American Board of Internal Medicine (ABIM) Certification Practice Exam

What imaging technique is most appropriate for diagnosing knee osteoarthritis?

1. Magnetic resonance imaging

2. Standing plain radiography

3. Computed tomography scan

4. Ultrasound

The correct answer is: Standing plain radiography

Standing plain radiography is considered the most appropriate imaging technique for diagnosing knee osteoarthritis. This method is favored because it allows for the assessment of joint space narrowing, osteophyte formation, and other characteristic changes associated with osteoarthritis. Radiographs taken in a weight-bearing position provide valuable information about the joint under functional conditions, enhancing the visibility of degenerative changes that might not be as apparent in non-weight-bearing images. While magnetic resonance imaging (MRI) offers detailed images of soft tissues and is useful for evaluating cartilage, ligament, and meniscus pathology, it is generally not the first-line diagnostic tool for knee osteoarthritis. Similarly, a computed tomography (CT) scan provides more detailed imaging of bone structures, but it is seldom used specifically for diagnosing osteoarthritis due to concerns over radiation exposure and cost-effectiveness as compared to radiography. Ultrasound can be useful in identifying effusions or evaluating soft tissue structures around the knee, but it is not as commonly employed for the initial evaluation of osteoarthritis, since it primarily provides functional assessment rather than direct visualization of joint space narrowing or osteophytes. In summary, standing plain radiography is the preferred method for diagnosing knee osteoarthritis, as it effectively depicts the structural changes associated with the condition,