Skeletal Radiology

https://doi.org/10.1007/s00256-019-03329-3

CASE REPORT

Talus Partitus: a review of five cases diagnosed by MRI

Corbin L. Pomeranz 1 & William B. Morrison 1 & Vishal Desai 1 & Adam C. Zoga & Jeffrey A. Belair 1

Received: 4 June 2019 / Revised: 19 September 2019 / Accepted: 2 October 2019

# ISS 2019

Abstract
Talus partitus is a rare skeletal developmental abnormality characterized by a split of the posterior talar bone in the coronal plane.
Patients with talus partitus typically present with posterior ankle pain and instability, often displaying varying degrees of chondrosis
and secondary degenerative change on imaging. To date, only few case reports describing the imaging appearance of talus partitus
have been published. The majority of these publications are limited to radiographic and computed tomography (CT) imaging
findings, despite the ubiquity of magnetic resonance imaging (MRI). To the authors’ knowledge, there is little description of typical
MRI findings of the symptomatic talus partitus in the radiologic literature. We present a series of five cases of talus partitus identified
on MRI and examine pitfalls in diagnosis, differential considerations, pathophysiology, and treatment options.

Keywords Talus partitus . MRI . Posterior ankle impingement

Introduction that the posterior fragment of talus partitus is developmental in

etiology rather than representing a fracture non-union, as the
Talus partitus, also known as talus bipartitus, is a rare osseous majority of cases do not have a history of severe trauma [2].
abnormality characterized by coronal segmentation of the ta- However, it has been postulated that repetitive minor trauma
lus into two separate anterior and posterior fragments. Talus during adolescent skeletal maturation may contribute to the
partitus was first described as an anatomic variant in a disser- development of the talus partitus [2, 3]. In support of this
tation by Emil Strehle in 1928. Subsequently in 1975, theory, a few patients have reported a history of multiple ankle
Weinstein and Bonfiglio first described a symptomatic case sprains in childhood [2, 4]. The condition is considered rare
that was treated with surgical excision [1]. Talus partitus poses based on the limited number of published case reports, though
a diagnostic challenge due to its rarity, as well as its clinical the prevalence may be higher than initially thought as more
and imaging overlap with other talar abnormalities such as cases are recognized by advanced imaging modalities.
posterior talar process fractures, os trigonum syndrome, and Definitive diagnosis is made almost exclusively by CT or
other symptomatic talar ossicles. It is generally hypothesized MRI, and radiologists play a key role in both initial diagnosis
at presentation and imaging follow-up.
In this article, we review the imaging findings of talus
partitus in five patients from our institution (summarized in
* Corbin L. Pomeranz
Corbin.Pomeranz@jefferson.edu Table 1), with a specific focus on MRI findings. We also
examine pitfalls in diagnosis and discuss other differential
William B. Morrison considerations.
William.Morrison@jefferson.edu
Vishal Desai
vishal.desai@jefferson.edu
Adam C. Zoga
Case reports
adam.zoga@jefferson.edu
Case 1
Jeffrey A. Belair
jeffrey.belair@jefferson.edu
A 16-year-old boy presented with a history of persistent lateral
1
Thomas Jefferson University, 132 South 10th Street, 10th Floor, ankle pain and swelling since an inversion injury. The patient
Main Building, Philadelphia, PA 19107, USA reported mild bruising and swelling at the time of injury.
 Skeletal Radiol

Tibiotalar joint
Lateral ankle radiograph obtained in the office at time of initial

involvement
injury revealed a large bony protuberance along the posterior
margin of the talus (Fig. 1). He was presumptively diagnosed
(%) with os trigonum syndrome and placed in a brace.
0

30

20

20
Approximately 1 year after initial injury, the patient visited
Degenerative changes Subtalar joint
involvement

an orthopedic surgery clinic with progressively worsening lat-

eral ankle pain and stiffness. On physical examination, a pal-
pable lump was noted along the posterior ankle anterior to the
(%)

