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Acute Fractures of the Tarsal Navicular
Andrew J. Rosenbaum, MD; Richard L. Uhl, MD; John A. DiPreta, MD
Abstract: The tarsal navicular plays an integral role in hindfoot motion and gait, and is the keystone of the foot’s medial
longitudinal arch. As such, injuries to the navicular can be
devastating. Acute avulsion, tuberosity, and body fractures
have been described. Fractures of the body result from highenergy trauma and are often seen in conjunction with additional ipsilateral foot injuries. Plain radiographs are the gold
standard for diagnosis, with computed tomography helpful
in the presence of intra-articular fracture extension. Nonoperative treatment is reserved for avulsion injuries and nondisplaced body fractures. Open reduction and internal fixation
must be performed for all other types, as failure to achieve
an anatomic reduction can impede proper locomotion. Complications following operative intervention include pain, stiffness, posttraumatic arthritis, avascular necrosis, nonunion,
and hindfoot deformity. [Orthopedics. 2014; 37(8):541-546.]
I
njuries of the tarsal bones result in significant long-term
morbidity, adversely impacting
overall outcome and long-term
function in polytraumatized
patients.1 Despite their association with high-energy trauma,
injuries of the tarsal bones are
often subtle and frequently only
diagnosed on a delayed basis.2
Midfoot fractures, which are
rare, are most commonly associated with motor vehicle
collisions.3,4 However, these
fractures are being seen with
increasing frequency, a find-
The authors are from the Division of Orthopaedic Surgery, Albany Medical Center, Albany, New York.
The authors have no relevant financial relationships to disclose.
Correspondence should be addressed to: Richard L. Uhl, MD, Division
of Orthopaedic Surgery, Albany Medical Center, 1367 Washington Ave, Ste
202, Albany, NY 12206 ([email protected]).
doi: 10.3928/01477447-20140728-07
ing attributed to enhancements
in automobile safety leading to
improved survival of patients
with significant foot injuries.5,6
The most frequently injured lesser tarsal bone is the
navicular, a vital component
of the foot’s medial column
and an active participant in
the transverse tarsal locking
mechanism. Avulsion, tuberosity, and body fractures have
been described. Body fractures,
although less common than
avulsion and tuberosity types,
are more severe and most often
associated with high-energy
mechanisms. In addition to
acute injuries, stress fractures
of the tarsal navicular have
been described and can also
have devastating consequences,
including avascular necrosis.7,8
Neither the adverse outcomes following fracture nor
the biomechanical significance
of the navicular can be refuted.
However, there is little literature
devoted to these injuries. This
article provides an overview of
acute fractures of the navicular,
reviewing the relevant anatomy
and biomechanics, the classification and presentation, and the
indications for and outcomes
following both conservative and
operative interventions.
Anatomy
The navicular derives its
name from its resemblance to
a small boat, as suggested by
its concave proximal articular surface. The bone articulates distally with the 3 cuneiforms, proximally with the
talar head, and laterally with
the cuboid (Figures 1-2). It is
located in the uppermost portion of the medial longitudinal
arch of the foot, acting as the
keystone of the arch (Figure
3).2 The body of the navicular
is a 6-sided, horseshoe-shaped
disk. The navicular’s distal
articulation with the cuneiforms is via 3 facets that share
a common synovial cavity. Its
medial surface slopes posteriorly, ending in the tuberosity.
Plantar and dorsal ligaments
reinforce each articulation,
with further stability provided
by the posterior tibial tendon
and plantar calcaneonavicular
(spring) ligament, which insert distally and medially on
the tuberosity, as well as the
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Figure 1: Drawing of the navicular’s
distal articular facets for the 3 cuneiform bones and cuboid.
anterior fibers of the deltoid
ligament, which enhance medial talonavicular joint stability.9 This robust ligamentous
network can only be disrupted
with significant force, which
is why displaced navicular
body fractures are most frequently seen in the setting of
high-energy trauma.
The extensive articular cartilage surrounding the navicular limits blood vessels to dorsal and plantar entry into the
bone. Branches of the dorsalis
pedis artery supply the dorsum, while the medial plantar
branch of the posterior tibial
artery supplies the bone’s
plantar surface. The navicular
tuberosity receives its blood
supply from an anastomosis
between these vessels.10 This
pattern renders the middle
one-third of the bone largely
avascular, making this area the
most vulnerable to stress fractures and nonunion.
Figure 2: Drawing of the navicular
tuberosity, at which the posterior
tibial tendon and spring ligament
insert. The articular surface at which
the navicular articulates with the talus is also shown.
for flexibility. Conversely, the
axes of these joints are divergent during inversion, locking
the joint and making the medial longitudinal arch rigid,
which facilitates effective heel
rise.
