Elbow
DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Elbow CRT04103 · Radiographic Techniques and Procedures START READING NOTES Study Elbow using the sections below. Use the topic navigation to continue through Radiographic Techniques and Procedures. Contents of This Topic INRODUCTION Elbow Note 1.LATERAL Direction and Centring of X-ray Beam Essential Image Characteristics Notes 2.Antero-posterior Direction and Centering of X-ray Beam MODIFIED TECHNIQUE ELBOW These are ; 1.Antero-posterior – partial flexion a.Antero-posterior – forearm in Direction and location of X-ray beam b.Antero-posterior – upper arm in 2.Antero-posterior – full flexion a.Axial – upper arm in contact b.Axial – forearm in contact Lateral head of radius Position of patient and image receptor Proximal radio-ulnar joint – oblique Ulnar groove – axial Radiological considerations ELBOW INRODUCTION Optimum projections of the elbow joint are obtained when the upper arm is in the same plane as the forearm. For many examinations, the patient will be seated at the table with the shoulder lowered, so that the upper arm, elbow and forearm are on the same horizontal level. Elbow To gain the patient’s confidence, the lateral projection is taken first, because the patient will find it easier to adopt this position. The humerus must be rotated through 90° to make sure that two projections at right-angles are obtained of the humerus as well as the ulna and radius. Alternatively, if the limb cannot be moved, two projections at right-angles to each other can be taken by keeping the limb in the same position and moving the tube through 90° between projections. If the patient cannot extend the elbow fully, modified positioning is necessary for the antero-posterior projection. Note Special care should be taken with a child suspected of having a supracondylar fracture of the humerus. Modified projections must be obtained without moving the arm from the collar and cuff that should be used to immobilize the arm. 1.LATERAL Position of Patient and Image Receptor The patient is seated alongside the table, with the affected side nearest to the table. The elbow is flexed to 90 degrees and the palm of the hand is rotated so that it is at 90 degrees to the tabletop. The shoulder is lowered so that it is at the same height as the elbow and wrist, such that the medial aspect of the entire arm is in contact with the tabletop. The image receptor is placed under the patient’s elbow, with its centre to the elbow joint. The limb is immobilized using sandbags. Direction and Centring of X-ray Beam The vertical central ray is centered over the lateral epicondyle of the humerus. Essential Image Characteristics The central ray must pass through the joint space at 90 degrees to the humerus, i.e. the epicondyles should be superimposed. The image should demonstrate the distal third of humerus and the proximal third of the radius and ulna. Notes Care should be taken when a supracondylar fracture of the humerus is suspected. In such cases, no attempt should be made to extend the elbow joint, and a modified technique must be employed RADIOGRAPHIC ANATOMY -LATERAL 2.Antero-posterior Position of Patient and Image Receptor The patient is seated alongside the table with the affected arm nearest to the table. The arm is extended fully, such that the posterior aspect of the entire limb is in contact with the tabletop and the palm of the hand is facing upwards. The image receptor is positioned under the elbow joint. The arm is adjusted such that the medial and lateral epicondyles are equidistant from the image receptor. The limb is immobilized using sandbags. Direction and Centering of X-ray Beam The vertical central ray is centered through the joint space 2.5 cm distal to the point midway between the medial and lateral epicondyles of the humerus. Essential Image Characteristics The central ray must pass through the joint space at 90 degrees to the humerus to provide a satisfactory view of the joint space. The image should demonstrate the distal third of humerus and the proximal third of the radius and ulna. RADIOGRAPHIC ANATOMY-AP Notes When the patient is unable to extend the elbow to 90 degrees, a modified technique is used for the antero-posterior projection. If the limb cannot be moved, two projections at right-angles to each other can be taken by keeping the limb in the same position and rotating the X-ray tube through 90 degrees. MODIFIED TECHNIQUE ELBOW These projections may be useful in cases of trauma when the patient is unable to extend the elbow joint. These are ; Forearm in contact with image receptor fosuspected radial head and olecranon fractures. Upper arm in contact with image receptor for suspectedsupracondylar fractures. Axial projection when the patient cannot extend their arm to any extent. 1.Antero-posterior – partial flexion Adaptation of technique If the patient is unable to extend the elbow fully, the positioning for the AP projection may be modified. For a general survey of the elbow, or if the main area of interest is the proximal end of the radius and ulna, then the posterior aspect of the forearm should be in contact with the image detector. If the main area of interest is the distal end of the humerus, however, then the posterior aspect of the humerus should be in contact with the image detector. If the elbow is immobilized in the fully flexed position, then an axial projection must be used instead of the AP projection. Notes In both of the above cases, some superimposition of the bones will occur. However, gross injury and general alignment can be demonstrated. a.Antero-posterior – forearm in contact Position of patient and image receptor The patient is seated alongside the table, with the affected side nearest to the table. The posterior aspect of the forearm is placed on the table, with the palm of the hand facing upwards. The image receptor is placed under the forearm, with its centre under the elbow joint. The arm is adjusted such that the medial and lateral epicondyles of the humerus are