Bontrager's Textbook Of Radiographic Positioning And Related Anatomy Chapter 3

The skeletal system, a framework of bones providing support, protection, and movement, forms the foundation of radiographic imaging. Understanding its anatomy and proper positioning techniques is paramount for producing high-quality radiographs, especially when referencing Bontrager's Textbook of Radiographic Positioning and Related Anatomy. Chapter 3 of this seminal text focuses on the upper limb, a complex assembly of bones, joints, and soft tissues that requires precise positioning for accurate diagnosis.

Anatomy of the Upper Limb: A Foundation for Radiographic Positioning

Before diving into specific radiographic positions, a solid understanding of the upper limb's anatomy is crucial. The upper limb consists of the shoulder girdle, the arm, the forearm, and the hand.

The Shoulder Girdle

The shoulder girdle connects the upper limb to the trunk and allows for a wide range of motion. It comprises two bones:

Clavicle (collarbone): This long bone articulates with the sternum medially and the acromion of the scapula laterally. It provides stability and support to the shoulder joint.
Scapula (shoulder blade): This flat, triangular bone lies on the posterior aspect of the thorax. Key features include the spine, acromion, coracoid process, glenoid cavity, and various borders and angles. The glenoid cavity articulates with the head of the humerus to form the glenohumeral joint (shoulder joint).

The Arm

The arm extends from the shoulder to the elbow and contains only one bone:

Humerus: This long bone articulates with the scapula at the shoulder joint and with the radius and ulna at the elbow joint. Important landmarks include the head, neck, greater and lesser tubercles, intertubercular groove, deltoid tuberosity, medial and lateral epicondyles, capitulum, trochlea, and olecranon fossa.

The Forearm

The forearm extends from the elbow to the wrist and consists of two bones:

Radius: This bone is located on the lateral (thumb) side of the forearm. It articulates with the humerus, ulna, and carpal bones. Key features include the head, neck, radial tuberosity, and styloid process.
Ulna: This bone is located on the medial (little finger) side of the forearm. It articulates with the humerus and radius. Important landmarks include the olecranon process, coronoid process, trochlear notch, radial notch, and styloid process.

The Wrist and Hand

The wrist and hand are complex structures composed of numerous small bones, allowing for fine motor skills.

Carpals (wrist bones): These eight small bones are arranged in two rows. The proximal row (from lateral to medial) consists of the scaphoid, lunate, triquetrum, and pisiform. The distal row consists of the trapezium, trapezoid, capitate, and hamate.
Metacarpals (hand bones): These five bones form the palm of the hand. Each metacarpal consists of a base, shaft, and head.
Phalanges (finger bones): Each finger (except the thumb) has three phalanges: proximal, middle, and distal. The thumb only has two: proximal and distal.

Essential Radiographic Positioning Techniques for the Upper Limb

Bontrager's Textbook provides detailed instructions for a wide range of radiographic projections of the upper limb. The following sections outline some of the most common and essential positions.

Shoulder

AP (Anteroposterior) Shoulder

Purpose: To visualize the humerus, glenohumeral joint, clavicle, and scapula.
Patient Position: Erect or supine, with the affected shoulder against the image receptor.
Part Position: Rotate the arm internally and externally to demonstrate different aspects of the humerus. For a true AP, the humerus should be in external rotation.
Central Ray: Perpendicular to the mid-glenohumeral joint.
Evaluation Criteria: Humeral head in profile, glenohumeral joint space open, and visualization of the clavicle and scapula.

AP Shoulder with Internal Rotation

Purpose: To visualize the greater tubercle in profile.
Patient Position: Erect or supine, with the affected shoulder against the image receptor.
Part Position: Internally rotate the arm until the epicondyles are perpendicular to the image receptor.
Central Ray: Perpendicular to the mid-glenohumeral joint.
Evaluation Criteria: Lesser tubercle in profile medially, greater tubercle superimposed on the humeral head.

AP Shoulder with External Rotation

Purpose: To visualize the lesser tubercle in profile.
Patient Position: Erect or supine, with the affected shoulder against the image receptor.
Part Position: Externally rotate the arm until the epicondyles are parallel to the image receptor.
Central Ray: Perpendicular to the mid-glenohumeral joint.
Evaluation Criteria: Greater tubercle in profile laterally, lesser tubercle superimposed on the humeral head.

