MSK X-Ray Interpretation
Interpreting an MSK scan is an essential skill for any junior doctor.
Learning how to interpret MSK Scans is often a skill that medical students are expected to pick up as they shadow on the wards.
Therefore, to help you learn this skill, you can use the following acronym DR BDE.
By using this, you will be able to go through MSK Scans in a systematic way to ensure you don’t miss any important details. It also gives you a great structure when you need to present the findings to your senior.
So if you are presented with an MSK X-Ray like this, let’s see how to go through it.
D – Details
When starting with any MSK X-Ray, the first thing to do is to confirm that it is of the right patient. This will involve checking for the following features.
- Confirm Name
- Confirm Age
- Confirm DoB
- Confirm Date and Time of Film
- Is there anything I can compare the film to?
Many patients’s who have prolonged admissions or background of MSK disease may have chronic MSK changes.
Therefore it is important to always ask whether there is a previous MSK X-Ray that you can compare to. This will help to identify whether any abnormality is longstanding or chronic.
R – RIPE
This is a sub-mnemonic. After you have confirmed that the MSK X-Ray is for the correct patient, you should then comment on the film quality.
This involves mentioning 4 key features: Rotation, “Inspiration”, Projection and Exposure.
Whilst “Inspiration” is used more for Chest X-rays, keeping it in the acronym let’s you comment on the field of view.
R - Rotation
- Is bone vertical/horizontal in the film?
"I - Inspiration" (Field of View)
- The whole bone should be visible including the joint
P - Projection
- Most MSK X-Rays are done anterior-posterior.
- For many bone and joint X-Rays, an AP as well as lateral view is required. Therefore, it is important to ask if the lateral view is also available to look at
E - Exposure
- Bones should be clearly visible
State what you believe to be obvious pathology if you can and then say you will work through it systematically.
B – Bone
Looking at the bones is the most important part of an MSK X-Ray. In this part of your analysis, you should primarily looking for 2 things: fractures and dislocations.
After doing this, it is important to look at the texture of the bone for increased lucency or hyperdensity as these may represent lytic or sclerotic lesions.
Fracture
A fracture is a discontinuity in the cortex of the bone. When describing a fracture on an MSK X-Ray you, should refer to the following features:
i) Open or closed?
– Closed fracture = a broken bone with no open wound
– Open fracture = a broken bone with a break in the skin
ii) Simple or comminuted?
– Simple = a fracture where the bone is broken into two fragments
– Comminuted = bone is splintered or crushed into several pieces
iii) Angle of break?
– Transverse = this is when the break is perpendicular to the long axis of the bone
– Oblique = bone is broken at an angle across the bone
– Spiral = a fracture in which the bone has been twisted apart.
iv) Is there any displacement?
– Displaced = a fracture where the ends no longer retain their normal alignment
– Non-displaced fracture = bone fracture where the ends do retain their normal alignment.
Displacement is a term which is split into 4 categories, each of which must be described:
Translation: This is medial/lateral, anterior/posterior movement of the distal segment relative to proximal
– It is described by the % of distal segment which has moved e.g. 1/3 displaced or off-ended
Rotation: This describes whether the distal segment has rotated relative to the proximal fragment
Angulation: This describes whether the distal segment has deviated away from proximal, given in degrees.
– In the legs AP view, angulation is valgus/Varus
– In the arms, we describe angulation using the words radial/ulnar and dorsal/volar
Shortening/Impaction: Shortening occurs when an off-ended segment is pulled closer, shortening limb
– Impaction is when distal segment is compressed into the proximal segment
Dislocation
A dislocation is an injury in which the ends of your bones are forced from their normal positions. In a disclocation is important to comment on the following:
- Which joint is affected
- The bones involved
- The direction of the dislocation, how the bone has moved in relation to the joint e.g. in a posterior hip dislocation, the head of the femur is displaced posteriorly in relation to the acetabulum of the hip joint
Texture
Bone should be fairly homogenous. The outer cortex is often more dense (white) on X-Ray than the inner medulla. However, increased lucency or hyperdensity may be a sign of a pathology
- Lucency – Osteopoenia, lytic lesions (e.g. myeloma)
- Sclerotic – Some cancers, rheumatoid arthritis
D – Degeneration
After looking for fractures and dislocations, which is usually the main focus in your analysis, it is important to look at the joint space.
X-Ray is not the most sensitive imaging modality to reveal inflammation in the joints, but conditions like osteoarthritis and rheumatoid arthritis do sometimes cause visible X-Ray changes, especially in the advanced stage.
Osteoarthritis
The following features are associated with osteoarthritis:
- Loss of joint space
- Subchondral sclerosis
- Subchondral cysts
- Osteophytes
Rheumatoid Arthritis
The following features are associated with rheumatoid arthritis:
- Loss of joint space
- Erosions
- Juxta-articular osteopenia
- Ulnar deviation of finge
E – Everything Else
The E in the acronym stands for everything else. Here it is important to check for additional features.
This may include man-made objects such as screws, wires, nails. This will indicate that the patient has had previous orthopaedic surgery.
Man made instruments
Below are some of the objects to look out for in an MSK X-Ray. You should be familiar with identifying the following and understanding in what situations they are used.
- Osteoporotic instruments
- DHS
- K-wires
- Plates
- Intramedullary nail
Example
Now that we know how to systematically go through an … X- Ray, let’s have a look at how we would interpret the X-Ray we saw at the beginning.
MSK X-Ray Interpretation
D – This is a … X-Ray taken on ….., of the following patient….. Is there a previous X-ray to compare to
R – Commenting first on the quality, it is not rotated, there is adequate field of view, the projection is AP and lateral and it is adequately exposed as I can see the bones clearly
On initial inspection, there appears to be a fracture of the distal radius, but I will proceed to go through it systematically.
B – Looking at the bones first, there is a fracture in the distal radius. It is a closed, simple, transverse fracture. There is dorsal angulation of the distal segment compared to the proximal, but no translation, rotation or shortening. There are no other fractures.
There are no obvious dislocations and the no abnormality in the texture of the bones
D – There are no degenerative changes in the joint spaces
E – There are no other man-made objects or signs of orthopaedic surgery.
In summary, this film shows a fracture of the distal radius with dorsal angulation of the distal segment. This is suggestive of a Colles’ Fracture
Check out the following pages to see more examples of common pathologies seen on MSK X-Ray.
Sources
Image 1: Lucien Monfils, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons
Disclaimer
The intended purpose of this website is to be used as a resource for revision for exams. It should not be used as a guideline or reference for clinical practice/decision making or by patients looking for medical information or advice. In2Med takes no responsibility for any loss or damaged resulting from the use of information from this website.
