Diagnostic Imaging Modalities And Procedures

Plain Radiography

Plain radiography remains the mainstay in initial imaging of suspected hip disease. Standard hip radiographic series include an anteroposterior (AP) view of the pelvis and coned-down AP and frog lateral views of the affected hip. The AP view of the pelvis is obtained to allow evaluation of symmetry of the hips, to detect concomitant contralateral hip disease, and to exclude abnormalities of the pelvis that could present clinically as hip pain. The AP views of the pelvis and hip are obtained with the X-ray beam aligned in the AP plane with the feet internally rotated.18 The frog lateral view of a hip is obtained with the hip abducted and the X-ray beam oriented in the AP direction.18 A groin lateral view (surgical lateral view) of the hip, instead of the frog lateral view, may be used in cases of an acute proximal femur fracture as the affected hip remains in neutral position. In this examination, the unaffected leg is abducted and elevated, and the X-ray beam is aligned parallel to the table with 20 degrees cephalad angulation.19 Oblique or Judet20 views are used to better demonstrate acetabular fractures and are obtained with the X-ray beam oriented in the AP plane with the patient in the supine position with rotation of the pelvis. The anterior Judet view depicts the anterior column and posterior acetabular rim and is obtained with the affected hip rotated 45 degrees anteriorly. The posterior Judet view demonstrates the posterior column and anterior acetabular rim and is taken with the affected hip rotated 45 degrees.

Historically, plain tomography of the hip was most commonly used in the evaluation of healing or nonunion of a proximal femur fracture treated with open reduction and internal fixation,21 collapse of the femoral head in osteonecrosis, or the depiction of a suspected osteoid osteoma. The basis for the use of plain tomography in the setting of an open reduction and internal fixation was decreased metallic artifact relative to CT. With the advent of multislice, multidetector, helical CT, thin collimation CT with two-dimensional (2D) reformatting has essentially replaced the use of plain tomograms, providing similar resolution and information with a much shorter examination time and less metallic artifact than conventional CT.

Computed Tomography

CT is used to further characterize bony abnormalities of the hip detected on plain radiographs by providing cross-sectional information not present on plain radiographs. CT of the hip is employed primarily in the setting of trauma or in characterizing neoplasm of the proximal femur or acetabulum. Occasionally, it is used in the evaluation of congenital hip dysplasia and pre-operative prosthesis planning. The emergence of helical and multislice helical CT has revolutionized our ability to acquire rapid high-resolution images of the hip and has several advantages over conventional CT, including improved resolution, shorter examination time, and lower radiation dose.1 CT of the hip in trauma is used primarily to better characterize a fracture or fracture/dislocation detected on plain radiography. CT can reveal the spatial relationship of fractures, articular surface fractures of the femoral head and acetabulum (Figure 4.1), and the presence of intraarticular loose fragments (Figure 4.2) and can yield information used in predicting hip instability in injuries involving posterior wall fractures.22 In the evaluation of neoplasm of the proximal femur or acetabulum, CT is typically used to help characterize the nature of the tumor matrix and demonstrate cortical thinning or destruction.

Gallstone Ileus
Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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