Talar fractures
The most common, albeit relatively rare in overall statistics, is a fracture of the talar neck (talar neck). The pathology occurs when a powerful force is applied from bottom to top against the sole. The main danger is that fragment displacement can disrupt the retrograde blood supply to the body of the bone, leading to avascular necrosis (avascular necrosis).
Lateral process fractures occur due to shearing forces (shearing forces) during foot eversion. The fracture line often extends into the posterior subtalar joint. This injury is frequently missed on initial radiographs, subsequently leading to nonunion and severe subtalar osteoarthritis. CT is mandatory for an accurate assessment of articular surface involvement.
Avulsion fractures (avulsion) are most commonly localized on the dorsal surface of the talar head (detachment of a fragment by the joint capsule) and rarely have significant clinical relevance. In addition, an osteochondral defect (Osteochondral Defect, OCD) may be visualized on the medial surface of the talar dome.
Calcaneal injuries
When analyzing radiographs of the calcaneus (calcaneus), the key parameter is Böhler's angle (Bohler angle), which is normally 30°. In posterior fractures, the bone arch drops, the angle flattens (flattening), and the reference points align almost into a straight line.
There are two main types of fractures:
- Tongue-type (Tongue-type fracture): A V-shaped line directed from the posterior surface into the body of the bone. Characterized by disruption of subtalar joint congruity.
- Vertical oblique (Vertical oblique): The line runs vertically posterior to the articular area. This is an extra-articular injury (extra-articular injury).
A fracture of the anterior process also occurs, presenting as persistent midfoot pain. It is best visualized on sagittal CT reconstructions.
Metatarsal injuries
Ankle inversion is frequently accompanied by forefoot injuries. An avulsion fracture of the base of the fifth metatarsal occurs due to sudden tension of the peroneus brevis muscle (peroneus brevis). Because this is a very common injury, all lateral ankle radiographs must necessarily include the base of the fifth metatarsal.
In children, this injury must be differentiated from a normal unfused apophysis. The growth plate (lucent growth plate) is always oriented longitudinally (longitudinal), whereas the fracture line runs transversely (transversely).
Another type is the Jones fracture (Jones fracture), which is located slightly more distally, involving the diaphysis of the fourth and fifth metatarsals. It occurs during inversion in plantar flexion (plantar flexion) and carries a high risk of nonunion.
Stress fractures ("march fractures") are a consequence of microtrauma. A favored localization is the diaphysis of the second metatarsal. In early stages, the typical radiolucent line is not visible; only periostatic reaction is detected. If radiographs show no pathology but pain persists, the imaging is repeated in 10–14 days. MRI is indicated for early diagnosis in athletes.
Lisfranc injury
A Lisfranc injury (Lisfranc Injury) is a fracture-dislocation of the tarsometatarsal articulation. The classic picture includes a fracture of the base of the second metatarsal with lateral displacement of the remaining metatarsals.
Joint alignment is evaluated for diagnosis:
- Anteroposterior (AP) view (AP view): The medial cortical margin of the base of the second metatarsal must align with the medial margin of the intermediate cuneiform. Axis disruption indicates lateral displacement.
- Oblique view (Oblique view): The medial margin of the third metatarsal must coincide with the medial margin of the lateral cuneiform.
Occult injuries (occult) without obvious displacement may not be detected on standard images. In such cases, weight-bearing radiographs (weight-bearing views) are performed or computed tomography is ordered to detect micro-displacements and small avulsion fragments.
Briefly: answers to topical questions
Which arteries supply retrograde blood flow to the body of the talus and can be damaged in a talar neck fracture?
The provided materials do not contain a complete answer regarding the specific names of the arteries supplying retrograde blood flow to the body of the talus. However, it is noted that the degree of fragment displacement in talar neck fractures is directly related to the risk of damaging the retrograde blood supply to the body of the bone, which can lead to avascular necrosis. It is also noted that vessels enter through a narrow area of the talar neck.
To quickly rule out a Lisfranc injury, remember the "Rule of 2-3": on the AP radiograph, evaluate the axis of the second metatarsal, and on the oblique view, the axis of the third metatarsal. Any "step-off" in these lines is a sign of dislocation.
Class and exam questions
What is the main danger of talar neck fractures?
In the risk of developing avascular necrosis. Severe fragment displacement damages the vascular network that provides retrograde blood supply to the body of the talus.
How to distinguish a fracture of the base of the fifth metatarsal from a growth plate in children?
It is necessary to evaluate the direction of the radiolucent line. The fracture line runs strictly transversely, whereas the normal growth plate of an unfused apophysis is oriented longitudinally.
What to do if there is a clinical suspicion of a metatarsal stress fracture, but the radiograph is normal?
Radiography should be repeated in 10–14 days—by that time, periosteal reaction will appear. An alternative method for early diagnosis (especially in athletes) is performing an MRI.
How to detect an occult Lisfranc injury?
If standard radiographs show no abnormalities, but clinical suspicion is high, a weight-bearing radiograph (standing position) or a CT scan of the foot should be performed.
What else to study on this topic
- Mechanisms of formation of osteochondral defects of the talar dome
- Anatomical features of the blood supply to the talus and pathways for the development of avascular necrosis
- Indications for surgical and conservative treatment of Jones fractures
- Differential diagnosis of periosteal reaction types in stress fractures
- CT semiotics of comminuted fractures of the lateral process of the talus
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