Film Critique of the Upper Extremity - Part 2: Elbow and Forearm


Anatomy and critique of the Forearm and Elbow

Author: Nicholas Joseph Jr. RT(R)(CT) B.S. M.S

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Anatomy of the Elbow Joints

Diagnostic Criteria for the AP, Oblique(s) and Lateral views of the Elbow

Diagnostic Criteria for the AP and Lateral views of the Forearm

Summary Points

Test



Objectives:

Upon completion, the reader should be able to:

  • Identify the required anatomy of the elbow and forearm on diagrams and radiographs.
  • Identify the required anatomy for each view of the elbow: AP, medial and lateral obliques, true lateral, and capitulum radial head projections.
  • List the three joints of the elbow and describe the structures forming them.
  • Discuss the location and importance of demonstrating the “fat pads” of the elbow.
  • State the proper positioning and diagnostic criteria for the AP projection of the elbow.
  • State the purpose and give the diagnostic criteria for the AP lateral oblique projection of the elbow.
  • State the purpose and give the diagnostic criteria for the AP medial oblique projection of the elbow.
  • State the diagnostic criteria for the true lateral projection of the elbow.
  • Discuss why it is important to demonstrate three concentric rings on the true lateral projection of the elbow.
  • State the diagnostic criteria for the capitulum radial head view, a.k.a. trauma lateral, tell why this view is often taken.
  • Explain what should be done when the patient is unable to straighten the elbow for the AP projection.
  • State the diagnostic criteria for the AP and lateral projections of the forearm.
  • Discuss how to correct poorly made radiographs of the elbow and forearm.

The purpose of this critique is to raise the technologist’s awareness of what radiologists and orthopedic physicians require when diagnosing and treating injuries and diseases of the upper extremity. It is hoped that your examination of this treatise will result in your producing better radiographs. This film Critique is a visual learning tool that is designed to help you understand the diagnostic criteria for each commonly taken view of the elbow and forearm. Critiquing radiographs is a good exercise in reverse learning. As you look at poorly made radiographs you should reaffirm what should have been done to not make the imaging errors being presented. It is important that you thoroughly review the anatomy of the elbow and forearm since anatomical terms are used in describing radiographs. Determining whether or not stated diagnostic criteria are achieved for each radiographic view is the key to this film critique series. Diagnostic criteria include demonstrating required anatomy, correct positioning, and using optimum radiographic exposure. Finally, the imaging professional must determine if each projection that is part of a complete imaging study is adequate for diagnosis. The basis of this learning module is to emphasize diagnostic standards for each projection, which is of paramount importance where the goal is the presentation of useful radiographic images.

Throughout this learning module radiographs are presented for critique. Before you review the author’s critique make your own observations. Write down your critique so you can compare your analysis with that of the author’s. Always use the diagnostic criteria given for each view as a guide for your critique. Upon completion, take the exam, which presents questions and some radiographs that test key concepts. When finished continue to Part III. Upon completion of Parts I, II and III you will be awarded your certificate of completion.

Anatomy of the Elbow Joints

The elbow is a complex structure formed in part by the distal humerus and proximal ulna and radius. The humeroulnar joint (a.k.a. elbow joint) is a complex hinge type joint. Other joints of the elbow are the radiohumeral and the radioulnar joints, which are pivot joints. These complex articulations can be evaluated when well-positioned radiographs are obtained. But before we can set the standard for diagnostic elbow imaging we must first review the anatomy of the elbow. To fully understanding what a radiologist requires to evaluate a radiograph is also part of the focus of this learning module. Radiographers know how important good positioning and exposure technique is for evaluating fractures, realignment, or soft tissue injury. Therefore, these are points of interest as we critique radiographs. So let’s begin this lesson with a basic review of the anatomy of the elbow and its joints.

In considering the normal anatomy of the elbow we must realize that there are different normal appearances of the elbow during growth and development. This is due to the presence of epiphyseal growth plates that facilitate lengthen of long bones. Epiphyseal growth plates can indicate developmental age of an individual. Normal intra-articular relationships that are age and growth dependent such as the development of the capitulum or olecranon process can also be appreciated. For our purposes we will just consider the normal appearance of the adult elbow in the frontal anteroposterior and lateral projections. The pediatric elbow will also be discuss only briefly to mention some more obvious epiphyseal growth plates.

imageElbow-01
This AP projection of the elbow has the following structures labeled: A) humerus, B) olecranon fossa, C) lateral epicondyle, D) capitulum, E) capitulum-radial joint, F) radial head, G) neck of radius, H) radial tuberosity, I) coronoid, J) medial trochlea, K) medial epicondyle. On the right, a coronal CT slice demonstrates the olecranon process of the ulna within the olecranon fossa of the distal humerus (M) and the coronoid process articulating on the trochlear (L).
imageElbow-02
The three drawing above: Left-anterior view, Right-inferior view, and Middle-posterior view of the distal humerus. (A) Medial supracondylar ridge, (B) lateral supracondylar ridge, (C) medial epicondyle, (D) trochlear, (E) capitulum, (F) radial coronoid fossa, (G) radial fossa, and (H) olecranon fossa.

On the distal medial surface of the humerus there is a pulley-like structure called the trochlea. Just lateral to it is a prominent convex structure called the capitulum. The half sphere structure, the capitulum articulates with the discoid surface of the radius on its inferior surface when the elbow is extended and with its anterior surface with flexion. Just superior to the capitulum is a shallow triangular fossa called the radial fossa. This fossa is related to the radial head during full flexion of the elbow joint. Medially the trochlea composes the inferior, anterior, and posterior portions of the medial condyle. Medial to it and slightly superior is the large medial epicondyle that is expanded to form a large palpatable process. Between the medial epicondyle and the trochlea is a groove for the ulnar nerve that passes posterior to the humerus here. The ulnar nerve often is stimulated causing the proverbial response that is often called the “funny bone” response. The trochlea articulates with the trochlear notch of the ulna to form the humeroulnar joint. Just superior to the trochlea is the coronoid fossa, which articulates with the coronoid process of the ulna to prevent hyperflexion of the elbow joint.

