking care of infants, and defense. In conjunction with other factors, this may have led to the development of the family’s social structure. The distal radioulnar joint, which developed as an adaptive change to brachiation and terminal branch feeding, was an excellent adaptive mechanism for the ultimate development of bipedalism. 3 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. The embryology of modem human wrists goes through a phase of separate radial and ulnar wrist joints. Supination-pronation is limited to about 90 degrees in the monkey, and it is consistent with its semi-brachiating locomotion. In evolving from monkeys to apes, the ulna lost its articulation with the triquetrum and pisiform, has regressed proximally, and has expanded into a neomorphic ulnar head with distinct synovial articulation with the radius. This accounts for the 160-180 degree supination-pronation in the great apes.4 3 ,4 5 The chimpanzee joint has a fully developed synovial inferior distal radioulnar join. It has a large, firmly anchored triangular fibrocartilage complex and a well- developed separate meniscus. The ulnar carpus is more open in chimpanzee wrist joints allowing more freedom of movement.4 3 The wrist joint has evolved over a period of approximately 280 million years. It began as a pectoral ray on amphibian creatures. In the last four million years the wrist has changed only slightly. One of the evolutionary changes in this more recent period of the last four million years is the further development of the distal radioulnar joint. Its development has come to allow increased range of pronation and supination in order to get more rotation at the wrist. Anatomy: Understanding the anatomy of the wrist j oint is essential in the understanding of the normal and pathological states and function of the hand. The human upper extremity, excluding the hand, consists of three main joint complexes: the shoulder, the elbow and the wrist. The wrist complex is made up of 8 carpal bones and two long bones, the radius 4 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. and ulna (see Appendix: Figure 2 and Figure 3). The carpal bones articulate with the ulna at the articular disc or triangulo-fibrocartilage complex (TFCC) (see Appendix: Figure 4). This articulation is known as the radiocarpal joint (see Appendix: Figure 2 and Figure 3). The distal radioulnar joint is located proximal to the radiocarpal joint and is comprised of the distal portion of the ulna, the ulnar styloid, and a small concavity, located medially in the distal portion of the radius, the ulnar notch (see Appendix: Figure 2 and Figure 3). The distal radioulnar joint is a pivot type of synovial joint. During active motion, the radius rotates around the relatively fixed ulna. The triangular ligament, a component of the TFCC, binds the ends of the ulna and radius together, operates as an articular disc, and is the main uniting structure of this joint. The base of the articular disc is attached to the medial edge of the ulnar notch of the radius, and its apex is attached to the lateral side of the base of the ulnar styloid. The proximal surface of this triangular ligament articulates with the distal aspect of the ulna. This articular disc separates the cavity of the distal radioulnar joint from the cavity of the radiocarpal joint. A fibrous capsule surrounds and encloses the distal radioulnar joint. The synovial membrane extends superiorly between the radius and the ulna to the sacciform recess. This redundancy of the synovial capsule accommodates the twisting of the capsule that occurs when the distal end of the radius travels around the fixed distal end of the ulna during pronation and supination. Two main ligaments are associated with the distal radioulnar joint. These are the anterior and posterior wrist ligaments, which strengthen the fibrous capsule. These are relatively weak transverse bands which extend from the radius to the ulna across the 5 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. anterior and posterior surfaces of the joint. The distal radioulnar joint is supplied blood via the anterior and posterior interosseous arteries. The anterior and posterior interosseous nerves supply innervation to the joint. A flat fibrous ligament runs the distal two-thirds of the length of the forearm between the radius and ulna. This is the interosseous membrane. The interosseous membrane divides the forearm into an anterior and posterior compartment. During pronation and supination, the interosseous membrane becomes taught and adds an endpoint to these motions. Purpose of Study: Fractures of the distal radius are among the most commonly seen fractures in orthopedics.1 The initial goals of treatment are directed toward restoration of normal anatomy, as judged by radiographic parameters of radial height, radial inclination, and volar tilt. Despite Colies’ original description of favorable outcome with this injury, more recent studies describe a significant rate of complications following fracture.2-4 While the severity of the fracture and involvement of the articular surfaces of the radiocarpal or distal radioulnar joint affect final outcome, the effect of extra-articular fracture reduction is less clear. In evaluating extra-articular fractures, several studies have evaluated the effects of radiographic outcome on clinical results.5-9 Biomechanical studies have evaluated the effects of fracture malunion on radiocarpal joint pressures to better determine acceptable degrees of deformity following distal radius fractures.10-17 A Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. range of acceptable radiographic parameters has been supported by both clinical and radiographic studies. Although recommended radiographic parameters are based on the effects on the radiocarpal joint, several clinical studies have attributed poor clinical outcome to 2 4 18 22 dysfunction at the distal radioulnar joint. ’ ’ Because of these findings, increased attention has recently been directed to the distal radioulnar joint in its intact and pathologic condition.' ’2 3 2 6 While few studies have evaluated normal contact pressures in 23 27 the distal radioulnar joint ’ , no studies have evaluated the effect of distal radial malunion on contact pressures in the distal radioulnar joint. The purpose of this study was to develop a model that would allow for the evaluation of contact pressures in the distal radioulnar joint as a function of sagittal plane angulation of the distal radius. A model that can accurately represent the changes in contact pressures at the distal radioulnar joint may provide insight into achieving better post-surgical outcomes following operative fixation of fractures of the distal radius. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Materials and Methods: Specimen Preparation: Eight fresh (unembalmed), frozen cadaveric arms transected at the mid-humerus were stripped of soft tissues, leaving intact the elbow and wrist joint capsule, the interosseous membrane, and the pronator quadratus muscle. A small incision was made at the dorsal surface of the distal radioulnar joint capsule for Fuji film insertion. Each specimen was potted in cement at the level of the metacarpals. Specimens were radiographed before any testing was done and after each individual test. The following (radiographic parameters) for each specimen was measured: radial inclination, radial height, and volar inclination (Figure 1). The normal sagittal plane angulation of the radiocarpal joint with respect to the radial shaft is 11 degrees (+/- 2.5) (see Appendix: Figure 5 and Figure 6). This is referred to as volar inclination or volar tilt. This angle is most commonly affected in distal radius fractures, again most commonly becoming a dorsal angular deformity. The malunion jig allowed control of the volar inclination in the sagittal plane while restricting deviation in other planes. Figure 1 Anteroposterior (left) and lateral radiographs (right) are used to measure radial inclination, radial height, and volar tilt. Radial inclination is indicated on the anteroposterior radiograph by a curved arrow. Volar tilt is indicated on the lateral radiograph by a curved arrow. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fuji film preparation: Two specifications of Fuji film were used for this project. “Super-low pressure,” type was used to measure within the range of 0.5 to 2.6 MPa. If the pressures observed on the film, once it was removed, were outside the range, or if high levels of saturation occurred, “low pressure,” film was used. The range for "low-pressure," film was 2.5 to 10 MPa. In order to prevent any contact with moisture while inside the wrist joint capsule, sheathes were made for each film specimen using two thin sheets of plastic. The two sheets were sealed together using a hot iron. The combined thickness was acceptable and comparable to transducers used in other joint pressure studies. All Fuji film tracings were scanned immediately to prevent any degradation. Data Acquisition: The specimens were placed into a Bl-axial servo hydraulic MTS loading frame (MTS, Minneapolis, MN) (Figures 2 and 3). Figures 2 and 3 The figure on the left shows a cadaver specimen fixed in the MTS load frame prepared to be tested. The figure on the right shows a cadaver specimen during a test (ulnar deviation). 