2. Contents
Accessory ossicles of the foot
Rocker bottom foot
Tarsal coalition
Fractures around the ankle
Plantar fascia
Brodie’s abscess in distal tibia
Soft tissue masses around ankle
Retrocalcaneal bursitis
Haglund syndrome
Achilles tendinopathy
Achilles tendon tears
3. Accessory ossicles of the foot
are secondary ossification centers that are separate from
the adjacent bone
Usually round or ovoid
have well defined smooth cortical margins on all sides.
Clinical importance
May fracture
Can cause pain
May be involved in rheumatoid arthritis, osteoarthritis, infections
& hyperparathyroidism
4. Accessory ossicles of the foot
Os tibiale externum
Os trigonum
Os peroneum
Os vesalianum
Os subtibiale
Os subfibulare
Os supratalare
Os cancaneus secundarius
5. Os tibiale externum
Also called accessory navicular
is present adjacent to the medial side of navicular
Can cause painful tendinosis of tibialis posterior
tendon
Imaging
best visualized on the lateral-oblique view
may appear as a 'hot spot' on bone scan
on MRI, bone marrow oedema can be seen
8. Os peroneum
Commonly found – 8%
located at the lateral plantar aspect of the cuboid
within the substance of the peroneus longus tendon
D/D
Os vesalianum
Apophysis of the 5th metatarsal
Avulsion fracture
12. Os vesalianum
situated at the base of the fifth metatarsal in the
peroneus brevis tendon
Less common than os peroneum
D/D
Os peroneum
Apophysis of 5th metatarsal – in children
Avulsion fracture
14. Os trigonum
sits posterior to the talus on the lateral foot radiograph
Incidence – about 7% of population
15. Less common accessory ossicles
Os subtibiale
related to the posterior colliculus of the medial malleolus
Os subfibulare
lies at the tip of the lateral malleolus
Os supratalare
located at the superior aspect of the talar head or neck
Os cancaneus secundarius
Located at anterior calcaneal process
17. Rocker bottom foot/ congenital vertical talus
Congenital anomaly
Characterized by prominent heel/ calcaneus & a convex
rounded sole
results from dorsal and lateral dislocation of the
talonavicular joint.
Foot resembles bottom of a rocking chair
In adult, it can occur secondary to
Neuromuscular disorder
Diabetic foot (charcot joint)
18. Imaging findings
fixed equinus: plantarflexion of the calcaneus
vertical talus: plantarflexion of the talus
irreducible dorsal subluxation or dislocation of the
navicular
forefoot valgus: divergence of bases of the metatarsal heads
on AP and superimposition of the metatarsal bones on the
lateral view
long axis of the talus passes plantar to metatarsal axis on
lateral view and medial to the first metatarsal on AP view
19. Rocker bottom foot
AP view shows calcaneus valgus
& metatarsal valgus. The long
axis of talus is much medial to
st
On lateral view, there is equinus of the
calcaneus and vertical orientation of talus.
Navicular has not yet ossified
21. Tarsal coalition
complete or partial union between two or more bones
in the midfoot & hindfoot
Incidence – about 5 % of population
Patient usually present in adolescence
refers to developmental fusion rather than fusion that
is acquired secondary to conditions such
as rheumatoid arthritis, trauma or post-surgical.
22. Types
They may be of 3 types, depending on the tissue which
bridges between the two bones. The three types are 1:
I. bony: synostosis
II. cartilaginous: synchondrosis
III. fibrous: syndesmosis
26. Talocalcaneal coalition
Although all three facets of the talocalcaneal joint can be
involved, the middle facet is most commonly involved.
Often requires cross-sectional imaging for accurate diagnosis
Plain radiograph
C-sign(lateral film) – posterior continuity of talus & sustentaculum
tali
Talar beak sign (latearal film) – prominent beak at the anterior end
of talus
non-visualisation of the middle articular facet
Sclerosis around the articular margins of the talocalcaneal joint
CT – coronal reformats are best
MRI
27. C sign in Talocalcaneal coalition
Red: talus; blue: sustentaculum tali - blue line is continuous between the talus
and sustentaculum tali demonstrating coalition.
29. Fractures around the ankle
Lateral malleolus fracture
Fracture through the Tibial plafond
Talus fracture
Calcaneus fracture
30. Lateral malleolus fracture
commonly the result of twisting injury of the talus in
ankle mortise.
Radiographs are usually sufficient for the management
of what are typically simple fractures.
CT axial images through both ankles are useful when
the integrity of the syndesmosis is questioned.