It is important for radiographers to understand that the elbow joint is a synovial diarthrodial type joint. Actually it is a complex articulation having three independent joints: the humeroulnar, humeroradial, and radioulnar joints. The most commonly thought of articulation is the humeroulnar articulation that is a classical hinge type joint. It is formed by the trochlea of the humerus and trochlear notch of the ulna. Its movements are uniaxial permitting only flexion and extension. The other articulation of the elbow is the humeroradial articulation that occurs between the capitulum of the humerus and the cup-like groove of the radial head. The radioulnar articulation occurs between the radial head on the radius and the radial notch on the proximal ulna. This articulation is a pivot type joint that allows supination and pronation of the forearm by permitting the radius to rotate on the ulna. These joints are enclosed in an articular capsule to stabilize the joints along with strong collateral ligaments.

imageElbow-03 imageElbow-04
Two radiographs of the elbow are shown, a true lateral projection on left, and an angled trauma lateral (a.k.a. radial head capitulum) projection on the right. The identified parts on these radiographs are: A) humerus, B) radius, C) ulna, D) supracondylar ridge, E) coronoid process of ulna seen through the radial head, F) olecranon process, G) olecranon, H) trochlear notch. The three joints of the elbow are seen on the trauma lateral view, the humeroulnar articulation (I); the humeroradial articulation (K), and the proximal radioulnar joint (J). The capitulum (L) and medial trochlea (M) are also demonstrated by this view.
image00005 image00006
These two 3-D volume rendered reconstructed images from axial thin-slice CT images demonstrate the articulations of the humeroulnar joint. The left image shows the coronoid process of the ulna (A) and its articulation with the coronoid fossa of the distal humerus (B). On the right is an image that shows the articulation of the olecranon process (C) and the olecranon fossa (D) on the distal posterior aspect of the humerus. The coronoid process limits hyperflexion and the olecranon process limits hyperextension.

The capitulum and the fovea of the head of the radius form the humeroradial joint. It too is a synovial joint. The radius articulates with the humerus during flexion and extension of the elbow. The radius articulates with the ulna both proximally and distally. The proximal lateral border of the ulna has a crescent notch called the radial notch that receives the smooth rounded head of the radius. This proximal articulation along with the distal articulation between the ulna and radius are responsible for pronation and supination movements of the forearm. During this action the radius turns on the ulna along the proximal and distal radioulnar joints.

imageElbow-07
These two CT images demonstrate the humeroradial joint. On the left is a 3-D volume rendered image demonstrating the humeroradial joint (A). The sagittal CT image on the right demonstrates this articulation formed by the articulation (B) fovea of the head of the radius, and (C) capitulum of the humerus.
imageElbow-08
The CT images above are reconstructions from axial data. On the left is a sagittal cut through the elbow and on the right a coronal cut through the elbow. Both pictures demonstrate the humeroradial joint formed by the capitulum of the humerus (A) and the head of the radius (B).
imageElbow-09
These two CT images demonstrate the radioulnar articulation. On the left is a coronal image of the elbow showing the radioulnar joint (A) and on the right the head of the humerus (C) and ulna (B) that form the joint.
The CT images above are reconstructions from axial data. On the left is a sagittal cut through the elbow and on the right a coronal cut through the elbow. Both pictures demonstrate the humeroradial joint formed by the capitulum of the humerus (A) and the head of the radius (B).
imageElbow-10 imageElbow-11
These two radiographs demonstrate the normal epiphyses of bones forming the elbow. These epiphyseal plates are seen at different growth phases of the bones and can mark chronological age. On the left is an AP view that shows the medial epicondylar epiphysis (white arrow) that presents at age 4 years; the lateral epiphysis (yellow arrow) that appears at about age 10 years. The epiphysis of the olecranon process (green arrow) is demonstrated on the lateral view.

Chronologically, the growing elbow will present the capitulum at approximately age 2 years; the medial epicondylar apophysis at 4 years; the trochlear epiphysis at approximately 8 years; and the lateral epicondylar apophysis at about 10 years of age. These epiphyseal plates can mimic fracture in children; therefore knowing their presentations can help avoid misdiagnosis. This means the technologist must correctly demonstrate the elbow to help the radiologist differentiate epiphyseal growth from fracture. These epiphyseal plates can be dislocated with sufficient trauma so good positioning is a must. Normal bone alignments must be evaluated as well so the radiographer should present the anterior humeral line and proximal midradial line relationship accurately. Demonstrating this relationship is critical for identifying subtle epiphyseal dislocations and subtle supracondylar fractures.

imageElbow-12
These two radiographs: Left - is an AP projection, Right - is a Lateral projection showing the developing capitulum (orange arrow), absence of the medial epicondyle (purple arrow), and the absence of the olecranon epiphysis (white arrow).

We have discussed some details of the anatomy of the elbow, which hopefully will guide you in understanding the diagnostic criteria for each view and what is to be demonstrated. Now we must also consider the importance of soft tissue injury. One of the most important indicators of fracture is seen in the soft tissue by the relationship of normal fat pads. We hear a lot about fat pads without defining what they are and why they are seen on routine plain films with the proper exposure. Fat pads are associated with synovial membranes and are often described with them. Their functions are complex and often debated. Basically they are described as articular fat pads. They are flexible, elastic cushions that occupy irregular spaces within joints where synovial fluid does not seem to occupy. Being flexible these folds of tissue promote distribution of lubricant within the joint much like the meniscus in the knee joint. There are three such fat pads in the elbow that should be demonstrated, but are seen only when the elbow is properly positioned at 90 degrees and true lateral. The technologist should know these fat pads, their locations, and how to properly demonstrate them.

The anterior fat pad is located along the anterior distal humerus. The posterior fat pad is located within the olecranon fossa and can only be seen when there is structural injury related to the olecranon fossa. The supinator muscle that contributes to rotation of the radius, it presents a fat stripe located parallel to the anterior distal radius on the true lateral view. Any elevation or displacement of these fat pads may be the only indication of a fracture or effusion in the elbow. The three concentric rings formed by the capitulum, trochlear sulcus, and medial trochlea must be superimposed to prove the elbow is in a true lateral. When these are not aligned the humeroulnar joint space will appear closed and fat pads of the elbow may not be demonstrated.

imageElbow-13 imageElbow-14
These two lateral projections of the elbow demonstrate the importance of “fat pads” when taking radiographs of the elbow. The radiograph on the left shows fat pad displacement due to swelling and effusion within the elbow (white arrows). The radiograph on the right shows the location of fat pads of the elbow, (A) anterior fat pad formed by superimposed coronoid and ulnar fat pads, (B) supinator fat stripe, which can indicate a fracture of the radial head or neck, (C) posterior fat pad located deep within the olecranon fossa and may not be visible on a well positioned normal lateral projection. The posterior fat pad when seen often indicates change within the joint such as a fracture or dislocation. To demonstrate fat pads the elbow must be positioned in a true lateral, be flexed 90 degrees, and have optimal exposure technique.
imageElbow-15
This midsagittal plane CT and drawing show the normal positions of the anterior (B) and posterior (A) fat pads. When these fat pads are elevated following trauma it may indicate intra-articular hemorrhage secondary to fracture of the radial head or neck.
imageElbow-16
This radiograph demonstrates two important lines used to evaluate the interarticular relationships of the elbow. The dotted white line represents the anterior humeral line; the solid white line represents the proximal radial line. The relationship of these two lines to the capitulum is important in evaluating the elbow for capitellar epiphyseal displacement, quality of post reduction, radial dislocations, and subtle supracondylar and transcondylar fractures. A true lateral must be achieved in order to evaluate interarticular relationships.