Grashey Method (Glenoid Cavity)

Purpose: To visualize the glenoid cavity in profile. This projection is crucial for evaluating dislocations and fractures of the glenoid rim.
Patient Position: Erect or supine, rotated 35-45 degrees towards the affected side.
Part Position: Arm in neutral rotation.
Central Ray: Perpendicular to the glenohumeral joint.
Evaluation Criteria: Glenoid cavity in profile, with equal joint space superiorly and inferiorly.

Transthoracic Lateral (Lawrence Method)

Purpose: To visualize the humerus when the patient cannot abduct the arm.
Patient Position: Lateral, with the affected side closest to the image receptor. Raise the unaffected arm above the head.
Part Position: Ensure the humerus is in the lateral position.
Central Ray: Perpendicular to the mid-humerus, through the thorax.
Evaluation Criteria: Lateral view of the humerus, visualized through the thorax. Requires careful attention to exposure factors due to varying tissue densities.

Humerus

AP Humerus

Purpose: To visualize the entire humerus from the shoulder to the elbow.
Patient Position: Erect or supine, with the affected arm abducted.
Part Position: Supinate the hand. Ensure the entire humerus is included.
Central Ray: Perpendicular to the mid-humerus.
Evaluation Criteria: Entire humerus visualized, including the shoulder and elbow joints.

Lateral Humerus

Purpose: To visualize the humerus in the lateral position.
Patient Position: Erect or supine, with the affected arm abducted.
Part Position: Flex the elbow 90 degrees and place the hand across the chest. Ensure the entire humerus is included.
Central Ray: Perpendicular to the mid-humerus.
Evaluation Criteria: Lateral view of the humerus, including the shoulder and elbow joints.

Elbow

AP Elbow

Purpose: To visualize the elbow joint.
Patient Position: Erect or supine, with the arm extended.
Part Position: Supinate the hand. Ensure the elbow joint is centered.
Central Ray: Perpendicular to the elbow joint.
Evaluation Criteria: Elbow joint open, with visualization of the distal humerus and proximal radius and ulna.

Lateral Elbow

Purpose: To visualize the elbow joint in the lateral position.
Patient Position: Erect or supine, with the arm extended.
Part Position: Flex the elbow 90 degrees. The hand should be in a lateral position (thumb up).
Central Ray: Perpendicular to the elbow joint.
Evaluation Criteria: Elbow joint in a true lateral position, with superimposition of the epicondyles.

Oblique Elbow

Purpose: To visualize specific structures of the elbow, such as the radial head or coronoid process, without superimposition.
Patient Position: Erect or supine, with the arm extended.
Part Position: Rotate the arm internally or externally 45 degrees, depending on the desired structure.
Central Ray: Perpendicular to the elbow joint.
Evaluation Criteria: Clear visualization of the radial head or coronoid process, depending on the obliquity.

Forearm

AP Forearm

Purpose: To visualize the radius and ulna.
Patient Position: Seated or standing, with the arm extended.
Part Position: Supinate the hand. Ensure the entire forearm is included, from the wrist to the elbow.
Central Ray: Perpendicular to the mid-forearm.
Evaluation Criteria: Entire radius and ulna visualized, including the wrist and elbow joints.

Lateral Forearm

Purpose: To visualize the radius and ulna in the lateral position.
Patient Position: Seated or standing, with the arm extended.
Part Position: Flex the elbow 90 degrees. The hand should be in a lateral position (thumb up). Ensure the entire forearm is included.
Central Ray: Perpendicular to the mid-forearm.
Evaluation Criteria: Radius and ulna in a true lateral position, with superimposition at the distal radioulnar joint.

Wrist

PA (Posteroanterior) Wrist

Purpose: To visualize the carpal bones.
Patient Position: Seated, with the forearm resting on the image receptor.
Part Position: Pronate the hand. Ensure the wrist is centered.
Central Ray: Perpendicular to the mid-carpal area.
Evaluation Criteria: Carpal bones visualized, with clear joint spaces.

Oblique Wrist

Purpose: To visualize specific carpal bones without superimposition, particularly the scaphoid.
Patient Position: Seated, with the forearm resting on the image receptor.
Part Position: Rotate the hand internally 45 degrees.
Central Ray: Perpendicular to the mid-carpal area.
Evaluation Criteria: Scaphoid visualized without significant superimposition.