9 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Each hand was potted to the level of the base of the metacarpals. The cemented portion of the hand was placed into a modular box and fixed to a U-joint that permitted rotation in one direction. For each of the specified loading conditions, the jig was rearranged to accommodate motion in the corresponding direction. The U-joint bearing could be set to allow either flexion or extension, or radial and ulnar deviation (see Appendix: Figure 6, Figure 7, and Figure 8). During pronation and supination of the wrist, a block was placed in the U-joint preventing any rotation at the radiocarpal joint (see Appendix: Figure 7). The humerus was secured in a horizontally mounted rotational bearing, which preserved rotational degree of freedom about the long axis of the humerus. A rotational degree of freedom was maintained at the elbow. This rotation about the long axis of the humerus is necessary in order to keep the wrist and elbow joints along the same vertical axis without damaging the specimen. The elbow was placed at 90 degrees with the forearm in neutral rotation. Length adjustable cables were attached to the base and to the pot, making each desired motion test stop at pre-determined angles of volar flexion, dorsiflexion, radial deviation, and ulnar deviation (see Appendix Figure 8 and Figure 9). Once in the load frame, the dorsal capsule of the distal radioulnar joint was opened. Low (2.5 -10 MPa) and super-low pressure (0.5 - 2.6 MPa) Fuji film (Fuji Film, Sensor Products, E. Hanover, NJ) strips were cut to fit the distal radioulnar joint. Each Fuji film strip was placed inside a sealed plastic sheath in order to prevent moisture from contacting the film. Thickness of the Fuji film inside the plastic sheath was 0.150 millimeters (± 0.005mm). This was inserted into the joint through the dorsally opened capsule. Once fully inserted, the film was marked at the dorsal aspect of the distal radius 10 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. with a soft tip felt pen. This reference mark was used as a landmark to film position relative to the joint. Separate tracings were obtained for insertion with 0 N applied load, and under each of the following load conditions: axial load (Figure 4) to 100 N, axial load to 100 N combined with radial deviation (Figure 9) to 10 degrees, ulnar deviation (Figure 10) to 20 degrees, pronation (Figure 7) to 70 degrees and supination (Figure 8) to 70 degrees. An axial load of 50 N was combined with volar flexion (Figure 5) and dorsiflexion (Figure 6) to 45 degrees each. This reduction in load axial load for volar flexion and dorsiflexion was necessary to prevent damage to the specimens. During these motions, much of the vertical load is transmitted to the joint through soft tissue TFCC and the carpal joint. Figure 4 This figure illustrates a normal wrist joint in neutral position in three planes of motion. 1 1 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figures 5 and 6 The figure on the left illustrates a normal wrist joint in volar flexion. The figure on the right illustrates a normal wrist joint in dorsiflexion. isa«isssiiies6 Figures 7 and 8 The figure on the left illustrates a normal wrist joint in supination. The figure on the right illustrates the normal wrist joint in pronation. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. __________________ Figures 9 and 10 The figure on the left illustrates a normal wrist joint in radial deviation. The figure on the right illustrates a normal wrist joint in ulnar deviation. After measuring contact pressures in the intact specimen, a radial osteotomy was made 1 cm proximal to the distal radioulnar joint. A thin, flexible bone bridge was left intact to aid in maintaining coronal plane alignment and to prevent any deviation in radial height. A locking ball-and-socket jig was then rigidly fixed to the proximal and distal fragments using stainless steel surgical screws. This jig was locked at desired positions, creating angles of simulated malunion (Figures 11 and 12). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figures II and 12 The figure on the left is and anteroposterior view of a cadaver arm after the radial osteotomy has been performed. The ball-and- socket jig is also shown from the top. The figure on the right is the lateral view of the same cadaver arm. The jig is shown from a side view here. Radiographs were used to confirm accurate simulated malunions of 0 degrees of normal, 5 degrees dorsal, 10 degrees dorsal, and 20 degrees of dorsal angulation. PA radiographs confirmed maintenance of radial height and inclination. The same loading conditions were repeated for each specimen at each simulated malunion angle. An example of a radiograph of one specimen locked into position using the malunion jig is seen in Appendix Figures 5 and 6. Data Analysis: All Fuji film specimens were digitized within ten minutes of their testing and removal from the distal radioulnar joint capsule. All specimens were scanned at a fixed level of brightness and contrast with all color auto-correct and gamma correct features inactive. No software or hardware filters were used in digitization of the film specimens. 14 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Image resolution was selected at 1400 dots-per-inch (dpi). 1400 dpi is the maximum resolution of the scanner hardware without requiring any software interpolation routines. This resolution was used throughout the experiment. The images were stored directly to the computer’s hard disk drive for data analysis. Each image used approximately 10 to 12 megabytes of disk space. Upon completion of testing, the cadaver arm was removed from the MTS load frame and the wrist joint capsule was dissected. Pictures were taken of the joint surface of the distal radius (sigmoid notch of radius) (see Appendix: Figure 10 and Figure 11). In order to calculate the area of the joint surface, small pieces of foil were pressed onto the surface, leaving a small mold that was subsequently cut and digitized (Figure 13). Figure 13 This figure shows the foil impressions that were pressed onto the dissected distal radioulnar joint surfaces of each of the eight specimens tested. This figure illustrates the variability of the surface area and contour among specimens. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. From the digitized image total surface area of the joint was calculated using imaging analysis software (Sigma Scan Pro, Jandel Scientific Inc.). Calibration of the surface area digitization was done by repeatedly scanning a penny, whose diameter had been measured with a micrometer, in order to find an accurate conversion factor of pixel- to-distance. The imaging software then used this ratio to correlate pixel values with physical distances. After obtaining values for the surface area of each individual cadaver specimen, a digital tracing was made of each of the specimens of foil using PhotoShop (Adobe Systems, Inc.). This tracing was used as an outline to be placed on each individual Fuji film specimen. Using PhotoShop, each joint tracing for that specific cadaver specimen was made as a transparent layer in standard PSD image file format. PSD format allows multiple layers in a single file. Therefore the position of the joint tracing could be manipulated to match position of the joint surface to the exposed film sample. The layer containing the joint tracing was then superimposed on each Fuji film sample from the specific cadaver specimen. To enable correct placement of the joint outline on the Fuji film sample, the distance from the dorsal margin of the joint capsule to the dorsal margin of the joint surface was measured. The distal margin of the joint outline was placed at this measured distance from the dorsal landmark created on each Fuji film specimen. Once each of the respective joint surface outlines had been properly placed on each film sample, the image layers were flattened and compressed into one layer. This image was then saved in Tagged Image File Format or TIFF image. TIFF images are easily recognized and imported by most image analysis software. Each TIFF file is a digitized 16 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fuji film image approximately 10-12 megabytes in size containing a tracing of the joint surface for that specimen (Figure 14). Figure 14 This figure shows Fuji film tracings for an intact specimen. Calibration of the low and super-low Fuji film was done using the MTS machine to simulate ten specified loads within the operational range of the film. Film samples used for calibration were placed in the same plastic sheaths used during the testing procedure. The load was transferred to the film specimens through the calibration jig seen (Figure 15). Load-density curves were generated using a 3rd degree polynomial curve equation obtained with digital-image density analysis software (Scion Corporation, Frederick, MD). A calibration curve was generated each for low pressure and for super- low pressure Fuji film. The images were then analyzed for mean pressure in the joint. Digital mean density subtraction of the 0 N load condition from the loaded condition was performed using the Scion Image software analysis program (Scion Corporation, Frederick, MD). The image analysis software determined the mean density of the Fuji film tracing and a corresponding pressure was calculated for each load condition. ANOVA (analysis of 1 7 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. variance) was used to compare the mean values of pressure among the different conditions of load and malunion. The calibration curves were programmed into Scion Image’s calibrated measurement table. In addition the distance scale was set using the same pixels-to-distance ratio obtained earlier while calculation joint surface areas. The calculation of mean pressure was done using a fixed measurement routine in the Scion Image analysis software. An “irregular section” tool was used to trace around the joint surface and then the measurement routine was activated. The mean density routine calculates average density value within the selection. This is the sum of the density values all the pixels in the selection divided by the joint surface area for that selection. The mean density measurement returned a calibrated pressure reading from each film specimen. Mean density was used over integrated density due to assumptions made by the integration routine. Scion Image’s integrated density routine is a sum of the density values in the selection, with background subtracted. It is computed using the following formula: Integrated Density = N * (Mean - Background), where N is number of pixels in the selection, and Background is the modal density value (Modal Value - Most frequently occurring density value within the selection. Corresponds to the highest peak in the histogram) after smoothing the histogram. Note that this formula assumes that the background is lighter (has lower pixel values) than the object being measured. The background level may be computed incorrectly if there is not a well-defined peak in the histogram. This will happen if there is not a specified selection 18 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. of background in the measurement included within the total selection or if the background is not very uniform. This routine was originally designed for analyzing electrophoresis gels. Mean density is more applicable to an experiment such as this. In order to obtain peak pressure and contact area measurements over the individual joint surfaces, surface plots were made of each digitized image in the region outlined by the joint surface. Each set of data is contained in three columns: x-position, y-position, and pressure. These surface plots assume that any pressure value less than the lowest possible pressure (0.5 MPa) measurable with our film will be flat. This assumption was necessary to reduce that amount of artifact in the surface plot. Any artifact introduced into the data set was most likely due to digitizing the Fuji film samples at such a high resolution (1400 dpi). The individual values from the surface plots were exported to a spreadsheet where the peak value could be obtained. Difficulty in obtaining peak location in many specimens was due to peak pressure reading in multiple locations on the joint surface. The contact areas were converted to percentages of the total surface area for each individual cadaver specimen. