Shoulder x-ray interpretation

Cite this article as:
PJ Whooley and James Foley. Shoulder x-ray interpretation, Don't Forget the Bubbles, 2020. Available at:
https://doi.org/10.31440/DFTB.29653

Don’t be bamboozled by a paediatric shoulder x-ray. Use an ABCD approach and pick up some tips and tricks in our step-by-step guide.

A – An adequate x-ray 

Is it the right patient and do you have the 2 views you want to see? The typical views are AP (external rotation) and the scapular Y view. (Not sure why then thisx meme may help).  Occasionally an axillary view is added to assess for dislocations and glenohumeral instability. 

B – Bones

Go through the bones one at a time. Follow the cortex of every bone in each view. Look for a disruption or a buckle in the cortex or any fracture fragments. They should all be smooth.  

  • The clavicle is a good bone to start with – it is by far the most common paediatric shoulder injury. Midshaft fractures account for 80% of clavicle fractures. Make sure there are no distal or medial fractures as they can often be subtle. 
  • Move onto the proximal humerus – check the epiphysis and metaphysis. A normal humeral head looks like a walking stick on the AP view. The most common fracture of the humerus is a metaphyseal fracture. Metaphyseal fractures occur in ages 5-12 and Salter-Harris fractures outside of this range. 
  • Don’t forget the scapula, seen best on the Y view. Management is conservative but a fracture here indicates a significant trauma. 

Like the paediatric elbow, the paediatric shoulder has ossification centres, so x-ray appearances differ depending on the age of the child.

At birth, the humeral diaphysis, mid position of clavicle and the body of the scapula are ossified – the rest are essentially cartilage.

The proximal humerus has three ossification centres:

  • Head – 1 year of age
  • Greater tubercle – 3 years
  • Lesser tubercle – 5 years

  • The scapula has 7 secondary ossification centres. 
Ossification centres of the scapula

Look carefully for the following two – if they appear early they may be the only sign of an avulsion fracture:

  • The sub-coracoid ossificiation centre appears between 8 to 10 years and completely fuses between 16 and 17 years of age, forming the upper third of the glenoid articular surface . If it appears before the age of 8, this may indicate an avulsion (pulled by the long head of biceps at its attachment to the superior glenoid). 
  • The inferior glenoid ossification centre, appears at the lower two-thirds of the glenoid articular surface. It grows and fuses to form a horseshoe shaped epiphysis that combines with glenoid rim and sub-coracoid ossification centre. This appears between 14 and 15 years (although sometimes as young as 11 years), with complete fusion by 17 to 18 years. It can be difficult to view on standard radiographs but sometimes it can be seen on the Grashey (AP oblique) view 

A top tip: If you are unsure whether what you are seeing is an avulsion fracture or a simple ossification centre, then press directly on the patient where the fragment is. If this isn’t painful then it is highly likely to be an ossification centre and not an avulsion. Range of movement is another great give-away – it is quite hard to have an avulsion fracture and intact range of movement! If in doubt, speak to a friendly radiologist (in hours) or be conservative and place in an arm sling and bring back to clinic (out of hours) for re-assessment (when the x-ray will have been reported).

Don’t forget the other bones that don’t make up the shoulder. Have a look for rib fractures, and if you see old healing rib fractures then consider non accidental injury.

C – Connections & Connective Tissue

Are all the bits connected to where they should be? Ask yourself a few questions when you’re looking at the different joints.

Glenohumeral joint:

  • Do the articular surfaces of the humerus and glenoid have 2 parallel lines with an even joint space?
  • Does the humeral head sit evenly on the glenoid in all views?
  • Does the humeral head sit adjacent to the glenoid on the AP view? Does it sit over the glenoid on the Y view? If the answers to these questions are no, and instead the humeral head is lying under the coracoid process, this indicates an anterior shoulder dislocation

Anterior Shoulder Dislocation (AP and Y views).The humeral head is located beneath the coracoid on the AP view and no longer located centrally on the Y view. In addition there is flattening of the humeral head suggesting a Hill Sachs lesion (more on this in the upcoming shoulder dislocation post)