Exact precision positioning of the elbow is required for the AP views and particularly for the lateral projections. Failed positioning of the lateral views like slight obliquity or rotation could obscure a positive fat pad sign, or a subtle fracture fragment. Post orthopedic reduction requires accurately positioned projections that allow the physician to accurately measure alignment. Poor positioning of the true lateral view can easily misrepresent a supracondylar fracture and other evaluations. Therefore, less than optimal images of the elbow are unacceptable. Because current standards for pediatric radiographic care do not support routine examining of the opposite normal elbow for “comparison,” well made radiographs of the affected elbow should always be taken. With this in mind let’s look at the diagnostic criteria for each routine projection of the elbow.

The routine views of the elbow are:
  1. AP neutral
  2. AP internal and external obliques
  3. True lateral
  4. Trauma lateral (capitulum radial head view)
Glossary of terms:
  • Overexposure (too much mAs)
  • Underexposure (too little mAs)
  • Overpenetrated (too much kVp)
  • Underpenetrated (too little kVp)
  • Positioning error (patient position)
  • Tube error (improper tube angle)
Diagnostic Criteria for the AP, Lateral and Medial Oblique(s) and Lateral views of the Elbow

Purpose: to identify fractures or dislocations of the elbow joints and to identify soft tissue injuries.

  • For the AP view of the elbow the hand and forearm is supinated and the humerus and forearm are placed on the same plane parallel with the image receptor. Make sure the medial and lateral humeral epicondyles are parallel and equal distant from the tabletop.
  • Radiographs should project the anatomy in the following manner:
    1. AP projection: The radiohumeral and humeroulnar joints should be clearly demonstrated and the medial and lateral humeral epicondyles profiled. The radial head and radial tuberosity should be slightly superimposed on the ulna. If the patient is unable to extend the elbow then two AP views should be taken. One is taken with the humerus parallel with the tabletop and the second radiograph taken with the forearm parallel with the tabletop. To properly open the humeroulnar joint the CR enters perpendicular to the joint approximately 2 cm below the medial epicondyle. Always include all soft tissue in the collimated field. At least a fourth of the distal humerus through a fourth of the proximal forearm should be included in the collimated field. Always include the entire fixation device when the elbow is imaged post-operatively. The radiographic exposure technique must demonstrate well penetrated bone architecture. Adequate penetration will demonstrate the lateral margins of the olecranon and olecranon process superimposed on the trochlea (arrows in the radiograph on the right below). The soft tissue shadows and lateral soft tissue margins must be visualized.
    2. imageElbow-17
      This AP projection of the elbow demonstrates well-penetrated bone architecture. These are the same radiograph; the one on the right outlines the olecranon process within the olecranon fossa. It shows what a well penetrated view should demonstrate including a well-penetrated look at the olecranon trochlea articulation. Notice the soft tissue detail is preserved.
    3. AP lateral oblique projection: Purpose is to demonstrate the radial head and radial neck free of superimposition, and an unobstructed view of the radioulnar joint. To do this the radius and ulna must be separated. With the humerus and forearm on the same plane parallel with the image receptor rotate the limb 45 degrees externally. The two radiographs below demonstrate what should be demonstrated on a well-positioned radiograph with optimal exposure. Structures that should be seen are: the radiohumeral joint, capitulum, radial head, radial neck, radial tuberosity, coronoid process, trochlea notch/trochlea articulation, and proximal radioulnar articulation.
    4. imageElbow-18
      This radiograph demonstrates a properly positioned AP lateral oblique projection. It profiles the radiohumeral joint (long white arrow), capitulum, radial head (yellow arrow), radial neck (orange arrow), radial tuberosity, coronoid process (dark blue arrowhead), trochlea notch/trochlea articulation (light blue arrowheads), and proximal radioulnar articulation.
    5. AP medial oblique projection: This view is taken to demonstrate the coronoid process, trochlear notch and medial trochlea in profile. The forearm and humerus are positioned on the same plane parallel to the image receptor. The limb is rotated medially 45 degrees; the hand is pronated. The perpendicular central ray enters 2 cm below the medial epicondyle. The field is well-collimated to include the lateral soft tissues and at least a fourth of the distal humerus and proximal forearm.
    6. imageElbow-19
    7. True lateral projection: For this view the elbow is in 90-degree flexion with the epicondyles superimposed and perpendicular to the image receptor. The humerus and forearm are placed on the same plane. The distal forearm may need to be elevated slightly to align the forearm parallel with the image receptor. The hand is supinated placing the wrist in a true lateral position. The CR is aligned perpendicular to the elbow entering at the elbow joint. Positioning the elbow at 90 degrees allows for visualization of the posterior fat pad when there is significant traumatic injury. The radiographic exposure technique should penetrate the thickest portion of the elbow. There should be sufficient soft tissue detail to see all fat pads without a hot light or windowing digital image. Structures demonstrated are: lateral view of the entire elbow with epicondyles of the humerus superimposed, medial supracondylar ridge, trochlea notch and humeroulnar joint, coronoid process, anterior fat pad of the humerus, and posterior fat pad when sufficient trauma has occurred. The elbow is in a true lateral when three concentric arcs are superimposed. These arcs are formed by the capitulum, trochlear sulcus, and medial aspect of the trochlea.
    8. imageElbow-20
      Structures that should be demonstrated on the true lateral elbow projection are: lateral view of the entire elbow with epicondyles of the humerus superimposed, medial supracondylar ridge (orange arrow), trochlea notch and humeroulnar joint (yellow arrow), coronoid process (blue arrow), and anterior fat pad of the humerus (white arrowhead).
    9. The trauma lateral: a.k.a radial head capitulum view. This view is made with the elbow in a true lateral position and the CR angled 25 degrees towards the head along the long axis of the humerus. Elbow in 90-degree flexion, epicondyles superimposed and perpendicular to the image receptor. The humerus and forearm are placed on the same plane. The distal forearm may need to be elevated slightly to align the forearm parallel with the image receptor. The hand is supinated placing the wrist in a true lateral position. This view should show the radial head in the lateral projection free of the olecranon process. Other structures that should be demonstrated are the humeroradial joint, radial head, capitulum, radial notch of the ulnar and radioulnar joint, and the neck of the radius. A properly positioned elbow with the correct tube angle will demonstrate the normal radial head aligned with the coronoid process, and the medial trochlea displayed distal to the capitulum free of superimposition.
    10. imageElbow-21
      The radial head capitulum view demonstrates the humeroradial joint (white arrow), radial head (dark blue arrow), capitulum (orange arrow), radial notch of the ulnar and radioulnar joint (yellow arrow), and the neck of the radius (light blue arrow). A properly positioned elbow with the correct tube angle will demonstrate the normal radial head aligned with the coronoid process, the medial trochlea (green arrowheads) will be seen distal to the capitulum without superimposition.
Radiograph #62

image062 What is your critique of this AP elbow projection given a history of hyperextension of the elbow?

