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In treating patients with hind-foot symptomatology, it is helpful to have an organized approach to eval-uating and managing the most com-mon process and tubercle fractures of the hindfoo

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

The calcaneus and talus are the most frequently fractured tarsal bones.1Most attention in the ortho-paedic literature has been devoted to fractures of the neck of the talus and the posterior facet of the calcaneus

Other hindfoot fractures have not been as well studied; fractures in-volving the peripheral processes and tubercles of the talus and calcaneus have been relatively neglected Con-sequently, questions persist regard-ing these fractures The mechanisms

of injury remain incompletely un-derstood, and misdiagnosis is not uncommon Uncertainty persists re-garding optimal treatment and prog-nosis In treating patients with hind-foot symptomatology, it is helpful to have an organized approach to

eval-uating and managing the most com-mon process and tubercle fractures

of the hindfoot, including the

later-al and posterior processes of the ta-lus, the medial and lateral tubercles

of the posterior talus, the os tri-gonum, and the anterior process of the calcaneus

Anatomy

The osseoligamentous anatomy of the hindfoot is complex and often confusing (Figure 1) Several

process-es and tuberclprocess-es project from the main body of the talus and calca-neus These structures serve as sites

of ligamentous attachment and con-tribute to the subtalar and calca-neocuboid articulations Because

Mark J Berkowitz, MD, MAJ,

MC, USA, and

David H 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.

these osseous projections are located

along the periphery of the talus and

calcaneus, they are referred to as the

peripheral structures of the

hind-foot

The talus has five peripheral

structures that may be fractured

The two talar processes, the lateral

and the posterior, project from the

body of the talus The lateral process

is a wide, wedge-shaped prominence

extending from the lateral aspect of

the body of the talus.2 It possesses two distinct articular facets: the dor-solateral and the inferomedial The dorsolateral facet articulates with the distal fibula; the inferomedial facet forms the anterolateral portion

of the subtalar joint The lateral pro-cess is the site of insertion of the lat-eral talocalcaneal ligament

The posterior process is

relative-ly large (Figure 1, B), and its inferior surface composes the posterior 25%

of the subtalar articulation.3It is the most variable aspect of hindfoot anatomy.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.5The

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

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

between the ages of 8 and 11 years

In most persons, it fuses to the

later-al tubercle within 1 year of its

ap-pearance However, it may persist as

a separate ossicle, attached to the

ta-lus by a cartilaginous

synchondro-sis.4Burman and Lapidus6observed

a distinct os trigonum in 64 of 1,000

radiographs of feet as well as a

“fused os trigonum” in the form of

an elongated lateral tubercle in 429

of the 1,000 radiographs

The anterior process is the most

commonly fractured peripheral

structure of the calcaneus.1This

pro-cess is a saddle-shaped projection of

bone at the superior aspect of the

calcaneal body that extends toward

the navicular7(Figure 1, A) Its infe-rior surface articulates with the cuboid The bifurcate ligament in-serts on the anterior process and 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.8Injuries 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.9In this setting, they are often 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 duoccur-ring athletic participation.11

In both types, the position of the foot and the vector of the forces applied

to it are critical in producing the fracture

Fractures of the lateral talar pro-cess initially were believed to occur after forced ankle dorsiflexion and inversion, usually because of a fall or motor vehicle accident.9,12,13 Snow-boarding now accounts for most lateral talar process fractures, with approximately 2,000 occurring an-nually.14 The mechanism of injury appears to be related to the forces transferred to the ankle while the foot is strapped to the board Boon et

al2produced cadaveric “snowboard-er’s fractures” only when external rotation force was applied to the dor-siflexed, inverted foot Similarly, Funk et al14demonstrated that ever-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.11,15This places the poste-rior talotibial component of the del-toid ligament under tension, causing avulsion of the tubercle In 1974, Cedell15originally 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 ta-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-rior malleolus and the calcaneus18,19

(Figure 2) The entire posterior pro-cess, the lateral talar tubercle, or the

os trigonum may be injured in this way

The os trigonum may be injured

by repetitive plantar flexion, similar

to a stress fracture.20This injury is often referred to as either os

trigo-Figure 2

Axial (A) and sagittal (B) computed tomography scans demonstrating fracture of

the entire posterior process of the talus Forceful plantar flexion compresses the

posterior process of the talus between the calcaneus and the tibia, resulting in

fracture (arrows)

num syndrome or posterior ankle

impingement It is seen most often

in professional ballet dancers, soccer

players, and runners.19,21,22 More

commonly, the synchondrosis is

acutely disrupted by a plantar

flex-ion–inversion mechanism, similar

to an ankle sprain.21,23 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.7This mech-anism of injury stretches the bifur-cate ligament and avulses the

anteri-or process Alternatively, fanteri-orced dorsiflexion and eversion may com-press the anterior process between the cuboid and the talus, resulting in

a shear fracture7(Figure 4)