  • Has the humeral head lost its characteristic walking stick appearance on the AP view? Does it instead look rounder, like a light bulb? If the answer to these questions is yes, this suggests a posterior shoulder dislocation.
  • Is there a joint effusion or lipohaemarthorsis present? This could indicate an intra-articular fracture of the glenoid or the humeral head. 
Case courtesy of Dr Garth Kruger, Radiopaedia.org. From the case rID: 21129

Acromioclavicular (AC) joint:

  • Does the bottom of the acromion lines up with the bottom of the distal clavicle? If there’s a step, think clavicle fracture or physeal injury
Normal alignment of the AC joint
  • Is there widening of the acromioclavicular joint (normal is 5-8mm) or coracoclavicular distance (normal is 10-13mm)? A widened AC joint > 8mm suggests an AC ligament rupture. If the coracoclavicular (CC)  distance is >13 mm consider CC ligament rupture. If you’re unsure, get weighted views of both AC or CC joints to compare each side (literally with the child holding weights in each hand to stress the joints).
AP view of shoulder

D – Don’t forget the other tissues

Always look around the area to look for foreign bodies or subcutaneous emphysema indicating a pneumothorax or pneumomediastinum. If there are, then a dedicated chest x-ray should be performed.

And finally, although the above may seem complicated, realistically common things are common.

  • Clavicle Fractures. By far the most common. 80% are mid-shaft and occur following a fall onto the outstretched hand or shoulder or direct trauma from a seatbelt or during sport.
  • Proximal humeral fractures. These occur in older children. 
  • Anterior shoulder dislocation. Usually in older children playing sports. Falls result in forced ABDuction, external rotation, and extension. Account for 95% of shoulder dislocations. 

Don’t miss

  • Acromioclavicular Joint injuries – widening or step at acromioclavicular joint and/or increased coraco-clavicular distance. 
  • Rib fractures – healing rib fracture? Consider NAI

References

  1. JS. Zember, ZS Rosenberg, S. Kwong, SP. Kothary, MA. Bedoya. Normal Skeletal Maturation and Imaging Pitfalls in the Pediatric Shoulder.  Radiographics. 2015 Jul-Aug;35(4):1108-22
  2. https://radiopaedia.org/articles/paediatric-shoulder-radiograph-an-approach

Thoracolumbar spine x-rays

Cite this article as:
Tessa Davis. Thoracolumbar spine x-rays, Don't Forget the Bubbles, 2019. Available at:
https://doi.org/10.31440/DFTB.17581

Read our step-by-step guide to interpreting thoracic and lumbar spine x-rays.

Thoracolumbar spine x-ray involves two views – AP and lateral.

 

  1. Check it’s an adequate view

For a lumbar spine view

  • you should be able to see L1-L5 but also the full T12 vertebral body, T11/12, and the sacrum on the AP view
  • the vertebral bodies, facet joints, and pedicles should be clearly visible on the lateral view
  • the transverse processes should also be visible (and are often obscured by gas)

For the thoracic spine view

  • make sure the whole thoracic spine is visible
  • you should be able to see the pedicles, spinous processes, and vertebral bodies
  • the ribs can cause difficulty seeing the thoracic spine on a lateral view

 

2. Know your anatomy

  • Clavicle is at T3
  • Tracheal bifurcation is T4/5
  • 12th rib is at T12
  • In the lumbar spine, the disc spaces also increase in size, although note that the L5/sacral space is narrower than the L4/L5 space

From https://www.wikiradiography.net/

3. Check the alignment

On the AP check that the vertebral bodies and spinous processes are aligned. On the lateral, check the alignment of the vertebral bodies.

 

 

4. Look for loss of vertebral height

In the thoracic spine, the vertebral bodies (and the disc spaces) should gradually increase in size as you get further down the spine.

Check all the vertebral bodies looking specifically for loss of height. This indicates a compression fracture.

 

 

 

5. Look for widened inter-spinous or inter-pedicle distance and check the processes

In the lumbar spine check that all the pedicles, spinal, and transverse processes are intact.

See below (under burst fracture) for an example of widened inter-pedicle distance and (under Chance fracture) widened spinous process process distance.

Transverse process fracture From https://www.imageinterpretation.co.uk/thoracolumbar.php

 

6. Check for translation/rotation or distraction

Translation or rotation is displacement in horizontal plane; and distraction is displacement in the vertical plane.