60

30

30

60

40
Achilles tendon. An ankle MRI revealed a large triangular
posterior talar bony fragment with extensive bone marrow

MRI (Fig. 6) 2.5 × 1.4 × 1.8 cm Moderate Pseudoarthrosis and

Pseudoarthrosis and

Pseudoarthrosis and
edema throughout both the talus and calcaneus, as well as
tibiotalar joint

subtalar joints
Pseudoarthrosis,
tibiotalar and
Pseudoarthrosis

subtalar joint

subtalar joint
adjacent subtalar joint effusion and synovitis (Fig. 2).
Initially, a diagnosis of fracture nonunion was suspected,
though no high-grade trauma was reported. After reviewing
the MRI in conjunction with the original radiographs and
discussing the clinical presentation with the referring orthope-
MRI (Fig. 4) 1.4 × 1.2 × 1.0 cm Minimal
Marrow

2.6 × 1.8 × 1.6 cm Severe

edema

dic surgeon, symptomatic talus partitus was diagnosed. A CT

2.6 × 1.1 × 1.4 cm None
Mild diffuse swelling and MRI (Fig. 5) 2.8 × 1.3 × 1.6 cm Mild

scan of the ankle obtained for preoperative planning demon-

strated a well-corticated bony fragment involving nearly 60%
Size(TV by CC

of the posterior subtalar joint with mild degenerative changes

spanning the pseudoarthrosis (Fig. 3). Surgery was recom-
Fragment

by AP)

mended due to the size of the posterior talar fragment and

the presence of degenerative changes on imaging, however
the patient was lost to follow-up.
(Figs. 1, 2

X-ray, MRI
X-ray, CT,

(Figs. 7
and 3)

and 8)
Imaging

MRI

Case 2

A 39-year-old man presented with medial ankle pain after a

minor tripping injury. Initial radiographs were negative for
restricted range of
Mild ankle swelling,

Gross swelling and

limited range of

acute fracture and the patient was diagnosed with an ankle

palpable lump
Physical exam

Palpable lump

Unremarkable
motion

motion
Ankle pain for 3 months following minor tripping

Clinically diagnosed with Achilles strain prior

Chronic ankle pain for 1 year after ankle injury.
Initially diagnosed as os trigonum syndrome.

Ankle pain for 4 months provoked by running.

Chronic ankle pain for 10–15 years, history of

psoriatic arthritis. No history of significant
Ankle pain for 2 weeks after twisting injury.
Initially misdiagnosed with posterior talar

TV transverse, CC craniocaudal, AP anteroposterior

Case Age Sex Clinical presentation

process fracture.
Patients with talus partitus

to MRI.

trauma.
injury.
M

M
16

39

52

23

60

Fig. 1 Case 1. Lateral ankle radiograph demonstrates a bony

Table 1

protuberance at the posterior talus (arrow), initially thought to represent

an os trigonum
1

5
Skeletal Radiol

Fig. 2 Case 1. Sagittal T1-

weighted (a) and axial proton
density (b) MRI sequences of the
ankle show a 2.6 × 1.8 × 1.6 cm
(transverse by craniocaudal by
anteroposterior) talus partitus
fragment with irregular, sclerotic
margins along the pseudoarthrosis
cleft (arrow, a and b). There is
slight offset of talus partitus frag-
ment, which involves the subtalar
joint and approximates the poste-
rior margin of the tibiotalar joint.
Sagittal (c) and axial (d) T2-
weighted fat-suppressed MRI se-
quences show extensive bone
marrow edema spanning both the
talus partitus pseudoarthrosis
(arrow, c and d) and the posterior
subtalar joint. Given degree of
marrow edema and presence of
synovitis along the posterior an-
kle, findings are highly suggestive
of instability of the talus partitus
fragment and posterior ankle
impingement

sprain. He presented 3 months later to an orthopedic clinic degenerative changes spanning the pseudoarthrosis and
with persistent medial pain. A palpable lump was noted along subtalar joint, and only minimal marrow edema within the
the posteromedial ankle on physical exam. partitus fragment (Fig. 4). The posterior talar fragment was
An ankle MRI was ordered due to concern for ligament only 1.0 cm in anteroposterior (AP) dimension and was con-
injury. MRI revealed a relatively small talus partitus with mild gruent with the talar body. The talus partitus involved