Diagnosis

A high level of suspicion is required when diagnosing process and tuber-cle fractures of the hindfoot These fractures can be challenging to dis-cern on standard radiographs and physical examination

Unfortunate-ly, misdiagnosis and delayed diagno-sis are frequent complications.25

Lateral talar process fractures mimic lateral ankle sprains.13,19,26

Missed lateral talar process fractures were found retrospectively in 0.86%

of patients initially diagnosed as having a lateral ankle sprain (13/ 1,500 patients).13In a series of 25 an-terior calcaneal process fractures, the diagnosis was initially incorrect

in 9 patients, with 7 initially mis-diagnosed with a sprain of the an-terior talofibular ligament.7 In

Figure 3

A,Lateral view of the ankle (taken for unrelated reasons before injury)

demonstrat-ing an intact lateral tubercle of the posterior process of the talus B, Repeat lateral

radiograph of the same patient after a plantar flexion–inversion injury demonstrating

fracture of the lateral tubercle with angulation of the fragment (arrow)

Figure 4

Mechanism of injury of a fracture of the anterior process of the calcaneus A, Inversion of the plantarflexed ankle (arrow) results

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.)

Cedell’s15 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 al5reported 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.17,27,28In treating

these injuries, process or tubercle

fractures may be easily missed

Un-fortunately, delayed detection of

these fractures increases the

likeli-hood of painful nonunion and

ar-throsis.7,11,17

Physical Examination

The initial step in diagnosing

these fractures is eliciting the

mech-anism of injury The position of the

foot and the force applied should raise suspicion that a particular frac-ture may have occurred Once the mechanism of injury has been deter-mined, a focused physical examina-tion is performed to elicit the maxi-mal point of tenderness The maximal point of tenderness repre-sents the most important diagnostic feature in distinguishing a

peripher-al fracture from an uncomplicated ankle sprain.11It can be difficult to discern in a patient with an acute, swollen ankle, and the patient may need to be reexamined 10 to 14 days 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 mlater-alleolus 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 the flexor hallucis longus tendon slides past a medial or lateral tuber-cle fracture of the posterior talar pro-cess.5

Anterior calcaneal process frac-ture usually produces tenderness in

an area approximately 2 cm anterior and 1 cm inferior to the anterior talofibular ligament.7Swelling and ecchymosis localized to this area are

signs of anterior calcaneal process fracture

Radiographic Evaluation

Radiographs must be carefully scrutinized to ensure prompt and ac-curate diagnosis of process and tu-bercle fractures As mentioned, these fractures are difficult to detect

on standard plain radiographs; there-fore, the use of specialized oblique radiographs, computed tomography (CT), magnetic resonance imaging (MRI), or bone scans may be re-quired

Plain Radiographs

Lateral talar process fractures are best seen on mortise or anteroposte-rior ankle radiographs, in which a fragment just inferior to the lateral malleolus can be visualized2,13 (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.17Paulos et al5described us-ing a special 30° subtalar oblique view to better visualize lateral tu-bercle and os trigonum fractures Kim et al30likewise used a medial oblique view to evaluate suspected posteromedial talus fractures (Fig-ure 6)

Anterior calcaneal process frac-tures are not well visualized on stan-dard anteroposterior views of the foot or ankle A lateral radiograph may reveal the fracture, but direct-ing the beam 20° superior and poste-rior to the midportion of the foot can project the anterior process away from the neck of the talus, enabling

Figure 5

Anteroposterior radiograph of the ankle

demonstrating a fracture of the lateral

process of the talus, which is visible

just inferior to the lateral malleolus

visualization of the fracture7

(Fig-ure 7)

Computed Tomography

When clinical suspicion is high

but radiographs are negative, CT

scans are very useful for detecting

hindfoot process and tubercle

frac-tures Multiplanar CT imaging with

fine 1-mm cuts allows accurate

as-sessment of fragment location, size,

displacement, and comminution10

(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.21,31CT

especially should be considered

when subtalar dislocation is

suspect-ed.28Subtalar 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 al10used CT to eval-uate 10 patients with fracture of the talus Eight process or tubercle frac-tures were initially identified on plain radiographs, but CT was re-quired to determine size, displace-ment, subtalar joint involvedisplace-ment, and treatment Two fractures

initial-ly missed on plain radiographs were diagnosed using CT 6 months and 1 year, respectively, after injury In several cases, the surgical approach was determined based on the CT findings

