Ankle and Foot 47 - Department of Radiology - University of ...

2304 VII Imaging of the Musculoskeletal System
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Figure 47-107. Early Jones fracture in a 21-year-old college athlete. A, On the initial anteroposterior radiograph of the base of the fifth
metatarsal there is a very subtle periosteal reaction (white arrow). There is a questionable lucency (open arrowheads) extending transversely
through the lateral cortex. B, Far lateral sagittal inversion recovery (IR) image reveals bone marrow edema throughout the fifth metatarsal.
C, Sagittal IR image through the asymptomatic fourth metatarsal for comparison revealed normal dark marrow signal. Because of the high
propensity for Jones fractures to have delayed union or nonunion, elective internal fixation with a lag screw was performed the next day.
D, Follow-up anteroposterior radiograph 2 weeks later reveals bone resorption (arrowheads) along the questionable lucency in A, part of the
normal early healing response. Subsequent radiographs (not shown) demonstrated solid bony bridging 1 month later.
D
itive stress in athletes, or as in the case of Sir Robert Jones,
“whilst dancing.” 25 The Jones fracture is well recognized to
have a high rate of nonunion or delayed union because of
the relative hypovascularity of this portion of the fifth
metatarsal, prompting orthopedic surgeons to recommend
early screw fixation. MRI is useful in confirming the diagnosis
when it is suspected in athletes with radiographically
occult injuries (Fig. 47-107).
March Fracture. The march fracture is found most commonly
in the mid- to distal diaphysis of the second metatarsal
and less often in the third. Unlike the Jones fracture,
which occurs in high-performance athletes, stress fractures
in the second and third metatarsals occur in individuals
who have previously led relatively sedentary lifestyles, then
suddenly increase their level of activity. This fracture was
first reported by Breithaupt in 1855, 11 when he described
foot pain and swelling in military recruits in the Prussian
army who were forced to go on long marches—hence the
name “march fracture.” This was of course 40 years before
Röntgen’s discovery of x-rays. The first radiographic reports
of march fractures were in 1897.* Radiographically, the
*In his 2006 academic dissertation for the University of Helsinki, Bone Stress
Injuries of the Foot and Ankle (http://ethesis.helsinki.fi/julkaisut/laa/kliin/vk/
sormaala/bonestre.pdf), Sormaala cites these two references:
Schulte: Die sogenannte Fussgeschwulst. Arch Klin Chir 1897;55:872.
Stechow: Fussödem und Röntgenstrahlen. Deutsche Militärärztliche Zeitschrift
1897;26:465-471.
second and third metatarsals respond to stress by forming
a periosteal reaction, although this may be imperceptible
or subtle early on (Fig. 47-108). Edema-sensitive MRI
reveals abnormally bright marrow signal in the diaphysis
as well as bright periosteal reaction outside the cortex.
• Sesamoid Stress Fractures
Sesamoid stress fractures are notoriously difficult to diagnosis
radiographically. Perhaps because of their varying
presence and appearance, radiologists tend to have a “blind
spot” when it comes to the sesamoids. However, when
looking at the sesamoids of the first metatarsophalangeal
joint, there are some helpful statistics to keep in mind.
Although the other sesamoid bones of the foot are present
in less than 10% of people, the two sesamoids plantar to
the head of the first metatarsal are present in 100% of the
population. 16 Absence of either the medial (tibial) or lateral
(fibular) sesamoids is always abnormal, and a destructive
process should be considered (see Fig. 47-92). And
although a multipartite medial sesamoid bone is a common
normal variant found in 13% to 30% of the population, a
multipartite lateral sesamoid bone is an uncommon variant,
found in only 1% of normal feet.
When symptoms are referable to the lateral sesamoid
and radiographs reveal it to be multipartite, this should be
diagnosed as a fracture (Fig. 47-109). Additional diagnostic
imaging should not be required, although MRI or a nuclear
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