Motion at the talonavicular
joint is tightly coupled with
subtalar motion. Fusion of the
talonavicular joint eliminates
all subtalar motion, while
fusion of the subtalar joint
leaves only 26% of normal talonavicular motion.11 Isolated
fusion of the calcaneocuboid
joint has less of an impact on
subtalar motion and hindfoot
stiffness, leaving 67% of talonavicular motion intact.11 This
further elucidates the important biomechanical role of the
navicular in hindfoot motion
and gait.
Biomechanics
Classification
The talonavicular and calcaneocuboid joints collectively form the transverse tarsal
joint, the proper functioning
of which is crucial for effective gait. The axes of the talonavicular and calcaneocuboid
joints are parallel when the
hindfoot is everted, allowing
Acute navicular fractures
are broadly classified into 3
types: avulsion fractures, tuberosity fractures, and body
fractures.2 In 1989, Sangeorzan et al9 further stratified
body fractures into 3 types on
the basis of the direction of the
fracture line, the direction of
542
Figure 3: A lateral drawing of the foot, depicting the navicular as the keystone
of the medial longitudinal arch.
displacement of the fore- and
midfoot, and the pattern of
joint disruption.
A type-1 body injury is
defined as having a transverse
fracture line in the coronal
plane, with the dorsal fragment consisting of less than
50% of the body. There is no
angulation of the forefoot, and
no disruption of the alignment
of the foot’s medial border.
A type-2 fracture, which is
the most common, has a primary fracture line extending
dorsal-lateral to plantar-medial, with the major fragment
and forefoot displaced medially. The naviculocuneiform
joint usually remains intact,
but the dorsal talonavicular
ligament is often involved.
Type-3 injuries involve a
comminuted fracture in the
sagittal plane of the navicular
body. The medial border of the
foot is usually disrupted at the
naviculocuneiform joint with
these injuries and there is lateral displacement of the forefoot, with some involvement
of the calcaneocuboid joint as
well.10
Mechanism of Injury
Approximately 50% of
navicular fractures are avulsion fractures.2,12 These lowenergy injuries result from
disruption of the dorsal talonavicular ligament, anterior
division of the deltoid ligament, or traction of the posterior tibial tendon or spring
ligament complex. Avulsion
of the talonavicular ligament
occurs in extreme inversion
and plantarflexion, while deltoid ligament failure is seen
with extreme eversion. Tuberosity avulsions are the result
of an acute eversion or valgus
injury to the forefoot.
Tuberosity fractures can
appear similar to type-2 body
fractures on radiographs.
However, the primary fracture
fragment in true tuberosity
injuries is smaller and more
lateral.
Acute navicular body fractures are caused by both direct
(eg, crush) and indirect (eg,
axial load) forces. There are
several theories regarding the
indirect mechanisms. Main
and Jowett13 describe a shearing mechanism in which longitudinal compression of the
plantarflexed foot causes impaction of the cuneiforms into
the navicular. Nyska et al14 hypothesize that the cuneiforms
are compressed backward
and medially, causing the navicular body to be crushed by
the talar head with the ankle
in plantarflexion. Both Eft-
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A
A
B
Figure 4: Anteroposterior (A) and
lateral (B) radiographs of the right
foot of a 49-year-old man involved
in a high-speed motor vehicle collision. A nondisplaced fracture of the
navicular body is present, in addition
to a Gustillo grade 1 open calcaneus
fracture. The patient was taken to
the operating room the day of presentation, where he underwent an irrigation and debridement of his calcaneus in association with an open
reduction and percutaneous pinning.
The navicular fracture was managed
non-operatively. Navicular body fractures are often seen concurrently with
other foot trauma. This is attributed to
the significant force required to fracture the navicular body.
ekhar et al15 and Nadeau and
Templeton16 believe that it is a
combination of plantarflexion
and abduction at the midtarsus. Although these theories
each have distinguishing features, they all involve fracture
secondary to axial loading of a
plantarflexed foot.
Rocket and Brage17 propose a different mechanism,
in which the medial forefoot
or midfoot is subjected to a
Figure 5: Coronal computed tomographic image of the patient in Figure
4. This image was obtained to better
delineate both the calcaneal and the
navicular fractures.
strong dorsiflexion force in the
setting of hindfoot eversion.
In this position, the subtalar
and transverse tarsal joints are
unlocked, causing plantarflexion and adduction of the talar
head. This leads to forceful
contact between the head of
the talus and the articular surface of the navicular body.