“Weber” staging system for ankle fractures – to
understand mechanism of syndesmotic injury.
syndesmotic injuries usually require screw fixation
31. Weber classification of lateral malleolar fractures
Type A
Below talar dome
Usually transverse
Syndesmosis intact
Deltoid ligament intact
Type B
distal extent at the level of the talar dome
Usually spiral
syndesmosis usually intact, but widening of the distal tibiofibular joint
(especially on stressed views) indicates syndesmotic injury
deltoid ligament may be torn, indicated by widening of the space between
the medial malleolus and talar dome
Type C
above the level of the ankle joint
tibiofibular syndesmosis disruption with widening of the distal tibiofibular
articulation
medial malleolus fracture or deltoid ligament injury often present
35. Weber B
There is oblique fracture of distal fibula.
fracture extends distally to the level of the ankle joint.
There is no significant widening of the tibiofibular joint to suggest syndesmosis tear.
38. Fracture through the Tibial plafond
In adult –
Pilon fracture
In adolescents
Tillaux fracture
Triplane fracture
39. Pilon Fracture
any tibial fracture that involves the distal articular
plafond and are typically the result of an axial loading
force
can produce significant comminution with multiple
displaced fracture fragments
X-ray & CT
fractures lines are seen extending into the tibiotalar
articular surface
40. Pilon fracture
28 yrs. after Road
Traffic Accident
There is a comminuted
distal tibial fracture
extending into
the tibial plafond
41. Juvenile Tillaux fracture
Salter-Harris type 3 fracture
Have characteristic appearance on CT
Mechanism - an external rotation force pulling on the
anterior tibiofibular ligament, causing avulsion of the
anterolateral corner of the distal tibial epiphysis with
variable amount of displacement
Why always laterally?
because the distal tibial physis fuses from medial to lateral as
a child matures
Age
Adolescents in whom, lateral growth plate has not fused
12-15 years
42. Tillaux fracture – 15 years male
Tillaux fracture, i.e. Salter-Harris III fracture of anterolateral
aspect of distal tibial epiphysis, minimally displaced.
43. Triplane fracture
Salter-Harris type 4
Multiplanar CT scans are ideally suited to visualize
these fractures in all planes
The name is due to the fact of the fracture
expanding both in frontal and lateral as well as
transverse planes
It comprises of
a vertical fracture through the epiphysis
a horizontal fracture through the physis
an oblique fracture through the metaphysis
Age
adolescents
44. Triplane fracture in adolescent
Tibial physis closed medially. Fracture in lateral tibia extending into epiphysis
and metaphysis consistent with Triplane fracture. No major dislocations.
47. Talar fracture
Location
Head
Neck
Body
Talar dome osteochondral fracture
Posterior talar process fracture
Lateral talar process fracture
48. Talar dome osteochondral defect/injury
These are are focal areas of articular damage with
cartilage damage and injury of the adjacent
subchondral bone
Plain x-ray findings can be normal in early stages
MRI more sensitive and specific
49. Anderson staging of osteochondral
defect
Stage I
“subchondral trabecular compression”
Plain film & CT negative
Bone marrow edema in MRI
Stage II
“incomplete separation of the fragment,”
X-ray – only thin sclerotic rim
IIa – if subchondral cyst
Stage III
“unattached, undisplaced fragment,”
Presence of synovial fluid in T2 around fragment
Stage IV
Displaced fragment
56. Bohler/Tuber/Calcaneal angle
Angle between 2 lines in
lateral film
Line 1 – vertex to
postero-superior edge
Line 2 – vertex to
anterior horn of
calcaneum
Normal
20-40
Less than 20 degrees in
calcaneal fracture
57. Gissane/critical angle
In lateral film, formed by
downward & upward
slopes of calcaneal
superior surface
Normal
120-145
Increased in calcaneal
fracture
58. Chopart fracture/injury
Fracture/dislocation of the mid-
tarsal joint i.e. talonavicular &
calcaneocuboid joints, which
separates hindfoot from midfoot
The commonly fractured bones are
calcaneum, cuboid & navicular
The foot is usually dislocated
medially & superiorly as it is
plantar flexed & inverted, usually
as a result of high energy impact
Where the foot is everted, lateral
displacement occurs
59. Lisfranc injury/fracture
are the most common type of
dislocation involving
the foot and correspond to the
dislocation of the articulation of
the tarsus with the metatarsal
bases
Displacement can also occur
from fractures at distal
metatarsals
60. A case of Lisfranc fracture/dislocation
Figure - Divergent Lisfranc dislocation in a 34-year-old who was the front passenger in
a motor vehicle accident. Radiographs were obtained in the emergency department.