Fig. 3 Case 1. Axial (a) and

sagittal (b) reformatted CT
images of the ankle show a large
posterior talar fragment with well-
corticated irregular margins, con-
sistent with mild degenerative
changes spanning the
pseudoarthrosis (arrow). The
fragment involves nearly 60% of
the posterior subtalar joint
(curved arrow) and approximates
the posterior margin of the
tibiotalar joint without clear artic-
ular surface involvement
 Skeletal Radiol

Fig. 4 Case 2. Axial T2-weighted

fat-suppressed (a) and axial T1
(b) MRI sequence of the ankle
demonstrate a 1.4 × 1.2 × 1.0 cm
(transverse by craniocaudal by
anteroposterior) triangular bony
fragment posterior to the talus
with mildly irregular, well-
corticated margins (arrows) and
only minimal bone marrow ede-
ma in the talus partitus fragment.
Sagittal T1-weighted MRI se-
quence (c) demonstrate approxi-
mately 30% involvement of both
the subtalar (arrow) and tibiotalar
(curved arrow) joints. Sagittal T2-
weighted fat-suppressed MRI se-
quence (d) shows cartilage thin-
ning and irregularity along the
posterior aspect of the tibiotalar
joint (arrowheads)

approximately 30% of both the subtalar and tibiotalar joints, approximately 30% of the subtalar joint and did not involve
with associated chondrosis along the posterior tibiotalar joint. the tibiotalar joint.
Nonoperative treatment with physical therapy and oral anal- Given fragment displacement and small size with relatively
gesia was recommended rather than surgery. At 1-year follow- limited involvement of the subtalar joint, the patient
up, the patient reported improvement in symptoms following underwent surgical excision. At 1-year follow-up, the patient
conservative management. reported substantial improvement in symptoms with mild re-
sidual medial ankle pain and no instability.

Case 3 Case 4

A 52-year-old man presented with left ankle pain since a A 23-year-old man presented to the emergency department at
twisting injury 2 weeks prior. On physical exam, there was a different institution with 4 months of posterior left ankle pain
mild diffuse swelling about the ankle. The patient had restrict- provoked by running. Initial radiographs were interpreted as
ed range of motion and tenderness over the posteromedial and normal. The patient was diagnosed with presumed Achilles
posterolateral ankle, localized anterior to the Achilles tendon. strain and placed in a walking boot. He subsequently present-
The patient was initially diagnosed with a posterior talar pro- ed to an orthopedic clinic 6 weeks later with persistent sharp
cess fracture on radiographs obtained in the office. An MRI pain on both sides of his ankle and “start-up” pain with walk-
was performed to evaluate for concurrent tarsal tunnel or pos- ing. Physical exam revealed no outward signs of trauma and
terior tibial tendon injury. MRI demonstrated a relatively the Achilles tendon was intact without a palpable defect. The
small talus partitus with slight offset of the fragment and ad- patient had no ankle instability and no reproducible tenderness
vanced osteoarthritis along the posteromedial aspect of the on passive or resisted plantar flexion. He had normal range of
subtalar joint (Fig. 5). The talus partitus involved motion and strength in his ankle with normal gait. Of note,
Skeletal Radiol

Fig. 5 Case 3. Axial proton

density (a) and axial (b) and
sagittal (c) T2-weighted fat-sup-
pressed MRI sequences of the
ankle demonstrate a talus partitus
measuring 2.8 × 1.3 × 1.6 cm
(transverse by craniocaudal by
anteroposterior). There is offset of
the posterior talar fragment
(arrow, c), which involves ap-
proximately 30% of the posterior
subtalar joint, but does not sig-
nificantly involve the tibiotalar
joint. Mild marrow edema and
degenerative cystic change spans
the talus partitus
pseudoarticulation (arrows, a and
b). Additional sagittal T2-
weighted fat-suppressed sequence
(d) demonstrates adjacent full-
thickness cartilage loss along the
medial aspect of the posterior
subtalar joint (arrow)

