Foot, Ankle, and Calf

Thomas H. Berquist

Protocols

Key Facts

Routine radiographs
- Ankle: anteroposterior (AP), lateral, mortise view
- Foot: standing AP, standing lateral, oblique (Certain patients may not be able to stand. In this case, non–weight-bearing views are obtained.)
Other Options Indication

AP, varus, valgus stress views Ligament injuries

Fluoroscopic spot views To align bones and reduce overlap

Sesamoid views Osteonecrosis or fracture
Computed tomography (CT)
- Bone and soft tissue settings
- 512 × 512 matrix
- Field of view 14 to 20 cm (depends on area and both ankles and/or feet done for comparison)
- Slice thickness 4 to 5 mm for routine, 1-mm sections at 0.5-mm intervals for reformatting in different planes, or three-dimensional reconstruction
Magnetic resonance imaging (MRI)
- Patient positioning: Supine with foot in neutral position for most ankle studies including the Achilles tendon. Slight plantar flexion (20 degrees) for the other ankle tendons. Prone to reduce motion for forefoot studies.
- Coil selection: Extremity coil for foot and ankle. Three- or five-inch flat coil for forefoot. Head coil for comparison studies. Dual circular coils for motion studies.
- Additional parameters are summarized in Table 6-1.

Other Options	Indication
AP, varus, valgus stress views	Ligament injuries
Fluoroscopic spot views	To align bones and reduce overlap
Sesamoid views	Osteonecrosis or fracture

TABLE 6-1 MAGNETIC RESONANCE PARAMETERS FOR THE FOOT, ANKLE, AND CALF

Plane	Sequence	Thickness/Skip	Matrix	FOV	Acquisitions
Calf
Scout Coronal	SE 200/10	Three 1 cm	256 × 128	24–32	1
Axial T2	FSE*4000/93	5 mm/0.5 mm	256 × 256	24–32	2
Axial T1	SE 450/17	5 mm/0.5 mm	256 × 256	24–32	1
Coronal or sagittal T2	FSE* 4000/93	5 mm/0.5 mm	256 ×256	24–32	2
Ankle
Scout axial or sagittal	SE 200/10	Three 1 cm	256 × 128	16–20	1
Sagittal T1	SE 450/17	3.5 mm/0.5 mm	512 × 512	12	1
Sagittal PD	FSE 2000/15	3.5 mm/0.5 mm	256 × 256	12	1
Coronal	DESS 23.3/7.7	1 mm/0.2 mm	256 × 256	12	1
Axial PD	FSE 3170/19	3.5 mm/0.5 mm	256 × 256	10	2
Axial T2	FSE 4000/93	3.5 mm/0.5 mm	256 × 256	10	2
Foot
Scout sagittal	SE 200/10	Three 1 cm	256 × 128	8–16	1
Oblique† axial T1	SE 450/17	3 mm/0.5 mm	256 × 256	10–12	1
Oblique† axial T2	FSE* 4000/93	3 mm/0.5 mm	256 × 256	10–12	2
Oblique coronal	DESS 23.5/7.7	1 mm/0.2 mm	256 × 256	10–12	1
Sagittal T1	SE 450/17	3 mm/0.5 mm	256 × 256	10–12	1
Sagittal T2	FSE* 4000/93	3 mm/0.5 mm	256 × 256	10–12	2
Additional Sequences
STIR	5680/109/165	4 mm/0.5 mm	256 × 256	10–24	2
Contrast-enhanced	SE* 450/17	3–4 mm/0.5 mm	256 × 256	10–24	1
* Fat suppression. †Image plane perpendicular to the sagittal to obtain true cross-sections of the forefoot. SE, spin-echo; FSE, fast spin echo; DESS, double-echo steady state; STIR, short TI inversion recovery; FOV, field of view; PD, proton density.

Suggested Reading

Berquist TH. MRI of the musculoskeletal system, 5th ed. Philadelphia: Lippincott Williams & Wilkins; 2006:430–556.

Farooki A, Sakoloff RM, Theudorou DJ, et al. Visualization of ankle tendons and ligaments with MR imaging. Influence of positioning. Foot Ankle 2002;23:554–559.

