A fourteen-year-old girl sustained a gunshot wound to the back of the ankle
when walking up the stairs in front of her house as she was returning from
school. The bullet entered the posterolateral aspect of the heel. Radiographs
revealed fractures of the talus and lateral malleolus, as well as a bullet
embedded in the talar neck and multiple shards of metal along the bullet track
(Fig. 1). The results of
neurovascular examination were normal.
In the emergency room, antibiotics and tetanus prophylaxis were
administered. She was taken to the operating room emergently for irrigation
and débridement of local soft tissue as well as the ankle and subtalar
joints. The bullet had passed between the fibula and tibia, removing bone from
each, and from the posterior aspect of the talar body into the talar neck,
where it had created a comminuted fracture. Because of softtissue swelling and
concerns for the vascular supply to the talus, no attempt was made initially
to access the talus or bullet from an anterior approach, and the bullet could
not be extracted from the talar neck through the posterior wound. The
posterior wound was copiously irrigated and débrided of necrotic soft
tissue, bone, and clothing fibers. The ankle was splinted, and the patient was
kept non-weight-bearing and on antibiotics until the follow-up visit one week
later.
At that follow-up visit, the blood lead concentration was checked and found
to be 27 µg/dL (normal, 0 to 10 µg/dL)
(Table I). The increased lead
level prompted removal of the bullet and as many of the smaller fragments as
possible the following day. Combined anterior and posterior approaches were
used. The defect in the talus caused by the bullet was packed with allograft
bone chips.
The Pediatric Environmental Health Center was consulted. A thorough
assessment of prior lead exposure risks revealed no occupational, behavioral,
or medical risk factors to suggest prior or ongoing lead exposure. The patient
denied any foreign travel or hobbies involving potential lead exposure. She
did not use imported cosmetics. Her family drank only bottled or filtered
water and used no imported cookware or ceramics in food preparation. The
patient denied any use of imported foodstuffs, herbs, dietary supplements,
calcium supplements, or ayurvedic remedies. Since she was well over the age
(five to six years) when hand-to-mouth behavior can be implicated in lead
paint exposure, no further home assessment was performed. The blood porphyrin
levels were normal, and the long-bone radiographs showed no evidence of growth
arrest lines. The lack of any abnormality on these tests suggested the lead
exposure was acute rather than chronic. The bullet was therefore considered
the cause of the increased blood lead concentration, and the patient was
started on chelation
therapy1,7,8.
After less than one week of chelation, the blood lead concentration
decreased to 16 µg/dL and the chelation was discontinued. The lead level
rebounded after chelation was discontinued, and the patient subsequently
required intermittent chelation therapy.
At the six-month follow-up visit, the talar fracture had healed and she was
back to normal activities. At nine months after the injury, she continued to
be followed by the occupational health center and had periodic follow-up
evaluations in orthopaedics.
Projectile trauma is often classified as high velocity or low velocity.
Typically, hunting and military weapons produce high-velocity injuries and
handguns produce low-velocity injuries; however, the classification is also
dependent on the degree of associated soft-tissue
injury2. Typically,
the orthopaedic literature supports nonoperative treatment of low-velocity
gunshot
wounds1,2;
however, some authors have recommended that even low-velocity gunshot wounds
resulting in a fracture should be classified as open
fractures9. While
removal of the retained bullet is not
routine2,9,
joint involvement has been one of the absolute indications for surgical
débridement and removal of the bullet and fragments from the
joint1,2.
In our patient, irrigation of the involved joints was done emergently, but
because of concerns with regard to soft-tissue and vascular injury, removal of
the bullet from its position in the talar neck was not attempted until an
elevated blood lead concentration was noted.
Adults store roughly 95% of lead in the skeleton, with a half-life of two
to seventeen years for trabecular bone and over twenty years for cortical
bone3,10,11.
Lead poisoning associated with retained bullets is unusual, and the cases of
fewer than 100 patients have been
reported11.
However, problems caused by a retained bullet are usually delayed, and the
symptoms of lead poisoning often appear only after the bullet has been
retained for more than ten
years4,12-16.
The location of the retained bullet is an important predictor of future lead
poisoning, with bullets in soft tissues presenting less of a problem than
those in contact with synovial fluid or an intervertebral
disk1-4,13,15-18.
Subsequent blood lead concentration is also higher in the presence of a
fracture10,11.
A recent study of over 500 patients with a retained bullet or fragments showed
that blood lead levels increase for up to three months and then decline to a
steady-state level approximately twelve months after the
injury11. In that
study, the serum lead level was significantly higher when the retained bullet
was near bone (32% higher; p < 0.0005) or in a joint (17% higher; p =
0.032). Bullet fragmentation also resulted in increased blood lead levels.
