MSK Basics

Approach

After years of training and practice, you will come across some radiologists who glance at a study and give excellent diagnosis. This technique can be referred to as “gestalt” radiology viewing and reporting. In my experience, this approach has never worked for anyone who is on their first musculoskeletal rotation.

Having a system of check marks is a better way to start learning. Once you train yourself to look for subtle findings beyond the obvious, and learn what your “blind spots” are, your own approach to viewing and reporting radiological studies will develop naturally. Speed will come with time. There are many systems and mnemonics that may aid in initial learning of musculoskeletal imaging, but all, pretty much come down to the following:

Look at:

  • Cortex of every bone on every film
  • Bone marrow of every bone on every film
  • Every joint on every film
  • Soft tissues

The order does not matter, what matters is that you remember to look for these four things. Realize that importance of each and order of your reporting will be different. For example, cortical fractures will predominate in acute trauma case, while joint space narrowing and sub-cortical cysts will be important in follow up of osteoarthritis.

Trauma

Today, images become available to ER doctors, orthopedic surgeons and radiologists almost as soon as they are acquired. It is not uncommon for a poly trauma victim to get CT “pan-scans” of head, neck, chest, abdomen pelvis, sometimes together with radiographs of entire extremities. In the past, it was very important to precisely describe displacement and angulation of a fracture. For example:

  • Comminuted mid tibial shaft fracture with medial displacement of the major distal fragment by full shaft bone width. There is apex lateral angulation at the fracture site.

Today, a surgeon can easily see the actual images of the fracture and it is more important for radiology resident to detect other subtle injuries on other films, which may not be as obvious to clinicians. As such, a bullet point in the report of obvious fracture allows for concise, easy to read report and saves time for looking at other studies:

  • Comminuted, displaced and angulated mid tibial shaft fracture.

For the sake of completeness, and as precise descriptions may become important to describe changes in fracture alignment during follow up, let’s go over the basics of detailed fracture reporting.

  • Fracture descriptors:
    • Comminuted or simple
      • Transverse, oblique, or spiral if not comminuted
    • What part of what bone
      • Shaft or diaphysis vs. intraarticular or epiphyseal
      • “Metaphyseal” is a very vague term in an adult. “Diametaphysis” is usually a more accurate descriptor
    • Displacement: always describe the distal fragment in relation to the proximal fragment
      • The only exception is the spinal listhesis, where a superior level subluxes over the inferior level.
    • Angulation:
      • Apex dorsal/lateral/anterior etc.
      • Or, slighly more ambiguous but still acceptable: “distal fragment is angulated laterally.”
    • Impaction
    • Overriding

Example:

5MT fx

Comminuted, slightly displaced, and angulated 5th metatarsal mid shaft fracture.