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Results: The results are presented in terms of three sets of data: 1) Mean pressure versus increasing dorsal angulation, 2) Peak pressure versus increasing dorsal angulation along with a linear regression line fit of this data, and 3) Contact area versus increasing dorsal angulation. The results are sectioned by loading condition. For example, all three sets of data from the axial loading condition will be presented, followed by volar flexion, etc. Mean and peak pressures are represented on the vertical axis in megaPascals. Dorsal angulation is represented in these plots on the horizontal axis as “malunion.” “Intact,” corresponds to an angulation that represents the anatomic volar tilt for that particular specimen. “0, d5, dlO, d20,” correspond to 0, 5, 10, and 20 degrees of dorsal angulation. Each black line represents an individual specimen throughout each test. A plot of peak pressures with a linear regression line fit to the data is also presented. Peak pressure on the vertical axis is presented in megaPascals. The horizontal axis shows dorsal angulation represented by “malunion.” “2, 3, 4, 5, and 6,” correspond to intact and 0, 5,10, and 20 degrees dorsal angulation respectively. Contact area for each specimen throughout the testing is presented on a plot similar to that of mean and peak pressure. The format is identical with the exception that on the vertical axis contact area is represented in millimeters squared. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Axial Load (figs. 15-18) Mean pressures ranged from 1.5 to 2.4 MPa. No overall trend was observed with increasing dorsal angulation below 5 degrees. At 5 degrees dorsal angulation 7 of 8 specimens were 5-30% lower than intact. Not all of these specimens remained lower with increasing malunion. 6 of 8 specimens showed an increase in mean pressure from 5 to 10 degrees, and from 10 to 20 degrees. The range of mean pressures between specimens was smallest for 5 degrees dorsal angulation (1.54-1.67 MPa). 5.0 4.0 3.0 < D L _ £ D. 2.0 c CO 0 ) 2 0.0 d20 intact 0 d5 d10 Malunion Figure 15 This plot shows mean pressures for eight specimens with increasing dorsal angulation. Each line represents a single specimen. The dorsal angulation is shown on the x- axis (‘Malunion’). Intact indicates that volar tilt was kept as close to anatomic as possible for each specimen. 0 indicates a volar tilt of 0 degrees (this is often considered neutral). d5,dl0,and d20 indicate simulated dorsal angulation of 5, 10, and 20 degrees, respectively. Peak pressures ranged from 1.9 to 3.5 MPa. Peak pressure during axial load appeared to show a decreasing trend with increasing dorsal angulation. 7 of 8 specimens showed a decrease in peak pressure from intact to 0 degrees. However, only 4 of 8 21 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. specimens maintained the lower value with increasing dorsal angulation. A linear regression was performed on the data and a distinct downward trend was observed with increasing degrees of dorsal angulation. The highest peak pressure seen was at 5 degrees dorsal angulation. 5.0 4.0 c o Q . 5 3.0 a. 2.0 c o C l ) CL 0.0 d10 intact 0 d5 d 2 0 Malunion Figure 16 This plot shows peak pressures for eight specimens with increasing dorsal angulation. Each line represents a single specimen. The dorsal angulation is shown on the x- axis (‘Malunion’). Intact indicates that volar tilt was kept as close to anatomic as possible for each specimen. 0 indicates a volar tilt of 0 degrees (this is often considered neutral). d5,dl0,and d20 indicate simulated dorsal angulation of 5, 10, and 20 degrees, respectively. M alunion Figure 17 This plot shows a linear regression line fit to the peak pressure data. The dorsal angulation is indicated (‘Malunion’). 2 corresponds to intact; 3, 4, 5, and 6 correspond to 0,5,10, and 20 degrees dorsal angulation, respectively. 22 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. The total contact area for each specimen did not show any overall trend either for individual specimens, or between specimens. However 6 of 8 specimens showed an increase in contact area from 0 to 5 degrees of dorsal angulation. The highest value for contact was seen at five degrees of dorsal angulation. 200 180 160 1 140 & 120 1 0 0 c o o d20 d10 intact 0 d5 Malunion Figure 18 This plot shows contact area for increasing dorsal angulation. Contact area is represented in millimeters squared. Each line represents a single specimen. The dorsal angulation is shown on the x-axis (‘Malunion’). Intact indicates that volar tilt was kept as close to anatomic as possible for each specimen. 0 indicates a volar tilt of 0 degrees (this is often considered neutral). d5,dl0,and d20 indicate simulated dorsal angulation of 5, 10, and 20 degrees, respectively. 23 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Volar Flexion (figs. 19-22) Mean pressures ranged from 1.5 to 2.6 MPa. No consistent trends were observed with increasing dorsal angulation. 5.0 4.0 < 0 C L 2 3.0 3 C L 2.0 i 0 > 5 0.0 d10 intact d5 d20 Malunion Figure 19 This plot shows mean pressures for eight specimens with increasing dorsal angulation. Each line represents a single specimen. The dorsal angulation is shown on the x- axis (‘Malunion’). Intact indicates that volar tilt was kept as close to anatomic as possible for each specimen. 0 indicates a volar tilt of 0 degrees (this is often considered neutral). d5,dl0,and d20 indicate simulated dorsal angulation of 5, 10, and 20 degrees, respectively. Peak pressures ranged from 2.1 to 4.2 MPa. 6 of 8 specimens showed a 4-46% decrease in peak pressure from intact to 0 degrees dorsal. 6 of 8 specimens also showed an increase from 5 to 10 degrees dorsal angulation. Highest pressures were observed at 10 degrees dorsal angulation. The linear regression line shows a slight decrease in peak pressure with increasing dorsal angulation. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 0.0__ intact 0 d5 d10 Malunion d20 Figure 20 This plot shows mean pressures for eight specimens with increasing dorsal angulation. Each line represents a single specimen. The dorsal angulation is shown on the x- axis (‘Malunion’). Intact indicates that volar tilt was kept as close to anatomic as possible for each specimen. 0 indicates a volar tilt of 0 degrees (this is often considered neutral). d5,dl0,and d20 indicate simulated dorsal angulation of 5, 10, and 20 degrees, respectively. 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 t ♦ r ♦ I t + $ 3 4 Malunion ♦ ♦ ♦ I Figure 21 This plot shows a linear regression line fit to the peak pressure data. The dorsal angulation is indicated (‘Malunion’). 2 corresponds to intact; 3, 4, 5, and 6 correspond to 0,5,10, and 20 degrees dorsal angulation, respectively. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. The highest contact areas for 4 of 8 specimens were seen at 5 degrees malunion. In addition, there was a consistent decrease in contact area from 5 to 10 degrees dorsal angulation. 200 180 160 £ 140 & 120 s * 100 1 80 O 60 O 20 d10 d20 d5 intact 0 Malunion Figure 22 This plot shows contact area for increasing dorsal angulation. Contact area is represented in millimeters squared. Each line represents a single specimen. The dorsal angulation is shown on the x-axis (‘Malunion’)- Intact indicates that volar tilt was kept as close to anatomic as possible for each specimen. 0 indicates a volar tilt of 0 degrees (this is often considered neutral). d5,dl0,and d20 indicate simulated dorsal angulation of 5, 10, and 20 degrees, respectively. 26 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Dorsiflexion (figs. 23-26) Mean pressures ranged from 1.45 to 3.2 MPa. 7 of 8 specimens showed a 3-44% decrease in pressure from intact to 0 degrees. 3 specimens showed little change in pressure below 10 degrees of dorsal angulation and then showed a dramatic increase in mean pressure at 20 degrees of malunion. 5.0 4.0 T O CL s g) 3.0 3 in in g > Q . 2.0 c < 0 < 0 2 0.0 intact 0 d5 d10 d20 Malunion Figure 23 This plot shows mean pressures for eight specimens with increasing dorsal angulation. Each line represents a single specimen. The dorsal angulation is shown on the x- axis (‘Malunion’). Intact indicates that volar tilt was kept as close to anatomic as possible for each specimen. 0 indicates a volar tilt of 0 degrees (this is often considered neutral). d5,dl0,and d20 indicate simulated dorsal angulation of 5, 10, and 20 degrees, respectively. Peak pressures ranged from 1.4 to 4.1 MPa. A consistent decrease in mean pressure of 9-28% from intact to 0 degrees of dorsal angulation was seen for 7 of 8 specimens. From 0 to 20 degrees there was a consistent increase in peak pressures with increasing degrees of dorsal angulation. The linear regression line confirms a definite increase in peak pressure as dorsal angulation increases. 