there was evidence of mild correctable planovalgus deformity posterolateral ankle and limited range of motion.
of his left foot. Previous x-rays obtained 12 years prior were reviewed,
An MRI was ordered to evaluate for posterior tibial ten- which demonstrate large bilateral posterior talar fragments
don dysfunction. MRI showed a talus partitus with moder- and advanced degenerative changes asymmetrically affect-
ate bone marrow edema spanning the synchondrosis ing the posterior left ankle (Fig. 7). At the time of initial
(Fig. 6). There was approximately 60% involvement of radiographs, the patient was diagnosed with bilateral os
the posterior subtalar joint and minimal (approximately trigonum syndrome and treated symptomatically. An MRI
10%) involvement of the tibiotalar joint. Associated degen- of the left ankle performed at the time of current presenta-
erative changes were present across the posterior subtalar tion showed a large triangular bony fragment at the poste-
joint, including an area of high-grade cartilage loss along rior talus involving 40% of the posterior subtalar joint and
the posterior articular facet. The patient was made non- 20% of the tibiotalar joint (Fig. 8). Advanced secondary
weightbearing for 6 weeks and his ankle was immobilized degenerative changes were noted spanning both joint
in a fracture boot in order to attempt to decrease osseous spaces without significant osseous stress response.
stress response. The patient was subsequently lost to fol- Though the patient was initially diagnosed with os
low-up. trigonum syndrome, the correct diagnosis of talus partitus
was confirmed by MRI. Following MRI, the patient was
Case 5 placed in an ankle brace for an extended period of time, but
symptoms failed to improve. He subsequently underwent
A 60-year-old man with psoriatic arthritis presented with ultrasound-guided corticosteroid injection of the posterior
chronic left ankle pain for approximately 10–15 years. right ankle with substantial, albeit temporary relief of symp-
There was no history of prior trauma or surgery. On phys- toms. He is currently scheduled for repeat ultrasound-guided
ical exam, the patient had gross swelling along the injection given recurrence of pain.
 Skeletal Radiol

Fig. 6 Case 4. Axial T2-weighted

fat-suppressed (a), axial T1-
weighted (b), and sagittal STIR
(c) MRI sequences of the ankle
show a large 2.5 × 1.4 × 1.8 cm
(transverse by craniocaudal by
anteroposterior) posterior talar
osseous fragment with moderate
bone marrow edema spanning the
synchondrosis (arrow, a and b),
compatible with a talus partitus.
There is approximately 60% in-
volvement of the posterior
subtalar joint and 20% involve-
ment of the tibiotalar joint.
Additional sagittal STIR (d) im-
age demonstrates high-grade car-
tilage loss along the posterior
subtalar joint (arrow)

Discussion compared other accessory ossicles in the ankle, such as os

trigonum which occurs in 7% to 14% of individuals [6, 7].
We report five cases of symptomatic talus partitus diagnosed Clinical presentation of the symptomatic talus partitus varies
by MRI. All cases were diagnosed in males, which may indi- widely, ranging from intermittent low-grade ankle pain to se-
cate a greater gender predilection than has been previously vere constant pain, decreased range of motion, joint laxity, and
reported. Age range at time of diagnosis was 16–52 years, antalgic gait [1, 2, 4, 5, 8]. Differentiating between symptom-
suggesting the condition may go undiagnosed into adulthood. atic talus partitus and os trigonum syndrome based on clinical
All cases demonstrated degenerative changes at the talus findings may be difficult, as both may present with posterior
partitus pseudoarthrosis. There were varying degrees of mar- ankle tenderness, painful restricted range of motion at the
row edema associated with the talus partitus, ranging from tibiotalar or subtalar joints, or ligamentous laxity without a
none (Case 5) to severe (Case 1). Involvement of the posterior history of significant trauma [5, 9]. On the other hand, history
subtalar joint was noted in all cases (range 30–60%). and physical exam is helpful for differentiating symptomatic
Involvement of the posterior subtalar joint was seen in only talus partitus and os trigonum syndrome from fractures of the
3/5 cases (range 20–30%). Associated chondrosis at the posterior talar process. Patients with posterior talar process
tibiotalar and posterior subtalar joints was variable. Talus fractures typically present with a history of high impact trau-
partitus fragments varied in size from 1.4 to 2.8 cm in largest ma, obvious external signs of injury (i.e. bruising and/or sig-
dimension. nificant swelling), and inability to bear weight [10–13]. The
According to a systematic review published by Zwiers, pathophysiology of talus partitus, thought to be due to desta-
et al., talus partitus is usually first recognized in adolescence, bilization of the cartilaginous synchondrosis, is similar to that
with a median age of presentation of 15.5 years and a slight of os trigonum syndrome and may also present with features
male-to-female predominance [5]. The true prevalence of talus of posterior ankle impingement [14]. This is supported by
partitus is unknown, but it is thought to be extremely rare histopathology as the junction between the ossicle and talar
Skeletal Radiol

