Pseudoaneurysm of an artery in close proximity to fractured bone is
a well-recognized entity, and various cases involving different sites have
been reported in the
literature1-5.
We report the case of a patient in whom a pseudoaneurysm of the posterior
tibial artery developed following a closed fracture of the calcaneus. As far
as we are aware, only one such case has previously been
reported6.
Our patient was informed that data concerning this case would be submitted
for publication.
A thirty-two-year-old manual laborer sustained injuries of the spine
and foot following a fall from a height. He was admitted with a Chance
fracture7,8
at the L1 level with paraparesis consisting of weakness mainly in the right
lower extremity as well as a right-sided intra-articular calcaneal fracture. A
computerized tomographic scan showed a grade-IV fracture according to the
classification system of Sanders and
associates9
(Fig. 1).
The spinal fracture was stabilized on an emergent basis. The calcaneal
fracture was treated nonoperatively because of the severe comminution.
Postoperatively, the patient had development of a deep-seated infection with
methicillin-resistant staphylococcus aureus at the site of the spinal
procedure; the infection was treated successfully with multiple
débridements and intravenous and oral antibiotics.
Approximately four weeks after the injury, a pulsatile mass was noticed on
the medial aspect of the ankle, posterior to the medial malleolus. The mass
corresponded with the anatomical course of the posterior tibial artery and was
compressible as well as pulsatile.
Axial radiographs of the calcaneus revealed a spike of bone projecting into
the medial soft tissue (Fig.
2). A computerized tomographic angiogram revealed a pseudoaneurysm
of the posterior tibial artery (Fig.
3).
During the next two weeks, the aneurysm was observed to increase in size
and the danger of rupture was explained to the patient, who consented to
surgical treatment.
In view of the history of spine infection and the fact that the
computerized tomographic angiogram revealed excellent circulation to the foot
from the anterior tibial and peroneal vessels, the decision was made to ligate
the posterior tibial artery and to excise the pseudoaneurysm. The vascularity
of the foot was assessed clinically with use of a technique, similar to the
Allen test, described by Sharma and
Kola10. With this
technique, the posterior tibial artery is compressed manually for a few
minutes and the patient is told to move his or her toes while any evidence of
vascular insufficiency is noted. No problem with the vascularity of the foot
was observed with this test.
Intraoperatively, the aneurysm was seen to be arising just prior to the
division of the artery into its medial and lateral branches
(Fig. 4). The posterior tibial
artery was clamped proximally and distally for about five minutes, and the
tourniquet was then released. The blood supply to the foot was found to be
adequate. The artery was then ligated, and the pseudoaneurysm was excised
(Fig. 5-A). Histopathological
examination of the specimen revealed a wall formed by a chronic inflammatory
reaction and granulation tissue, which confirmed the diagnosis of
pseudoaneurysm (Figs. 5-B and
5-C). The spike of bone that
was thought to be responsible for causing the aneurysm was pared but was not
completely removed.
Postoperatively, the patient did well. There was no infection, and repeat
computerized tomographic angiography showed good blood supply to the foot. The
patient had recovered grade-4 power in both lower limbs and went home after
being adequately mobilized with the help of axillary crutches.
At the time of the seven-month follow-up, there was no evidence of any
arterial insufficiency of the foot. The patient was able to walk independently
without external support.
Intra-articular fractures of the calcaneus are commonly caused by a
fall from a height. They may be treated either operatively or nonoperatively.
Acute complications following such a fracture include compartment syndrome of
the foot and soft-tissue injury. Single cases of pseudoaneurysm of the
posterior tibial artery and entrapment of the medial neurovascular bundle also
have been
reported6,11.
Pseudoaneurysms of an artery can be caused by blunt or penetrating trauma
and are due to full-thickness tears or lacerations of the vessel wall. In the
case of our patient, a spike of bone from the medial aspect of the body of the
calcaneus, as seen on the axial radiograph, probably resulted in a laceration
of the vessel wall. This finding was confirmed on intraoperative
exploration.
The other important observation was the slowly progressive increase in the
size of the pseudoaneurysm, which could even be appreciated by the patient
because of the superficial location of the artery. Sudden potentially
catastrophic bleeding due to acute rupture of the pseudoaneurysm is a real
danger and has been reported in the
literature12-14,
although in this particular location it probably would not be fatal.
We considered three treatment options. The first option was excision of the
pseudoaneurysm and the involved vessel followed by reconstruction of the
defect with a venous graft. We thought that the risk of local infection was
too great in light of the patient's recent infection with
methicillin-resistant staphylococcus aureus. The second option was
embolization of the feeding vessels with use of a percutaneous technique. In
this case, both the proximal and distal (retrograde) flow would have had to
have been contained, and we did not have the resources or the technical
expertise to implement such a plan. The third option was ligation of the
artery proximally and distally and excision of the aneurysmal sac. The only
question was whether the blood supply to the foot would be adequate. The
preoperative computerized tomographic angiogram showed adequate flow through
the anterior tibial and peroneal supply. Intraoperatively, the blood supply to
the foot was found to be adequate with the posterior tibial artery clamped for
five minutes. Furthermore, the posterior tibial artery is routinely divided at
the ankle to procure flaps during certain plastic surgical procedures, without
resultant ischemia of the
foot15,16.
In summary, pseudoaneurysm of the posterior tibial artery can be associated
with a displaced fracture of the calcaneus, and orthopaedic surgeons should be
aware of this potential complication following a fracture of the calcaneus.
?
Note: The authors thank Dr. M.E. Yeolekar, Dean, Lokmanya Tilak
Medical College and Sion Hospital, for permission to use the clinical
material. They also thank the radiology and pathology departments for their
input.