Translation/rotation is due to a side-to-side motion (can be left-to-right or front-to-back). It is a serious injury and always involves the posterior ligamentous complex.

Distraction is where the vertebrae are pulled apart and carries a high risk of cord injury. Often there is compression at the other side (see Chance fracture below).

 

7. Know the common types of fractures

Compression fracture

This is the most common type of fracture and is identified through loss of vertebral height (see number 4 above). It involves one column only and is a stable fracture.

 

Burst fracture

On x-ray alone 25% of burst fractures are misdiagnosed as vertebral compression fractures. A burst fracture is where there is a compression, but part of the vertebral body has been projected out anteriorly.

On AP view there will be an increased interpedicular distance in 80% of burst fractures.

On lateral view there will be reduced vertebral height and disrupted anterior alignment.

A burst fracture involves two columns and is usually considered to be unstable.

 

Chance fracture

Usually from a seatbelts injury and is commonly at L2/L3

This is a flexion-distraction injury where there is horizontal splitting of the vertebral body with ligament rupture. This is an unstable fracture and involves all three columns

Sometimes there is increased distance between the spinous processed on the lateral view (but not always).

On the AP view there can be increased distance between the spinous processes at the level of the Chance fracture.

 

Jumper’s/lover’s fracture

So-called because it’s usually from people jumping out of windows to escape the police or angry partners. This is severe axial loading leading to compression/burst fractures alongside a calcaneus fracture.

https://radiopaedia.org/articles/lovers-fracture-2?lang=us

References

Radiopaedia

Radiology Assistant

Norwich Image Interpretation Course

Radiology Masterclass

Pulled elbows

Cite this article as:
Tessa Davis. Pulled elbows, Don't Forget the Bubbles, 2018. Available at:
https://doi.org/10.31440/DFTB.16407

Annie is a 2 year old who has a painful arm. Her mum was holding her hand as she walked along the pavement. Annie tripped and Annie’s mum tried to stop the fall. Since then she hasn’t been using the arm as much.

 

Thanks to Simon Craig for his post-publication contribution.

 

Anatomy

The medial and lateral collateral ligaments each hold the humerus and ulna together (one on either side).

The annular ligament hold the radius and ulna together.

In a pulled elbow, the annular ligament slips of the head of the radius and can get trapped in between the radius and humerus. This causes restriction of movement and pain on pronation and supination.

from Wikipedia

 

If you want to review your anatomy then check out our elbow radiology section.

Mechanism

The mechanism is usually from a pull of the arm e.g. when the child fall down while holding the parent’s hand and the parent tries to stop them falling by pulling the arm.

 

Presentation

The child most commonly presents as not using their arm and on assessment has the arm hanging limply by their side. When asked, they may point to distal radius as the point of pain, which can lead us to suspect a buckle fracture. There will be pain on pronation and supination.

 

Techniques

There are two main techniques to reduce a pulled elbow.

The first is hyper-pronation. For this technique apply pressure over the radial head, then hyper-pronate the arm.

 

The second technique is supination-flexion. Again apply pressure over the radial head, supinate the arm, and then flex the elbow (while the arm is still supinated).

 

A 2017 Cochrane review found low quality evidence that the hyperpronation technique had a better success rate at first attempt reduction that the supination technique (NNT 6).

 

And as Simon Craig nicely illustrated – the Yin and Yang of pulled elbows:

Failed reduction

Sevencan et al (2015) looked at 66 patients presenting with pulled elbows. 57 were successfully reduced on first attempt. A first attempt successful reduction was more likely in patients presenting within 2 hours of the injury. After two year follow up 24% had recurrence (but they will eventually grow out of it).

After a successful reduction, the child should be using the arm normally within 10-15 minutes. If the reduction fails on the first attempt, then try again using the other technique. If the child is still not using the arm, then get an x-ray.

Sometimes you feel like the reduction was successful (you may have felt a click) but the child is not using the arm normally. This may be because the annular ligament was torn when the elbow was pulled and it may take time to heal. In these cases, put the child in a broad arm sling and review them again in a few days.