Fig. 7 Case 5. Side-by-side later-

al x-ray of the right and left ankles
demonstrates the presence of talus
partitus bilaterally (arrows), with
severe degenerative changes and
osseous spurring asymmetrically
on the left

body typically resembles a pseudoarthrosis, and apposed frag- body [1, 20]. Findings of acute-on-chronic degenerative
ments may be destabilized by low-force impact [15]. change are common on histopathology, including an edema-
While the actual cause of talus partitus is unclear, the dom- tous synovial membrane with infiltration of inflammatory
inant theory is that it represents a developmental anomaly due cells, degeneration of the articular hyaline cartilage, fibroblast
to failed fusion of a secondary talar ossification center. It is infiltration, and increased osteoblastic and osteoclastic activity
unclear whether the partitus fragment represents fragmenta- [2]. Weinstein and Bonfiglio attributed findings of an injury-
tion of a single ossification center or a secondary accessory repair response on histology to repetitive microtrauma causing
ossification center, as the talus generally forms from a single separation of cartilage from the main body of the talus and
primary center of ossification [16–19]. To date, a secondary formation of a separate posterior ossification center [1].
ossification center has not been surgically proven, as the ma- Radiographs are the first-line imaging modality for patients
jority of patients present after skeletal maturity [2]. It has also with symptomatic talus partitus and typically demonstrate an
been suggested that repetitive microtrauma during skeletal osseous fragment along the posterior aspect of the talus, which
maturation may contribute to the development of the talus may be mistaken for an os trigonum. There may be secondary
partitus. Eichenbaum et al. presented two cases of symptom- signs of osteoarthritis such as joint space narrowing, osteo-
atic talus partitus in skeletally mature adolescents with histo- phyte formation, and subchondral sclerosis [16]. Initial radio-
ries of tibial torsion and subsequent attempted mechanical graphic imaging findings of talus partitus also overlap with
correction via physical therapy, which could conceivably re- other less common accessory ankle ossicles, including, os
sult in altered biomechanics and abnormal stresses upon the talus accessorius, and os talus secundarius [21]. The lateral
talar bone [2]. A competing alternative theory is that the radiograph is the most helpful in visualizing the fragment of
fragmented talus represents a post-traumatic pseudoarthrosis talus partitus, whereas frontal radiographs are more helpful in
from prior fracture, though this remains largely unproven. localizing talus accessorius and secundarius accessory ossi-
At pathologic analysis, talus partitus consists of a cles [22]. Correct diagnosis of talus partitus is very rarely
pseudoarthrosis with a fibrocartilaginous zone separating the made by radiographs alone and cross-sectional imaging is
talus partitus, lacking a fluid cleft to suggest a synovialized generally needed to confirm the diagnosis.
articulation [1, 2]. The talus partitus fragment typically dem- CT can be useful for measuring the size of the fragment,
onstrates normal trabecular architecture with hyaline cartilage which helps differentiate talus partitus from os trigonum, as
along the tibiotalar and subtalar joints, and a thin layer of the latter is almost always <1.0 cm. Talus partitus fragments
fibrocartilage between the pseudoarticulation with the talar are generally >1.0 cm with some fragments reportedly
 Skeletal Radiol

