Case presentation
A 39-year-old man was admitted to our
emergency room at Prince Rashid Bin Al-Hassan Hospital in the North of Jordan,
on 22nd of November 2016, about three hours after the injury, with
severe left ankle pain and swelling. He had fallen from a ladder about 3 m
height and what he described was an inversion and plantar flexion injury of his
left ankle after landing on a hard surface. On physical examination, he was
observed to have swelling and deformity of his left ankle with the foot shifted
medially. No signs of neurovascular injury were observed. X-ray examination
showed dislocation of the talonavicular and talocalcaneal joints (medial
subtalar dislocation) with a fracture fragment of unknown origin (Figure 1).
Figure 1: X-Ray shows medial subtalar dislocation
With the patient under adequate
intravenous sedation, closed reduction was done and after that, the computed
tomography revealed a comminuted fracture of the posterior process of the talus
in both the medial and lateral tubercles of the posterior process and displaced
fracture of the anterior process of calcaneus Figure 2 (A-D), Patient was kept
on posterior slab for 12 days after the injury, until the swelling
decreased. Patient was then sent to the operating theatre for open reduction
and internal fixation of these fractures.
Surgical
technique
In the operating room, under general
anesthesia, the patient was placed in prone position and non-sterile pneumatic
tourniquet was applied on the left thigh. One gram of cefazolin was
administered intravenously. The posterior aspect of the talus was then followed
using posteromedial approach longitudinal incision placed medial to the medial
margin of the achilles tendon (Figure 3A),
which was retracted laterally (Figure 3B), the flexor hallucis longus (FHL)
sheath was opened and the FHL and the posterior tibial neurovascular bundle
were then identified and protected by means of careful retraction to the medial
aspect of the surgical wound, using two kirschner wires were applied at the
posterior surface of tibia to retract soft tissues medially and laterally (Figure 3C). The posterior capsule were incised
and reflected by exposing the fracture of the posterior process of the talus,
including the medial and lateral tubercles. Small loose bodies were removed and
the fracture was reduced under direct vision and then temporarily stabilized
with 2 kirschner wires. The reduction was confirmed with image-intensification
fluoroscopy. Definitive fixation was then achieved by using two screws 2.7 mm
fully threaded self-tapping. The heads of screws buried flush with the
articular surface after use of countersunk (Figure 3D). The wound was closed in layers. Another
incision was done over the calcaneocuboid joint with anterolateral foot
approach Fig. 3E, retraction of extensor digitorum
brevis, identification of fracture site and reduction. The provisional fixation
using two kirshner wires was carried out as well. Then, the definite fixation
using 2.7 mm screws was done and was confirmed by fluoroscopy and then the
closure in layers and short leg cast was applied for 3 weeks. Later, the
patient sent to physiotherapy for six months, and 12 months after surgery
clinical evaluation was done using American Orthopedic Foot and Ankle Society
(AOFAS) ankle-hindfoot scale score, it was 95, which considered excellent
outcome (Figure 4A and 4B).
Fig. 2 2A, 2B: CT scan shows entire posterior
process talus fracture with comminution, 2C, 2D: CT scan anterior process
calcaneal fracture.
Figure 3: 3A: skin incision just medial to
Achilles tendon, 3B: incision of flexor hallucis longus fascia, 3C: temporary
fixation of posterior process fracture with k. wires, 3D: definitive fixation
of posterior process fracture with screws, 3E: anterolateral approach for
fixation of anterior process of calcaneum fracture.
Figure 4: Postoperative X-ray done two weeks postoperatively.
Discussion
Fractures involving the posterior process of
talus with concomitant subtalar dislocation are extremely rare and easily
missed. If ended with malunion, it may lead to severe complications [2] [4].
The
posterior process of talus is composed of medial and lateral tubercles and
separated by a groove for the FHL, tendon. The lateral tubercle (Steida’s
process) is larger than the medial and more posteriorly placed. However, there
is some confusion regarding the classification of the posterior process
fractures in literature [2] [4].
Anatomically,
fractures involving posterior talus, either involve entire process, or are confined
to medial tubercle or lateral tubercle.
The
first fracture described in the posterior part of talus was by Shepherd in 1882
based on anatomical dissections which included the lateral tubercle (Steida’s
process) [5].
Medial
tubercle fractures were first described by Cedell in 1974 [6]. He described an
avulsion injury secondary to a pronation-dorsiflexion force with avulsion of talotibial
ligament [6].
Fracture of posterior process is less common than either of the tubercle
fracture, as it involves both tubercles, fracture of the entire posterior
process of talus with subtalar dislocation is extremely rare in literature and it
involves both the ankle and the subtalar joint. The mechanism of injury that
causes entire posterior process fractures is still unclear [7] [8]. Nasser and Manoli believed
that maximum plantar flexion of the ankle could cause compression of the
posterior part of the tibia on the posterior part of calcaneum and fracture the
posterior process [7]. It can be easily
missed, if subtalar dislocation has occurred simultaneously or when a fracture
fragment is small.
The first
report of subtalar dislocation was in 1811 [4] [9], which was defined
as the dislocation of the talocalcaneal and talonavicular joints. The mechanism
of a medial subtalar dislocation is believed to be forceful inversion of the
foot, with the sustentaculum used as the fulcrum causing the talus to leave the
subtalar and talonavicular joints. The most common pattern is medial
dislocation about 85% with most
of them occurring in younger aged men [9].
Forced
plantar flexion with inversion could cause fracture of the posterior process of
the talus with concomitant subtalar dislocation [3].
We need a high index of suspicion for diagnosis of associated fractures, and
early surgical management for a displaced fracture.
Regarding
the surgery in posterior process fractures, most authors believe that fracture displacement
(>2 mm) and joint involvement is an indication for open reduction and
internal fixation to minimize the risk of complications [10] [8]. Undiagnosed
displaced fractures may lead to posterior impingement, subtalar arthritis, and
entrapment of the FHL tendon, malunion of the groove for the FHL tendon and can
might cause FHL tendinitis [3].
Regarding
surgical approach, open reduction internal fixation was performed either through
the posterolateral [11] or posteromedial
approach [8] [1]. The posteromedial
approach is the most common approach used in posterior process fractures and may
be more reliable, provide good surgical exposure and easier, because the FHL
tendon can be used as a guide. The disadvantage to a lateral approach is the
risk of injuring the sural nerve.
Comprehensive
knowledge of the local anatomy and various surgical techniques for fracture
reduction and fixation to obtain optimal results and gentle handling of the
neurovascular structures is important. Fixation of the fracture can be done by
plates, screws (cancellous screws, headless screws, absorbable screws), or kirschner
wires.
Nyska
et al have described displaced fractures of the posterior process of the talus
in four patients which were initially missed and treated conservatively. He
reported poor outcome with malunion, pain, and early onset arthritis [12] .
Anterior process of calcaneus fractures often
result from a forced inversion and plantar flexion injury, which increases
tension on the bifurcate ligament, and produces an avulsion fracture [13]. This
mechanism is consistent with our patient’s injury.
Conclusion
Posterior process fractures associated with
subtalar dislocation are extremely rare, and easily missed, hence, it is important
to do computed tomography post reduction for assessment and planning management.
Open reduction internal fixation using posteromedial approach for displaced
fractures produces good results.
Conflict of interest
No conflict of interest
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