Presentation and
Diagnosis
Patients with avulsion and
tuberosity fractures will usually describe a low-energy
twisting injury, while those
with body fractures present
following a high-energy mechanism. On physical examination, swelling is most often
localized to the dorsomedial
midfoot, but can be present diffusely. Patients are extremely
tender at the navicular and report limited weight bearing and
pain with push-off during gait.
When presenting in a delayed
fashion, observation of the
patient during weight bearing
may reveal foot deformities,
such as loss of the longitudi-
B
Figure 6: Lateral radiographs of the patient from Figure 4 taken 1 month (A)
and 8 months (B) following the injury. The calcaneus was treated with an open
reduction and percutaneous pinning, followed by a subsequent removal of
hardware once healed. The navicular was followed serially to evaluate for displacement requiring surgical intervention. It is evident from these radiographs
that talonavicular and naviculocuneiform joints remained well aligned, with no
signs of medial longitudinal arch collapse.
nal height. As with any evaluation of the foot in the setting
of trauma, a detailed neurovascular examination must also
be performed. Further, compartment syndrome should be
ruled out if there is significant
swelling. Additional ipsilateral
foot injuries may also be present, with one study identifying
a 62% incidence of concurrent
midfoot and hindfoot injuries
(Figure 4).6
Anteroposterior, lateral, and
oblique radiographs of the foot
are mandatory and are usually sufficient to make the diagnosis. Weight-bearing radiographs are ideal, and should be
obtained if the patient is able to
comply. Stress views can also
be obtained and can identify serious ligamentous injury. Avulsion fractures will demonstrate
a fleck of cortical bone, which
may be present on only one
view. Tuberosity fractures must
be distinguished from an accessory navicular, which appears
well corticated and smooth on
radiographs. Comparison radiographs of the other foot can
be helpful to identify an accessory navicular, which is often
bilateral. Of note, an external
oblique view of the foot (opposite to the oblique view of the
foot usually obtained) will provide the best visualization of
the navicular tuberosity. Given
the high-energy nature of body
fractures, ankle radiographs
should also be obtained to identify any additional injuries.
Computed tomography is
not mandatory, but can be used
to better delineate the geometry of the talonavicular joint
and midfoot anatomy, identify
more subtle injuries, assess for
intra-articular fracture involvement, and assist the orthopedic
surgeon in selecting the most
appropriate treatment (Figure
5). Magnetic resonance imaging has a limited role in the
setting of acute navicular fractures, and is obtained more often in the setting of a suspected
stress fracture, in the presence
of an accessory navicular, or
when concern exists for injury
to the posterior tibial tendon.
Treatment
Avulsion fractures can be
managed non-operatively in a
supportive shoe, cast boot, or
short-leg weight-bearing cast.
However, if major soft tissue
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B
A
A
D
Figure 7: Anteroposterior (A) and lateral (B) radiographs and coronal (C)
and sagittal (D) computed tomographic images of the foot of a 52-year-old
woman who was the restrained driver
in a high-speed motor vehicle collision. A type-2 displaced navicular body
fracture with involvement of the talonavicular joint is evident. The patient
also suffered an ipsilateral tibial shaft
fracture and a contralateral calcaneus
fracture.
C
swelling or severe pain is present, a more serious ligamentous injury may have occurred
and the patient should be kept
non-weight bearing with immobilization for 6 weeks.
Simple, nondisplaced body
fractures can also be managed
conservatively with immobilization and protected weight
bearing in a short-leg cast. Radiographs should be obtained
at monthly intervals to assess
for any displacement neces-
544
B
sitating operative intervention
(Figure 6).
Indications for surgical
fixation of navicular body fractures include displacement or
joint incongruity greater than 1
mm, medial column shortening
greater than 2 to 3 mm, resultant subluxation or dislocation,
lateral column involvement,
open wounds, compartment
syndrome, gross instability,
skin tenting, and irreducible
dislocations (Figure 7).18 The
goals of open reduction and
internal fixation (ORIF) include anatomic reduction of
the talonavicular joint, restoration of medial column length,
and rigid fixation allowing for
early range of motion. At least
60% of the navicular’s proximal articular surface must be
restored to prevent talonavicular subluxation after healing.13
With fracture malreduction,
medial column stability is
compromised, which can have
devastating effects on push-off
strength and hindfoot motion.
Type-1 body fractures are
approached through an anteromedial incision, which
proceeds between the anterior
tibial and the posterior tibial
tendons. Exposure of the talonavicular and naviculocuneiform joints is performed via
capsulotomies. Ideal fixation
of these injuries is with two
3.5-mm cortical lag screws
placed in a dorsal-to-plantar
trajectory.
