Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
Foot injuries
Essentials
- 1
Most calcaneal fractures are intra-articular; they are associated with a Bohler angle of less than 20 degrees and are at risk of developing compartment syndrome.
- 2
Major talar fractures have a significant risk of subsequent avascular necrosis.
- 3
Fractures of the base of the second metatarsal are pathognomic of Lisfranc injury (Fleck sign).
- 4
Computed tomography (CT) imaging is indicated in Lisfranc injuries as well as complicated talar, calcaneal and navicular fractures.
- 5
Jones fractures are clinically distinct from tuberosity avulsion fractures and have a significant rate of nonunion.
Anatomy
The foot is composed of 28 bones with 57 articular surfaces. It may be divided into three anatomical regions: the hindfoot, containing the talus and calcaneum; the midfoot, containing the navicular, cuboid and cuneiforms; and the forefoot, containing the metatarsals and phalanges.
The subtalar joint collectively describes the three articulations of the inferior aspect of the talus with the calcaneus. It allows inversion and eversion of the hindfoot. The midtarsal joints incorporate the talonavicular and calcaneocuboid joints that connect the hindfoot and midfoot and allow abduction and adduction of the forefoot. The five tarsometatarsal joints (Lisfranc joint complex) connect the midfoot and forefoot and form an arch, which gives stability to the foot.
Clinical assessment
History
Injury to the foot occurs as a result of direct or indirect trauma. Direct trauma is often associated with considerable soft-tissue swelling and fracture. Indirect trauma from a twisting injury usually results in minor avulsion-type injuries. Record any pain, swelling, loss of function, reduced sensation and deformity or associated ankle injury.
Examination
Inspect the area with the patient lying on a bed with both lower limbs exposed and compare the affected with the unaffected limb to identify bruising, swelling, deformity, skin wounds, pallor or cyanosis.
Point tenderness or crepitus may be elicited at the site of fracture. Specific areas to palpate include the Achilles tendon, calcaneus, base of the fifth metatarsal, the navicular and the area under the head of the second metatarsal.
Ask the patient to demonstrate active foot movements before performing gentle passive movements and compare with the other foot. Evaluate subtalar motion with the foot in a neutral position with one hand on the lower leg and the other holding the heel. The heel is inverted and everted and should attain 25 degrees of movement.
Midtarsal motion is assessed with one hand stabilizing the heel while the other hand grasps the forefoot at the bases of the metatarsals. The forefoot is pronated, supinated, adducted and abducted. Finally, forefoot motion is evaluated by individually flexing and extending the metatarsophalangeal (MTP) and interphalangeal (IP) joints.
If no obvious focus of the pain is found during the initial examination, ask the patient to stand and walk. Assess the circulation by observing capillary refill, skin colour and the presence of the dorsalis pedis and posterior tibial pulses. Neurological assessment includes motor and sensory function.
Radiology
Standard imaging includes anteroposterior (AP), lateral and 45-degree internal oblique projections. The lateral view visualizes the hindfoot and soft tissues, whereas the oblique and AP projections image the midfoot and forefoot. An axial calcaneal view should also be requested as clinically indicated to best visualize the hindfoot; it may reveal a subtle calcaneal fracture.
Ottawa ankle and foot rules
The Ottawa ankle and foot rules provide indications for x-ray of suspected midfoot fractures. All patients with obvious deformities should have x-rays. However, if clinical findings are more subtle, a foot x-ray is required only if there is pain in the midfoot region and any one of the following:
-
Βone tenderness over the navicular
-
Βone tenderness at the base of the fifth metatarsal
-
Ιnability to bear weight for at least four steps, both immediately after the injury and at the time of emergency department (ED) evaluation
This clinical decision rule has a sensitivity approaching 100% and its routine use has been predicted to reduce unnecessary x-rays by 30% to 40%. These rules do not apply to suspected hindfoot or forefoot fractures.
Other imaging
Magnetic resonance imaging (MRI) is indicated when a stress fracture is suspected and may be positive 2 to 3 weeks before conventional radiographs demonstrate a fracture. Computed tomography (CT) is used for imaging the calcaneum, subtalar joint and Lisfranc joint in more complex injuries or when a fracture is strongly suspected but plain x-rays are inconclusive.
