The Foot




Foot Checklists



Radiographic examination





  • AP



  • Oblique



  • Lateral



  • Axial view of calcaneus




Common sites of injury in adults





  • Metatarsals




    • Neck, base, shaft



    • Fifth MT – tuberosity, Jones’ fracture




  • Phalanges



  • Metatarsal/tarsal fracture-dislocation (Lisfranc)



  • Calcaneus – compression fracture



  • Talus




    • Neck



    • Lateral process (snowboarder’s fracture)




  • Subtalar fracture-dislocation



  • Chopart’s fracture-dislocation



  • Navicular




    • Body



    • Proximal pole




  • Tarsal avulsion




    • Lateral view




      • Head of talus



      • Anterior cortex navicular



      • Posterior tuberosity of talus



      • Dorsal surface of calcaneal tuberosity



      • Anterior process of calcaneus




    • AP view




      • Lateral surface of calcaneus






Common sites of injury in children and adolescents





  • Metatarsal




    • Bunk bed fracture (buckle fracture base of first MT)



    • Apophysis base of fifth MT (do not mistake for fracture)




  • Phalanges




    • Salter-Harris types 1 and 2 epiphyseal separation




  • Calcaneus




    • Under age 14 – extra articular fx of tuberosity



    • Over age 14 – adult pattern intraarticular compression fx




  • Talus




    • Nondisplaced fx of neck of talus; may be torus or buckle-type fx





Injuries likely to be missed





  • Minimally displaced Lisfranc fracture-dislocations



  • Fracture of adjacent metatarsals



  • Lateral process fractures of talus (snowboarder’s fx)



  • Subtle nondisplaced fractures of base of metatarsals




Where else to look when you see something obvious



















Obvious Look for
Fx metatarsal Fxs adjacent metatarsals
Compression fx calcaneus Similar fx opposite calcaneus
Compression fx thoracolumbar spine



Where to look when you see nothing at all





  • Lisfranc fracture-dislocation



  • Fine nondisplaced fracture of the neck of the talus



  • Fine nondisplaced fracture of anterior process of calcaneus



  • Subtle fine fracture of neck or base of metatarsals



  • If questionable radiographic findings – CT to clarify abnormality



  • If radiographs negative – MRI to identify ligament tears, tendon injuries, and bone contusions





Foot – The Primer



Radiographic examination





  • AP



  • Oblique



  • Lateral



  • Axial view of calcaneus



A minimum of three views—AP ( Figure 12-1 A ), internal oblique ( Figure 12-1 B ) and lateral ( Figure 12-1 C )—should be obtained. In some cases fractures of the phalanges are seen only on the internal oblique view and, therefore, may be overlooked if the internal oblique is omitted. If there is a question of injury to the calcaneus, an axial view of the calcaneus ( Figures 12-1 D and 12-1 E ) should be obtained in addition to the standard views of the foot. When the suspected injury is confined to the toes, AP ( Figure 12-1 F ), oblique, and lateral views of the toes should be obtained rather than the foot, as detail is increased and disclosure of injuries is enhanced.




FIGURE 12-1


AP ( A ), internal oblique ( B ), and lateral ( C ). If there is a question of injury to the calcaneus, an axial view of the calcaneus ( D, E ) should be obtained in addition to the standard views of the foot. When the suspected injury is confined to the toes, AP ( F ), oblique, and lateral views of the toes should be obtained rather than of the foot, as detail is increased and disclosure of injuries is enhanced.



Common sites of injury in adults





  • Metatarsals




    • Neck, base, shaft



    • Fifth MT – tuberosity, Jones’ fracture




  • Phalanges



  • Calcaneus




    • Compression fracture



    • Noncompressive fractures




      • Avulsion




        • Anterior process



        • Beak fracture tuberosity



        • Lateral body (extensor digitorum brevis avulsion)






  • Talus




    • Neck



    • Lateral process (snowboarder’s)



    • Posterior tuberosity




  • Navicular




    • Body



    • Proximal pole



    • Anterior-superior cortical avulsion




  • Dislocation




    • Metatarsal/tarsal fracture-dislocation (Lisfranc)



    • Subtalar fracture-dislocation



    • Chopart’s fracture-dislocation




Pattern of search in adults


AP and lateral diagrams of the foot ( Figure 12-2 ) pinpoint the common sites of fracture. The most common sites of fracture are identified by broad red lines. Less common sites are designated by fine red lines. Your pattern of search should include all sites.