Anteroposterior (A) and oblique (B) views of the foot reveal lateral dislocation of the
second through fifth metatarsals. The white arrow points to a fragment fractured off
the base of the second metatarsal.
Less obvious on the lateral view
62. Plantar fascia
dense collection of collagen fibres on the sole (plantar
surface) of the foot. These fibres are mostly longitudinal
but also transverse
Attachments
Posteriorly it attaches to the medial process of the tuberosity
of the calcaneus, proximal to flexor digitorum brevis. It is
narrow and thick at this attachment and becomes more broad
and thin distally and anteriorly.
Anteriorly it divides into five heads, one for each toe, just
proximal to the heads of the metatarsals. The superficial
layers of these fibres insert into the dermis at the ball of the
foot and the crease between the ball and the toes via the
retinacula cutis (skin ligaments). The deep layers of each digit
become septa that separate the digital flexor tendons from
the lumbricals and the digital vessels and nerves.
Laterally it covers abductor digiti minimi.
Medially it covers abductor hallucis and merges with
the flexor retinaculum and dorsalis paedis fascia.
65. Plantar fascitis
Most common cause of pain in heel
is a stress reaction occurring at the origin of the
plantar aponeurosis from the calcaneus, typically at
the medial calcaneal tubercle.
Etiology - degenerative changes from repetitive
microtrauma in the origin of the plantar fascia cause
traction periostitis and microtears
66. Imaging Plantar Fascitis
Plain radiograph
Non-specific
Associated calcaneal spur can be found
MRI
Thickened >4.5 mm
Edema around the origin of the aponeurosis
there may be edema in the underlying calcaneal
bone marrow
67. A case of plantar fasciitis –
Thick fascia near origin with high signal intensity
68. Plantar fascial tear
refer to disruption of plantar fascial fibres which
can occur in associated with longstanding plantar
fascitis or those treated with steroid injections.
The tears can be complete (i.e. rupture) or
incomplete.
MRI – T1WI
absence of T1-weighted low signal intensity at the site
of complete rupture or partial loss of T1-weighted low
signal intensity.
70. Brodie’s abscess in distal tibia
chronic intraosseous abscess resulting from
incomplete resolution of acute osteomyelitis
Distal tibial metaphysis – 1 of the common location of
brodie’s abscess.
Rarely cross the growth plate & epiphysis in children
Age- children with unfused epiphyseal plates
Pathology – Staphylococcus aureus
71. Imaging
Plain radiograph
lytic lesion often oval that is oriented along the long axis of
the bone
surrounded by a thick dense rim of reactive sclerosis
Periosteal reaction - +-
CT
central intramedullary hypodense cystic lesion with thick rim
ossification
Extensive periosteal reaction and bone sclerosis around the
lesion
MRI
T2 & STIR hyperintense rim with surrounding hypointense
sclerotic rim
Adjacent bone marrow edema +-
72. Case of 13 yrs. Old with Brodie’s abscess in distal tibia
Lytic lesion in
metadiaphyseal
region of distal tibia
MRI
Bilobed T1 hypointense and T2 hyperintense lesion
with surrounding sclerosis.
Adjacent marrow edema is also present
73. Soft tissue masses/tumors around Ankle
I. Synovial cysts or ganglia
II. Schwannomas
III. Plantar fibromas
IV. Giant cell tumor of the tendon sheath
74. Synovial cysts or ganglia
Most common around ankle & foot
are para-articular fluid-filled sacs or pouch-
like structures containing synovial fluid and lined by
synovial membrane
MRI – uniformly bright on fluid-sensitive images
75. Synovial cyst in 51 year old
Lateral radiograph shows a
round soft tissue mass
dorsal to the metatarsals
T1 – Iso
T2 – Bright
Post contrast – peripheral
enhancement
76. Plantar fibromas
Plantar fibromas can have variable signal
characteristics but are typically dark on all sequences
These are usually found in the plantar fat adjacent to
the aponeurosis, usually close to the calcaneus
77. A case of Plantar fibroma in a 44-year-old
Coronal T1-weighted (A), proton-density–weighted
(B), and T2-weighted (C) images reveal that the lesion (arrows) is relatively dark on
all sequences and confined to the fat of the plantar heel pad
78. Giant cell tumor of tendon sheath
is a localized form of pigmented villonodular synovitis
usually benign lesions that arise from the tendon
sheath
localized solitary subcutaneous soft tissue nodules
79. Plain radiograph
they may cause pressure erosions on the underlying
bone in 10-20% of cases
more commonly these masses arise from the palmar
tendons
the mass itself is of soft tissue density
periosteal reaction and calcification are uncommon
80. MRI
T1WI
low signal
T2WI
low signal
Post contrast
moderate enhancement
GRE
low and may demonstrate blooming
81. Case of Giant cell tumor of tendon sheath in 18 year-old
A well defined oval shape mass is seen anterior to the talus, extra articular in
position and underneath the tendon of the Extensor hallucis longus. The mass
displays low signal on T1, lower signal on T2 likely from hemosiderin deposition,
heterogeneous high signal on STIR, and avid enhancement on post contrast study.