27 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 5.0 4.0 3.0 CL 2.0 m C D C L' 0.0 intact d10 d20 0 d5 Malunion Figure 24 This plot shows mean pressures for eight specimens with increasing dorsal angulation. Each line represents a single specimen. The dorsal angulation is shown on the x- axis (‘Malunion’). Intact indicates that volar tilt was kept as close to anatomic as possible for each specimen. 0 indicates a volar tilt of 0 degrees (this is often considered neutral). d5,dl0,and d20 indicate simulated dorsal angulation of 5, 10, and 20 degrees, respectively. 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 3 4 Malunion Figure 25 This plot shows a linear regression line fit to the peak pressure data. The dorsal angulation is indicated (‘Malunion’). 2 corresponds to intact; 3, 4, 5, and 6 correspond to 0,5,10, and 20 degrees dorsal angulation, respectively. 28 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Contact areas initially decreased and then increased with increasing dorsal angulation. 200 180 160 £ 140 & 120 < 0 0 3 ^ 1 0 0 < T > 0 3 - t — * c o o intact d10 d20 Malunion Figure 26 This plot shows contact area for increasing dorsal angulation. Contact area is represented in millimeters squared. Each line represents a single specimen. The dorsal angulation is shown on the x-axis (‘Malunion’)- Intact indicates that volar tilt was kept as close to anatomic as possible for each specimen. 0 indicates a volar tilt of 0 degrees (this is often considered neutral). d5,dl0,and d20 indicate simulated dorsal angulation of 5, 10, and 20 degrees, respectively. 29 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Pronation (figs. 27-30) Mean pressures ranged from 1.4 to 3.6 MPa. 6 of 8 specimens showed a consistent increase (5-28%) in mean pressure with increasing dorsal angulation. These specimens also showed highest mean pressures at 20 degrees of dorsal angulation. 5.0 4.0 0 5 CL s £ CL c to 0 5 2 0.0___ intact d5 d10 d20 0 Malunion Figure 27 This plot shows mean pressures for eight specimens with increasing dorsal angulation. Each line represents a single specimen. The dorsal angulation is shown on the x- axis (‘Malunion’). Intact indicates that volar tilt was kept as close to anatomic as possible for each specimen. 0 indicates a volar tilt of 0 degrees (this is often considered neutral). d5,dl0,and d20 indicate simulated dorsal angulation of 5, 10, and 20 degrees, respectively. Peak pressures ranged from 2.7 to 3.97 MPa. An initial increase in peak pressure was seen from intact to 0 degrees, followed by a decrease from 0 to 5 degrees, and a gradual increase from 5 to 20 degrees of dorsal angulation. All specimens showed a 3- 27% increase in peak pressure from 10 to 20 degrees dorsal angulation. The linear regression shows a definite trend of increasing peak pressure with higher dorsal angulations. 30 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 5.0 4.0 3.0 2.0 .0 0.0 d20 d5 intact 0 d10 Malunion Figure 28 This plot shows peak pressures for eight specimens with increasing dorsal angulation. Each line represents a single specimen. The dorsal angulation is shown on the x- axis (‘Malunion’). Intact indicates that volar tilt was kept as close to anatomic as possible for each specimen. 0 indicates a volar tilt of 0 degrees (this is often considered neutral). d5,dl0,and d20 indicate simulated dorsal angulation of 5 , 10, and 20 degrees, respectively. C U Q - < A < / ) 2 CL < 1 ) CL 4.5 4 3.5 # 3 ♦ 2.5 i 2 1.5 1 - 0.5 - 0 - ..... — | - r ♦ * ♦ t - r 3 4 Malunion I i « Figure 29 This plot shows a linear regression line fit to the peak pressure data. The dorsal angulation is indicated (‘Malunion’). 2 corresponds to intact; 3, 4, 5, and 6 correspond to 0,5,10, and 20 degrees dorsal angulation, respectively. 3 1 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. The largest are of contact was seen at 5 degrees of dorsal angulation. However, no consistent trend was seen with increasing dorsal angulation. 200 180 160 E 140 & 120 n s < D < 100 C J T O • * — . C o O 40 d20 d5 d10 intact 0 Malunion Figure 30 This plot shows contact area for increasing dorsal angulation. Contact area is represented in millimeters squared. Each line represents a single specimen. The dorsal angulation is shown on the x-axis (‘Malunion’). Intact indicates that volar tilt was kept as close to anatomic as possible for each specimen. 0 indicates a volar tilt of 0 degrees (this is often considered neutral). d5,dl0,and d20 indicate simulated dorsal angulation of 5, 10, and 20 degrees, respectively. 32 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Supination (figs. 31-34) Mean pressures ranged from 1.38 to 3.9 MPa. No consistent trend was observed during supination. The highest value for mean pressure was seen during supination at 10 degrees of dorsal angulation. 5.0 4.0 to Q _ 5 0) 3.0 i — 3 co co CD (X 2.0 c CO 0 ) 5 0.0 d20 intact d10 Malunion Figure 31 This plot shows mean pressures for eight specimens with increasing dorsal angulation. Each line represents a single specimen. The dorsal angulation is shown on the x- axis (‘Malunion’)- Intact indicates that volar tilt was kept as close to anatomic as possible for each specimen. 0 indicates a volar tilt of 0 degrees (this is often considered neutral). d5,dl0,and d20 indicate simulated dorsal angulation of 5, 10, and 20 degrees, respectively. Peak pressures ranged from 2.6 to 4.1 MPa. An initial decrease followed by a minimal, if any, increase was observed with increasing degrees of angulation. Linear regression of the data confirmed no consistent increase or decrease with increasing angulation. 33 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. C t) 2 Q . ■ S C CD m OL 2.0 1.0 0.0 , intact d5 Malunion d10 d20 Figure 32 This plot shows peak pressures for eight specimens with increasing dorsal angulation. Each line represents a single specimen. The dorsal angulation is shown on the x- axis (‘Malunion’). Intact indicates that volar tilt was kept as close to anatomic as possible for each specimen. 0 indicates a volar tilt of 0 degrees (this is often considered neutral). d5,dl0,and d20 indicate simulated dorsal angulation of 5, 10, and 20 degrees, respectively. C O 4.5 4 I 2.5 \ < / ) I < 8 2 - I C L I 1 5 j T O » - 3 j < L > ; 1 0.5 - 0 - Malunion Figure 33 This plot shows a linear regression line fit to the peak pressure data. The dorsal angulation is indicated (‘Malunion’). 2 corresponds to intact; 3, 4, 5, and 6 correspond to 0,5,10, and 20 degrees dorsal angulation, respectively. 34 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Contact areas were greatest at 0 and 5 degrees of dorsal angulation. However there is still significant variability between the specimens. No clear trends were seen in contact area for supination 200 180 160 CM 140 120 100 80 40 intact d10 d20 0 d5 Malunion Figure 34 This plot shows contact area for increasing dorsal angulation. Contact area is represented in millimeters squared. Each line represents a singie specimen. The dorsal angulation is shown on the x-axis (‘Malunion’). Intact indicates that volar tilt was kept as close to anatomic as possible for each specimen. 0 indicates a volar tilt of 0 degrees (this is often considered neutral). d5,dl0,and d20 indicate simulated dorsal angulation of 5, 10, and 20 degrees, respectively. 35 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Radial Deviation (figs. 35-38) Mean pressures ranged from 1.6 to 3.2 MPa. 5 of 8 specimens showed little or no change from intact to 5 degrees of dorsal angulation. The highest pressure was seen during this motion was for an intact specimen. 5.0 4.0 CO CL 0) 3.0 c 1 3 C / > (ft 2 Q. 2.0 c ( 0 CD 2 0.0 d20 intact 0 d5 d10 Malunion Figure 35 This plot shows mean pressures for eight specimens with increasing dorsal angulation. Each line represents a single specimen. The dorsal angulation is shown on the x- axis (‘Malunion’). Intact indicates that volar tilt was kept as close to anatomic as possible for each specimen. 0 indicates a volar tilt of 0 degrees (this is often considered neutral), d5,dl0,and d20 indicate simulated dorsal angulation of 5 , 10, and 20 degrees, respectively. Peak pressures ranged from 2.2 to 4.05 MPa. 7 of 8 specimens showed an increase in peak pressure from 5 to 10 degrees and then a decrease from 10 the 20 degrees of dorsal angulation. Linear regression showed a very small, if any, decrease in pressure with increasing angulation. 36 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 5.0 4.0 3.0 8 ! 2.0 OL 1 . 0 . 0.01 ____________ intact 0 d5 c(10 d20 Malunion Figure 36 This plot shows peak pressures for eight specimens with increasing dorsal angulation. Each line represents a single specimen. The dorsal angulation is shown on the x- axis (‘Malunion’). Intact indicates that volar tilt was kept as close to anatomic as possible for each specimen. 0 indicates a volar tilt of 0 degrees (this is often considered neutral). d5,dl0,and d20 indicate simulated dorsal angulation of 5, 10, and 20 degrees, respectively. 4.5 4 3.5 3 2.5 - i 2 1.5 1 0.5 0 # * . t — r 3 4 Malunion Figure 37 This plot shows a linear regression line fit to the peak pressure data. The dorsal angulation is indicated (‘Malunion’). 2 corresponds to intact; 3, 4, 5, and 6 correspond to 0,5,10, and 20 degrees dorsal angulation, respectively. 37 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 7 of 8 specimens showed a decrease in contact area from 0 to 5 degrees. 6 of 8 specimens decreased from 5 to 10 degrees. 5 of 8 specimens decreased from 10 -20 degrees. No consistency among specimens was noted for radial deviation. 200 180 160 I 140 & 120 1 0 0 < - 4 — * o ro c o o intact 0 d5 d10 d20 Malunion Figure 38 This plot shows contact area for increasing dorsal angulation. Contact area is represented in millimeters squared. Each line represents a single specimen. The dorsal angulation is shown on the x-axis (‘Malunion’). Intact indicates that volar tilt was kept as close to anatomic as possible for each specimen. 0 indicates a volar tilt of 0 degrees (this is often considered neutral). d5,dl0,and d20 indicate simulated dorsal angulation of 5, 10, and 20 degrees, respectively. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Ulnar Deviation (figs. 39-42) Mean pressures ranged from 1.5 to 3.2 MPa. All specimens showed an initial decrease (5-24%) in pressure from intact to 0 degrees, followed by an overall increase from 0 to 10 degrees dorsal angulation. 