Process and Tubercle
Fractures of the Hindfoot
Abstract
Process and tubercle fractures of the talus and calcaneus can be a
source of significant pain and dysfunction. Successful management
requires extensive knowledge of the complex osseoligamentous
anatomy of the hindfoot. The large posterior process of the talus is
composed of a medial and a lateral tubercle; an os trigonum may
exist posterior to the lateral tubercle. The talus has a lateral
process that articulates with the fibula and subtalar joint; the
calcaneus possesses a frequently injured anterior process that
articulates with the cuboid. Injury to these hindfoot structures is
caused by inversion and eversion of the ankle, which can occur
during athletic activity. These injuries often are misdiagnosed as
ankle sprains. A high degree of clinical suspicion is warranted, and
specialized radiographs or other imaging modalities may be
required for accurate diagnosis. Nonsurgical management with cast
immobilization is frequently successful when the fracture is
correctly diagnosed acutely. Large fragments may be amenable to
open reduction and internal fixation. Untreated, chronic injuries
can cause significant pain and functional impairment that may be
improved substantially with late surgical intervention.
T
he calcaneus and talus are the
most frequently fractured tarsal
bones.
1
Most attention in the ortho-
paedic literature has been devoted to
fractures of the neck of the talus and
the posterior facet of the calcaneus.

tribute to the subtalar and calca-
neocuboid articulations. Because
Mark J. Berkowitz, MD, MAJ,
MC, USA, and
DavidH.Kim,MD
Dr. Berkowitz is Chief, Foot and Ankle
Section, Orthopaedic Surgery Service,
Tripler Army Medical Center, Honolulu,
HI. Dr. Kim is Assistant Clinical
Professor, Orthopaedic Surgery,
University of Colorado School of
Medicine, Denver, CO, and Orthopaedic
Foot and Ankle Surgeon, Colorado
Permanente Medical Group, Denver.
None of the following authors or the
departments with which they are
affiliated has received anything of value
from or owns stock in a commercial
company or institution related directly or
indirectly to the subject of this article:
Dr. Berkowitz and Dr. Kim.
Reprint requests: Dr. Berkowitz, Tripler
Army Medical Center, 1 Jarrett-White
Road, Honolulu, HI 96859-5000.
J Am Acad Orthop Surg 2005;13:492-
502
Copyright 2005 by the American
Academy of Orthopaedic Surgeons.
492 Journal of the American Academy of Orthopaedic Surgeons
these osseous projections are located

4
The posterior process is
composed of two tubercles: the me-
dial and the lateral. These tubercles
are separated by a groove within
which lies the flexor hallucis longus
tendon. Forming a roof over this
groove is the Y-shaped, bifurcate
talocalcaneal ligament, which in-
serts onto each tubercle.
5
The later-
al tubercle (ie, Stieda’s process) is
Figure 1
Osseous anatomy of the hindfoot. A, Lateral view of the talus and calcaneus. B, Posterior view of the ankle and hindfoot.
C, Superior view of the talus.
Mark J. Berkowitz, MD, MAJ, MC, USA, and David H. Kim, MD
Volume 13, Number 8, December 2005 493
larger than the medial tubercle and
projects more posteriorly. The poste-
rior talofibular ligament inserts onto
the lateral tubercle of the talus. The
posterior talotibial portion of the
deltoid ligament attaches to the me-
dial tubercle.
The os trigonum is located direct-
ly posterior to the lateral tubercle
(Figure 1, C). It is an accessory bone
of variable size and shape that arises
from a secondary ossification center

connects the cuboid and navicular
bones. Additionally, the extensor
digitorum brevis muscle takes at
least a portion of its origin from the
anterior process.
Other peripheral structures of the
calcaneus include the sustentacu-
lum tali, the peroneal tubercle, and
the medial and lateral calcaneal tu-
bercles.
8
Injuries to these structures
are rare.
Mechanism of Injury
Process and tubercle fractures of the
hindfoot occur in two distinct pat-
terns. These fractures may be caused
by high-energy trauma, such as a fall
from a height or a motor vehicle ac-
cident.
9
In this setting, they are o ften
found concomitantly with fracture-
dislocations of the subtalar and an-
kle joints.
10
Process and tubercle
fractures also may be caused by low-
energy sprains, such as those occur-
ring during athletic participation.