Fig. 8 Case 5. Axial T2-weighted

fat-suppressed (a), axial T1-
weighted (b), and sagittal T1-
weighted (c) MRI sequences of
the ankle show a talus partitus
with mild degenerative changes
spanning the pseudoarthrosis cleft
(arrow, a and b). Overall, the ta-
lus partitus fragment measures
2.6 × 1.1 × 1.4 cm (transverse by
craniocaudal by anteroposterior)
and involves approximately 40%
of the subtalar joint and 20% of
the tibiotalar joint. Sagittal T2-
weighted fat-suppressed sequence
(d) demonstrates full-thickness
cartilage loss along the posterior
tibiotalar (arrow) and subtalar
(curved arrow) joints with mar-
ginal osteophytes. No appreciable
osseous stress response is identi-
fied on fluid-sensitive sequences
(a and d)

measuring up to 4.0 cm [2]. Weinstein and Bonfiglio differ-

entiated cases of talus partitus from other reports of posterior
talar ossicles, stating that in none of the prior studies did the
fragment “encompass as much of the talus as it did in our
report” [1]. CT is also useful for measuring the degree of
involvement of the tibiotalar and/or posterior subtalar joints
and may be helpful for pre-surgical planning.
The cleft of talus partitus is anterior to the posterior talar
process, creating a separate talar body fragment that articulates
with the posterior calcaneal facet at the subtalar joint and
sometimes the tibial plafond at the tibiotalar joint (Fig. 9)
[5]. In some cases, involvement of the subtalar joint is greater
than 50%, which is associated with increased osseous stress
response, more severe arthritis, and greater instability [2]. The
talus partitus cleft may be obliquely oriented, making its
course difficult to follow through the talus, thereby confound-
ing measurements and clarity of the diagnosis [23].
Differentiation between talus partitus and acute posterior talar
Fig. 9 Sagittal diagram of the talus and calcaneus demonstrating the
fractures can be made on CT or MRI by visualization of
anatomical difference of talus partitus versus the os trigonum with corticated margins [12]. On MRI, acute fractures are typically
regard to involvement of the subtalar joint and location of the cleft evident by a hypointense fracture line with intense
Skeletal Radiol

Fig. 10 Axial T2-weighted fat-

suppressed (a) and sagittal STIR
(b) MRI sequences of the ankle
demonstrate a moderate-sized os
trigonum with intense stress mar-
row edema throughout the ossicle
(arrow, a) and degenerative cystic
change spanning the
synchondrosis (curved arrow, b).
There is adjacent joint effusion
and synovitis in the posterior joint
recess (arrows, b). Findings are
typical for os trigonum syndrome/
posterior ankle impingement

surrounding marrow edema, though fracture margins may be MRI findings in os trigonum syndrome mimic those of
obscured depending on the degree of associated bone marrow symptomatic talus partitus, however the os trigonum will al-
edema. most never involve the subtalar or tibiotalar joints (Fig. 10).
MRI is routinely used in the workup of ankle pain; howev- Fractures of the posterior talar process can involve a large
er, little has been previously described in the literature with portion of the talar body but almost always exhibit additional
regard to MRI findings of talus partitus. MRI is particularly findings on MRI including significant surrounding soft tissue
useful in highlighting the degree of degenerative change span- edema, hemorrhagic joint effusions, and non-corticated bony
ning the pseudoarthrosis, accompanying osseous stress re- margins (Figs. 11 and 12). Fractures of the posterior talar
sponse, secondary chondrosis at the posterior subtalar and/or process involving the medial or lateral tubercles often extend
tibiotalar joints, joint effusions, and associated synovitis or to the articular surface of the subtalar joint [24]. Hemarthrosis
inflammatory changes in the adjacent posterior soft tissues. or lipohemarthrosis is nearly pathognomonic for an intra-
Almost all cases of talus partitus in the literature have some articular fracture in the post-traumatic setting. Lastly, the cleft
degree of arthritis on imaging, which range from low-grade of talus partitus always extends across the entirety of the talus
chondrosis to severe joint space narrowing with grade IV in the coronal plane, whereas the fracture margin in posterior
chondrosis and associated subchondral cystic change [20]. talar process fractures often does not.
In their systematic review of 23 cases of talus partitus, MR and CT arthrography of the ankle has been used to
Zwiers et al. found degenerative changes in 38% of the pa- identify communication of the talus partitus cleft with the
tients with the degree of degenerative changes dependent on tibiotalar and subtalar joints, associated articular cartilage le-
the congruency of fragments [5]. sions, and intra-articular bodies [25]. Nuclear medicine bone

