Chapter 7: Imaging Studies in Orthopaedics

CHAPTER OBJECTIVES

At the completion of this chapter, the reader will be able to:

1. List the various imaging studies available and give a brief discussion of each.

2. Describe how the various musculoskeletal tissues are depicted in imaging studies.

3. Understand the strengths and weaknesses of each of the imaging studies.

4. Outline the rationale for the choice of one imaging technique versus another.

5. Describe how the results of imaging studies may help in the clinical decision-making process.

OVERVIEW

For healthcare professionals involved in the primary management of neuromusculoskeletal disorders, diagnostic imaging is an essential tool. The availability of diagnostic images to physical therapists greatly depends on the practice setting. For example, physical therapists in the US Army have had privileges for ordering diagnostic imaging procedures since the early 1970s. A few published examples describe civilian-sector practice models outside the US military health system, including physical therapists referring patients directly for imaging tests.¹ The role of imaging based on the Physical Therapy Practice Act language for the 50 states and the District of Columbia reveals tremendous variability, ranging from “prohibiting the use of roentgen rays for any purpose” to the prohibition of physical therapists from referring patients for diagnostic imaging, to being “silent” on the issue.¹ This is somewhat surprising given the drive to pass direct access to physical therapy services, as the ability to directly refer patients to other providers, including a radiologist, would seem paramount.² At the heart of the issue is whether physical therapists are adequately educated regarding appropriate imaging referral. Although Springer et al.³ demonstrated that military physical therapists were as competent as orthopaedists in utilizing the modified Ottawa ankle rules (determining whether ankle-foot radiographs are indicated for patients post ankle injury), the participating physical therapists had completed an advanced training program.³ Concerning those physical therapists trained in the civilian sector, the advent of Doctor of Physical Therapy (DPT) degree programs has resulted in an increased emphasis on imaging as a content area in these degree programs, although it is difficult to find publications that describe current imaging curricular within these programs.² Boissonnault et al.² performed a descriptive survey to describe the status of diagnostic and procedural imaging curricula within US physical therapist professional degree programs and found that while most programs reported including imaging curricula, variability was noted in all curricular aspects.

Although imaging study ordering is not currently within the scope of many physical therapy practices, clinicians frequently request or receive imaging study reports. Although the interpretation of diagnostic images is always the responsibility of the radiologist, the physical therapist needs to know how much importance to attach to these reports and the strengths and weaknesses of the various techniques that image bone and soft tissues, such as muscle, fat, tendon, cartilage, and ligament. In general, imaging tests have a high sensitivity (few false negatives) but low specificity (high false positive ...