 

Annie’s pulled elbow was successfully reduced on the first attempt using the hyper-pronation technique. Five minutes later she was using her arm normally. She was discharged from ED.

Foot x-rays

Cite this article as:
Tessa Davis. Foot x-rays, Don't Forget the Bubbles, 2018. Available at:
https://doi.org/10.31440/DFTB.12924

1. Check you have the right views. There are two views in foot x-rays DP (dorsal-plantar) and oblique. Both should ideally be done when weight-bearing if your patient can manage it.

 

2. Review the bones. 

Work round the bones one by one (including the metatarsals). Start proximally and work your way down, going medial lateral. This will ensure you check them all.

 

3. Find any bits that aren’t attached. 

Consider whether any floaty bits might be an ossicle. Pay particular attention to small avulsions from the bones – these are very easy to miss.

There are a couple of common ossicles that you might see:

Os tibiale externum – this is an ossicle present at the medial aspect of the navicular bone (it appears at adolescence)

Os peroneum – this an accessory bone in the peroneus longus tendon

Avulsions commonly occur on:

The lateral aspect of the cuboid

The dorsal surface of navicular and talus (seen only a lateral ankle view)

4. Check the base of fifth.

Most fractures here are avulsions of the metatarsal tuberosity. This is where peroneus brevis attaches and an inversion injury can cause the fracture.

https://sprintforever.blogspot.co.uk/

A Jones fracture is a transverse fracture at the proximal shaft of the fifth metatarsal. It is managed differently (non-weight bearing).

Also, don’t confuse a base of fifth fracture with an unfused apophysis or vice versa. An unfused apophysis runs longitudinally, whereas fractures are usually transverse. The apophysis appears at age 12 for boys and age 10 for girls, and it usually fuses over the next few years.

https://radiopaedia.org/cases/fifth-metatarsal-apophysis

 

5. Check for calcaneus fractures. Look for an avulsion of the anterior process of the calcaneum (oblique view). Look lateral to the calcaneum where extensor digitorum brevis inserts (on the DP view). You can also get injuries to the anterio-lateral aspect of the calcaneus.

 

6. Check for Lisfranc injuries. Normally aligned bones should have the second metatarsal aligning with the intermediate cuneiform on the DP view; and the third metatarsal aligning with the lateral cuneiform on the oblique view. The Lisfranc ligament connects the cuneiforms and the second metatarsal. Disruption of this ligament leaves an unstable foot and so it’s an important one not to miss.

https://emergencymedicineireland.com/

https://emergencymedicineireland.com/

To see more about Lisfranc injuries, check out Andy Neill’s great video on this here.

 

7. Consider stress fractures

These commonly occur on the second or third metatarsals. Sometimes they just present with callous formation or sometimes cannot be seen on plain x-ray and require further imaging (e.g. MRI) to diagnose.

C-spine x-ray interpretation

Cite this article as:
Chris Partyka. C-spine x-ray interpretation, Don't Forget the Bubbles, 2017. Available at:
https://doi.org/10.31440/DFTB.13656

The ABC’s of the cervical spine provide a helpful mnemonic to guide the systematic assessment of these x-rays. Remember; you require all three views (lateral, AP and odontoid/open mouth view) for an adequate study.

Mandible x-rays

Cite this article as:
Tessa Davis. Mandible x-rays, Don't Forget the Bubbles, 2016. Available at:
https://doi.org/10.31440/DFTB.10597

An orthopantomogram (OPG) is a good view to demonstrate most mandibular fractures.

 

A PA mandible shows the displacement of fractures. It also demonstrates symphysis menti fractures which can be missed on the OPG.

pa-anatomy

Image from WikiRadiography

If an OPG cannot be obtained, a lateral view can be helpful. The body and ramus can be viewed along with the TMJ articulation.

lateral-anatomy

Image from WikiRadiography

 

Know your anatomy

mandible-anatomy

Image from WikiRadiography

 

 

Follow the line of the mandible.

  • Remember that the air-filled oesophagus often means that black lines cross the mandible near the angle of the mandible (see image above).

 

Look at the condylar and coronoid process, rami and body, submental symphysis, and alveolar ridge for fractures

  • Condylar process fractures can occur at the base so look carefully as they are easily missed.
  • In general, if you see one mandibular fracture then look for another one as it is common to have more than one, or TMJ dislocation.