5 of 8 specimens continued to show an increase in pressure above 10 degrees dorsal angulation, whereas 3 showed a decrease above 10 degrees. 5.0 4.0 co CL S 3.0 Q- 2.0 c CO 0 ) 0.0 intact d20 Malunion Figure 39 This plot shows mean pressures for eight specimens with increasing dorsal angulation. Each line represents a single specimen. The dorsal angulation is shown on the x- axis (‘Malunion’). Intact indicates that volar tilt was kept as close to anatomic as possible for each specimen. 0 indicates a volar tilt o f 0 degrees (this is often considered neutral). d5,dl0,and d20 indicate simulated dorsal angulation of 5, 10, and 20 degrees, respectively. Peak pressures ranged from 2.7 to 4.2 MPa. No consistent trend was seen from specimen to specimen, however linear regression showed increasing pressure with increasing dorsal malunion. 39 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 0 .0 intact 0 d5 d10 d20 Malunion Figure 40 This plot shows mean pressures for eight specimens with increasing dorsal angulation. Each line represents a single specimen. The dorsal angulation is shown on the x- axis (‘Malunion’). Intact indicates that volar tilt was kept as close to anatomic as possible for each specimen. 0 indicates a volar tilt of 0 degrees (this is often considered neutral). d5,dl0,and d20 indicate simulated dorsal angulation of 5, 10, and 20 degrees, respectively. CL 1 H 0.5 0 1 2 3 4 5 6 7 Malunion Figure 41 This plot shows a linear regression line fit to the peak pressure data. The dorsal angulation is indicated (‘Malunion’). 2 corresponds to intact; 3, 4, 5, and 6 correspond to 0,5,10, and 20 degrees dorsal angulation, respectively. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. No overall trend was seen with contact area during ulnar deviation. 200 180 160 f 140 & 120 1 0 0 < o (0 -.—I c o o 20 d20 intact d5 d10 0 Malunion Figure 42 This plot shows contact area for increasing dorsal angulation. Contact area is represented in millimeters squared. Each line represents a single specimen. The dorsal angulation is shown on the x-axis (‘Malunion’). Intact indicates that volar tilt was kept as close to anatomic as possible for each specimen. 0 indicates a volar tilt of 0 degrees (this is often considered neutral). d5,dl0,and d20 indicate simulated dorsal angulation of 5, 10, and 20 degrees, respectively. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Discussion: Loads across the wrist joint are difficult to measure. Brand et al calculated a potential 500 kg across the wrist based on muscle cross-sectional areas and excursion length.3 3 In this study, the load applied across the radiocarpal joint was a 100 N (22.5 lbs.) axial load, which corresponds to loads used in other biomechanical studies of the wrist.1 0 n’1 4 ' 1 6 > 2 3 -2 7 > H 3 5 These studies differ in the means of loading, or the load was applied through free hanging weights attached to selected muscles acting across the wrist joint 2 5 - 3 4 , or whether the load was applied directly along the longitudinal axis of the radius.1 1 ’,2 ’ 1 4 The ranges of data reported using the different loading mechanisms do not vary significantly, and does not strongly support the superiority of one loading technique. Viegas et al compared radiocarpal joint pressures using three different loading techniques. In their study, they found no significant difference in the contact pressures using axial loading through the second and third metacarpals, axial loading through all five metacarpals, and axial load applied through the wrist flexor and extensor muscles. While no statistically significant difference was noted, a trend towards greater load (by 40%) was found when a direct axial load through all five metacarpals is applied, as compared with loading using free weights attached to the wrist flexors and extensors.3 6 It is less clear how the loading technique affects measured pressures at the distal radioulnar joint, as it could be argued that the vector pull of the pronators (pronator teres and pronator quadratus) and supinators (biceps and supinator) results in a compressive or distractive force across the distal radioulnar joint. While it is technically feasible to apply 42 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. suspended free weights to the pronator teres and biceps, it is difficult to do this with the pronator quadratus or the supinator muscle, whose vector pull would be more directly compressive across the distal radioulnar joint. Regardless of the loading technique, it is not possible to reproduce in vivo pressures. However, in comparing our pressure data in the intact condition with that of other studies, our data are consistent with pressure data obtained in other studies of intact joints, including radiocarpal, tibiofemoral, and ankle joint pressure studies.12,17,30,36,3 7 Only one study in my review of the literature reported pressure measurements in the distal radioulnar joint, in the intact state, and as affected by joint leveling procedures used to treat Keinboeck’s disease.2 7 There is have difficulty comparing this study’s pressure data with that of Werner et al because of the methodology in opening the distal radioulnar joint, and lack of applied axial load. Mean Pressure Variation in joint pressure and contact areas were noted throughout the given loading conditions and with varying degrees of dorsal angulation of the distal radial fragment. Some consistent trends were identified for mean and peak pressures. No consistent trends were noted for contact area. Factors affecting mean and peak pressure would theoretically be the amount of compression force vectors across the distal radioulnar joint associated with the loading condition, and the degree of joint congruity between the sigmoid notch and the ulnar styloid or ulnar head. This can be altered by joint translation, which occurs most sharply with pronation and supination, and to a lesser extent with volar flexion, dorisflexion, 43 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. radial deviation, and ulnar deviation. In addition, the angular deformity for the simulated function affects joint congruity between the sigmoid notch and ulnar head. For mean pressure, a few trends were identified. For almost all specimens there was a difference (decrease) from intact to 0 degrees. This difference may represent in part the difference between the intact and osteotomized radius. Unfortunately, there is no value for the osteotomized radius in anatomic adjustment. The conditions where a trend could be clearly seen were under ulnar deviation and pronation. Ulnar deviation could increase compressive loads across the distal radioulnar joint. That radial deviation did not show a definite trend, may reflect our selection of loading to only 10 degrees of radial deviation versus 20 degrees of ulnar deviation based on typical ranges of motion for adults. Regardless, the mean pressure showed a steady increase with increasing dorsal angular deformity of the distal radius. Since the major function of the distal radioulnar joint is to allow rotation of the radius about the ulna, one would expect a greater effect on contact pressures during pronation and supination. In addition, the increase in dorsal angular deformity would further cause a reduction in contact of the ulnar head in the sigmoid notch. During pronation, there is a relative increase in mean pressure with increasing dorsal angular deformity. This result is expected due to the reduced amount of translation between the radius and the ulna at the distal radioulnar joint during pronation. An increase in the amount of dorsal angulation would further increase contact area at the distal radioulnar joint increasing the compressive forces at the distal radioulnar joint as the radius moves anterior to the ulna. However, during supination there was no increase in mean pressure 44 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. with increasing dorsal angulation. During supination there is more translation of the sigmoid notch dorsally, hence there would be increased incongruity of the articular surface at the distal radioulnar joint, which can lead to either an increase or decrease in pressure. This would account for lack of a consistent trend with increasing dorsal angulation during this loading condition. During volar flexion and dorsiflexion no trends were observed with increasing dorsal angulation. With these loading conditions, as opposed to the others, the load vector is no longer near parallel with the long axis of either the radius or ulna. The result may be an increase in incongruity at the distal radioulnar joint leading to inconsistency in measured pressures between specimens. Peak Pressure Similar trends were observed for peak pressures. Consistent increases in peak pressure were recorded for pronation, ulnar deviation, and dorsiflexion. However, during the condition of axial load, a steady decrease in peak pressure was observed with increasing dorsal angulation. During axial load the force vector is directly along the long axis of the radial shaft and may represent a distracting force at the distal radioulnar joint. The decrease in peak pressure with increasing dorsal angulation may be due to the increase in incongruity at the joint, resulting in increased distribution of the load through the soft tissues, hence a decrease in compressive forces at the distal radioulnar joint itself. The increase in peak pressure with increasing dorsal angulation during pronation 45 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. may be due, once again, to decreased translation of the radial head under this loading condition. The resulting increase in joint congruity would result in an increase in peak pressures seen at the distal radioulnar joint. The initial decrease seen in dorsiflexion may be due to some amount of joint incongruity introduced by the osteotomy. However, a consistent increase in peak pressure was identified with increasing dorsal angulation. During dorsal flexion there may be an increase in tensile forces along the volar aspect of the TFCC (triangular fibrocartilage complex) and other soft tissues surrounding the joint (i.e. the joint