sion of an axially loaded, dorsiflexed
ankle may produce a lateral process
fracture.
The medial tubercle of the poste-
rior process may be fractured when
the foot is suddenly forced into a po-
sition of combined dorsiflexion and
pronation.
11,15
This places the poste-
rior talotibial component of the del-
toid ligament under tension, causing
avulsion of the tubercle. In 1974,
Cedell
15
originally described this in-
jury and its mechanism in four pa-
tients injured during sports activity.
This injury also has been reported af-
ter motor vehicle accidents and falls
in association with subtalar disloca-
tion, talar neck fracture, and total t a-
lar dislocation.
16,17
Fractures of the posterior talar
process most likely are caused by
forceful plantar flexion of the ankle.
Maximum plantar flexion produces
a nutcracker-like compression of the
posterior process between the poste-

This same
mechanism also may cause a frac-
ture of the lateral tubercle of the pos-
terior talar process. Ankle inversion
tensions the posterior talofibular lig-
ament, producing avulsion of the lat-
eral tubercle (Figure 3). Shepherd
first described this fracture and
mechanism in 1883, and some au-
thors still refer to it as “Shepherd’s
fracture.”
24
Fractures of the anterior calcaneal
process also occur after inversion of
the plantarflexed ankle.
7
This mech-
anism of injury stretches the bifur-
cate ligament and avulses the anteri-
or process. Alternatively, forced
dorsiflexion and eversion may com-
press the anterior process between
the cuboid and the talus, resulting in
a shear fracture
7
(Figure 4).
Diagnosis
A high level of suspicion is required
when diagnosing process and tuber-
cle fractures of the hindfoot. These

in anterior process avulsion by the bifurcate ligament (inset). B, Dorsiflexion and eversion (arrow) may create a shear fracture
of the anterior process of the calcaneus (inset). (Courtesy of the Mayo Foundation. Copyright 1980.)
Mark J. Berkowitz, MD, MAJ, MC, USA, and David H. Kim, MD
Volume 13, Number 8, December 2005 495
Cedell’s
15
original article on frac-
tures of the medial tubercle of the
posterior talar process, each of the
four patients was initially misdiag-
nosed with a sprain and treated with
a compression bandage and rest.
Paulos et al
5
reported on 20 patients
with avulsion fractures of the poste-
rior talus, all of which were initially
diagnosed as ankle sprain. The aver-
age number of physician visits per
patient before correct diagnosis was
made was 5.8; one patient was seen
17 times.
Failure to diagnose also occurs
with multiple trauma. Process and
tubercle fractures occur in associa-
tion with significant lower extremi-
ty injuries, such as subtalar and an-
kle fracture-dislocations, total talar
dislocations, and lower extremity
long bone fractures.

later.
Lateral talar process fractures can
be particularly difficult to differenti-
ate from sprains on physical exami-
nation. However, careful palpation
just anterior and inferior to the later-
al malleolus should raise suspicion
of this injury. The patient with pos-
terior process fracture demonstrates
deep tenderness anterior to the
Achilles tendon but posterior to the
talus. Fracture of the lateral tubercle
of the posterior talar process and of
the os trigonum provokes point ten-
derness over the posterolateral an-
kle, just medial to the peroneal ten-
dons. Fracture of the medial tubercle
of the posterior talar process demon-
strates localized tenderness medial-
ly, just posterior to the medial mal-
leolus.
11
Forced plantar flexion is another
important test. The patient with
posterior talar process or os trigo-
num fracture frequently reports pain
when the posterior talus is com-
pressed against the tibia during this
maneuver. Likewise, resisted mo-
tion of the great toe can elicit pain as

rior ankle radiographs, in which a
fragment just inferior to the lateral
malleolus can be visualized
2,13
(Fig-
ure 5). Occasionally, an avulsed frag-
ment is visible on a lateral radio-
graph. Dorsiflexing and inverting the
ankle while taking the lateral radio-
graph may further improve visual-
ization of the fragment.
29
Posterior talar fractures are par-
ticularly difficult to detect and dif-
ferentiate on standard radiographs.
Large posterior process fractures
may demonstrate a prominent frac-
ture line on a standard lateral radio-
graph, but distinguishing between
medial and lateral tubercle frac-
tures and differentiating them from
a normal os trigonum can be chal-
lenging.
17
Paulos et al
5
described us-
ing a special 30° subtalar oblique
view to better visualize lateral tu-
bercle and os trigonum fractures.