 

A Guardsman’s fracture is where there is a fracture of the symphysis and both condyles. This is due to a fall with impact on the midpoint of the chin.


Management

  • Favourable fractures are held in alignment.
  • Unfavourable fracture are displaced by the muscles pulling them.
  • Mandibular fractures of the body or angle of the mandible can be managed conservatively, unless they are displaced, in which case reduction and internal fixation may be required.
  • Condylar fractures are usually managed conservatively, unless there is occlusion of normal movement due to dislocation of the condylar head.

If you want to test yourself then Norwich Image Interpretation Course has a great online facial x-ray quiz.

Facial bone x-rays

Cite this article as:
Tessa Davis. Facial bone x-rays, Don't Forget the Bubbles, 2016. Available at:
https://doi.org/10.31440/DFTB.10471

There are two views – occipito-mental view and occipito-mental 30o view

The occipito-mental view demonstrates the upper and middle thirds of the face including the orbital margins, frontal sinuses, zygomatic arches and maxillary antra

The occipito-mental 30o view shows 30o of caudal angulation. The orbits are seen less well, but zygomatic arches and the walls of the maxillary antra are seen clearly.

Look at the McGrigor lines on these two views:

Line 1:

Look for

  • Widening of the zygomatico-frontal sutures
  • Fractures of the superior rim of the orbits
  • ‘Black eyebrow’ sign due to orbital emphysema
  • Opacification/air-fluid level in the frontal sinuses

Line 2:

Look for

  • Fractures of the superior aspect of the zygomatic arch
  • Fractures of the inferior rim of the orbits
  • Soft tissue shadow in the superior maxillary antrum
  • Fractures of the nasoethmoid bones and medial orbits

Line 3:

Look for

  • Fractures of the inferior aspect of the zygomatic arch
  • Fractures of the lateral maxillary antrum
  • Opacification/air-fluid level in the maxillary sinuses
  • Fractures of the alveolar ridge

 


 

Common fractures and their management

Orbital fractures

Blowout fracture

  • A direct blow to the eye causes the intraocular pressure to rise
  • This causes a fracture to the orbital floor (the weakest part of the orbit)
  • Muscle/fat herniates down into the maxillary sinus
  • Results in a ‘teardrop’ of soft tissue in the roof of the maxillary sinus
  • Can be associated with tropia in upward gaze
  • Will require a facial bones CT (with reconstruction) and urgent maxillofacial referral

Image from RCEMLearning

Orbital emphysema

  • The medial wall of the orbit can also fracture
  • There can be movement of air from the ethmoid sinuses into the orbit
  • This causes the ‘black eyebrow’ sign

Case courtesy of Dr Brendon Friesen, Radiopaedia.org. From the case rID: 41399

Zygoma fractures

Image from Wikipedia

  • The zygoma is made up of three arms:
  • The orbital process leads up to the zygomatic-frontal suture
  • The zygomatic arch
  • The maxillary process
  • A fracture in one can be accompanied by fractures in the others (tripod fracture)

Zygomatic arch fracture

  • Always check the other arms to make sure this is not a tripod fracture
  • Does not usually require surgical intervention unless there is an issue with mouth opening
  • The temporalis muscle can become trapped in a depressed zygomatic arch fracture

zygomatic-arch

Image from RCEMLearning

Tripod fracture (zygomaticomaxillary complex fracture)

  • Look for widening of the zygomatic-frontal suture
  • Look at the arch itself
  • If there is an inferior orbital rim fracture, then look along to see if there is a maxillary sinus wall fracture
  • Can be associated with an air-fluid level in the maxillary sinus
  • Can be associated with trismus due to temporalis muscle impingement
  • Can be associated with infraorbital nerve damage – infraorbital numbness

Image from RCEMLearning

  • If there is any diplopia or reduced visual acuity then urgent maxillofacial surgery referral is required, otherwise this can be done as an outpatient
  • Advise the patient:
    • Not to blow their nose
    • Not to hold their nose closed when they sneeze
  • The reason for this advice is that it could cause surgical emphysema

Maxilla fractures

These are classified using the Le Fort classification system. Fracture of the pterygoid process is mandatory for a Le Fort fracture to be diagnosed.