Critique of Radiograph #62

image062

    This radiograph meets the diagnostic criteria for the AP projection of the elbow. The radiohumeral and humeroulnar joints are properly demonstrated and the medial and lateral humeral epicondyles profiled. The radial head and tuberosity slightly superimposes the ulna as it should be on the AP view. The subject contrast is good. The joint spaces of the radiohumeral and humeroulnar joints are optimally penetrated. We can see sharp edges of the cortex, good bone trabecular pattern, and soft tissues. This is a good radiographic exposure technique because the trochlea and margins of the olecranon process and coronoid process are defined.

Radiograph #63

image063 Give your critique of this AP view of the elbow taken for acute trauma; name the structure at the pointer in the radiograph.

Critique of Radiograph #63

image070

    The structure at the pointer is the olecranon process. Its function is to limit hyperextension of the elbow joint. The anatomy is properly demonstrated for diagnosis. Notice that the radiohumeral and humeroulnar joints are clearly seen with their joint spaces opened. This is because the forearm and humerus are on the same plane. There is slight overlap of the radial tuberosity marking this as a correctly positioned radiograph. Adequate exposure technique has been used to penetrate bone and provide adequate bone detail. Lateral soft tissues are somewhat obliterated; but not enough to warrant repeating this radiograph. Optimal exposure would provide subject contrast that demonstrates bone trabeculae and enable us to see soft tissue better.

Radiograph #64

image064 Consider this AP projection of the elbow, should this radiograph be repeated, state your reasons for why it should or should not be?

Critique of Radiograph #64

image064

    This radiograph should be repeated. Close inspection reveals there is excessive motion artifact. Bone detail is obliterated to the point of not having full diagnostic value. It may have been difficult for this patient to hold completely still due to involuntary motion, to hold still. You may need to seat the patient comfortably and use sand bags or tape to secure the arm and forearm. Using high MA while decreasing the exposure time will help further reduce motion artifact. The patient’s arm is rotated medially just a little too much as the radius superimposes the ulna more than a quarter of an inch. Overall subject contrast and radiographic density seems adequate.

Radiograph #65

image065 Name the structure at the pointer, and discuss whether or not this radiograph meets the diagnostic criteria for the AP projection of the elbow?

Critique of Radiograph #65

image065
  • The pointer identifies the olecranon fossa with an olecranon foramen. This is a normal anatomical variant.
  • The pointer identifies an olecranon foramen. This is a normal anatomical variant not a pathological finding. The positioning seems good, but because this radiograph is underpenetrated it is difficult to determine if the radiohumeral joint is projected open. To correct this grossly underpenetrated part increase the kVp using the 50/15 percent rule. A compensatory decrease in the mAs would be necessary to maintain radiographic density. This adjustment will also produce slightly lower radiographic contrast that will make it easier to evaluate soft tissue. This radiograph should definitely be repeated.

Radiograph #66

image066 What is the structure at the pointer, and give your critique of this AP projection of the elbow?

Critique of Radiograph #66

image066

    The pointer identifies the capitulum. This is a good radiograph that properly demonstrates the humeroulnar and humeroradial joints. What is good about this radiograph is that bone is well penetration. There is a good balance between the subject contrast and radiographic density. Soft tissues are adequately demonstrated as well. The radial tuberosity appropriately overlaps the ulna and the epicondyles are properly displayed. Good positioning and exposure parameters.

Radiograph #67

image067 Clearly this radiograph does not meet diagnostic standards for the AP projection of the elbow. Discuss why this radiograph is unacceptable and tell how the patient should be positioned to make a diagnostic radiograph.

Critique of Radiograph #67

image067

    This radiograph fails the diagnostic standard for several reasons. Foremost is that the elbow is not fully extended so that the humerus and forearm are on the same plane. Another position error seen here is that neither the humerus nor the forearm is parallel with the image receptor. It looks like the forearm and humerus are at 90 degrees to each other and 45 degrees to the film. Some technologists will take this type of radiograph when the patient is unable to extend the elbow joint. As a result the humeroulnar and humeroradial joints are not properly demonstrated. This method of positioning contributes nothing to evaluating the elbow for fractures. The CR passing through a flexed elbow causes the loss of density through the proximal forearm. Instead of this projection take two projections: one with the humerus parallel to the cassette and a second one with the forearm parallel to the cassette. Keep the CR perpendicular to the part for each view. The two-view method should be used whenever the forearm is flexed greater than 30 degrees with the tabletop when the humerus parallel to the tabletop.

Radiograph #68

image068 Do you think this AP projection of the elbow meets the diagnostic criteria for imaging; consider that it is taken for trauma and the patient is complaining of great pain?

Critique of Radiograph #68

image068a

    This is the same radiograph magnified so you can see the anatomy better. Our purpose for taking a radiograph with this patient’s history is to identify fractures and/or dislocations of the elbow. We can conclude that this radiograph does not complete the diagnostic standards. Although dislocation is identified, a fracture could not be completely ruled out based on the radiographic exposure technique. This is because the radiographic exposure provides insufficient penetration of the distal humerus and olecranon process of the ulna. Taking a projection in the “as is” position is acceptable so long as all factors like exposure technique and anatomical presentation are considered. The dislocation placed the forearm more superior affecting the path of the CR causing excessive attenuation of the beam. Before reducing this dislocation the orthopedic surgeon may want to see if there is a fracture that could be displaced by manipulating the joint. This radiograph should be repeated with greater penetration of the elbow.

Radiograph #69

image069 What view of the elbow is demonstrated; tell whether or not it meets the diagnostic criteria?

Critique of Radiograph #69

image069

    This is suppose to be a lateral oblique view; however, the elbow is rotated laterally too much. The proximal ulna, especially the coronoid process is superimposing the radial head. A portion of the radial neck and tuberosity is obstructed. The purpose of this view is to demonstrate the radial head free of superimposition. With this amount of obliquity the olecranon process is profiled in the olecranon fossa. Reduce the amount of lateral rotation to 45 degrees to correct the positioning. The exposure technique is good. It demonstrates a well penetrated elbow with good bone detail. The soft tissue detail shows stratification of muscle and fat and the lateral soft tissue margins are included in a well collimated field.

Radiograph #70

image070

What view of the elbow is this and tell why is does or does not meet the diagnostic criteria?
Critique of Radiograph #70

image070

    This is a medial oblique projection. The radius is rotated over the ulna and the arm obliqued medially. The flaw in this projection is that the elbow is obliqued too much. The olecranon is not well visualized although the olecranon process in the olecranon fossa is demonstrated. Decreasing the angle of the elbow to 45 degrees will improve the positioning and quality of this radiograph. The exposure technique optimally demonstrates good penetrated, bone detail, and required soft tissue shadows.