hindfoot process and tubercle frac-
tures. Multiplanar CT imaging with
fine 1-mm cuts allows accurate as-
sessment of fragment location, size,
displacement, and comminution
10
(Figure 8). Additionally, CT provides
adequate cortical detail to distin-
guish the smooth, sclerotic margins
of an os trigonum from the jagged, ir-
regular contour of an acute lateral
tubercle fracture. This important
distinction is frequently not possible
with standard lateral radiographs.
CT is also sensitive for early degen-
erative changes that may not be de-
tectable on plain radiographs.
21,31
CT
especially should be considered
when subtalar dislocation is suspect-
ed.
28
Subtalar dislocation rarely oc-
curs in isolation, and CT often re-
veals associated process or tubercle
fractures not visualized on plain ra-
diographs.
17
Ebraheim et al

nosed in each case. Sanders et al
33
re-
ported on a 59-year-old man who
underwent MRI for evaluation of
Figure 8
Axial computed tomography scan
demonstrating a fragment medial to the
flexor hallucis longus groove (arrow),
consistent with a fracture of the medial
tubercle of the posterior process of
the talus. Compare with the lateral
radiograph in Figure 6, A, in which it is
difficult to determine whether there
is an os trigonum, a lateral tubercle
fracture, a medial tubercle fracture, or a
posterior process fracture.
Figure 6
A, Lateral radiograph demonstrating nonspecific fracture of the posterior process
of the talus. B, Medial oblique view demonstrating avulsion fracture of the medial
tubercle fracture of the posterior process of the talus (arrow). (Reproduced with
permission from Kim DH, Hrutkay JM, Samson MM: Fracture of the medial tubercle
of the posterior process of the talus: A case report and literature review. Foot Ankle
Int 1996;17:186-188.)
Figure 7
Oblique lateral view allowing
visualization of fracture of the anterior
process of the calcaneus (arrow).
Mark J. Berkowitz, MD, MAJ, MC, USA, and David H. Kim, MD
Volume 13, Number 8, December 2005 497

finitive test for diagnosing occult
fractures of the posterior talus. They
found it particularly useful for differ-
entiating an acute lateral tubercle
fracture from a normal os trigonum.
Abramowitz et al
21
likewise report-
ed that 32 of 35 patients with os trig-
onum injury demonstrated increased
focal uptake in the posterolateral as-
pect of the talus on bone scan.
However, bone scanning may in-
dicate false positives and false nega-
tives. Sopov et al
35
evaluated the
scintigraphic findings of 100 consec-
utive soldiers. Of 200 feet, 27
(13.5%) demonstrated uptake in the
region of the os trigonum; however,
only 10 of the 27 feet (37%) were
symptomatic. They concluded that a
positive Tc-99m bone scan is a fre-
quent finding in active individuals
and may even be considered a nor-
mal variant in this population. Sim-
ilarly, i n three patients with negative
bone scans, Abramowitz et al
21

resonance image of a patient with
chronic posterior ankle pain
demonstrating intraosseous edema in
the os trigonum and adjacent talus and
calcaneus (asterisks), which is
consistent with posterior ankle
impingement.
Figure 10
Lateral projection in a patient with an os trigonum demonstrating focal intense
radioisotope Tc-99m uptake in the posterior aspect of the talus and adjacent tibia
as well as in the calcaneus, consistent with os trigonum syndrome.
Process and Tubercle Fractures of the Hindfoot
498 Journal of the American Academy of Orthopaedic Surgeons
an os trigonum in four patients with
chronic posterior ankle pain. Each
patient experienced transient pain
relief and subsequently underwent
excision of the os trigonum with
complete resolution of symptoms.
Management
The optimal management of process
and tubercle fractures remains con-
troversial. Relatively simple classifi-
cation schemes have been proposed
to help guide treatment (Tables 1
and 2). The most critical factors in-
clude the size of the fragment, dis-
placement, comminution, and de-
gree of articular involvement.
7,14

and progressive weight bearing with
crutches is allowed. When the pa-
tient remains symptomatic after 6
weeks of protected weight bearing
and immobilization, continued re-
striction of activity may be warrant-
ed for several months.
Early diagnosis and management
of hindfoot process and tubercle frac-
tures appear to be critical factors af-
fecting the success of nonsurgical
management.
1,5,7,9,11,26,29,30
Degan et
al
7
successfully used immobilization
for a mean of 5.4 weeks to treat 18 of
25 patients with early diagnosed
acute anterior calcaneal process frac-
tures. A satisfactory result consist-
ing of no or minimal pain and full re-
turn to activity was achieved in
those 18 patients.
Kim and colleagues
11,30
described
successful management of acutely
diagnosed posterior medial talar tu-
bercle fractures. The patients under-