Fractures/Dislocations: Ankle Fractures—Pediatric

Key Facts

Image features of ankle fractures depend on age (growth plate development), relationship of ligaments to epiphyses, and mechanism of injury.
Metaphyseal and diaphyseal fractures frequently are incomplete.
Fractures of the distal tibia and fibula frequently involve the growth plate.
Fracture of the distal tibial physis is the second most common growth plate injury.
The Salter-Harris classification frequently is used for growth plate fractures:
- Type I Separation of epiphysis, fracture confined to growth plate (6%)
- Type II Fracture through growth plate extending into the metaphysis (75%)
- Type III Fracture through growth plate extending through epiphysis (8%)
- Type IV Extends from articular surface of epiphysis through growth plate and metaphysis (10%)
- Type V Compression of growth plate (1%)
- Complications are more significant with Types III to V.

FIGURE 6-1 The five Salter-Harris fracture patterns.

FIGURE 6-2 AP (A) and lateral (B) radiographs demonstrating marked swelling with a Salter-Harris Type IV (arrows) tibial fracture and Type II fibular fracture (arrow) as the result of an inversion injury.

FIGURE 6-3 AP (A) and lateral (B) radiographs of an eversion injury with opening of the tibial physis (arrow) and an incomplete fibular fracture (open arrow).

Suggested Reading

Rogers LF. Radiology of epiphyseal injuries. Radiology 1970;96:289–299.

Fractures/Dislocations: Ankle Fractures—Pediatric: Triplane Fracture

Key Facts

Triplane fractures are the result of external rotation forces and account for 6% of physeal fractures.
The fracture consists of three fragments instead of two seen with most growth plate fractures.
Fracture fragments include (1) anterior lateral tibial epiphysis (Salter-Harris III); (2) remainder of the tibial epiphysis with metaphyseal attachment (looks like Salter-Harris II); and (3) tibial metaphysis.
Complication rates are similar to those for a Salter-Harris Type IV fracture.
CT may be required to properly characterize the injury.

FIGURE 6-4 Triplane fracture seen from the front and side (A) and from the articular surface and with fragments separated (B).

FIGURE 6-5 AP (A) and lateral (B) radiographs demonstrate a triplane fracture (arrows). Coronal (C) and sagittal (D) reformatted CT images define the fractures (arrow) and degree of displacement.

Suggested Reading

Cone RO III, Nguyen V, Flournoyr JG, et al. Triplane fracture of the distal tibial epiphysis. Radiologic and CT studies. Radiology 1984;153:763–767.

Fractures/Dislocations: Ankle Fractures—Pediatric: Juvenile Tillaux

FIGURE 6-6 Mechanism of injury for juvenile Tillaux fractures.

FIGURE 6-7 AP radiograph shows a Salter-Harris III fracture—juvenile Tillaux fracture (arrows).

Suggested Reading

Mann DC, Rajmaira S. Distribution of physeal and nonphyseal fractures in 2,650 long bone fractures in children aged 10 to 16 years. J Pediatr Orthop 1990;10:713–716.

Fractures/Dislocations: Ankle Fractures—Pediatric Complications

Key Facts

Fractures not involving the growth plate generally heal without sequelae.
Growth plate fractures may heal with premature or asymmetric closure. Complications vary with Salter-Harris fracture type.
Low risk (6.7% complications): Types I and II fibular fractures; Types I, III, and IV tibial fractures with less than 2 mm of displacement
High risk (32% complications): Types III and IV tibial fractures with more than 2 mm of displacement; juvenile Tillaux fractures, triplane fractures, comminuted epiphyseal fractures, and Type V fractures
Complications include leg length discrepancy, rotational deformity, malunion, nonunion, and avascular necrosis.
Routine radiographs usually are adequate to define complications. CT or MRI may be required to assess growth plate involvement.

FIGURE 6-8 Prior Salter-Harris IV fracture of the distal tibia. AP (A) and lateral (B) radiographs demonstrate premature closure and angular deformity of the anteromedial growth plate (arrow). The physis remains open laterally and posteriorly (open arrow). Standing radiographs (C) in a different patient with an old physeal fracture on the right and leg length discrepancy and angular deformity of the articular surface (lines).