Radiograph #71

image071 What is your critique of this radiograph taken for acute traumatic injury; state whether it is positioned correctly?

Critique of Radiograph #71

image071

    A recurring theme with dislocation in which the patient presents with obvious deformity is that you need a harder beam to penetrate the part. This is because often dislocations result in bone overlap. It is important to always evaluate traumatic injury for possible fracture as well as dislocation. Here we see obvious dislocations of the humeroulnar and humeroradial joints; however it is difficult to evaluate areas of bone overlap for fractures. This radiograph is underpenetrated in areas like the olecranon, trochlear notch, coronoid process, and portion of the proximal radius. So don’t think that because you can see obvious pathology you have provided a radiograph that completes diagnostic quality. The diagnostic criteria have not been met for this projection, it should be repeated. This AP view is positioned correctly with the humerus parallel with the cassette and epicondyles equal distance from the tabletop.

Radiograph #72

image072 Name this projection of the elbow and tell why or why this radiograph does not meet the diagnostic criteria for the view?

Critique of Radiograph #72

image072

    This is a lateral oblique (external oblique) projection. When properly positioned this view should profile the radial head and neck without superimposition on the ulna. The humeroradial joint should be opened and the radial tuberosity is seen unobstructed. The coronoid process overlapping the radial head indicates the elbow is over obliqued. This is easily corrected by decreasing external rotation so that the elbow is rotated no more than 45 degrees. No other positioning discrepancies are seen. The humerus and forearm are on the same plane and parallel with the image receptor. The exposure technique shows good trabecular bone pattern and good bone density.

Radiograph #73

image073 This patient’s chief complaint was pain and a laceration from a fall on a glass bottle. Is this a diagnostic radiograph based on the patient’s trauma history, why or why not?

Critique of Radiograph #73

image073

    This radiograph demonstrates correct positioning for the lateral oblique view. When we look at the exposure technique we must decide if it allows for evaluation of soft tissue for glass or bacterial seeding. We should also be able to see the laceration when there is correct balance of the densities caused by different tissues like muscle and fat and air. Soft tissue is best displayed with low contrast rather than the high contrast seen here. Glass particles or other foreign bodies may not be demonstrated when the kVp is too low. High contrast is often mistaken for meaning high detail, but this is not always true. Demonstrating high contrast on a radiograph may hide metal because bone is also radiopaque. To see glass or a laceration, you must penetrate it so that it is visible. Low contrast means there are more shades of gray and varying densities that may show differences. Also, use a position marker such as an arrow, or paper clip to mark the site on the skin. It is helpful to write a brief description of the patient’s injury on the order request. This radiograph should be repeated using greater kVp to penetrate the part.

Radiograph #74

image074 Name this projection and discuss the rationale for it; tell whether or not it satisfies the diagnostic criteria in your critique?

Critique of Radiograph #74

image074

    This is the radial head capitulum view of the elbow. It is commonly called the trauma lateral projection. The quality of this view is dependent on positioning the patient’s elbow in a true lateral with the forearm and humerus on the same plane. The distal forearm is slightly raised placing it parallel to the cassette. The hand is supinated placing the wrist in a true lateral position. When properly positioned this projection demonstrates an opened humeroradial joint space, radial head and neck free of superimposition, and good soft tissue detail. With that in mind this radiograph contains several positioning errors. The radius overlaps the capitulum and the capitulum radial head joint space is closed. The radial head is distal to the coronoid process. Also notice that the capitulum is grossly anterior to the medial trochlea. The cause of these findings is failure to elevate the distal forearm placing it parallel to the cassette.

Radiograph #75

image075 Is this an acceptable lateral view of the elbow, give the reasons for your answer in your critique?

Critique of Radiograph #75

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    The true lateromedial elbow projection must be accurately positioned to get the best diagnostic information. This radiograph does not meet the diagnostic criteria for the true lateral projection of the elbow. Notice that the arcs of the humeroulnar joint space are not superimposed. On an accurately positioned true lateral projection three concentric arcs are demonstrated. These are the formed by the capitulum, trochlear sulcus, and medial aspect of the trochlear all superimposed. These arcs are not superimposed on this radiograph. Another key to determining what should be done is observing that the radial head overlaps the capitulum projecting the humeroradial joint space closed. Also, the capitulum is slightly anterior to the medial trochlea. These findings indicate the distal forearm should be elevated aligning the forearm parallel with the cassette. Additionally, three fat pads should be seen: the anterior, posterior and supinator fat stripe. The radiographic exposure does not display soft tissue very well. Evaluation for fracture or indications of fat pad elevation is not possible using this radiograph; therefore, it must be repeated.

Radiograph #76

image076 Does this radiograph meet the diagnostic criteria for the true lateral projection of the elbow; give reasons for your answer?

Critique of Radiograph #76

image076

    The main problem with this radiograph is that the radial head is distal to the coronoid process. This indicates the distal forearm should be slightly elevated. Otherwise the exposure is adequate for bone penetration and soft tissue detail. The fat pads and soft tissues are obliterated by the exposure technique chosen. Slight motion may also contribute to the loss of soft tissue detail. Adjust the exposure using the 50/15 percent rule to decrease the mAs while maintaining overall density.

Radiograph #77

image077 As you consider this radiograph discuss whether it completes the diagnostic criteria for the lateral projection, and discuss what indicator of injury is demonstrated.

Critique of Radiograph #77

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    This radiograph shows good bone and soft tissue detail. The part is accurately positioned. Notice the anterior fat pad is elevated and the posterior fat pad is visible. These indicate bone injury and/or effusion within the elbow. This is a good lateral projection; however, the medial trochlea and capitulum are not well superimposed. Correct position by slightly raising the distal humerus, but this is not essential since the humeroulnar joint space is easily seen. The coronoid and olecranon processes are seen and the alignment of the radial head and coronoid process is accurately presented. Notice the olecranon epiphysis indicating this is a pediatric patient. The radiologist will have to evaluate this area carefully for possible fracture. A bit more penetration of the elbow would have made this a better radiograph. I would not recommend repeating this projection because of the patient’s age.

Radiograph #78

image078 This is a radiograph that was given to a radiologist for interpretation with a history of trauma. Considering this radiograph, what other information should the technologist have provided to the radiologist?

Critique of Radiograph #78

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    If you noticed the scattered debris on the radiograph then you understood why this is not an acceptable radiograph. The problem stem from the failure to provide the radiologist with sufficient information to determine if these artifacts are caused by dirty screens, or on the patient’s skin, or are pressed into the tissues by abrasion type trauma. There is no obvious laceration, which raised the radiologist's suspicion of it being a film artifact. The patient’s arm was washed and the radiograph repeated without artifact. The point of this radiograph is that you should always repeat a radiograph that has artifacts. If there is contamination due to an open laceration you should include a detailed description on the order requisition. This will save time so the radiologist does not have to make calls to inquire about this information from you.