Le Fort 1 (floating palate):

  • Horizontal maxillary fracture at the level of the nasal fossa
  • Leaves a ‘floating’ palette
  • Fractures are through the lateral and inferior walls of the maxillary sinus, and the alveolar ridge

 

Le Fort 2 (floating maxilla):

  • Pyramid shape
  • Base of pyramid is the alveolar ridge
  • Fractures pass through the lower nasal bridge, the inferior orbital rim, lateral wall of the maxillary sinus, and the lacrimal bones

lefort-ii

Image from LITFL

Le Fort 3 (floating face):

  • The entire facial skeleton is separated from the skull
  • Fractures go through the nasofrontal suture, the maxillo-frontal suture,  the orbital wall, and the zygomatic arch
  • The fracture line runs parallel to the base of the skull

lefortclassification

Image from LITFL

If you want to test yourself then Norwich Image Interpretation Course has a great online facial x-ray quiz.

Ankle x-rays

Cite this article as:
Tessa Davis. Ankle x-rays, Don't Forget the Bubbles, 2016. Available at:
https://doi.org/10.31440/DFTB.9992

The ankle joint consists of three bones – the tibia, the fibula, and the talus.

The ankle also consists of two joints – the ankle joint (where the tibia, fibula and talus meet) and the syndesmosis joint (the joint between the tibia and fibula which is held together by ligaments).

There are three main sets of ligaments:

  • Medial: deltoid ligament
  • Lateral: posterior talofibular, anterior talofibular and calcaneofibular ligaments
  • Syndesmotic ligament

Ankle views

An x-ray of the ankle will have three views – AP, mortise, and lateral. It should be noted though, that in some countries, including the UK, only the mortise and lateral are used. See the annotated images below from WikiFoundry, and thanks also to Radiopaedia:

In the AP view:

  • The distal fibula should be slightly superimposed on the tibia
  • The lateral and medial malleoli should be in profile
  • The tibiotalar space should be open (although the full mortise isn’t visible)

In the mortise view:

  • This aims to assess the articulation of the ankle joint
  • The lateral and medial malleoli should be in profile
  • The mortise should be uniformly visible
  • The base of the fifth metatarsal should be included in the view

In the lateral view

  • The following bones can be assessed: tibia, fibula, talus, cuboid, navicular, calcaneus, and fifth metatarsal
  • The distal fibula should be superimposed by the posterior part of the distal tibia
  • The talar domes should be superimposed
  • The joint space between the tibia and the talus should be uniform

N.B. Assess each bone individually, and if you see a break in one, then look for a second break.

1. Trace around the tibia and fibula in both views.

Be mindful that an ankle fracture can be unstable and therefore it’s important not to miss them.

2. Pay particular attention to the fibula on the lateral view for an oblique fracture.

Oblique fracture (from Radiology Key)

3. Look at the mortise and the talar dome.

Make sure the space is uniform, and that the talar dome surface is smooth.

Osteochondral fracture (from Radiopaedia)

4. Look at the interosseous ligament.

Measure the gap between the tibia and the fibula 1cm proximal to the tibial plafond. It should be less than 6mm, otherwise consider a ligament rupture which could be associated with a fracture.

Image result for interosseous ligament rupture xray
Widened gap between tibia and fibula

5. On the lateral view trace the lateral and medial malleolus, the posterior tibia, the calcaneus, and the base of the 5th metatarsal.

6. Assess the Bohler’s angle

  • Draw two lines at tangents to the anterior and posterior aspects of the calcaneus
  • The angle should be 20-40°
  • If it’s less than 20° then consider a calcaneus fracture
Calcaneus fracture (from Radiopaedia)

7. Do a final check around the bones to make sure you haven’t missed anything the first time around.

8. Remember about accessory ossicles – they aren’t fractures!

  • There are three common accessory ossicles in the ankle: os trigunum (usually forms at 7-13 years old); os subtibiale (when the medial malleolus epiphysis fails to fuse with the tibia in the later teenage years); os subfibulare (can also be an unfused ossification centre or an avulsion fracture).