Suggested Reading

Spiegel PG, Cooperman DR, Laros GS. Epiphyseal fractures of the distal ends of the tibia and fibula. J Bone Joint Surg 1978;60A:1046–1050.

Fractures/Dislocations: Ankle Fractures—Adult

Key Facts

The mechanism of injury for ankle fractures is rarely pure inversion (supination) or eversion (pronation). Abduction, adduction, lateral rotation, and axial loading forces usually are associated.
Fracture patterns, specifically the location and appearance of the fibular fracture and talar shift in the ankle mortise, can allow definition of the mechanism of injury and ligament involvement in more than 90% of cases.
AP, lateral, and mortise views usually are adequate for diagnosis.
The lateral view is particularly useful to define joint effusions. An effusion should raise the question of subtle osteochondral injury, which may require CT or MRI for further evaluation.

FIGURE 6-9 (A) Joint effusion (arrow) seen on the lateral radiograph. Coronal T2- (B) and sagittal fat-suppressed T2- (C) weighted images demonstrate a large effusion (open arrows) with a lateral talar dome fracture (arrow).

Suggested Reading

Arimoto HR, Forrester DM. Classification of ankle fractures. An algorithm. AJR Am J Roentgenol 1980;135:1057–1063.

Fractures/Dislocations: Ankle Adult—Supination-Adduction Injuries

FIGURE 6-10 Inversion (supination)-adduction injury. The forces cause a transverse fracture below the joint line (Stage I) or ligament tear. With continued stress a steep oblique fracture of the medial malleolus occurs (Stage II).

FIGURE 6-11 Supination-adduction injury with a transverse fracture of the lateral malleolus (arrow) below the level of the ankle joint (line).

FIGURE 6-12 Supination-adduction Stage II injury with an oblique fracture (arrow) of the medial malleolus and avulsed fragments from the lateral malleolus (arrow).

Suggested Reading

Lauge-Hansen N. Fractures of the ankle. II. Combined experimental-surgical once experimental roentgenologic investigations. Arch Surg 1950;60:957–985.

Fractures/Dislocations: Ankle Adult—Supination Lateral Rotation Injuries

Key Facts

Supination lateral rotation injuries cause medial tension, with the talus causing posterior displacement of the lateral malleolus.
The anterior distal tibiofibular ligament is injured (Stage I). If force continues, a spiral fracture of the lateral malleolus occurs just above the joint (best seen on the lateral view). This Stage II injury is the most common ankle fracture. With continued force, a posterior tibial fracture or distal tibiofibular ligament tear occurs (Stage III), and eventually a transverse medial malleolar or medial (deltoid) ligament injury occurs (Stage IV) (Fig. 6-13).
Supination lateral rotation injuries account for 55% to 58% of ankle fractures.
All supination or inversion injuries account for 75% to 78% of ankle fractures.
Treatment is conservative if displacement is 2 mm or less.

FIGURE 6-13 Supination-lateral rotation injuries. The talus causes posterior fibular displacement with disruption of the anterior distal tibiofibular ligament (Stage I). If force continues a spiral fracture of the fibula occurs just above the joint line (best seen on the lateral view) (Stage II). Continued force results in a posterior tibial fracture or tear in the posterior distal tibiofibular ligament (Stage III) and finally a transverse medial malleolar fracture or deltoid ligament tear (Stage IV).

FIGURE 6-14 Supination-lateral rotation Stage II injury. AP (A), mortise (B), and lateral (C) radiographs. The fracture is only clearly demonstrated on the lateral (C) view (arrows).

Suggested Reading

Berquist TH. Radiology of the foot and ankle, 2nd ed. Philadelphia: Lippincott Williams & Wilkins; 2000:171–280.

Fractures/Dislocations: Ankle Adult—Pronation-Abduction Injuries

FIGURE 6-15 Pronation (eversion)-abduction injuries. Medial tension causes a transverse malleolar fracture or deltoid ligament tear (Stage I). Continued force results in disruption of the distal anterior and posterior tibiofibular ligaments or a posterior tibial fracture (Stage II) followed by an oblique fibular fracture near the joint line best seen on the AP radiograph (Stage III).