Radiograph #79

image079 This patient presented with a history of “not using arm, keeps it bent, complains of pain,” the parent assumed there was trauma, what is your critique of this radiograph?

Critique of Radiograph #79

image079

    Positioning for this projection is good. The elbow is in a true lateral projection, which demonstrates both the anterior and posterior fat pads. Notice that they are elevated away from the humerus indicating traumatic injury to the elbow. The technologist has nicely demonstrated good bone detail free of motion artifact. A nice balance in subject contrast and soft tissue detail has been achieved.

Radiograph #80

image080 What is your critique of this radiograph taken for trauma?

Critique of Radiograph #80

image080

    This radiograph shows how difficult it can be to position the elbow in a true lateral. The forearm and humerus are not on the same plane. Notice the fractured radial head is seen on end. Correct this by lowering the humerus so it is parallel with the tabletop and raise the distal forearm to align it parallel with the tabletop. This will place the elbow in a true lateral.

Radiograph #81

image081 Consider this radiograph taken for trauma, has the diagnostic criteria been met for this radial head projection; if not tell what should be done?

Critique of Radiograph #81

image081

    This is the trauma lateral or radial head capitulum view. Although the humeroradial joint is projected open the positioning of the elbow is not in a true lateral. This can easily be corrected by placing the humerus parallel to the image receptor. Increase the kVp slightly to get better penetration of the part. A decrease in the mAs will improve the visualization of the olecranon process, which is slightly overexposed. Unfortunately this radiograph should be repeated. The fracture of the radial head should be better visualized.

Radiograph #82

image082 Does this trauma lateral projection meet the diagnostic standard, and tell whether or not it should be repeated?

Critique of Radiograph #82

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    The key to deciding whether or not this radiograph should be repeated is to evaluate it by the diagnostic criteria. The humeroradial joint is not projected opened, and the radial head is not aligned with the coronoid process. The cause of this misalignment is the distal forearm is not properly elevated. Always be sure the elbow is in a true lateral with the forearm and humerus on the same plane and parallel with the tabletop. Placing a sponge or towel under the wrist will properly elevate the forearm. To project the radius free of the ulna the tube should be angled approximately 25-30 degrees along the long axis of the humerus.

Radiograph #83

image083 How would you critique the positioning and exposure technique used to take this projection?

Critique of Radiograph #83

image083

    The first thing that comes to mind is “wow” what a fracture of the olecranon. But keep in mind that there may be other injuries not evident by the poor positioning seen here. Unfortunately, to get a complete diagnosis you need to get a good true lateral. Without causing further injury it is possible to place the humerus and forearm on the same plane. Being able to see the humeroulnar joint and humeroradial joint is very important. The anterior fat pad is elevated; however the posterior fat pad cannot be seen. Correctly position the part and increase the kVp and adjust the mAs to bring out soft tissues that are overexposed.

Radiograph #84

image084 This projection was taken for trauma and the patient had obvious deformity of the extremity; does this radiograph meet the diagnostic criteria for a trauma lateral view?

Critique of Radiograph #84

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    Both the humeroulnar and humeroradial joints are dislocated. Posterior dislocation of the elbow is more common than anterior dislocation. When taking the “as is” radiograph it is important to achieve a true lateral projection. Sometimes the x-ray tube must be manipulated like when taking a horizontal beam lateral. Regardless of the imaging method the diagnostic criteria for positioning must be met. While dislocation can be diagnosed a fracture could be missed because of inadequate penetration of the part. This radiograph represents high contrast, which has made soft tissue difficult to evaluate. Consider using more kVp, then further adjusting the exposure technique using the 50/15 rule to get an overall lower contrast image. The main reason this radiograph should be repeated is because the exposure technique does not penetrate the bony structures.

Radiograph #85

image085 There was a high suspicion for fracture so a splint was applied in the emergency room. The technologist took this radiograph with the splint on. What is your critique of this radiograph; tell what should be done to improve it?

Critique of Radiograph #85

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    It is not possible to achieve good initial diagnostic images gawking through plaster. Whenever possible remove a wet plaster splint or metallic splint for the initial trauma imaging. It is important to get an unobstructed series of images for the initial diagnosis. Radiographers are skilled at handling suspected fractures. Using both hands positioned above and below the suspected area will provide good support for the injured area When it is not possible to remove splints or casts be sure to use enough kVp to penetrate the material and bone. Remember a diagnostic radiograph must meet the diagnostic criteria regardless of the presentation of the patient. This radiograph is underpenetrated which makes it difficult to diagnose or to critique. It appears the humeroradial and humeroulnar joints are not presented in a true lateral. The distal forearm should be lowered and the humerus positioned parallel with the image receptor. Of course a well-penetrated study would give better insight to any positioning discrepancies.

Summary of Criteria for the AP, Oblique(s) and Lateral Views of the Elbow

  • The following structures should be identifiable on the radiographs:
    1. AP view-hand supinated and humerus and forearm on the same plane. The radiohumeral and humeroulnar joints should be clearly seen. Epicondyles of the humerus parallel to the imaging device. AP lateral oblique should demonstrate the entire radial head free of superimposition. AP medial oblique with pronation of the hand should demonstrate the coronoid and olecranon processes, and trochlear notch in profile. Also demonstrated are the coronoid process, trochlear notch and medial trochlea in profile.
    2. Lateral views- elbow in 90 degree flexion, epicondyles superimposed and perpendicular to the image receptor. The humerus and forearm on the same plane.
    3. The trauma lateral (capitulum radial head view) is made with the elbow in the true lateral position and the CR angled 25 degrees along the long axis of the humerus. This view should show the radial head in the lateral projection free of the olecranon process, and the humeroradial joint in profile.
  • All radiographs of the elbow should be well penetrated and demonstrate good bone and soft tissue detail. The fat pads of the elbow should be visualized on the lateral view.
Diagnostic Criteria for the AP and Lateral views of the Forearm

  • Purpose: to identify fractures or dislocations, and to identify soft tissue injuries involving the ulna and radius.
  • The following should be identifiable:
    1. AP Forearm view:The hand is supinated and humerus and forearm on the same plane. The epicondyles are positioned equal distant from the cassette parallel to the tabletop. The proximal forearm should demonstrate the radiohumeral and humeroulnar joints. Distally the wrist should be included. A properly positioned AP forearm will present radial styloid in profile and minimal to no superimposition of the ulna and radius distally. Joints at both ends of the forearm may not be completely open due to divergence of the x-ray beam along the long axis of the forearm. To properly display the elbow or wrist either should be imaged as a separate study.
    2. Lateral view: Elbow in 90 degree flexion, humeral epicondyles superimposed and perpendicular to the image receptor. Place the humerus and forearm on the same plane, which may require the distal forearm to be slightly elevated using a radiolucent sponge or towel. The wrist is placed in a true lateral position.
  • Soft tissue detail should include differentiation of muscle, fat, and air when present, and the fat pads of the elbow and wrist. Use the anode-heel-effect to maximize penetration of the elbow while avoiding “burn out” of the wrist. The wrist is positioned towards the anode end of the x-ray tube and the elbow aligned with the cathode end of the tube.
Radiograph #86

image086 Critique this AP projection of the forearm and tell whether or not it meets the diagnostic criteria?