6 to 8 weeks of immobilization in a
non–weight-bearing cast
14
(Figure
11).
Large fragments, particularly
those resulting from high-energy
trauma, do not reliably respond to
nonsurgical management. Although
Kim and colleagues
11,30
reported suc-
cess with nonsurgical treatment of
patients with acute posterior medial
talar tubercle fractures, Giuffrida et
al
17
reported failure in each of their
patients despite prompt cast immo-
bilization. A comparison of the two
series, however, highlights impor-
tant differences. Each of the patients
in the report by Kim et al
11
sustained
low-energy athletic injuries that re-
sulted in small avulsion fragments
with minimal articular disruption.
In the report by Giuffrida et al,
17

Classification of Fractures of the
Anterior Process of the Calcaneus
7
Type I Nondisplaced tip avulsion
Type II Displaced avulsion fracture
not involving the
calcaneocuboid
articulation
Type III Displaced, larger
fragments involving the
calcaneocuboid joint
Table 2
Classification of Fractures of the
Lateral Process of the Talus
14
Type A Small, minimally displaced,
extra-articular avulsion
Type B Medium-sized fracture
involving only the
talocalcaneal articular
surface
Type C Larger fracture involving
both talocalcaneal and
talofibular articulations
Mark J. Berkowitz, MD, MAJ, MC, USA, and David H. Kim, MD
Volume 13, Number 8, December 2005 499
worst outcomes were found in pa-
tients with the longest delay in diag-
nosis and treatment.
Surgical Management

required to make this determina-
tion. CT also precisely localizes the
fracture and helps determine the
most appropriate surgical ap-
proach.
10
Fractures most commonly ame-
nable to ORIF include large lateral
talar process fractures, medial talar
tubercle fractures, and fractures of
the entire posterior talar process.
Stable fixation usually may be
achieved with small or mini-
fragment screws or with Kirschner
wires. Although anterior calcaneal
process fractures may be considered
for ORIF, they are rarely of sufficient
size to warrant this approach.
7
ORIF has been recommended in
several small case series for large,
noncomminuted fractures of the lat-
eral talar process that disrupt either
the talocalcaneal or talofibular artic-
ulations.
9,13,26,29,38
Although results
of ORIF are considered to be superi-
or to those of nonsurgical manage-
ment, persistence of symptoms is

The fractured tubercle is visual-
ized medial to the tendon of the flex-
or hallucis longus.
Fracture of the entire posterior
talar process is rare, but it frequently
requires ORIF because of the
relatively large size and signifi-
cant involvement of the subtalar
joint.
18,42-44
Several case reports doc-
ument good results after anatomic
fixation of these fractures.
3,18,42-45
Ei-
ther a posteromedial or posterolat-
eral approach may be used. When the
major displacement is posterome-
dial, the fracture is approached
through a posteromedial dissection
between the flexor digitorum longus
tendon anteriorly and the neurovas-
cular bundle posteriorly.
3
When the
major displacement is posterolateral,
an approach between the peroneal
tendons and the Achilles tendon
should be performed.
43

proach is identical to that for ORIF,
except that all loose articular frag-
ments are removed. Immobilization
usually consists of 2 to 3 weeks in a
weight-bearing cast or a removable
boot.
Late Excision
Patients who develop symptom-
atic nonunion of a peripheral hind-
foot fracture may improve signifi-
cantly with late fragment excision.
Abramowitz et al
21
excised the os
trigonum via a posterolateral ap-
proach in 41 patients who had failed
nonsurgical management. Improve-
ment in the 100-point AOFAS ankle-
hindfoot score averaged 36 points,
with the best results in patients who
had been symptomatic for fewer
than 2 years. Marumoto and Fer-
kel
31
documented an average 41-
point improvement in the AOFAS
ankle-hindfoot score after arthro-
scopic excision in 11 patients with
os trigonum syndrome. Similar im-
provement has been repor ted after

ably to excision, large fracture frag-
ments tend to produce articular in-
congruity, and arthrosis of the
subtalar joint can develop (Figure
12). In these cases, subtalar arthro-
desis may be required.
9,16,17
Summary
Process and tubercle fractures of the
hindfoot are challenging to diagnose
and manage. An understanding of
the complex anatomy of the hind-
foot is required. The clinician must
be diligent and knowledgeable in the
interpretation of plain radiographs
and in the use of additional studies,
such as specialized oblique views,
CT, MRI, and bone scanning. The
most critical prognostic factor is cor-
rect initial diagnosis. Prompt man-
agement, whether cast immobiliza-
tion, ORIF, or primary excision,
provides the best opportunity for
complete recovery. Delay in diagno-
sis increases the likelihood of chron-
ic pain and disability. In these pa-
tients, late excision can provide
significant improvement in symp-
toms, but arthrodesis of the involved
joints also may be considered. Im-