FIGURE 6-16 Pronation-abduction Stage III injuries. (A) There is a transverse medial malleolar fracture (white arrow), tibiofibular ligament tears with separation of the tibia and fibula (open arrows), and an oblique fibular fracture (black arrows). (B) Widening of the medial ankle mortise (white arrow) caused by a ligament tear with increased tibiofibular distance (open arrows) and oblique fibular fracture (black arrows).

Suggested Reading

Arimoto HR, Forrester DM. Classification of ankle fractures: An algorithm. AJR Am J Roentgenol 1980;135:1057–1063.

Fractures/Dislocations: Ankle Adult—Pronation Lateral Rotation Injuries

Key Facts

Pronation lateral rotation injuries cause medial tension as the talus rotates laterally.
The medical malleolus (low transverse fracture) or medial ligaments are injured initially (Stage I). As force continues, the anterior tibiofibular and interosseous membranes are torn (Stage II), followed by a high fibular fracture (more than 5 to 6 cm above the joint) (Stage III). Posterior tibial avulsion or distal tibiofibular ligament tears occur with continued force (Stage IV) (Fig. 6-17).
Pronation injuries account for 22% to 25% of ankle fractures.
Treatment of these fractures usually requires internal fixation of the fibular fracture and screw fixation of the medial malleolus.

FIGURE 6-17 Pronation-lateral rotation injuries. Medial tension results in a low transverse medial malleolar fracture or deltoid ligament tear (Stage I), followed by tearing of the distal anterior tibiofibular ligament and interosseous membrane (Stage II). With continued force a high (>6 cm) fibular fracture occurs (Stage III) followed by a posterior distal tibiofibular ligament tear or avulsion fracture (Stage IV).

FIGURE 6-18 Pronation lateral rotation Stage IV injury with a transverse medial malleolar fracture (small arrow), disruption of the tibiofibular and interosseous ligaments (arrowhead), and a high fibular fracture (large arrow).

Suggested Reading

Arimoto HR, Forrester DM. Classification of ankle fractures: An algorithm. AJR Am J Roentgenol 1980;135:1057–1063.

Fractures/Dislocations: Ankle Adult—Plafond Fractures (Pilon)

Key Facts

Plafond fractures do not fit neatly into other fracture classifications. Tibial plafond fractures account for less than 10% of lower extremity fractures.
Fractures are the result of axial loading; 72% occur in patients less than 50 years of age.
Up to 20% of plafond fractures are open, resulting in increased incidence of infection.
Treatment of these fractures is difficult, because the articular surface needs to be anatomically reduced.
CT and MRI may be required to clearly demonstrate the extent of injury for surgical treatment planning.

FIGURE 6-19 Mortise view of a tibial plafond fracture reduced with external fixateur and tibial screws. Note the residual articular deformity (arrow).

Suggested Reading

Bonar SK, Marsh JL. Tibial plafond fractures: Changing principles of treatment. J Am Acad Orthop Surg 1994;2:297–304.

Ovadia DN, Beals RK. Fractures of the tibial plafond. J Bone Joint Surg 1986;68A:543–551.

Fractures/Dislocations: Ankle Adult—Complications

Key Facts

Complications resulting from ankle fractures may be related to injury or treatment.
Loss of reduction occurs more commonly with closed techniques (casting) than internal fixation.
Degenerative arthritis is the most common long-term complication, occurring in 30% to 40% of cases.
Complications are summarized as follows:
- Loss of reduction (up to 26% treated by casting alone)
- Osteoarthritis
- Chronic instability
- Loss of motion
- Nonunion
- Malunion
- Reflex sympathetic dystrophy
- Infection
- Adhesive capsulitis
- Tendon rupture
- Neurovascular injury

FIGURE 6-20 AP (A) and lateral (B) radiographs demonstrating severe posttraumatic arthritis with osseous fragments in the joint and marked tibiotalar joint asymmetry.

Suggested Reading

Pettrone FA, Gail M, Pee D, et al. Quantitative criteria for prediction of results of displaced fracture of the ankle. J Bone Joint Surg 1983;65A:667–677.