Critique of Radiograph #86

image086

    The forearm is properly positioned at the wrist and elbows. The epicondyles of the humerus are equal distance from the cassette; the hand is supinated. There is an appropriate amount of overlap of the radial tuberosity proximally and no superimposition of the radius and ulna distally. Soft tissues of the elbow, forearm, and wrist are adequately demonstrated. This is a good radiograph for evaluating the forearm.

Radiograph #87

image087 Does this radiograph meet the diagnostic criteria for a trauma projection of the forearm; is this an AP or Lateral projection?

Critique of Radiograph #87

image087

    This radiograph was taken with the patient’s hand pronated and the elbow in the lateral position. This is a properly taken projection when fractures involving both the ulna and radius are suspected. The key to positioning this way is to make sure the wrist is in a true AP and the elbow in a true lateral. Likewise, when the elbow is in an AP projection the wrist is in a true lateral projection. The radiographic exposure is good, but excessive patient motion makes this radiograph unacceptable. Notice how blurred the epiphyseal plates are at both ends of the forearm. Injuries involving the elbow or wrist cannot be evaluated because of excessive motion artifact. This motion obliterates the fat pads too. To reduce involuntary motion, increase the mA and decrease the exposure time. You can use tape or sponges with sand bags to immobilize the part. You can also increase the kVp and decrease the mAs along with the other changes mentioned if necessary to further reduce motion.

Radiograph #88

image088 When giving your critique of this radiograph discuss why the contrast changes so abruptly from proximal to the distal, discuss what could be done to correct this.

Critique of Radiograph #88

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    The primary reason for the abrupt difference in subject contrast is that a high radiographic contrast exposure was used. Using low kVp and high mAs causes this. As a result there is underpenetration of the proximal forearm and overexposure of the wrist. Aligning the elbow with the anode to take advantage of the anode heel effect will also contribute to lower contrast. Good bone detail is needed, but not at the expense of soft tissue detail. At least 65-70 kVp should be used when imaging the adult sized forearm. Unfortunately, this radiograph must be repeated to demonstrate good bone penetration and better subject detail.

Radiograph #89

image089 This radiograph was taken with a metal splint supporting the patient’s wrist. Discuss whether or not this is an acceptable approach to imaging in your overall critique of this PA forearm projection?

Critique of Radiograph #89

image089

    This radiograph definitely does not meet the diagnostic criteria for imaging. Metallic splints and other obstructing objects must be removed. There is no potential for a quality evaluation of the wrist with this metal splint on as you can see. Also, the proximal forearm is not well positioned because the hand is pronated. This rotates the radius over the ulna obscuring anatomy of the elbow. Make sure the humeral epicondyles are equal distance from the cassette and parallel. If you must keep the hand prone take a PA and horizontal beam lateral wrist views, then take AP and lateral projections of the elbow. Be sure to overlap the shafts of the ulna and radius when using this method. Increase the kVp to penetrate the elbow, and compensate by lowering the mAs to bring out soft tissue detail.

Radiograph #90

image090 What is your critique of this film; tell what could have been done to make it a better radiograph?

Critique of Radiograph #90

image090a

    What stands out about this radiograph is that the wrist is over exposed and the elbow is inaccurately positioned. Obviously the exposure needs to be corrected using less mAs. The elbow shows the capitulum superimposing the trochlear notch of the ulna. This indicates the humerus is not flush with the cassette and parallel with the forearm. An old healing fracture demonstrating a well formed callus is seen (arrow). This indicates that the patient could have been positioned with the wrist lateral on this view. It is important to attempt correct positioning because it will describe the patient’s functional ability in addition to the healing seen here.

Radiograph #91

image091 This radiograph of the forearm was taken in the “as is” position. Does it meet the diagnostic criteria for the AP elbow projection?

Critique of Radiograph #91

image091

    It is acceptable to take any radiograph in the “as is” presentation when deformity is obviously present. The diagnostic criterion of including the joints at the extremities of long bones must always be met. It is not uncommon for there to be injuries remote from the site of fractures. Because the elbow is cut off this radiograph must be repeated. Turning the cassette so that the extremities are along the corners will allow you to include the entire forearm.

Radiograph #92

image092 This radiograph was taken for possible foreign body. What is right and wrong about this radiograph?

Critique of Radiograph #92

image092

    There are several things that could have been done differently. First, identify the area of suspicion for foreign body using markers. This will help the radiologist to localize the area of concern. As for soft tissue detail, it is better to penetrate bone while providing soft tissue detail. This is usually accomplished using a standard exposure not specifically one for soft tissue. Using kVp in the range of 70-80 will provide good bone penetration and soft tissue detail.

Radiograph #93

image093 The history for this exam is s/p ORIF of proximal radius and distal ulna. Does this radiograph meet the diagnostic standards for which it was taken?

Critique of Radiograph #93

image093

    Here is an example of a film in which the hand is not supinated. It is obvious that there are functional reasons that this patient could not be positioned in the standard way. Strive to get the elbow lateral when making your radiographs in this manner. Get the humerus and forearm on the same plane even if you must use a radiolucent sponge to achieve your goal. The radiographic exposure technique is good in that it shows both proximal and distal joints.

Radiograph #94

image094 The history given for this radiograph is traumatic amputation. Evaluate for possible reattachment of distal extremity. What is your critique of this radiograph?

Critique of Radiograph #94

image094

    Amputation is a special case in radiography. When imaging for amputation try to position the part in anatomical position. The second radiograph should be at 90 degrees to anatomical position. This radiograph was taken "as is.” This makes evaluation for reattachment more difficult. Likewise, if the avulsed portion is supplied, try to position it in a matching anatomical position. This will help determine goodness of fit for reattachment surgery.

Radiograph #95

image095 What is your critique of this lateral projection of the forearm having a history or trauma?

Critique of Radiograph #95

image095

    When the forearm is specified both the wrist and elbow should be correctly positioned in the lateral projection. The wrist is correctly aligned; however, the elbow is not positioned in a true lateral projection. The humeroulnar joint is not opened. The capitulum and medial trochlear are not aligned. Assuming the arm is flush with the cassette the distal humerus should be raised slightly to superimpose the epicondyles. Decrease the mAs to reduce the overall image density.

Radiograph #96

image096 Consider this radiograph taken for trauma; does it meet the diagnostic criteria for the lateromedial projection of the forearm?