Common fractures and their management

The level of the fracture directs the treatment – fractures can be classified according to the Salter-Harris classification.

Lateral malleolus fracture

In children, a fibula fracture usually requires a short leg cast and six weeks of non-weight bearing. Salter-Harris I distal fibula fractures can be diagnosed if there is tenderness directly on the lateral malleolus (rather than the ligaments) and many recommend treating as a fracture even if no radiographic fracture is noted.

However, a study in JAMA carried out MRI scans on 135 children with presumed SH1 distal fibula fractures. All children were treated with a removable leg brace and advised to continue regular activities as tolerated. 4 of the children had an SH1 on MRI, 38 had an avulsion fracture, and the rest showed ligamentous injury or bony contusion. By 1 month, 72.1% had full weight-bearing activity and by 3 months 96.9% had returned to normal activities (it didn’t matter which type of injury they had on MRI). Therefore, a removable brace may be appropriate for a Salter Harris I, if your department stocks them. (See a full summary of this article on ALiEM).

Medial malleolus fracture

An undisplaced distal tibia (Salter-Harris I or II) can be managed with a long leg cast and non-weight bearing. SH3 or 4 needs discussion with ortho. All will have a fracture clinic follow up in a week or so.

Salter-Harris I distal tibia fractures can be diagnosed if there is tenderness directly on the medial malleolus (rather than the ligaments) and many recommend treating as a fracture even if no radiographic fracture is noted.

The most common distal tibial epiphysis injury is a Salter Harris II

The high occurrence of Salter-Harris III and IV fractures is because the lateral and deltoid ligaments insert here and they are stronger than the physis itself.

A Tillaux fracture is a Salter-Harris III but with avulsion of the anterolateral corner of the distal tibial epiphysis. If there is <2mm displacement then the patient can have a long leg cast, and be non-weight bearing, with ortho discussion and follow-up. If there is >2mm displacement then an ortho review will be required as typically this need operative management.

Pilon fracture

A pilon fracture is where there is an axial load on the tibia and the talus is pushed into the tibia plafond.

If the fracture is non-displaced or very distal, it is unlikely to require surgery. It would usually be treated with a short leg cast, and weight bearing would be avoided for six weeks.

If it is displaced or the ankle is unstable, then surgery may be required to avoid non-union, so speak to the ortho team.

Posterior malleolus fracture

Posterior malleolus fracture (from Wikiradiography)

Usually when this has happened, there is also a lateral malleolus fracture (because they share ligament attachments). The ankle can be unstable if a large piece is broken and therefore surgery may be indicated – so speak to the ortho team.

An untreated posterior malleolus fracture can lead to arthritis because of the disruption to the cartilage surface.

If the fracture is not displaced then it would usually be treated with a short leg cast, and weight-bearing would be avoided for six weeks.

Talar neck fracture

Talar neck fracture

This fracture carries a high risk of avascular necrosis.

If the fracture is non-displaced then it can be managed with a short leg cast or a boot. If it is displaced then surgery will be required.

Bimalleolar fracture

Bimalleolar fracture (from Radiopaedia)

If two parts of the malleoli are broken then the ankle is not stable and surgery is usually needed.

Trimalleolar fracture

Trimalleolar fracture (from Radiopaedia)

If all three malleoli are broken then there can be associated dislocation. The ankle will be unstable and will require ortho input.

Maisonneuve fracture

This fracture is uncommon in children but can occur. It is where there is a spiral fracture of the proximal fibula along with ankle instability. On x-ray there can be syndesmotic widening.

mason1
From Wheeles Online

In adults this can be managed with a long leg cast, but in children it will require operative fixation.

Syndesmotic injury

Overlap between the tibia and fibula in a syndestomic injury (thanks to Bone School)

The joint between the tibia and fibula are held together by ligaments. If this ligament is sprained then this is a syndesmotic injury.

As mentioned above, there can be widening of the clear space between the medial border of the fibula and the lateral border of the posterior tibia (>5mm). You can also get an overlap of the fibula and the anterior tibial tubercle (>6mm on the AP views, >1mm on the mort

When do I need an orthopaedic review immediately?

  • Open fracture
  • Salter-Harris III or IV
  • Neurovascular injury
  • Compartment syndrome
  • Unable to reduce the fracture

Ref: RCH

Should we be worried about growth plates?