capsule). Increasing the amount of dorsal angulation may add to the tension on the volar surface resulting in compressive forces directed at the distal radioulnar joint. Contact Area Consideration should also be given to joint translation and contact areas. Translation occurred between the radius and ulna during pronation and supination, and to a lesser extent in volar flexion, dorsiflexion, radial deviation, and ulnar deviation. This too can affect the congruity of the ulnar head in the sigmoid notch, thus affecting pressure. The force vectors under radial and ulnar deviation would increase compressive load at the distal radioulnar joint. This is in part supported by the differences in mean contact pressure between loading conditions for intact specimens. The largest differences between loading conditions for intact specimens are between axial load and ulnar 46 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. deviation; axial load and pronation; axial load and supination. Muscle force vectors and soft tissue tension, as well as loading properties, will also affect pressures at the distal radioulnar joint. Finally, joint contact area plays a role in recorded mean pressures with joint translation. The joint area variation during loading is evidenced by the data for each loading condition. Overview and Current Understanding of DRUJ Contact Pressure Increased interest has been shown in problems of the distal radioulnar joint following distal radius fractures.2 ’ 1 8 ‘ 2 1 ’ 2 8 Distal radioulnar joint dysfunction, even in fractures not involving the articular surface of the distal radioulnar joint has been reported to be as high as 19 - 26%.4 , 2 9 In reviewing complications of distal radius fractures, Cooney et al report a higher rate of distal radioulnar joint arthrosis (4.8%) than radiocarpal joint arthrosis (1.8%), again implicating the distal radioulnar joint as a significant factor in outcome following distal radius fracture. However, several biomechanical studies have evaluated the effects of extra- articular distal radius fracture malunion on joint contact pressures in the radiocarpal joint, based on the hypothesis that altered joint contact pressures have the potential lead to degenerative changes in the articular cartilage.3 0 - 3 2 Few studies have examined joint loads over a range of motion. The ranges of flexion, extension, radial and ulnar deviation, pronation and supination selected for this study were held constant for each specimen. They did not reflect the extremes of range of 47 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. motion, which can vary from specimen to specimen. All predetermined angles selected exceed the minimum ranges required for most activities of daily living, as described separately by Brumfield and Palmer.3 8 ’3 9 Using pressure sensors, Ishii et al recorded location of pressure concentration in the distal radioulnar joint at several points of forearm rotation, tracking the change in centroid position throughout range of motion.2 3 The use of Fuji film footprints allowed us to record pressure over a range of motion. While it does not identify the exact angle at which the peak pressure occurs, it does provide a dynamic tracing of pressures over a range of motion, perhaps better reflecting actual surface contact areas and pressures. In the review of literature, there have been no studies describing contact pressures in the distal radioulnar joint under functional motion and loading. Werner et al reported contact pressures in the DRUJ. However, no load was applied across the wrist joint in their study. More recently, Ishii et al have described surface contact areas and pressure centroid location throughout a loaded range of rotation. No pressures were reported in their study, making comparison of methodology difficult. Our data provide a starting basis for future studies of the distal radioulnar joint. Although the simulation of dorsal malunion caused variations in the pressures recorded in the distal radioulnar joint, no consistent changes were seen under any loading conditions with the exception of axial load combined with pronation and supination. This is consistent with the role of the distal radioulnar joint in forearm rotation. The majority of flexion, extension, radial and ulnar deviation occur at the radiocarpal joint and 48 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. therefore would not be expected to have as significant an influence on the load experienced at the distal radioulnar joint. The introduction of increasing degrees of dorsal malunion did not have a linear effect on contact pressures under any of the loading conditions. Interestingly, the greater effects at the distal radioulnar joint were seen at the smaller degrees of malunion (with a marked increase in pressure for pronation, and a similarly marked decrease in pressure for supination). With dorsal angulation of the distal radius, the sigmoid notch sits dorsal to the ulnar head. As described by other authors, when the forearm is rotated into a position of supination, the radius translates into a slightly more dorsal position.2 3 ’4 0 '4 2 Combined with a dorsally anguiated distal radial fragment, there would be increased incongruity of the ulnar head within the sigmoid notch, consistent with in decreased surface contact area between the articular surfaces,' with increase load transfer to the surrounding soft tissues and ligamentous constraints. With pronation, the radius translates slightly volar relative to the ulnar head. The creation of dorsal radial malunion would, therefore, compensate for the dorsal translation, maintaining, and, perhaps, increasing joint congruity in this position, resulting in greater average surface contact pressure. The limitations of this study include the inability to reproduce in-vivo conditions, for several reasons, as previously described. There is considerable technical difficulty in incorporating all of the forearm muscle vectors across the wrist joint. In addition, muscle tension is a dynamic rather than static property, and is not well known or defined even under static conditions. This study only evaluated the effect of sagittal plane malunion on 49 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. contact pressures. Greater effects may be seen with changes in radial height or inclination, as suggested by Adams et al. The use of cadaver specimens introduces variability in results, as no two specimens are identical. The small number of specimens used makes it difficult to achieve statistical significance, although under the conditions of axial load combined with pronation (p = 0.07) and supination (p = .0001), the pressure changes were consistent throughout the various malunions, even with this limited sample size. The use of Fuji film is technically demanding. The film insertion alone can create film artifact, which we tried to minimize by recording and subtracting the 0 N load condition from each load condition. Short et al attempted to reduce film artifact, by excluding values less than 0.97 MPa from their data. This excludes 20 % of the range of the pressure sensitive film, and potentially eliminates 20% of their data. Our technique of film insertion through a limited opening in the dorsal capsule, while designed to minimize joint disruption, allowed only an indirect method of recording the position of the sigmoid notch relative to the Fuji film footprint. Werner et al were able to more accurately record the position of the sigmoid notch, at the cost of significant sofit-tissue disruption, as well as the placement of pin markers, which could affect pressure readings. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Conclusion Fuji film was used to measure contact pressure in the distal radioulnar joints of cadaveric specimens. Consistent and statistically significant data were obtained, despite relatively small sample size, under the condition of axial load combined with rotation. Pressure changes of 1.5-2 times the intact values were seen in three of six specimens under pronation with small degrees of malunion. The relationship between degenerative changes in articular cartilage and changes in contact pressure is not clear. However, there does seem to be a threshold of increase in contact pressures, above which, there seems to be, clinically, an observed increased incidence of degenerative changes. McKellop et al conservatively estimates this to be approximately 150% of normal joint contact pressures.3 0 In evaluating our data, the findings of increase in contact pressures under pronation may help to explain the clinically poor results related to pain and dysfunction at the distal radioulnar joint, despite good radiographic outcome following distal radius fractures. Fractures healing with an acceptable deformity with respect to the radiocarpal joint may result in increased pressure at the distal radioulnar joint, leading to early degenerative changes. While many factors can affect the outcome following fractures of the distal radius, increased interest has been raised in the area of the distal radioulnar joint since it has been clinically identified as a source of post fracture pain and disability. This study attempted to find correlation between sagittal plane malunion of the distal radius and contact pressures at the distal radioulnar joint. The data suggests that a correlation between 51 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. increased sagittal plane deformity and increased contact pressures in the distal radioulnar joint, particularly with coronal plane motion and rotation, does exist. The increase in contact pressure, which may contribute to joint arthrosis, occurs outside of the clinically acceptable parameters for fracture reduction. The model could be expanded to include additional parameters, which may also affect the distal radioulnar joint to an equal or larger extent. However, this model is valid because of the consistency in ranges of pressure. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. References: 1. Owen, R., Melton, L., and Johnson, K., Incidence o f C olies’ Fractures in a North American Community. Am J Public Health, 1982. 72: p. 605-613. 2. Cooney, W., Dobyns, J., and Linsheid, R., Complications o f Colies' Fractures. J Bone Joint Surg, 1980. 