Hindfoot injuries
Calcaneal fractures
The calcaneus is the largest bone in the foot and is the most commonly fractured tarsal bone. It forms the heel of the foot, provides vertical support for the body’s weight and functions as a springboard for locomotion. The majority of fractures of the calcaneus occur as a result of direct axial compression during a fall from a height. Seven per cent are bilateral. Injuries to the lower extremity are present in 25% of cases and vertebral compression fractures are found in 10%; therefore these regions must be examined as well.
Mechanism and classification
Patients usually present following a fall with direct trauma to the heel. Approximately 75% of calcaneal fractures are intra-articular (body and posterior facet compression fractures), with the remainder extra-articular (anterior process, calcaneal tuberosity or sustentaculum tali). Intra-articular fractures may be non-displaced or displaced but are frequently comminuted owing to cancellous bone in the calcaneus and the magnitude of associated force ( Fig. 4.12.1 ).
An isolated fracture of the anterior process of the calcaneus is commonly misdiagnosed as an ankle sprain. It results from inversion causing an avulsion fracture or forced dorsiflexion producing compression against the cuboid.
Clinical assessment
The patient may be able to walk, but weight bearing on the heel is impossible. Examination reveals pain, swelling and tenderness over the heel, with bruising that may extend over the sole of the foot. Associated fractures are common, so examination of the vertebral column, pelvis, affected lower extremity and opposing calcaneus is essential.
Radiology
Standard x-rays usually reveal most comminuted calcaneal fractures, whereas more subtle fractures are visualized with the aid of specific axial (Harris) calcaneal views or on CT. The AP view demonstrates the anterosuperior calcaneus and calcaneocuboid joint. The lateral view may reveal compression fractures of the body and posterior facet.
The Bohler angle
The Bohler angle is formed by the intersection of a line drawn from the most cephalad point on the tuberosity to the highest point of the posterior facet, with the line from the latter to the most cephalad part of the posterior process of the calcaneus. It normally ranges from 20 to 40 degrees measured on the lateral x-ray. A compression fracture is likely if the Bohler angle is less than 20 degrees. A CT scan is necessary to define complex or equivocal fractures and is useful in preoperative planning.
Management
Calcaneal fractures notoriously have poor outcomes, with up to 50% of such patients suffering chronic pain and functional disability. Intra-articular, displaced and comminuted fractures are prone to gross swelling of the foot with a risk of compartment syndrome. Admit patients with these fractures for elevation, CT scan and consideration of surgical intervention. Operative intervention may be indicated in younger patients and those with greater degrees of Bohler angle disruption.
Extra-articular fractures and fractures of the anterior process of the calcaneus are usually non-displaced and are treated conservatively in a posterior non-weight-bearing cast for 10 to 12 weeks.
Talar fractures
The talus provides support for the body when standing and bears more weight per surface area than any other foot bone. It has no muscular attachments; instead, it and is held in place by the malleoli and ligaments and comprises a head, neck and body.
The head has articulations with the navicular and calcaneus and the body articulates with the tibia, fibula and calcaneus. The neck joins the head and body and is extra-articular. The blood supply to the talus arises from an anastomotic ring from the peroneal, posterior and anterior tibial arteries and is tenuous and easily disrupted, leading to avascular necrosis (AVN).
Mechanism and classification
Talar fractures are the second most common tarsal fracture. Minor fractures do not involve the weight-bearing surfaces of the bone and are commonly caused by inversion injuries to the plantar- or dorsiflexed foot. They frequently result from minimal trauma and may present as an apparent ankle sprain. They include avulsion fractures, lateral process fractures (commonly seen in snowboarders) and posterior talar process fractures. A high index of suspicion is needed to identify these injuries and avoid long-term complications from a delay in diagnosis and treatment.
Talar fractures of the neck, body or head follow significant force, such as a motor vehicle accident (MVA), or involve axial loading in a fall from a height (when they are associated with calcaneal fracture). They are commonly accompanied by a subtalar dislocation.
You're Reading a Preview
Become a Clinical Tree membership for Full access and enjoy Unlimited articles
If you are a member. Log in here