Fractures/Dislocations: Talar Fractures—Talar Neck

Key Facts

Fractures of the talar neck are common in adults and rare in children.
Talar fractures account for 6% of foot and ankle injuries and 30% of talar fractures.
The mechanism of injury is abrupt dorsiflexion of the foot during a fall or motor vehicle accident.
Talar neck fractures may be undisplaced or displaced. The latter are associated with subtalar subluxation/dislocation.
Displaced fractures usually require internal fixation.
Complications include avascular necrosis (usually evident by 6 to 8 weeks), osteoarthritis (97%), and malunion or nonunion (15%).

FIGURE 6-21 Lateral radiograph of the foot showing a comminuted talar neck fracture (arrow).

FIGURE 6-22 Hawkins sign. AP radiograph after fixation of talar neck and medial malleolar fractures. The lateral talus is sclerotic, indicating loss of flow. There is normal subchondral osteopenia (arrow) medially.

Suggested Reading

Daniels TR, Smith JW. Talar neck fractures (review). Foot Ankle 1993;14:225–234.

Hawkins LG. Fractures of the neck of the talus. J Bone Joint Surg 1970;52A:991–1002.

Fractures/Dislocations: Talar Fractures—Body, Head, Process Fractures

Key Facts

Fractures of the talar body and posterior or lateral processes are uncommon in adults and rare in children.
Most fractures are the result of significant falls or motor vehicle accidents with axial compression.
Lateral talar process fractures (“snowboarder’s fracture”) are easily missed on radiographs (40% are overlooked initially).
CT is important to detect and manage talar body and process fractures.
Treatment is anatomic reduction, which requires internal fixation for displaced fractures.
Complications are the same as with talar neck fractures. Malunion and avascular necrosis occur in 16%.

FIGURE 6-23 Lateral radiograph of a posterior talar body and process fracture (arrow).

FIGURE 6-24 Coronal CT image demonstrating talar body fractures (arrows) entering the posterior subtalar joint.

Suggested Reading

Boack DH, Manegold S. Peripheral talar fractures. Injury 2004;35(S2):B23–B25.

Sneppen O, Christensen SB, Krogsoe O, et al. Fracture of the body of the talus. Acta Orthop Scand 1977;48:317–324.

Fractures/Dislocations: Talar Fractures—Talar Dome Fractures

Key Facts

This is the most common talar fracture.
Talar dome fractures are difficult to detect (50% missed), and prognosis is more guarded compared with nonarticular chip or avulsion fractures.
Fractures are most common in adults. Only 8% occur in patients less than 16 years of age.
Acute lesions are most often lateral. Ten percent involve both the lateral and medial talar dome.
CT or MRI is important for detection, localization, and measurement of lesion size and displacement.
Displaced lesions should be resected or arthroscopically removed.
Arthrosis is the most common complication (50%).

FIGURE 6-25 Coronal T1- (A) and fat-suppressed sagittal T2-weighted (B) images demonstrate marrow edema and a subtle nondisplaced talar dome fracture (arrows).

FIGURE 6-26 Mortise view of a slightly displaced lateral talar dome fracture (arrow).

Suggested Reading

Clark TWI, Janzen DL, Kendall H, et al. Detection of radiographically occult ankle fractures following acute trauma. Positive predictive value of ankle effusion. AJR Am J Roentgenol 1995;164:1185–1189.

Fractures/Dislocations: Talar and Subtalar Dislocations

Key Facts

The majority of eversion and inversion motion occurs in the subtalar joint.
Talar dislocations account for only 1% of all dislocations.
Fifteen percent of talar injuries are caused by dislocation.
Subtalar dislocations may be medial (56%), lateral (34%), posterior (6%), or anterior (4%).
Associated talar or calcaneal fractures occur in 75% of lateral and 45% of medial dislocations.
Total dislocation is rare. There is a high incidence of infection, which may require talectomy. Avascular necrosis also is common.
Post-reduction CT with coronal and sagittal reformatting is essential to assess reduction and detect associated fractures.

FIGURE 6-27 Subtalar and talonavicular dislocation. (A) AP view of the ankle showing the talus (T), calcaneus (C), and navicular (N). The calcaneus is rotated under the talus. (B) Oblique view showing the talus lateral to the calcaneus.