Growth arrest doesn’t occur immediately after the injury, and can even occur in seemingly benign fractures. It can be delayed for up to 6 months and so it is important to follow up ankle fractures post-injury.

References:

Wheeles Online

Radiopaedia

Royal Children’s Hospital, Melbourne

Radiology Masterclass

(Ed: Thanks to Eyston Vaughan-Huxley for his input too).

Knee X-rays

Cite this article as:
Tessa Davis. Knee X-rays, Don't Forget the Bubbles, 2014. Available at:
https://doi.org/10.31440/DFTB.6471

1.  Know your knee anatomy

See the the anatomical landmarks on the diagrams below.

landmarks2

From wikiradiography.net

From https://www.wikiradiography.net/

From wikiradiography.net

 

Remember that the knees of younger children will look different, as the patella forms, and the ossification centres form.

childknee

From thesebonesofmine.wordpress.com

 

2. Look for an effusion

There are two fat pads in the knee

  • the suprapatellar fat pad
  • the prefemoral fat pad

Make sure they are next to each other. Soft tissue density in between the two fat pads indicates an effusion – this is only reliably seen on the lateral view (see images below).

It is sometimes helpful to rotate the PACS view so you are looking at the knee in the horizontal plane, in the same way the image is taken.  Your eyes are much more adept at picking up an effusion or even a fat/fluid level (lipohaemarthrosis) that way.

fatpads

Case courtesy of Dr Jeremy Jones, Radiopaedia.org, rID: 29039

kneeeffusion2

Case courtesy of Dr Henry Knipe, Radiopaedia.org, rID: 32559

3. Look at the main bones

Check for fractures in the fibular head, femur and tibia.

 

4. Check the tibio-femoral alignment

Draw a line along the margin of  the lateral femoral condyle. The tibia should be within 0.5 cm of this line, otherwise it suggests a tibial plateau fracture.

tibiofemoral alignment

Case courtesy of Dr Jeremy Jones, Radiopaedia.org, rID: 29039

 

5. Looks at the tibial plateaus

These most commonly happen on the lateral tibial plateau.

tibialplateau

Check for a tibial plateau avulsion from the lateral edge (Segond fracture)

segond

From orthopaedicsone.com

Tibial plateau fractures in children are exceedingly rare and require a marked degree of axial force. They are more likely to get a Salter-Harris V.

6. Look at the intercondylar eminence

A fracture here is most common in adolescents following hyperextension of the knee. It’s an avulsion fracture at the tibial attachment of the ACL.

tibial eminence

Case courtesy of Gerry Gardner, Radiopaedia.org, rID: 13915

 

 

7. Look for patellar tendon disruption

The patellar tendon goes from the inferior pole of the patella to the tibial tuberosity. Its length should be the same as the patellar length +/- 20%. If it’s too long then think of a patellar tendon rupture. This is the Insall-Salvatti ratio and should ideally me measure with the knee flexed at 30 degrees.

insall-salvatti

Case courtesy of Dr Wael Nemattalla, Radiopaedia.org, rID: 10329

 

8. Look for a patellar fracture

Bipartite patellas are common. It is a congenital condition that occurs when the patella is made of two bones instead of a single bone. Normally the two bones would fuse together as the child grows but in bipartite patella they remain as two separate bones. The edges appear well corticated as compared to in a fracture. See an example below.

bipartate

Case courtesy of Radiopaedia.org, rID: 11236

Most patella fractures are transverse, but they can be vertical.

Patella_fracture

 

Consider a skyline view. This gives a clearer view of the patella in cases of clinically suspected patella fracture where the AP and laterals look ok. It gives a good view of the space between the patella and the femur. See a normal skyline view below.

skyline

From wikiradiography.com

 

9. Remember the fabella…

This is a normal variant and not a floating fracture! It’s normal sesamoid bone that lies in the posterior knee.

fabella

Case courtesy of Dr David Cuete, Radiopaedia.org, rID: 27428

 

References

Interpreting x-rays of the knee join – YouTube video

Knee radiograph: an approach. Radiopaedia

Trauma x-ray, Radiology Masterclass