6. Burman MS, Lapidus PW: The func-
tional disturbances caused by the in-
constant bones and sesamoids of the
foot. Arch Surg 1931;22:936-975.
7. Degan TJ, Morrey BF, Braun DP: Sur-
gical excision for anterior-process
fractures of the calcaneus. J Bone
Joint Surg Am 1982;64:519-524.
8. Fitzgibbons T, McMullen S, Mormino
M: Fractures and dislocations of the
calcaneus, in Bucholz R, Heckman J
(eds): Rockwood and Green’s Frac-
tures in Adults, ed 5. Philadelphia,
PA: Lippincott Williams & Wilkins,
2001, vol 2, pp 2131-2179.
9. Hawkins LG: Fracture of the lateral
process of the talus. J Bone Joint Surg
Figure 12
Coronal computed tomography image
demonstrating sclerosis, subchondral
cysts, and irregularity of the subtalar
and talofibular articulations of the
lateral process of the talus. These
findings are consistent with
degenerative arthrosis (arrows).
Mark J. Berkowitz, MD, MAJ, MC, USA, and David H. Kim, MD
Volume 13, Number 8, December 2005 501
Am 1965;47:1170-1175.
10. Ebraheim NA, Skie MC, Podeszwa
DA, Jackson WT: Evaluation of pro-

rian W, Berkman A, Behrens FF: Pseu-
do os trigonum sign: Missed postero-
medial talar facet fracture. Foot
Ankle Int 2003;24:642-649.
18. Nasser S, Manoli A II: Fracture of the
entire posterior process of the talus: A
case report. Foot Ankle 1990;10:235-
238.
19. Hedrick MR, McBryde AM: Posterior
ankle impingement. Foot Ankle Int
1994;15:2-8.
20. McDougall A: The os trigonum.
J Bone Joint Surg Br 1955;37:257-265.
21. Abramowitz Y, Wollstein R, Barzilay
Y, et al: Outcome of resection of a
symptomatic os trigonum. J Bone
Joint Surg Am 2003;85:1051-1057.
22. Johnson RP, Collier BD, Carrera GF:
The os trigonum syndrome: Use of
bone scan in the diagnosis. J Trauma
1984;24:761-764.
23. Veazey BL, Heckman JD, Galindo MJ,
McGanity PL: Excision of ununited
fractures of the posterior process of
the talus: A treatment for chronic pos-
terior ankle pain. Foot Ankle 1992;
13:453-457.
24. Shepherd F: A hitherto undescribed
fracture of the astralgus. Journal of
Anatomy and Physiology 1883;17:

32. Wakeley CJ, Johnson DP, Watt I: The
value of MR imaging in the diagnosis
of the os trigonum syndrome.
Skeletal Radiol 1996;25:133-136.
33. Sanders TG, Ptaszek AJ, Morrison
WB: Fracture of the lateral process of
the talus: Appearance at MR imaging
and clinical significance. Skeletal
Radiol 1999;28:236-239.
34. Karasick D, Schweitzer ME: The os
trigonum syndrome: Imaging fea-
tures. AJR Am J Roentgenol 1996;
166:125-129.
35. Sopov V, Liberson A, Groshar D: Bone
scintigraphic findings of os trigonum:
A prospective study of 100 soldiers on
active duty. Foot Ankle Int 2000;21:
822-824.
36. Jones DM, Saltzman CL, El-Khoury
G: The diagnosis of the os trigonum
syndrome with a fluoroscopically
controlled injection of local anesthet-
ic. Iowa Orthop J 1999;19:122-126.
37. Stefko RM, Lauerman WC, Heckman
JD: Tarsal tunnel syndrome caused by
an unrecognized fracture of the poste-
rior process of the talus (Cedell frac-
ture): A case report. J Bone Joint Surg
Am 1994;76:116-118.
38. Kirkpatrick DP, Hunter RE, Janes PC,

talus. J Orthop Trauma 1996;10:142-
144.
45. Chen YJ, Hsu RW, Shih HN, Huang
TJ: Fracture of the entire posterior
process of talus associated with subta-
lar dislocation: A case report. Foot
Ankle Int 1996;17:226-229.
Process and Tubercle Fractures of the Hindfoot
502 Journal of the American Academy of Orthopaedic Surgeons