Imaging Findings of Lower Extr emity Stress Fractures

Imaging Findings of Lower Extr
emity Stress Fractures in Militar
y Soldiers emphasizing on MRI
Yoon-Ki Cha, M.D., Hyeon Kyeong Lee, M.D.,
PhD
Department of Radiology, Armed Forces
Capital Hospital, Republic of Korea
Correspondence to Yoon-Ki Cha, M.D.
E-mail : sublime256@naver.com
EE 28
Educational Review
Disclosure
♣
The following authors have no potential
conflicts with this presentation :
- Yoon-Ki Cha, M.D.
- Hyeon Kyeong Lee, M.D., PhD
Introduction
♣
Stress fracture is an overuse injury usually cause
d by changes in training regimen in the populatio
n of military soldiers and athletes
- Newer studies show that military soldiers and athletes ha
ve similar incidence and distribution of stress fractures
♣
♣
Bones constantly remodel and repair themselve
s and if stress exhausts the capacity of the bon
e to remodel, stress fracture occurs
Stress fractures are most common in the weigh
t-bearing bones of lower extremities
Introduction
♣
♣
♣
Radiography is useful when positive, but has low
sensitivity and it is difficult for an early detection
Radionuclide bone scanning is highly sensitive, b
ut lacks specificity and ability to visualize fracture
lines
MRI has equal sensitivity as radionuclide bone sc
anning in detecting stress fractures but has highe
r specificity due to better anatomical detail and d
epicting involved tissues
Purpose
♣
In this review, we focus on MRI to evaluate stress
fractures in lower extremities, which provides hig
hly sensitive and specific evaluation for bone mar
row edema and periosteal reaction as well as det
ection of subtle fracture lines in Korean military s
oldiers
High and Low Risk Stress Fractures
High risk fracture sites
Low risk fracture sites
Femoral neck tension fracture
Femoral neck compression
fracture
Patella
Fracture of posteromedial aspect
of tibia
Anterior tibial midshaft
Fibula
Medial malleolus
Calcaneus
Talus
Cuneiform
Tarsal navicular
2nd and 3rd metatarsal
5th metatarsal
Great
♣
toerisk
sesamoid
High
stress fractures are prone to develop delayed
union, nonunion and fracture with displacement and should
be treated more aggressively
Specific Locations – Femoral Neck
Two types of stress fractures involve femoral neck
1. Compression fracture
♣
- Younger patients
- Located on the inner side of the femoral neck
- Low risk of complicated healing with conservative therapy
because fracture parts are compressed
2. Tension fracture (distraction)
- Older patients
- Located on the outer side of the femoral neck
- High risk of complicated healing due to tension exerted on
fracture elements
Femur case 1
Femoral Neck – Compression Fracture
a
b
20 year old male soldier suffering from progressive pain in Lt.
hip during running. MRI with coronal FS T2WI (a) and coronal
T1WI (b) show both overt hypointense fracture lines (large
arrows) in inner side of femur neck and surrounding bone
marrow edema (small arrows).
Femoral Shaft
♣
Posteromedial cortex of proximal femur has great
est strain and susceptible to repetitive submaxim
al stress
- This location serves as origin of vastus medialis muscle an
d insertion of adductor brevis muscle, both are causative fa
ctors in development of stress fracture at this site
♣
Femoral neck and diaphyseal lesions are more
common than distal femoral lesions
Femur case 2
Femoral Shaft
a
c
b
24 year old male soldier with stress reaction in posteromedial
proximal femur. Patient had insidious onset of pain during
sports activities. MRI with coronal FS T2WI (a) shows
periosteal reaction (large arrow) and endosteal edema (small
arrow). Coronal T1WI (b) also shows periosteal reaction (large
arrow). Axial FS T2WI (c) shows periosteal reaction (large
Femur case 3
Distal Femur
a
20 year old male military recruit complained of knee pain
after the long march. MRI with coronal FS T2WI (a) and
coronal PD (b) show both discrete fracture lines (large
arrows).
b
Tibia
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Tibia is the most common location of stress fractures(20~75%)
Posteromedial aspect (compression sided fracture)
- Most common and will mostly heal with relative rest
♣
Anterior tibial midshaft (tension sided fracture)
- Prone to develop delayed union and non-union
- ‘Dreaded black line’ – lateral radiographic finding of transverse break of a
nterior cortex
♣
Medial malleolus fracture (unusual site)
- Classically, fracture extends vertically or obliquely upwards from junction o
f medial malleolus and tibial plafond
♣
Medial or lateral tibial plateau stress fracture (unusual site)
Tibia case 1
Proximal Tibia
a
b
20 year old male military recruit complained of pain during initial entry
training. MRI with coronal FS T2WI (a) shows discrete fracture line (large
arrow) with massive surrounding marrow edema (small arrows). Coronal
PD (b) and sagittal PD (c) also show discrete fracture lines (large arrows)
in posteromedial aspect of proximal tibia.
c
Tibia case 2
High risk
Anterior Tibial Midshaft
fracture
c
a
b
d
22 year old male bodyguard martial art instructor suffered from anterior
shin pain. MRI with coronal FS T2WI (a) and coronal T1WI (b) both show
focal bulge (large arrows) at anterior tibial cortex. Axial T1WI with
contrast enhancement (c) shows focal enhancement in corresponding
anterior cortex (small arrow) indicating fracture. Sagittal CT (d) shows 4
transverse areas of intracortical lucencies (small arrows), the so called
‘dreaded black lines’ with diffuse thickening of anterior tibial cortex.