Critique of Radiograph #96

image096

    For the most part this is a well positioned radiograph. We see the wrist and elbow are superimposed and the entire forearm is in true lateral projection. The elbow is not at 90 degrees which partially closes the humeroulnar joint. In addition, the divergence of the x-ray beam makes it difficult to always open the elbow joints when the entire forearm is requested. Clipping the elbow and soft tissues is not acceptable radiography. The radiographic exposure demonstrates good detail at the wrist joint; however, the elbow is underpenetrated. Repeat only the elbow in a true lateral position and use sufficient kVp to evaluate the proximal ulna and radius.

Radiograph #97

image097 How does this radiograph measure up to the diagnostic criteria; tell what is good about it or what you would have done differently if anything?

Critique of Radiograph #97

image097

    What is good about this radiograph is that the wrist is in a true lateral and the elbow in a true AP projection. This position favors the trauma lateral because it causes the least amount of risk of further injury to the patient. Likewise, the lateral view of the elbow will demonstrate a PA view of the wrist in the same view. These are trauma positions and are an acceptable style of radiographic imaging. The radiographic exposure technique shows good detail at the wrist and elbow.

Radiograph #98

image098 What is your critique of this lateromedial projection taken for follow-up of a healing fracture?

Critique of Radiograph #98

image098

    The purpose for this radiograph was to obtain images in anatomical and true lateral positions. The technologist failed to provide the requested functional anatomy. Don’t confuse the trauma imaging scenario with the follow-up seen here. Notice the callus formation in the distal forearm. The patient should be able to flex the elbow and place it in a true lateral projection. If not, then the radiograph should be taken with the elbow true lateral and the maximum amount of supination the patient can handle. Then a collimated true lateral of the wrist could be added. This will provide the greatest amount of diagnostic information.

Radiograph #99

image099 Give your critique of this radiograph and discuss the quality of the soft tissue detail demonstrated?

Critique of Radiograph #99

image099

    This is a great radiograph of the forearm demonstrating the elbow in the AP and wrist in the lateral projection. The joint spaces of the humeroulnar and humeroradial joints are clearly seen. The anterior fat pad of the wrist is nicely visualized. There is good balance between soft tissues and bone. The soft tissues and lateral skin margins are well demonstrated without loosing bone detail. This is what a good exposure technique should look like. Excellent radiograph!

Radiograph #100

image100 What is your critique of this lateromedial projection of the forearm?

Critique of Radiograph #100

image100

    This is a well positioned lateral forearm view. The distal ulna and radius are superimposed and the elbow is in a true lateral as well. The humeroulnar and humeroradial joints are properly demonstrated. The radiographic technique shows good bone and soft tissue detail. The anterior fat pad of the wrist is well demonstrated.

Summary: Critique of Forearm

  • Purpose is to properly identify fractures or dislocations, and to identify soft tissue injuries involving the ulna and radius.
  • The following points should be identifiable on the appropriate radiograph:
    1. AP Projection: The radiohumeral and humeroulnar joints should be clearly demonstrated and the medial and lateral humeral epicondyles profiled. The radial head and tuberosity should be slightly superimposed on the ulna. If the patient is unable to extend the elbow then two AP views should be taken. One is taken with the humerus parallel with the tabletop and the second radiograph taken with the forearm parallel with the tabletop.
    2. Lateral projection: For this view the elbow is in 90 degree flexion, epicondyles superimposed and perpendicular to the image receptor. The humerus and forearm are placed on the same plane. The distal forearm may need to be elevated slightly to align the forearm parallel with the image receptor. The hand is supinated placing the wrist in a true lateral position. The CR is aligned perpendicular to the elbow entering at the elbow joint. The radiographic exposure technique should penetrate the thickest portion of the elbow. There should be sufficient soft tissue detail to see all fat pads of the wrist and elbow. Structures demonstrated are: the entire forearm with epicondyles of the humerus superimposed. The wrist in a true lateral, well penetrated, and the anterior fat pad visualized.
    3. Trauma positioning is acceptable when the patient’s condition warrants it. For this projection the lateral wrist and AP elbow are demonstrated together. The PA wrist and lateral elbow can be demonstrated in the same view.
  • Soft tissue detail should include the fat pads of the elbow and wrist.



Summary Points



  • The trochlea described as a pulley-like structure located on the distal humerus. Relatively and adjacent to each other, the trochlea is medial and the capitulum is lateral to it. The capitulum is a half sphere structure that articulates with the discoid surface of the radius. The radius articulates with its inferior surface when the elbow is extended in anatomical position and with its anterior surface when the elbow is in flexion.
  • It is important for radiographers to understand that the elbow joint is a synovial diarthrodial type joint. It is actually a complex joint with three independent articulations, the humeroulnar joint, humeroradial joint, and radioulnar joints.
  • The most obvious articulation of the elbow joint is the humeroulnar articulation that is a classical hinge type joint. It is formed by the trochlea of the humerus and trochlear notch of the ulna. Its movements are uniaxial permitting only flexion and extension.
  • The radioulnar articulation occurs between the radial head and the radial notch on the proximal ulna. This articulation is a pivot type joint. Through this articulation the radius rotates on the fixed ulna during supination and pronation of the forearm.
  • The radius is the lateral bone of the forearm, and the ulna is the medial bone of the forearm.
  • If the patient is unable to extend the elbow then two AP views should be taken. One is taken with the humerus parallel with the tabletop and the second radiograph taken with the forearm parallel with the tabletop.
  • Purpose for the lateral oblique elbow projection is to demonstrate the radial head and neck free of superimposition, and to provide an unobstructed view of the radioulnar joint. The humerus and forearm are aligned parallel with the image receptor. Rotate the limb 45 degrees externally so that the thumb is pointing down.
  • Adequate penetration of the elbow for the AP projection will demonstrate the lateral margins of the olecranon and olecranon process superimposed on the trochlea.
  • The purpose for the lateral oblique elbow projection is to demonstrate the radial head and radial neck free of superimposition, and an unobstructed view of the radioulnar joint.
  • The purpose for the medial oblique elbow projection is to demonstrate the coronoid process, trochlear notch and medial trochlea in profile.
  • The lateral elbow view is taken with the humerus and forearm on the same plane and in 90 degree flexion. The epicondyles are perpendicular to the image receptor and superimposed.
  • Chronological growth patterns of the elbow will present the capitulum at approximately age 2 years; the medial epicondylar apophysis at 4 years; the trochlear epiphysis at approximately 8 years; and the lateral epicondylar apophysis at about 10 years of age. These epiphyseal plates can mimic fracture in children.
  • The radial head capitulum view is made with the elbow in a true lateral position and the CR angled 25 degrees towards the head along the long axis of the humerus.
  • The three concentric rings formed by the capitulum, trochlear sulcus, and medial trochlea must be superimposed to prove the elbow is in a true lateral. When these are not aligned the humeroulnar joint space will appear closed and fat pads of the elbow may not be demonstrated.
Copyright image Copyright 2007 Nicholas Joseph Jr.




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