Magnetic Resonance Imaging

The ability of fluid-sensitive mag-netic resonance sequences to dem-onstrate edema adjacent to injured structures makes it a useful modal-ity, particularly in the chronic set-ting32,33 (Figure 9) Wakeley et al32

performed sagittal and coronal spin-echo sequences on three patients

with chronic posterior ankle pain Based on the MRI results, os trigo-num syndrome was accurately diag-nosed in each case Sanders et al33 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)

chronic lateral ankle pain MRI

re-vealed a previously undetected

later-al tlater-alar process fracture for which

the patient eventually underwent

surgical excision MRI also may

pro-vide useful information regarding

adjacent soft-tissue structures, such

as tenosynovitis of the flexor

hallu-cis longus tendon or peroneal

tendi-nopathy

Nuclear Medicine Imaging

Technetium Tc-99m bone

scan-ning is another important technique

for evaluation of hindfoot process

and tubercle fractures.21,22 In the

presence of an acute or chronically

symptomatic fracture, a bone scan

demonstrates an area of focal

radio-isotope uptake This may be useful

in detecting occult fractures and in

distinguishing fractures from

nor-mal ossicles34(Figure 10)

Paulos et al5consider technetium

Tc-99m bone scanning to be the

de-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 al21likewise

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 al35 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, in three patients with negative bone scans, Abramowitz et al21 iden-tified and removed symptomatic os

trigonum with excellent results, leading the authors to reject the no-tion that a normal bone scan elimi-nates the possibility of os trigonum injury

Fluoroscopic Injection

Injection of lidocaine under fluo-roscopic guidance is another useful diagnostic tool.34When physical ex-amination reveals a point of maxi-mum tenderness suspicious of a process or tubercle fracture, a fluoro-scope can be used to precisely guide the placement of local anesthetic Significant relief of symptoms after injection strongly points to that structure as the source of pain A flu-oroscopically guided injection also may have predictive value with re-spect to surgical treatment Jones et

al36 used fluoroscopic injection of lidocaine into the synchondrosis of

Figure 9

Sagittal T2-weighted magnetic

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

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

Nonsurgical Management

Nonsurgical management should

be considered for acute process and

tubercle fractures with small (<1

cm), minimally displaced (<2 mm)

fragments.1,8 The small size of the

fragment leaves the adjacent

articu-lar surface almost completely intact

Therefore, talofibular, subtalar, or

calcaneocuboid incongruity usually

is not a problem Nonsurgical

man-agement also is appropriate for

larg-er fragments that are eithlarg-er

non-displaced or minimally non-displaced

These fractures are likely to heal or

result in a stable, asymptomatic

fi-brous union.11

When these requirements are

met, immobilization in a

below-knee, non–weight-bearing cast can

result in a favorable outcome.5,7,9,30

Generally, 6 weeks of

non–weight-bearing and cast immobilization is

recommended When the patient is

asymptomatic after 6 weeks,

transi-tion into a removable walking boot

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

al7successfully 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 colleagues11,30described successful management of acutely diagnosed posterior medial talar tu-bercle fractures The patients under-went immediate immobilization in a non–weight-bearing cast for an aver-age of 6 weeks At 2-year follow-up, the average AOFAS ankle-hindfoot score was 95 of a total of 100 points

One patient who healed with a radio-graphic fibrous union nevertheless achieved a score of 97.11

Certain peripheral hindfoot frac-tures do less well with nonsurgical management.5,7,9-11,13,16,17,23,37,38

Later-al tLater-alar process fractures have been reported to result in generally poor outcomes when managed with casting alone.9,13,26,39 For this rea-son, Kirkpatrick et al38recommend against nonsurgical management of all but the truly nondisplaced

later-al tlater-alar process fracture Neverthe-less, fractures that are acute, extra-articular, smaller than 1 cm, and displaced <2 mm may be considered for conservative management with

6 to 8 weeks of immobilization in a non–weight-bearing cast14 (Figure 11)

Large fragments, particularly those resulting from high-energy trauma, do not reliably respond to nonsurgical management Although Kim and colleagues11,30reported suc-cess with nonsurgical treatment of patients with acute posterior medial talar tubercle fractures, Giuffrida et

al17reported 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 al11sustained low-energy athletic injuries that

re-sulted in small avulsion fragments with minimal articular disruption

In the report by Giuffrida et al,17six fractures occurred in association with medial subtalar dislocation This high-energy mechanism pro-duced much larger fracture frag-ments and a high rate of subtalar subluxation and incongruity This comparison emphasizes that, even for a single type of fracture, no uni-versal treatment prescription can be given