Tibia case 3
Tibial Shaft
c
a
b
21 year old male military recruit suffered from leg pain. MRI with
sagittal FS T2WI (a) and coronal T1WI (b) show periosteal reaction
(large arrows) and endosteal edema (small arrows) in posterior
aspect of tibial diaphysis. Axial FS T2WI (c) shows focal discrete
fracture line (small arrow) with periosteal reaction and endosteal
edema.
Tibia case 4
High risk
Tibia – Medial Malleolus
fracture
a
b
c
54 year old male marine officer complained of ankle pain. MRI with
coronal FS T2WI (a) shows medial malleolus stress fracture at classical
anatomic landmark (junction of tibial plafond and medial malleolus,
large arrows) with surrounding bone marrow edema (small arrows). Axial
T1WI (b) shows discrete fracture line (large arrow) with surrounding
bone marrow edema (small arrows). Axial T2WI (c) also shows discrete
fracture line (large arrow)
Tibia – Medial and Lateral Tibial Plateau
Tibia case 5
a
b
c
d
20 (a, b) and 22 (c, d) year
old military recruit with knee
pain. MRI with coronal FS
T2WI (a, c) and coronal PD
(b, d) show both overt
hypointense fracture lines
(large arrows) and
surrounding bone marrow
edema (small arrows, a, c) in
medial and lateral tibial
plateaus.
Fibula
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♣
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Fibula stress fractures usually occur in the distal
one third, so called ‘runners fracture’
More proximal fibula stress fracture is less comm
on
Causes of stress fractures in fibula are due to co
mpression, torsion and muscle contractions
Fibula case 1
Distal Fibula
c
a
b
22 year old male military recruit complained of pain after the long march.
MRI with coronal FS T2WI (a) and coronal T1WI (b) show discrete fracture
lines (small arrows). Axial FS T2WI (c) shows periosteal edema (large
arrow) in distal fibula.
Fibula case 2
Proximal Fibula
c
a
b
20 year old male military recruit complained of pain during initial entry
training. MRI with coronal FS T2WI (a) and coronal T1WI (b) show
hypointense lines (small arrows) suggesting of fracture. Axial FS T2WI (c)
shows periosteal reaction (large arrow) in proximal shaft of fibula.
Calcaneus case
1
Calcaneal Body
a
♣
Calcaneal stress fracture usually occurs in calcaneal body posterior to talus
21 year old male soldier complained of foot pain after the long
march. MRI with sagittal FS T2WI (a) and sagittal T1WI (b) show
subtle hypodense line (large arrows) indicating stress fracture in
calcaneal body. Also note stress reaction (small arrows) in medial
cuneiform bone.
b
Anterior Process of Calcane
us
Calcaneus case
2
a
♣
Stress fracture of anterior process of calcaneus is an unusual site for calcaneal fracture
22 year old male soldier with stress reaction in anterior process of
calcaneus. MRI with sagittal T1WI (a) shows location of calcaneal
anterior process (large arrow). Sagittal FS T2WI (b) shows bone
marrow edema in anterior process (small arrows) without discrete
fracture line.
b
Talus case 1
Talus
High risk
fracture
a
b
24 year old male soldier with foot pain for several months after
having an initial entry training. MRI with sagittal FS T2WI (a)
and sagittal T1WI (b) show fracture line in talar head (large
arrows) and also stress reaction in navicular bone (small arrow).
Tarsal Bones – Navicular High
Borisk
fracture
ne
Tarsal bones case
1
a
b
24 year old male soldier with medial ankle pain for 1 month. MRI
with axial T1WI (a) shows hypointense fracture line (large arrow)
in navicular bone. Sagittal FS T2WI (b) shows bone marrow
edema (small arrows) in corresponding navicular bone.
Tarsal bones case
2
Tarsal Bones – Medial Cuneiform Bone
a
b
19 year old male military recruit with stress reaction in medial
cuneiform bone. MRI with long axial FS T2WI (a) and T1WI (b)
show bone marrow edema (small arrows) in medial cuneiform
bone without definite fracture line.
Metatarsals
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♣
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Stress fractures on metatarsal bones were first de
scribed in military recruits and referred to as a “
march fracture”
Most common locations are neck or distal shaft of
2nd and 3rd metatarsals
Jones fracture (high risk fracture) is stress fractur
e of 5th metatarsal base ocurring approximately
1.5cm distal to tubercle
Metatarsal case
1
Metatarsals
b
a
22 year old male soldier with foot pain after the long march.
MRI with long axial FS T2WI (a) shows extensive bone marrow
edema in 3rd metatarsal bone with fracture line in diaphysis
(long arrow). Also note stress reaction in lateral cuneiform bone
(small arrow). Corresponding T1WI (b) shows fracture line and
periosteal reaction with low signal representing callus
Sesamoid case 1
Great Toe Sesamoid
a
High risk
fracture
b
36 year old male noncom with increasing pain at base of great
toe. MRI with sagittal T1WI (a) and FS T2WI (b) show fracture
line in lateral sesamoid bone (large arrows) and surrounding
bone marrow edema
Summary
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Stress fractures in military recruits are not uncom
mon due to their rigorous activities and training,
which lead to stress fractures
With help of MRI, we diagnosed stress fractures e
asily due to its highly sensitive and specific evalu
ation for bone marrow edema and periosteal reac
tion as well as detection of subtle fracture lines
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