Lead intoxication manifests clinically in adults in the hematologic system
(anemia and basophilic stippling), the digestive system (anorexia, vomiting,
constipation, and abdominal pain), the cardiovascular system (hypertension),
and the nervous system (peripheral neuropathy, acute encephalopathy with
lethargy, stupor, coma, and
convulsions)1,7,14
and has even led to
death19. Children
and fetuses have a special sensitivity to lead intoxication. Lead can
profoundly impact the developing brain leading to measurable decreases in
intelligence
quotient5,
behavioral changes, learning disabilities, and fetal
anomalies3,6.
Many patients with a retained bullet have not reported long-term symptoms
or consequences, yet the literature has shown many reports of patients with
lead poisoning decades after the injury. Our patient had several risk factors
for the development of lead toxicity from this bullet, including the fact that
it was lodged near a joint and in bone. Even greater concerns arose in this
case because of the potential of the patient to bear children at some point in
the next two decades, with the subsequent risk of lead toxicity to the
fetus.
Childhood lead toxicity has been recognized since the early part of the
twentieth century5,
with lead-based paint being the most commonly implicated cause. While some
retained bullet fragments in children have not been shown to produce evidence
of lead toxicity20,
there have been reports of retained bullets in children that have demonstrated
such
evidence7,8.
In such patients, removal of the bullets, if possible, is recommended and
chelation therapy is an additional line of
treatment1,7,8.
Lead has been shown to cross the
placenta4,5,10,
and even low levels of lead have been shown to produce irreversible disorders
of fetal growth and
development5,6.
Exposure of the fetus to lead in utero at levels not high enough to cause
clinical symptoms in the mother has been associated with lower
intelligence-quotient scores, reductions in physical growth, behavioral
changes, and learning
deficit5-7,10.
One case report demonstrated fetal anomalies as a result of lead poisoning
from a retained bullet that the mother had sustained fifteen years
earlier3.
There was some initial concern that the elevated blood lead levels in our
patient were not a result of the bullet but instead were from other
environmental factors. However, a full exposure history was undertaken by
occupational health experts and no source of chronic lead toxicity could be
identified. Erythrocyte protoporphyrins are extremely sensitive to childhood
lead poisoning and are elevated soon after exposure since they are a
reflection of the earliest insult of lead to red blood
cells21. Normal
levels of erythrocyte zinc-chelated protoporphyrius in our patient indicated
that the lead exposure was temporally very acute. Finally, elevated lead
levels affect long-bone growth, and this can be evident by the appearance of
lead lines22. Since
our patient had recently finished her adolescent growth spurt, lead lines
would be evident on the long-bone radiographs, and their absence implies a
more acute circumstance leading to lead exposure.
The serum lead levels in our patient remained elevated after removal of the
bullet, but they responded to chelation therapy. The persistently elevated
blood lead levels at nine months after the injury could have been from either
continued absorption from additional small retained fragments within the talus
or from the redistribution of lead from other body compartments (e.g., soft
tissues and bone) after chelation had reduced it in the blood.
The Association of Occupational and Environmental Clinics recently proposed
guidelines for the management of retained
bullets23. They
noted that retained bullets pose a risk for causing increased blood lead
levels, and "individuals with retained bullets should receive baseline
and periodic blood lead testing to monitor their lead status." They do
not give more specific recommendations about the schedule of blood lead
testing. However, the current literature supports the monitoring of blood lead
levels during the first three months after injury, since this is when the peak
levels are likely to occur. The first blood lead level should be checked at
the time that the bullet wound is sustained to establish the baseline value.
The second blood lead level should be checked within the first week after the
injury, as deposition within the body tissues can be relatively rapid. If,
after three months, the blood lead level has not increased perceptibly, the
current literature suggests that it is probably safe to assume that the bullet
is inert. Recommendations regarding bullet removal should be made jointly by
the treating physician and surgeon.
The case of our patient and the review of the literature bring to light the
potential long-term consequences of a retained bullet. It is not currently
common practice in orthopaedics to consider blood lead levels in the treatment
of patients with a retained bullet. However, the consequences of an elevated
blood lead level may not be evident for decades and may result in substantial
harm to the patient. The recommendations of the Association of Occupational
and Environmental
Clinics23 for
serial evaluation of serum lead levels in all patients with a retained bullet
should be complied with, and bullet removal should be considered if blood lead
levels become substantially elevated. ?