Chronic injuries seem to have the worst outcome when managed with casting Failure to promptly diag-nose and initiate proper immobiliza-tion frequently results in a chroni-cally painful nonunion Paulos et

al5found that only 6 of 17 chronic lateral talar tubercle and os trigo-num injuries responded to a regi-men of rest, nonsteroidal anti-inflammatory drugs, stretching, and activity restriction In the series of anterior calcaneal process fractures reported on by Degan et al,7 the

Table 1 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

worst outcomes were found in

pa-tients with the longest delay in

diag-nosis and treatment

Surgical Management

Surgical management of hindfoot

process and tubercle fractures

should be strongly considered for

large (>1 cm), displaced (>2 mm)

frag-ments with significant articular

in-volvement.1,8Surgery generally

con-sists of open reduction and internal

fixation (ORIF) for large fragments,

primary excision for highly

commi-nuted fractures, and delayed

exci-sion for chronic nonunions The

sur-gical approach is tailored to the

particular fracture being treated

Open Reduction and Internal

Fixation

Noncomminuted, displaced

frac-tures that compromise articular

con-gruity should be considered for

pri-mary ORIF Unreduced large,

displaced, articular fragments have a

high propensity for nonunion, and

the subsequent articular malunion

may progress to arthrosis.12,16,17,29,40

Accurate assessment of fragment size and comminution is necessary

to determine whether ORIF is appro-priate and feasible CT is frequently 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 not uncommon even in fractures managed surgically.1The fracture is exposed via an incision over the tar-sal sinus, with distal reflection of the extensor digitorum brevis muscle ORIF is also the best treatment for medial tubercle fractures of the posterior talus that affect a signifi-cant amount of the subtalar joint Kanbe et al41performed ORIF on two patients with posterior talar medial tubercle fractures Neither patient reported pain at 2-year follow-up, and radiographs demonstrated no subtalar arthrosis Conversely, fail-ure to anatomically restore this frac-ture may result in subtalar sublux-ation and arthrosis.17This fracture is approached through a posteromedial dissection between the flexor digi-torum longus tendon anteriorly and the neurovascular bundle

posterior-ly.11The 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.18,42-44Several 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.3When the major displacement is posterolateral,

an approach between the peroneal tendons and the Achilles tendon should be performed.43 This ap-proach requires identification and protection of the sural nerve Like-wise, dissection medial to the flexor hallucis longus tendon should be performed cautiously to avoid injury

to the medial neurovascular bundle

Figure 11

A,Initial coronal computed tomography scan of a fracture of the lateral process of

the talus shown in Figure 5 demonstrating moderate comminution, minimal

displacement, and no significant subtalar incongruity B, Coronal computed

tomography scan 6 months later demonstrating healing of the fracture fragments

with preservation of subtalar congruity The patient was asymptomatic

Primary Excision

Displaced, intra-articular process

and tubercle fractures that are too

comminuted to fix internally can be

considered for primary excision

Pri-mary excision allows early

mobiliza-tion without the risk of developing

painful nonunion.1,8 This approach

has been recommended primarily for

comminuted fractures of the lateral

talar process.9,13,29 The surgical

ap-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 al21 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-kel31 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 reported after late excision of the medial tubercle

of the posterior talar process and anterior calcaneal process frac-tures.7,11,23 Results of late excision seem to deteriorate the longer symp-toms have been present.7,21

Complications

The primary complications

associat-ed with process and tubercle frac-tures of the hindfoot are chronic pain and late arthrosis Chronic symptomatic nonunion is particu-larly likely when these fractures are not diagnosed and treated

acute-ly.5,7,11,30Even when treated appropri-ately, patients may remain symp-tomatic for a prolonged period (up to

2 years in one report7) Persistence of mild pain and stiffness after union also may occur.1 Although small fractures frequently respond favor-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-proved understanding of peripheral hindfoot anatomy and injury pat-terns should increase physician awareness of and vigilance for these fractures

References

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Bucholz R, Heckman J (eds): Rock-wood and Green’s Fractures in Adults, ed 5 Philadelphia, PA:

Lippin-cott Williams & Wilkins, 2001, vol 2,

pp 2091-2132.

2 Boon AJ, Smith J, Zobitz ME, Amrami

KM: Snowboarder’s talus fracture:

Mechanism of injury Am J Sports Med2001;29:333-338.

3 Nadim Y, Tosic A, Ebraheim N: Open reduction and internal fixation of fracture of the posterior process of the talus: A case report and review of the

literature Foot Ankle Int 1999;20:

50-52.

4 Grogan DP, Walling AK, Ogden JA: Anatomy of the os trigonum.

J Pediatr Orthop1990;10:618-622.

5 Paulos LE, Johnson CL, Noyes FR: Posterior compartment fractures of the ankle: A commonly missed

ath-letic injury Am J Sports Med 1983;

11:439-443.

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 Am1982;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)