Type-2 fractures are approached through a dorsal
incision directly over the fracture. Simple fractures can be
fixed with lag screws. However, most type-2 fractures are
usually more complex with
some comminution present.
In these instances, additional
incisions may be required and
plate and screw constructs
must be used (Figure 8). The
traditional 2-incision approach
C
Figure 8: Anteroposterior (A), lateral
(B), and oblique (C) fluoroscopy images obtained during open reduction
and internal fixation of the type-2 body
fracture shown in Figure 7. A dual anteromedial and lateral approach was
used. A 2.4-mm navicular plate was
used.
uses the aforementioned anteromedial incision as well as
a lateral incision. The intermuscular plane encountered
during the lateral exposure is
between the extensor hallucis
and the extensor digitorum
brevis muscles. One must be
careful to protect the superficial peroneal nerve and motor
branch of the deep peroneal
nerve during this approach.
Type-3 fractures are not
amenable to percutaneous
screw fixation. Instead, plate
fixation must be used to provide stable fixation. Bone graft
is sometimes needed secondary to the comminution present and can help buttress the
talonavicular articular reduction. The plates available for
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B
A
body fractures include small
washer plates, one-quarter
tubular plates with 2.7-mm
screws, 2.4-mm miniplates
with 2.4-mm screws, and 2.0mm miniplates and T plates
with 2.0-mm screws.
When the orthopedic surgeon is faced with a severely
comminuted navicular body
fracture, ORIF may be a suboptimal intervention. In this
setting, the surgeon has several options, including primary
arthrodesis of the naviculocuneiform joints, spanning
external fixation, delayed reconstruction, temporary medial column bridge plating,
or primary medial column arthrodesis.19
Outcomes
Fracture pattern and quality
of reduction have been shown
to correlate with outcome following ORIF of navicular
body fractures (Figure 9).6 Of
the 21 patients reported on by
Sangeorzan et al,9 satisfactory
reduction was obtained in all
type-1 fractures, 67% of type2 fractures, and 50% of type-3
fractures. Radiographic evidence of healing was seen at an
average of 8.5 weeks.10 In a ret-
C
Figure 9: Anteroposterior (A), lateral
(B), and oblique (C) radiographs obtained 6 months following the open
reduction and internal fixation of the
type-2 body fracture shown in Figure
7. Despite anatomic reduction of the
navicular and initiation of early weight
bearing, diffuse osteopenia is evident
throughout the foot. Due to the patient’s other injuries, her mobility was
significantly limited during the initial
recovery period. As mentioned, it is
not uncommon for navicular fractures
to present as only one of multiple injuries in a polytraumatized patient.
rospective review of 24 patients
treated with miniplate fixation,
Evans et al6 found no instances
of nonunion, loss of reduction,
or deep infection. They concluded that minifragment fixation was a good fixation option
for rigid stabilization of navicular body fractures.
Complications
All patients who have been
treated with navicular body
ORIF should be counseled
on the possibility of persistent stiffness, pain, and loss of
hindfoot motion. The development of posttraumatic arthritis may be the cause of these
symptoms, for which arthrodesis is an effective intervention. Although talonavicular
fusion reliably relieves pain, it
does so at the expense of hindfoot motion. Avascular necrosis can also occur and is attributed to the bone’s tenuous
blood supply and soft tissue
stripping performed during
surgery. It leads to collapse of
the navicular and joint space
narrowing, which is most appropriately managed with fusion. Nonunion can also occur due to the bone’s limited
blood supply. As mentioned
previously, it typically occurs
in the central watershed area
of the bone. This complication is usually amenable to
bone grafting with rigid fixation. An additional complication is the progressive and late
development of hindfoot varus, which occurs secondary
to progressive collapse of the
lateral side of the navicular.
This should be treated with
deformity correction and concurrent talonavicular or triple
arthrodesis.19
Conclusion
Acute fractures of the tarsal
navicular can present as lowenergy avulsion injuries, fractures of the tuberosity, or highenergy body fractures. While
both direct and indirect loading of the navicular can lead to
injury, it is only with tremendous force that a fracture will
occur. This is attributed to the
stout ligamentous network surrounding the navicular and its
various articulations. Because
the navicular is the keystone of
the foot’s medial longitudinal
arch, and intimately involved
in hindfoot motion and effective locomotion, most navicular body fractures should be
treated with ORIF. However,
in those fractures that are nondisplaced, as well as in the
setting of avulsion injuries,
conservative interventions are
appropriate. All patients must
be advised of the risk of experiencing postoperative complications, which include pain
and loss of motion, as well as
the need for a future arthrodesis secondary to the development of posttraumatic arthritis
or avascular necrosis.
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