No evidence of infiltration of the adjacent structures.
82. Retrocalcaneal Bursitis
refers to inflammation of the retrocalcaneal bursa,
which lies between the antero-inferior calcaneal
tendon and posterosuperior calcaneus.
It forms part of Haglund syndrome.
Note – there is another 1 bursa i.e. subcutaneous
calcaneal bursa (between the tendon and the skin)
rarely occurs in isolation and is almost always
associated with calcaneal tendinitis and/or Haglund
deformity
Bursae - are small fluid-filled sacs lined by synovial
membrane with an inner capillary layer of synovial
fluid
84. Imaging
Plain film
prominence of the posterosuperior calcanum can be
frequently seen 1
decreased lucency of the retrocalcaneal soft tissue (Kager
triangle)
Ultrasound
bursa distension by a hypoechogenic fluid collection: > 1 mm
anteroposteriorly, > 7 mm craniocaudally, or > 11 mm
transversely is considered abnormal
MRI
fluid collection:
T1: low signal
T2: high signal
STIR: high signal
86. Haglund syndrome
Refers to Haglund triad of
1) insertional Achilles
tendinopathy
2) retrocalcaneal bursitis
3) posterosuperior
calcaneal exostosis
Associated with calcaneal spurs
Wearing high heels
Stiffed backed shoes
87. Imaging
Plain film
loss of the Kager triangle due to retrocalcaneal bursitis
Achilles tendon measuring over 9 mm in thickness 2
cm above the bursal projection due to Achilles
tendinopathy
Postero-superior calcaneal spur
MRI
focal enlargement and abnormal signal at Achilles
tendon insertion segment
retrocalcaneal and retroachilles bursal fluid collection
calcaneal bony spur better appreciated on T1 sagittal
images
marrow oedema of the posterior calcaneal tuberosity
88. Case of Haglund syndrome in 20 yrs. male
High signal near
achilles insertion
89. Achilles tendinopathy
Macroscopically, tendinopathy results in
enlargement, disruption of fibrillar pattern and an
increase in tendon vascularity
Ultrasound
shows thickening and rounding of the affected portion of the
tendon. The cutoff value of 1 cm in anteroposterior diameter
is usually used for diagnosis.
Additional signs include increased Kager’s fat pad
echogenicity.
MRI
shows increased intratendinous signal and tendon
enlargement, with oedema in Kager's fat pad in cases of
tendinosis.
90. Case of Achilles tendinopathy.
Patient with pain on dorsiflexion
Thickening of the achilles tendon
on the lateral view of the ankle can
be seen 5-6 cm above its insertion
into the calcaneum
91. Achilles tendon tears
Pathology
interstitial tears (parallel to the long axis of
the Achilles)
partial tears
complete tears.
Location
ruptures in the 'critical zone', which is a region
of relative watershed hypovascularity 2-6 cm
proximal to insertion
92. Kuwada classification of Achilles
tendon tear
type I: partial ruptures ≤50%
typically treated with conservative management
type II: complete rupture with tendinous gap ≤3 cm
typically treated with end-end anastomosis
type III: complete rupture with tendinous gap 3 to 6 cm
often requires tendon/synthetic graft
type IV: complete rupture with defect of >6 cm (neglected
ruptures)
often requires tendon/synthetic graft and gastrocnemius
recession
93. Case of Kuwada type I tear
thickened and hypoechoic right Achilles tendon with discontinuation of its deep
fibers at its insertion site at calcaneum with adjacent fluid.
Findings are suggestive of tendinopathy with partial thickness tear
involving less than 50% fibres
94. Case of Kuwada Type II tear
Achilles tear, just above the insertion