Lower limb 13/01/2023 Flashcards
What can be confused with avulsion fractures? on the foot
Os tibial externum
An ossicle present at the medial aspect of the navicular bone which normally appears in adolescence
Os Peroneum
An accessory bone in the peroneus longus tendon
Avulsions are common where on the foot?
These commonly occur on the lateral aspect of the cuboid and the dorsal surface of the navicular and talus.
Commonly confused is a Base of the 5th Metatarsal fracture?
This could also be an unfused apophysis!
An unfused apophysis will run longitudinally
The apophysis appears at age 12 for boys and 10 for girls, it usually fuses over the next few years.
The Base of the 5th Metatarsal fracture information
These fractures are invariably transverse.
Often caused by an inversion injury.
As this is where peroneus brevis tendon attaches & most fractures are avulsions of the metatarsal tuberosity.
The Jones fracture of the 5th Metatarsal information
The Jones fractures is generally transverse and occurs at a transition zone within the bone.
Where it goes from diaphyseal to metaphyseal. Either the result of specific traumatic event or chronic overuse, slow to heal.
These fracture are generally difficulty because the fracture occurs in the area within the bone of lessened vascularity, medically termed a watershed area.
Treatment may be with castings and/or surgery.
Treatment often depends on patients age, activity and overall health.
Lisfranc injury information
Normally aligned bones should have the 2nd MT aligning with the intermediate cuneiform on the DP view, the 3rd MT should align with the lateral cuneiform on the oblique view
Downwards force on the leg, foot
Surgery will depend on the extent and involvement of the injury, from simple repair of the ligament to multiple fracture dislocation injuries.
CT is a useful tool in the diagnosis, if unconfirmed with plain film, CT will also show unsuspected associated fractures. Also useful in the surgery planning due to its ability to produce 3D reconstruction and bone windowing.
Can also be used for follow up however there will be an increased dose, therefore plain film is often used unless there are complications.
MRI, may be useful for assessing the ligamentous injury, especially if there is a high clinical concern and plain film is inconclusive.
Flake fractures information
Small flakes of bone are a common finding following trauma
The significance of these injuries depends on their anatomical location
The fracture of 5th metatarsal base shown here is at the insertion point of the peroneus brevis tendon and is therefore potentially more significant than the fracture of the cuboid bone
Hallux Valgus information
This is a medial deviation or adduction for the first metatarsal with an increased first-second metatarsal angle.
The normal angle is below 15 degrees, anything greater indicates hallux valgus.
This angle can only be measured on weight bearing images, usually DP and Lateral projections.
Treatment can be non-surgical or surgical.
Calcaneum projections
Lateral View
The largest tarsal bone in the hindfoot.
Demonstrates the articulation of the talus superiorly and the cuboid anteriorly
Posteriorly may demonstrates the Achilles tendon
Axial View
Demonstrates the inferior aspect of the calcaneum and soft tissue borders
The subtalar joint and sustentaculum tali should be visible on the axial
To assess the Bohler’s angle calcaneum
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
What can be confused with avulsion fractures? on the ankle
Os trigunum
Usually forms at 7 – 13 years of age
Os subtibiale
The medial malleolus epiphysis fails to fuse with the tibia in the later teenage years
Os subfibulare
This can also be an unfussed ossification centre and also an avulsion fracture
Slater-Harris classifications
Slipped = Type 1, fracture plane passes all the way through the growth plate.
Above = Type 11, fracture passes across most of the growth plate and up through the metaphysis.
Lower = Type 111, fracture plane passes some distance along the growth plate and down through the epiphysis.
Through = Type 1v, fracture plane passes directly through the metaphysis, growth plate and down through the epiphysis.
Ruined = Type v, crushing type injury does not displace the growth plate but damages it by direct compression.
What is bimalleor and trimalleolar fractures?
Bimalleolar = If two parts of the malleoli are broken then the ankle is not stable and surgery is usually needed
Trimalleolar = If all three malleoli are broken then there can be associated dislocation. The ankle will be unstable and will require ortho input. (lateral, medial, posterior)
Maisonneuve fracture information
Combination of a fracture to the proximal fibula together with an unstable ankle injury.
When these ankle injury types are seen it is advised that further imaging of the entire fibula is needed to assess the proximal fibular shaft.
Maisonneuve = 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. In adults this can be managed with a long leg cast, but in children it will require operative fixation
Osteochondral fracture information
Often called talar dome or snowboarders fracture.
Look at the mortise view and the assess the talar dome.
Make sure the space is uniform, and that the talar dome surface is smooth
Often referred to CT for diagnosis
Tibia & Fibula Fractures Fixings?
Intramedullary Nail fixation remains the treatment for unstable or displaced tibial shaft fractures in the adult. The ultimate goal is to achieve union to restore length, alignment and rotation of any fracture of the tibia.
External fixation for the lower leg (tibia and fibula), this is used to externally immobilise and fix the bone which will allow the bones to heal effectively. It can also be used for increasing bone length for some patients. Infection rates are high with this method.
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
Intercondylar View
Demonstrates any loose bodies as the lower femur and the upper tibia are included with the intercondylar notch clearly seen
This is an additional projection of the knee, used to better examine the tibial plateau and femoral intercondylar spaces
What is the fabella?
This is a normal variant and not a floating fracture
A normal sesamoid that lies in the posterior knee
What is a Bipartite Patella?
Bipartite patella 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.
Most patella fractures are transverse but they can be vertical
Patella Tendon Disruption info
The patellar tendon goes from the inferior pole of the patella to the tibial tuberosity.
The 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 measure with the knee flexed at 30 degrees.
Patella Fractures information?
Fractures of the patella is sometimes only visible on the lateral view
Horizontal beam imaging for trauma is important here which shows;
An increased density separating the fat pads indicating a joint infusion
This is due to the leakage of blood, known as:
Haemarthrosis
Tibial Plateau Injuries mechanisms?
Most commonly as a result of a fall
25% as result of collision with car bumper
Force directed from femoral condyles onto medial & lateral portions of plateau
Complications may include injury to the arteries or nerves, arthritis and in extreme cases compartment syndrome
Tibial plateau Fractures
Tibial plateau fractures can be very subtle and have little displacement,
It can also be widely displaced
Look for depression of the plateau surface and displacement of the fragment
Most are spotted through the formation on the lateral view of;
Lipohaemarthrosis