62A: p. 613-619. 3. Zemel, N., The Prevention and Treatment o f Complications from Fractures o f the D istal Radius and Ulna. Hand Clinics, 1987. 3(1): p. 1-11. 4. Frykman, G., Fracture o f the D istal Radius Including Sequelae - Shoulder Hand Finger Syndrome, Disturbance o f the D istal Radioulner Joint and Impairment o f Nerve Function. A clinical and Experimental Study. Acta Orthop Scand (Suppl.), 1967. 108: p. 1-155. 5. Solgaard, S., Function after D istal Radius Fracture. Acta Orthop Scand, 1988. 59(1): p. 39-42. 6. Szabo, R., Comminuted D istal Radius Fractures. Orthopedic Clinics o f North America, 1992. 23(No. 1): p. 1-6. 7. Fernandez, D., Fractures o f the D istal Radius: Operative Treatment. AAOS Instructional Course Lectures, 1993. 42: p. 73-88. 8. McQueen, M. and Caspers, J., Colles Fracture: Does the Anatom ical Result Affect Final Function? Journal o f Bone and Joint Surgery [British], 1988. 70-B(No. 4): p. 649-651. 9. Sarmiento, A., Pratt, G., Berry, N., and Sinclair, W., Colies' Fractures: Functional Bracing in Supination. Journal o f Bone and Joint Surgery, 1975. 57-A(No. 3): p. 311- 317. 10. Kazuki, K., Kunsunoki, M., and Shimazu, A., Pressure Distribution in the Radiocarpal Joint M easured with a Densitom eter D esigned fo r Pressure Sensitive Film. J Hand Surg [Am], 1 991.16A(3): p. 401-408. 11. Pogue, D., et a l, Effect o f D istal Radius Fracture Malunion on Wrist Joint Mechanics. J Hand Surg [Am], 1 9 9 0 .15A(5): p. 721-727. 12. Tencer, A., et al., Pressure Distribution in the Wrist Joint. J Orthop Res, 1988. 6(4): p. 509-517. 13. Viegas, S. and Patterson, R., L oad Mechanics o f the Wrist. Hand Clinics, 1997. 13(1): p. 109-128. 14. Viegas, S., et a l, Load Transfer Characteristics o f the Wrist. P art I. The Normal Joint. J Hand Surg [Am], 1987. 12A(6); p. 971-977. 53 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 15. Viegas, S., et a l, Load Transfer Characteristics o f the Wrist. Part II. Perilunate Instability. J Hand Surg [Am], 1987. 12A(6): p. 978-984. 16. Miyake, T., Hashizume, H., Inoue, H., Shi, Q., and Nagayama, N ., M alunited Colies Fracture: Analysis o f Stress Distribution. J Hand Surg, 1 9 9 4 .19B(6): p. 737-742. 17. Wagner, W., Tencer, A., Kiser, P., and Trumble, T., Effects o f Intra-Articular D istal Radius Depression on Wrist Joint Contact Characteristics. J Hand Surg [Am], 1996. 21A(4): p. 554-560. 18. Stoeffeln, D., De Smet, L., and Broos, P., The Importance o f the D istal Radioulnar Joint in D istal Radial Fractures. J Hand Surg [Br], 1998. 23B(4): p. 507-511. 19. Adams, B., Effects o f Radial Deform ity on D istal Radioulnar Mechanics. J Hand Surg [Am], 1993. 18-A(3): p. 492-498. 20. Hagert, C., D istal Radius Fracture and D istal Radioulnar Joint Anatomical Considerations. Handchir Mikrochir Plast Chir, 1994. 26: p. 22-26. 21. Hunt, T., Hastings II, H., and Graham, T., A Systematic Approach to Handling the D istal Radioulnar Joint in Cases o f M alunited D istal Radial Fractures. Hand Clinics, 1998. 14(2): p. 239-249. 22. Kihara, H., Palmer, A., Werner, F., Short, W., and Fortino, M., The Effect o f D orsally Angulated D istal Radius Fractures on D istal Radioulnar Joint Congruency cmd Forearm Rotation. J Hand Surg, 1996. 21A(1): p. 40-47. 23. Ishii, S., Palmer, A., Werner, F., Short, W., and Fortino, M., Pressure Distribution in the D istal Radioulnar Joint. J Hand Surg, 1998. 23A(5): p. 909-913. 24. Kihara, H., Short, W., Werner, F., Fortino, M., and Palmer, A., The Stabilizing Mechanism o f the D istal Radioulnar Joint During Pronation and Supination. J Hand Surg, 1995. 20A(6): p. 930-936. 25. Palmer, A. and Werner, F., Biomechanics o f the D istal radioulnar Joint. Clin Orthop Rel Res, 1984.187: p. 26-35. 26. Palmer, A., The D istal Radioulnar Joint. Hand Clin, 1987. 3: p. 31-40. 27. Werner, F., Murphy, D., and Palmer, A ., Pressures in the D istal Radioulnar Joint: Effect o f Surgical Procedures Used fo r Kienboeck's Disease. J Orthop Res, 1989. 7: p. 445- 450. 28. Biyani, A., Simison, A., and Klenerman, L., Fractures o f the D istal Radius and Ulna. J Hand Surg [Br], 1995. 20B(3): p. 357-364. 54 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 29. Okstam, J., Bongers, K., Karthaus, A., Frima, A., and Klasen, H., Corrective Osteotomy fo r Malunion o f the D istal Radius: The Effect o f Concommitant Ulnar Shortening Osteotomy. Arch Orthop Trauma Surg, 1996. 115: p. 219-222. 30. McKellop, H., et al., The Effect o f Sim ulated Fracture-Angulations o f the Tibia on Cartilage Press, in the Knee Joint. J Bone Joint Surg [Am], 1991. 73A(9): p. 1382-1391. 31. Kettlekamp, D., Hillberry, B., Murrish, D., and Heck, D., Degenerative Arthritis o f the Knee Secondary to Fracture Malunion. Clin Orthop Rel Res, 1988. 234: p. 159-169. 32. Merchant, T. and Dietz, F., Long-term follow -up after fractures o f the tibial and fibular shafts. Journal o f Bone and Joint Surg. [AM], 1989. 71(4): p. 599-606. 33. Brand, P., Beach, M., and Thompson, D., Relative Tension and Potential Excursion o f Muscles in the Forearm and Hand. J Hand surg [Am], 1981. 6A(3): p. 209-219. 34. Wolfe, S., Lorenze, M., Austin, M., Swigart, C., and Panjabi, M., Load Displacem ent Behavior in a D istal Radial Fracture Model. The Effect o f Simulated Healing on Motion. J Bone Joint Surg, 1999. 81A(1): p. 53-59. 35. Short, W., Werner, F., Fortino, M., and Palmer, A., Distribution o f Pressures and Forces on the Wrist After Simulated Lntercarpal Fusion and Kienboeck's Disease. J Hand Surg, 1992. 17A(3): p. 443-449. 36. Viegas, S., et al., The Effects o f Various Load Paths and Different Loads on the Load Transfer Characteristics o f the Wrist. J Hand Surg [Am], 1989. 14A(3): p. 458-465. 37. Thordarson, D., Motamed, S., Hedman, T., Ebramzadeh, E., and Bakshian, S., The Effect o f Fibular M alreduction on Contact Pressures in an Ankle Fracture Malunion Model. J Bone Joint Surg, 1997. 79A( 12): p. 1809-1815. 38. Brumfield, R. and JA Champoux, A Biomechanical Study o f Normal Functional Wrist Motion. Clin Orthop, 1984.187: p. 23-35. 39. Palmer, A., Werner, F., Murphy, D., and Glisson, R., Functional Wrist M otion: A Biomechanical Study. J Hand Surg, 1 9 8 5 .10A(1): p. 39-46. 40. Kapandji, I., The Inferior Radioulnar Joint and Pronosupination, in The Hand, Tubiana, Editor, p. 121-129. 41. Linsheid, R., Biomechanics o f the D istal Radioulnar Joint. Clin Orthop Rel Res, 1992. 275: p. 46-55. 42. Bowers, W., Instability o f the D istal Radioulnar Articulation. Hand Clinic, 1991. 7(2): p. 311-327. 43. Almquist, E., Evolution o f the D istal Radioulnar Joint, Clinical Orthopaedics and Related Research, 1992. 275: p. 5-13. 55 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 44. Ekenstam, F., Anatomy o f the D istal Radioulnar Joint, Clinical Orthopaedics and Related Research, 1992. 275: p. 14-18. 45. Wing, A., Haggard, P., Flanagan, J., Hand and Brain: The Neurophysiology and Psychology o f H and Movements, Academic Press, Inc., San Diego, CA, 1996. p. 1-13. 46. Brumfield, R., Champoux, J., A Biomechanical Study o f Norm al Functional Wrist Joint Motion, Clinical Orthopaedics and Related Research, 1984.187: p. 23-25. 47. Kauer, J., The D istal Radioulnar Joint: Anatomical and Functional Considerations, Clinical Orthopaedics and Related Research, 1984. 187: p. 37-45 48. Moore, K.L., Clincally Oriented Anatomy, W illiams & Wilkins Company, N ew York, NY, 1999. p. 803-804. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Appendix: 1 f i- s ir a & N P ! YA V .\ ll \ C ' \ j / 1 j I .'r-A ) — { j'-i ~ 1 ■ ! ■Ui . ■ ' : ,. s , _ ■ ! Supinal ion Pro nut i on Appendix Figure 1 This drawing shows the rotation of the radius around a stable ulna during supination and pronation. I Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. W f G t o c . 'i r p . m s [?.2A and 5) tnapozoia iTd} Triquetrum (T) „ Pisiform <P) iL: StyiotcJ pro ;< > ... r; ■jfca (SU) Adiculm oi'jC (A) H <?ad oi ulna {HU} ! mprvi-.m ( ' - .} i'istai radi-.-jlnac joint ;Ji Seapnc-d (S) ■’I . ' ; ' 5 „.S ; S R ) Appendix Figure 2 This is a radiograph of the normal anatomy of the human wrist j oint .4 8 II Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. i r , t - r ! V c trp-'C. ;» •-! ... >:acarpas Garoornetacarpai -••'joinquyhTil {oir.t Jtva: collate’ai ligament \rticwiar ■ -iso 'R if-a/: ' .. * a wp*,.w> j \ ''Synoviai , \ ’nombrariH f‘ ’’ ^“ 'P*5 1 - ■ "*U*aearpal Joint ^ , • f n t e r c a r p a l Ulna D'stai radioulnar joint Rad joints Appendix Figure 3 This diagram shows the anatomic components of the normal human wrist.4 8 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Radius •Resting position* (midway between pronation and supination) so that paint faces down v \ Pronation ‘ Supination Articular disc Sfylcd (triangular process ligament) Appendix Figure 4 This drawing illustrates the role of the articular disc or TFCC during pronation and supination.4 8 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Appendix Figure 5 This figure shows an AP radiograph of the a cadaver wrist joint with the malunion jig installed in the radius. This particular example is in normal anatomic position. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Appendix Figure 6 This figure shows a medial-lateral radiograph of the a cadaver wrist joint with the malunion jig installed into the radius. This particular example is in normal anatomic position. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Appendix Figure 7 This figure shows an example of a cadaver wrist during pronation. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Appendix Figure 8 This figure shows an example of a cadaver wrist during volar flexion. VIII Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Appendix Figure 9 This figure shows an example of a cadaver wrist during radial deviation. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Appendix Figure 10 This is a picture of the sigmoid notch of the distal radius. The ulnar styloid articulates with the radius at this, the distal radioulnar joint. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Appendix Figure 11 This is a picture of the ulnar styloid of one cadaver wrist. The superior portion of bone shows a thin layer of articular cartilage. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