Fig. 11 Sagittal STIR (a) and

axial T2-weighted fat-suppressed
(b) MRI sequences of the ankle
show an acute fracture of the lat-
eral tubercle of the posterior pro-
cess of the talus (Shepherd’s
fracture), with intense marrow
edema (arrow, a and b) and ex-
tensive surrounding soft tissue
edema throughout Kager’s fat
pad. There are large subtalar and
tibiotalar joint effusions with in-
trinsic T1-hyperintensity (not
shown), consistent with
hemarthrosis
 Skeletal Radiol

Fig. 12 Sagittal STIR (a) and

axial T2-weighted fat-suppressed
(b) MRI sequences of the ankle
show an acute fracture of the me-
dial tubercle of the posterior talar
process (Cedell fracture). A subtle
hypointense fracture line is seen
with intense surrounding marrow
edema (arrow, a and b)

scan has been used in the past as part of the diagnostic workup observed varying degrees of marrow edema and degenerative
of talus partitus, though we feel it has little utility given poor changes spanning the pseudoarthrosis cleft and posterior
specificity and exposure to ionizing radiation [14]. subtalar and tibiotalar joints. Familiarity with characteristic
Treatment of talus partitus has historically revolved around MRI appearance of talus partitus and accurately describing
two general principles, surgery and conservative management, relevant imaging findings, including fragment size, joint in-
with surgery being the more common strategy based on sys- volvement, osseous stress response, and secondary degenera-
tematic analyses [5]. Conservative therapy may include oral tive change, is essential for guiding effective management
analgesics, physical therapy, orthotics, or steroid injection. decisions and optimizing treatment outcomes.
Surgery generally involves either excision or internal fixation,
and is based largely on imaging findings [11]. For example,
some orthopedic surgeons have found that fragment excision References
alone may lead to ankle or subtalar instability in larger frag-
ments, some constituting up to 50% of the subtalar articular 1. Weinstein S, Bonfiglio M. Unusual accessory (bipartite) talus sim-
ulating fracture. A case report. The Journal of Bone & Joint
surface [1, 2, 4]. Eichenbaum et al. has suggested that excision
Surgery. 1975;57(8):1161–3.
should be performed for fragments covering <20% of the 2. Eichenbaum MD, Austin LS, Raikin SM. Chronic ankle pain sec-
subtalar articular surface, as arthrodesis may result in non- ondary to talus partitus: two case reports. Foot Ankle Int.
union [26]. In addition, recent case reports have described 2010;31(3):247–50.
favorable arthrodesis when the fragments are congruent with 3. Strehle E: Über Abnormitäten im Bereich der Tarsalknochen und
ihre klinische Bedeutung: mit besonderer Berücksichtigung eines
each other and there is little to no secondary degenerative selbst beobachteten Falles einer Talusmißbildung: Oberreuter;
change [2, 20]. Prompt and accurate diagnosis of talus partitus 1928.
is crucial as delayed or erroneous treatment can lead to pro- 4. O'Rahilly R. A survey of carpal and tarsal anomalies. J Bone Joint
gressive osteoarthritis, flexor tendon impingement or tearing, Surg Am. 1953;35-A(3):626–42.
chronic pain, and long-term disability. If treated expeditiously, 5. Zwiers R, de Leeuw PAJ, Kerkhoffs G, van Dijk CN. Talus
bipartitus: a systematic review and report of two cases with arthro-
surgical outcomes may be more favorable, with substantial scopic treatment. Knee Surg Sports Traumatol Arthrosc.
reduction in symptoms and only mild residual physical limi- 2018;26(7):2131–41.
tations [20]. 6. Imaging of the musculoskeletal system. Philadelphia: Saunders/
Elsevier; 2008.
7. Zwiers R, Baltes TPA, Opdam KTM, Wiegerinck JI, van Dijk CN.
Prevalence of Os Trigonum on CT imaging. Foot Ankle Int.
Conclusion 2018;39(3):338–42.
8. Rose B, Southgate C, Louette L. Bipartite talus: a case series and
Talus partitus is a rare developmental osseous abnormality algorithm for treatment. Foot Ankle Surg. 2013;19(2):96–102.
typically presenting in late adolescence or adulthood, charac- 9. Nault ML, Kocher MS, Micheli LJ. Os trigonum syndrome. The
terized by a split posterior talar bone in the coronal plane. Journal of the American Academy of Orthopaedic Surgeons.
2014;22(9):545–53.
Clinical and radiographic imaging findings overlap with other 10. Letonoff EJ, Najarian CB, Suleiman J. The posteromedial process
posterior talar abnormalities, including posterior talar fractures fracture of the talus: a case report. J Foot Ankle Surg. 2002;41(1):
and os trigonum syndrome. On MRI, we have anecdotally 52–6.
Skeletal Radiol

