CHAPTER 5
Musculoskeletal Imaging Studies
• Imaging studies often aid in the diagnosis and management of musculoskeletal injuries and conditions.
• Because most imaging studies involve exposure to radiation, time, and financial expense, they are used only when essential in establishing a diagnosis or determining proper treatment.
• Consult with a radiologist or orthopaedic specialist if there is uncertainty as to which study or views are appropriate.
• Box 5-1 lists strategies for minimizing radiation exposure. Most importantly, only necessary studies should be performed, using the correct imaging views, modalities, and radiation dosages in compliance with Image Gently principles (see www.imagegently.org).
Box 5-1. Strategies for Minimizing Radiation Exposure
• Order imaging studies only when the information is likely to affect patient management. |
• Whenever possible, try to use imaging modalities that do not involve radiation exposure. |
• Communicate with the radiologist to make certain the most appropriate imaging study is performed. |
• Routine shielding of the gonads is no longer considered necessary,a but shielding can be done if a parent requests, except for the initial pelvic image. |
• Request that parents obtain copies of outside radiographs to avoid duplicating examinations, and advise them to carry these to the appointment with the orthopaedic consultant. |
• Limit follow-up images. |
• Avoid routinely ordering comparison views of the opposite limb. |
a Frush D, Reid J. X-ray shields going by the wayside: what you and your patients need to know. AAP News. https://www.aappublications.org/news/2020/03/31/xrayshields040120. Updated March 31, 2020. Accessed August 20, 2020.
Effective Radiation Doses
• Absorption of radiation by the tissues depends on the technology employed, technique used, and density of the tissues imaged (Table 5-1).
— Because computed tomography (CT) produces a large number of scans, it exposes the patient to significantly higher effective radiation doses compared with plain radiography; CT scans with narrower cuts and higher resolution result in even greater radiation exposure.
— Because of differences in tissue properties, radiographs of the extremities are associated with a lower effective radiation dose than radiographs of the torso.
Table 5-1. Effective Radiation Doses
Abbreviation: CT, computed tomography.
From Gaca AM. Radiation protection and safety in pediatric imaging. Pediatr Ann. 2008;37(6):383–387. Reproduced with permission. Copyright by Slack Inc.
Radiography
• When evaluating for bone injury or pathology, plain radiographs are always obtained before considering advanced imaging studies.
• It is the physician’s responsibility to ensure the most appropriate views are ordered, based on evaluation of the patient’s injury or condition.
— The number and type of views recommended depends on the anatomic location and suspected diagnosis (Table 5-2). Generally, at least 2 views are recommended, but in some cases a single radiograph may suffice (eg, anteroposterior [AP] pelvis may be sufficient to evaluate for hip dysplasia).
— The area of interest (point of maximal tenderness) should be in the center of the radiograph, because x-ray beams are most concentrated at the center. Structures at the edges of an imaging field do not appear as clearly.
Table 5-2. Common Radiographic Views
| Anatomic Area | Standard Viewsa | Common Special Views |
|---|---|---|
| Shoulder | AP view in ER AP view in IR Axillary view (best true lateral view of shoul -der to assess for dislocation [humeral head position in the glenoid cavity]) Scapular Y-view (another lateral view to assess humeral head position in patients who cannot abduct the arm for axillary view) | Clavicle view Scapular outlet view to assess subacromial space and supraspinatus outlet for bony causes of impingement Stryker notch view to assess for Hill-Sachs lesion after dislocation |
| Elbow | AP, lateral, oblique views | Radial head view Oblique views: external oblique to assess medial condyle; internal oblique to assess lateral condyle |
| Hand/Wrist | AP, lateral, oblique views | AP view in ulnar deviation to assess scaphoid |
| Hips/Pelvis | AP and frog pelvis | AP view alone is sufficient for evaluating for hip dysplasia Cross-table lateral if patient cannot abduct hips for frog view Judet views to assess for acetabular fractures Dunn view to assess for femoroacetabular impingement |
| Knee | AP, lateral, oblique views Tunnel/notch view (AP, weight-bearing view with knees flexed to 30°) to assess for osteochondritis dissecans Merchant or sunrise views to assess patellofemoral joint | None |