FIGURE 12-2


AP ( A ) and lateral ( B ) diagrams of the foot pinpoint the common sites of fracture.


Metatarsal and phalangeal fractures account for the majority of fractures of the foot. Metatarsal fractures are frequently multiple, with similar fractures involving the same site: neck ( Figure 12-3 A ), shaft, or base ( Figure 12-3 B ) of adjacent metacarpals. Having identified one metatarsal fracture, look closely at adjacent metatarsals for similar fractures. Similar fractures of adjacent phalanges are less common.




FIGURE 12-3


Metatarsal fractures are frequently multiple with similar fractures involving the same site: neck ( A ), shaft, or base ( B ) of adjacent metacarpals.


Fractures of the fifth metatarsal are quite common. Avulsions of the tuberosity ( Figure 12-4 A ) should be distinguished from fractures of the base or the shaft of the metatarsal (also known as Jones’ fracture) ( Figure 12-4 B ).




FIGURE 12-4


Fractures of the fifth metatarsal. Avulsions of the tuberosity ( A ) should be distinguished from fractures of the base of the shaft of the metatarsal (also known as Jones’ fracture) ( B ).


Fractures of the phalanges are often due to heavy objects falling on the foot ( Figure 12-5 A ) or stubbing the toe while walking barefoot ( Figure 12-5 B ). Mach bands formed by the underlying sole of the foot or overlapping toes ( Figure 12-5 C ) should not be mistaken for fractures. It is imperative that oblique views of the toes be obtained to avoid missing fractures, as some fractures of the phalanges may only be visualized on the oblique projection ( Figures 12-6 A and 12-6 B ). Dislocations of the metatarsophalangeal and interphalangeal joints are common ( Figure 12-7 A ). Make certain the joint is properly aligned on the postreduction radiograph. Note the slight malalignment of the third PIP joint on the postreduction examination ( Figure 12-7 B ). This malalignment proved to be due to entrapment of a flexor tendon.




FIGURE 12-5


Fractures of the phalanges are often due to heavy objects falling on the foot ( A ) or stubbing the toe while walking barefoot ( B ). Mach bands formed by the underlying sole of the foot or overlapping toes ( C ) should not be mistaken for fractures.



FIGURE 12-6


It is imperative that oblique views of the toes be obtained to avoid missing fractures, as some fractures of the phalanges may only be visualized on the oblique projection ( A, B ).



FIGURE 12-7


Dislocations of the metatarsophalangeal and interphalangeal joints ( A ). Make certain the joint is properly aligned on the postreduction radiograph. Note the slight malalignment of the third PIP joint on the postreduction examination ( B ) due to entrapment of tendon.


Calcaneus


Fractures of the calcaneus are divided into two types, noncompressive and compression.


Noncompressive are avulsions of the periphery of the bone: extensor digitorum brevis avulsion from the lateral aspect of the body as seen on AP views of the ankle beneath the lateral malleolus, posterior superior tuberosity (beak fracture) ( Figure 12-8 A ), and anterior process avulsion (arrow) ( Figure 12-8 B ). An anterior process avulsion should be differentiated from a secondary center of ossification, the os calcaneus secondarius (arrow) ( Figure 12-8 C ).




FIGURE 12-8


Noncompressive fractures of the calcaneus are avulsions of the periphery of the bone: posterior superior tuberosity (beak fracture) ( A ), and anterior process avulsion (arrow) ( B ). An anterior process avulsion should be differentiated from a secondary center of ossification, the os calcaneus secondarius (arrow) ( C ).


Compression fractures are due to high-impact trauma either falls from great heights and landing on the feet or in motor vehicle crashes. In compression fractures the posterior facet is fractured and compressed into the body of the calcaneus ( Figure 12-9 A ).


Mar 23, 2019 | Posted by in MUSCULOSKELETAL IMAGING | Comments Off on The Foot
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