Linked assets

University of Southern California Dissertations and Theses

Conceptually similar

PDF

Finite element analysis of the effects of stem geometry, surface finish and cement viscoelasticity on debonding and subsidence of total hip prosthesis

PDF

Comparisons of deconvolution algorithms in pharmacokinetic analysis

PDF

Effects of prenatal cocaine exposure in quantitative sleep measures in infants

PDF

Acidity near degrading poly(DL-lactide-co-glycolide): An in vivo and in vitro study

PDF

Characteristics and properties of modified gelatin cross-linked with saline for tissue engineering applications

PDF

Cellular kinetic models of the antiviral agent (R)-9-(2-phosphonylmethoxypropyl)adenine (PMPA)

PDF

Evaluation of R.F. transmitters for optimized operation of muscle stimulating implants

PDF

Development of ceramic-to-metal package for BION microstimulator

PDF

A model of cardiorespiratory autoregulation in obstructive sleep apnea

PDF

A model of upper airway dynamics in obstructive sleep apnea syndrome

PDF

A finite element model of the forefoot region of ankle foot orthoses fabricated with advanced composite materials

PDF

Design of a portable infrared spectrometer: application to the noninvasive measurement of glucose

PDF

A multimodal screen reader for the visually impaired

PDF

Functional impacts of morphology on synaptic transmission

PDF

Head injury biomechanics: Quantification of head injury measures in rear-end motor vehicle collisions

PDF

An open ear canal sound delivery system

PDF

Cardiorespiratory interactions in sleep apnea: A comprehensive model

PDF

English phoneme and word recognition by nonnative English speakers as a function of spectral resolution and English experience

PDF

Estimation of optical fluorescent impulse response kernel in combined time and wavelength spaces

PDF

A preliminary investigation to determine the effects of a crosslinking reagent on the fatigue resistance of the posterior annulus of the intervertebral disc

Asset Metadata

Creator Buhari, Cyrus Fram (author)

Core Title Contact pressures in the distal radioulnar joint as a function of radial malunion

School Graduate School

Degree Master of Science

Degree Program Biomedical Engineering

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag biology, anatomy,engineering, biomedical,OAI-PMH Harvest

Language English

Contributor Digitized by ProQuest (provenance)

Advisor Ebramzadeh, Edward (committee chair), Khoo, Michael C.K. (committee member), McKellop, Harry (committee member)

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c16-36722

Unique identifier UC11342300

Identifier 1406438.pdf (filename),usctheses-c16-36722 (legacy record id)

Legacy Identifier 1406438.pdf

Dmrecord 36722

Document Type Thesis

Rights Buhari, Cyrus Fram

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the au...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus, Los Angeles, California 90089, USA