Ep 176 Orthopedic X-rays Master Class – Pitfalls in Obtaining and Interpreting MSK X-rays

Do not let a negative X-ray rule the day! Like almost all medical tests X-rays are far from perfect and should be ordered and interpreted only in the context of a thorough history and physical exam. In this 2nd part of our 2-part series on orthopedic X-rays with Dr. Arun Sayal and Dr. Yatin Chadha we discuss the pitfalls of obtaining and interpreting orthopedic X-rays, when orthopedic X-ray decision tools lead us astray, how understanding the concept of central ray helps dictate how we should order X-rays and interpret them, how the ring structure concept of the forearm and lower leg can remind us where to look for a second injury, when we need 3 views vs 2 views, when extra views like the clenched fist view and weight bearing views are indicated, why we should always look at the lateral view first, the limitations of ultrasound and CT in long bone and joint injuries and more...

Podcast production, sound design & editing by Anton Helman. Voice editing by Braedon Paul.

Written Summary and blog post by Kate Dillon & Ian Beamish,

edited by Anton Helman Nov, 2022

Cite this podcast as: Helman, A. Chadha, Y. Sayal, A. Orthopedic X-rays Masterclass - Obtaining and Interpreting MSK X-rays. Emergency Medicine Cases. November, 2022. https://emergencymedicinecases.com/orthopedic-x-rays-pitfalls. Accessed May 30, 2024

Résumés EM CasesPitfalls in the use orthopedic x-ray clinical decision tools

Do not rely solely on decision tools like the Ottawa Ankle and Foot Rules to decide whether patients need x-rays, or as a guide for how to examine patients. Use the decision rules to support your decision not to image for patients in whom you have a very low clinical suspicion for fracture based on thorough history and physical exam. Anterior ankle injuries such as syndesmosis injuries can be missed by the Ottawa Ankle Rule. Examine the entire ankle, rather than only the areas indicated by the decision tools.

Pitfall: The Ottawa Foot Rule is not applicable to everyone who has a foot injury; it is applicable only to patients with an inversion-type ankle injury (i.e., rolled ankle) where the patient has foot pain; do not use this for a patient who has dropped something on their foot!

"Rule out fracture" is not enough: What more should we write on orthopedic X-ray requisitions and the concept of the central ray

Important pieces of information to communicate to radiologists that can help them with their orthopedic X-ray interpretation include:

* Was there an injury?

* Point of maximal pain/tenderness? (see below re: central ray)

* You differential diagnosis (ie, infection, inflammatory etc)

* Acute or chronic

What is an X-ray central ray and why does it matter?

The central ray is the theoretical center of the X-ray beam that designates the direction of the X-ray photons as projected from the focal spot of the X-ray tube to the radiographic film. It delineates the area of interest and when directed appropriately maximizes the focus/clarity of the area in question. Hence communicating the point of maximal pain/tenderness improves the quality of orthopedic X-rays and allows ideal interpretation conditions. Examples of the central ray concept include:

* Suspect a fracture at the elbow and shoulder? Do not rely on a humerus x-ray, the joints are too far from the central ray to achieve an adequately focused view

* Suspect a fracture in upper L-spine/lower T-spine? A single lumbar spine x-ray series may not show the lower thoracic spine adequately; a dedicated thoracic spine x-ray series should be ordered and the spinal level of concern should be communic...