Suggested Reading

Detenbeck LC, Kelly PJ. Total dislocation of the talus. J Bone Joint Surg 1969:51A:283–288.

Fractures/Dislocations: Calcaneal Fractures—Intra-articular

Key Facts

The calcaneus is the most commonly fractured bone in the adult foot, accounting for 60% of foot fractures, but only 2% of all skeletal fractures.
Calcaneal fractures in children account for only 5% of calcaneal fractures.
Pediatric fractures usually are extra-articular (63%), whereas adult fractures usually are intra-articular (70% to 75%).
Most adult fractures are the result of axial loading resulting from falls or motor vehicle accidents. Ten percent are bilateral. Associated vertebral fractures occur in 10%.
CT with coronal and sagittal reformatting is required to classify the injury and access articular involvement and fracture complexity.
Treatment goals are to re-establish articular alignment, calcaneal width, and the posterior facet (Böhler’s angle).
Complications include
- Prolonged pain and disability
- Lower extremity fractures (20%–46%)
- Soft tissue injury
- Neurovascular injury

FIGURE 6-28 Lateral radiograph in a patient with a comminuted calcaneal fracture. Böhler’s angle measures 10 degrees.

FIGURE 6-29 Comminuted intra-articular calcaneal fracture. Axial (A,B) and coronal (C) CT images clearly show fragment position and articular involvement.

Suggested Reading

Crosby LA, Fitzgibbons I. Computerized tomographic scanning of acute intra-articular fractures of the calcaneus. J Bone Joint Surg 1990:72A:852–859.

Daftary A, Haims AH, Baumgartner MR. Fractures of the calcaneus: A review with emphasis on CT. Radiographics 2005;25:1215–1226.

Fractures/Dislocations: Calcaneal Fractures—Extra-articular

Key Facts

Extra-articular fractures account for 25% of calcaneal fractures. This includes all fractures that do not involve the posterior facet.
Mechanism of injury: twisting, compression, or avulsion forces.
Certain fractures may present as ankle sprains: anterior calcaneal process, peroneal tubercle, lateral calcaneal process, sustentaculum tali, calcaneal tuberosity, and medial calcaneal process fractures.
CT is frequently required to detect the injury and exclude intra-articular involvement.

FIGURE 6-30 Lateral radiograph of an anterior calcaneal process fracture (arrow).

FIGURE 6-31 Lateral radiograph of a calcaneal tuberosity avulsion fracture.

Suggested Reading

Gilheany MF. Injury to the anterior process of the calcaneus. Foot 2002;12:142–149.

Fractures/Dislocations: Midfoot Injuries

Key Facts

The midfoot consists of the lesser tarsal bones (navicular, cuboid, three cuneiforms) and tarsometatarsal (Lisfranc) joints.
Injuries may be the result of medial (30%), longitudinal (41%), lateral (17%), or plantar (4%) forces, and crush injuries (5%).
Isolated tarsal fractures are uncommon.
Tarsometatarsal fracture/dislocations are Lisfranc injuries (1% of all fracture/dislocations). The mechanism of injury is forced plantar flexion of the forefoot. CT with reformatting is essential to define the extent of injury.

FIGURE 6-32 Patterns of Lisfranc fracture/dislocations. (A) Type A: total incongruity; (B) Type B: partial incongruity; (C) Lateral dislocation; (D) Type C or divergent with total displacement (A) and partial displacement (B).

FIGURE 6-33 Lisfranc fracture/dislocation. (A) AP radiograph shows a fracture/dislocation (arrow) at the tarsometatarsal joints. There is also a dislocation (arrowhead) of the second metatarsophalangeal (MTP) joint. CT images in the axial (B), sagittal and coronal (C,D) planes demonstrate widening of the 1–2 metatarsal bases (arrow) with multiple osteochondral fractures (arrowheads).

Suggested Reading

Karasick D. Fracture and dislocation of the foot. Semin Roentgenol 1994;29:152–175.

Makawana NK, Van Lefland MR. Injuries of the midfoot. Curr Orthop 2005;19:231–242.

Fractures/Dislocations: Forefoot Injuries—Fifth Metatarsal Fractures

Key Facts