1. Imaging Studies in Orthopaedics
Chapter 31
Imaging Studies in Orthopaedics

2. Overview
The availability of diagnostic images to physical therapists greatly depends on the practice setting.
Outside of the United States military health system, the ordering of imaging studies is not within the scope of physical therapy practice

3. Imaging Studies
The results from imaging studies should be used in conjunction with other clinical findings
In general, imaging tests have a high sensitivity (few false negatives), but low specificity (high false-positive rate)

4. Radiology
Conventional (plain film) radiography is generally considered to be the first order diagnostic imaging modality.
X-rays are part of the electromagnetic spectrum and have the ability to penetrate through body tissues of varying densities
Exposure to the x-ray particles causes the film to darken, while those areas of absorption appear lighter on the x-ray film or radiograph
The denser a tissue is, the lighter it appears on the film or radiograph.

5. Radiology The following structures are in order of descending density:
Metal
Bone. Bone can have varying densities within the body. For example, cancellous bone is less dense than cortical bone, and will thus appear lighter than the cortical bone
Soft tissue
Water or body fluid
Fat
Air. As air is the least dense material in the body, it absorbs the least amount of x-ray particles, resulting in the darkest portion of the film

6. Radiology
Plain-film, or conventional, radiographs are relatively inexpensive and give an excellent view of cortical bone
May be more specific than MRI in differentiating potential causes of bony lesions
Not considered sensitive to the early changes associated with tumors, infections, and some fractures

7. Radiology
When evaluating radiographs, a systematic approach such as the mnemonic ABCS is recommended;
A = Architecture or alignment
B = Bone density
C = Cartilage spaces
S = Soft tissue evaluation

8. Radiology
A stress radiograph is a procedure using radiographs taken while stress is applied to a joint
Can be helpful in assessing spinal stability
Video fluoroscopy procedures involve the use of x-rays to evaluate the quality and quantity of joint motion

9. Radiology
Contrast-enhanced radiography procedures involve the use of a contrasting agent to highlight different structures. Examples include:
Arthrography
Angiography

10. Computed Tomography (CT)
Also known as computerized axial tomography (CAT) and computerized transaxial tomography (CTI).
Uses a fan-like beam of x-rays to provide an almost three-dimensional or tomographic image
Helpful in the examination of acute fractures, aneurysms, infections, hematomas, cysts and tumors

11. Computed Tomography (CT)
Image quality in CT imaging depends on a variety of factors which are mostly selected by the operator. Two parameters are used to define the image quality of a given system:
Spatial resolution: the ability of the system to distinguish between two closely spaced objects.
Contrast resolution: the ability of the system to discriminate between two adjacent areas with different attenuation values

12. Computed Tomography (CT)
CT scan provides good visualization of the shape, symmetry, and position of structures by delineating specific areas
This information can be helpful in the examination of acute trauma, aneurysms, infections, hematomas, cysts, and tumors

13. CT Myelogram
A diagnostic tool that uses radiographic contrast media (dye) to illuminate the spinal canal, cord, and nerve roots during imaging

14. Magnetic Resonance Imaging (MRI)
MRI images are the result of the interaction of body tissues with electromagnetic forces
Commonly used to assess the central nervous system, and soft tissue injuries

15. Magnetic Resonance Imaging (MRI)
The advantages of MRI include its excellent tissue contrast, ability to provide cross-sectional images, noninvasive nature, and complete lack of ionizing radiation. MRI provides an excellent view of anatomic and physiologic tissues

16. Diagnostic Ultrasound
Based on the transmission of sound waves through tissue and the time it takes for the waves to be reflected back to the transducing probe
Currently used to help detect soft tissue injuries, tumors, bone infections, bone mineral density, and arthropathy

17. Radionuclide Scanning
Involve the diagnostic use of radioactive material or isotopes that are administered orally or intravenously
This test is used to detect particular areas of abnormal metabolic activity within a bone