Lateral Wrist

Purpose: To visualize the carpal bones in the lateral position and evaluate for dislocations.
Patient Position: Seated, with the forearm resting on the image receptor.
Part Position: Place the hand in a true lateral position (thumb up).
Central Ray: Perpendicular to the mid-carpal area.
Evaluation Criteria: Carpal bones in a lateral position, with the radius and ulna superimposed.

Carpal Tunnel View (Gaynor-Hart Method)

Purpose: To visualize the carpal tunnel and evaluate for abnormalities, such as carpal tunnel syndrome.
Patient Position: Seated, with the forearm resting on the image receptor.
Part Position: Hyperextend the wrist as much as possible. Angle the central ray 25-30 degrees towards the long axis of the forearm.
Central Ray: Angled 25-30 degrees to the long axis of the forearm, entering at the base of the palm.
Evaluation Criteria: Carpal tunnel visualized, with clear visualization of the carpal bones and soft tissues.

Hand

PA Hand

Purpose: To visualize the metacarpals and phalanges.
Patient Position: Seated, with the hand resting on the image receptor.
Part Position: Pronate the hand, with the fingers slightly separated.
Central Ray: Perpendicular to the mid-metacarpals.
Evaluation Criteria: Metacarpals and phalanges visualized, with clear joint spaces.

Oblique Hand

Purpose: To visualize the metacarpals and phalanges without superimposition.
Patient Position: Seated, with the hand resting on the image receptor.
Part Position: Rotate the hand internally 45 degrees.
Central Ray: Perpendicular to the mid-metacarpals.
Evaluation Criteria: Metacarpals and phalanges visualized without significant superimposition.

Lateral Hand (Fan Lateral)

Purpose: To evaluate for foreign bodies or soft tissue abnormalities.
Patient Position: Seated, with the hand resting on the image receptor.
Part Position: Place the hand in a lateral position, with the fingers fanned out.
Central Ray: Perpendicular to the mid-metacarpals.
Evaluation Criteria: Lateral view of the hand, with the fingers separated.

Key Considerations for Optimal Radiographic Imaging of the Upper Limb

Beyond specific positioning techniques, several general principles contribute to producing high-quality radiographs of the upper limb.

Patient Communication: Clearly explain the procedure to the patient and instruct them on how to cooperate. This reduces anxiety and improves the likelihood of obtaining a diagnostic image.
Immobilization: Use immobilization devices, such as sandbags or sponges, to minimize patient movement and prevent blurring.
Collimation: Restrict the beam to the area of interest. This reduces patient dose and improves image quality by decreasing scatter radiation.
Shielding: Use lead shielding to protect radiosensitive organs, such as the gonads.
Exposure Factors: Select appropriate exposure factors (kVp, mAs) to optimize image contrast and density. Adjust factors based on patient size and the specific body part being imaged.
Image Evaluation: Carefully evaluate the radiograph to ensure proper positioning, exposure, and anatomical visualization.

Common Pathologies and Radiographic Appearance

Understanding common pathologies of the upper limb and their radiographic appearance is crucial for accurate diagnosis. Some examples include:

Fractures: Radiographs are essential for identifying fractures, which can range from simple hairline fractures to complex comminuted fractures.
Dislocations: Dislocations occur when the bones of a joint are displaced. Radiographs can confirm the dislocation and assess for associated fractures.
Osteoarthritis: This degenerative joint disease can cause narrowing of the joint space, bone spurs (osteophytes), and sclerosis.
Rheumatoid Arthritis: This autoimmune disease can cause joint inflammation, erosion, and deformities.
Osteomyelitis: This bone infection can cause bone destruction and periosteal reaction.
Tumors: Bone tumors can be benign or malignant and may present as lytic or sclerotic lesions on radiographs.

Conclusion

Mastering radiographic positioning techniques and understanding related anatomy, as detailed in Bontrager's Textbook of Radiographic Positioning and Related Anatomy Chapter 3, is essential for radiographers. By applying these principles, radiographers can produce high-quality images that aid in the accurate diagnosis and treatment of upper limb conditions. Continuous learning and refinement of skills are crucial for providing optimal patient care.