11. Mehrpour SR, Aghamirsalim MR, Sheshvan MK, Sorbi R. Entire 20. Rammelt S, Zwipp H, Prescher A. Talus bipartitus: a rare skeletal
posterior process talus fracture: a report of two cases. J Foot Ankle variation: a report of four cases. J Bone Joint Surg Am.
Surg. 2012;51(3):326–9. 2011;93(6):e21.
12. Melenevsky Y, Mackey RA, Abrahams RB, Thomson NB 3rd. 21. Kose O, May H, Acar B, Unal M. Symptomatic os talus
Talar fractures and dislocations: a Radiologist's guide to timely secundarius: a case report and review of the literature. Skelet
diagnosis and classification. Radiographics. 2015;35(3):765–79. Radiol. 2018;47(4):553–62.
13. Santavirta S, Seitsalo S, Kiviluoto O, Myllynen P. Fractures of the 22. Keles-Celik N, Kose O, Sekerci R, Aytac G, Turan A, Güler F.
talus. J Trauma. 1984;24(11):986–9. Accessory Ossicles of the foot and ankle: disorders and a review
14. Karasick D, Schweitzer ME. The os trigonum syndrome: imaging of the literature. Cureus. 2017;9(11):e1881–1.
features. AJR Am J Roentgenol. 1996;166(1):125–9. 23. Mann HA, Myerson MS. Treatment of posterior ankle pain by
15. Thiel E, Feibel J, Chorey N, Gorsline R. Bipartite talus: a case excision of a bipartite talar fragment. J Bone Joint Surg Br.
report. Foot Ankle Int. 2010;31(6):552–5. 2010;92(7):954–7.
16. Bell J, Warren M, Cotnoir S. Fracture of the Lateral Process of the 24. Majeed H, McBride DJ. Talar process fractures: an overview and
Talus. 2017;47(8):579–9. update of the literature. EFORT Open Rev. 2018;3(3):85–92.
17. Blauth W, Harten K. Kirgis a: [frontal talus cleft–talus bipartitus]. Z 25. Schreiber A, Differding P, Zollinger H. Talus partitus. A case report.
Orthop Ihre Grenzgeb. 1987;125(3):302–7. J Bone Joint Surg Br. 1985;67(3):430–1.
18. Boszczyk AM, Kolodziej L. Talus Bipartitus etiology - is neonatal 26. Gomez Robledo J. Associated lateral process and posteromedial
infection involved? Acta Chir Orthop Traumatol Cechoslov. tubercle talus fractures with entrapment of the medial neurovascular
2016;83(1):47–9. bundle: a case report. Foot (Edinb). 2013;23(4):149–53.
19. Jones DM, Saltzman CL, El-Khoury G. The diagnosis of the os
trigonum syndrome with a fluoroscopically controlled injection of Publisher’s note Springer Nature remains neutral with regard to jurisdic-
local anesthetic. Iowa Orthop J. 1999;19:122–6. tional claims in published maps and institutional affiliations.