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Percutaneous CT Guidance:
Screw Fixation of Acetabular Fractures Preliminary Results of a New Technique
Spencer B. Gay,1 Christopher and Henry T. Goitz2
Sistrom,1
Gwo-Jaw
Wang,2
Treatment of acetabular fractures generally consists of either bed rest and traction for simple minimally displaced fractures, or open reduction and internal fixation for complex or significantly displaced fractures. Internal fixation permits
early ambulation and can significantly time spent in bed [1]. Open reduction
ture,
however,
is a significant
reduce the amount of of an acetabular frac-
physiological
trauma
patient and has the associated risks of postoperative tion, wound healing problems, formation of heterotopic
and neurologic fusion,
during
injury. Many such patients or after
the procedure.
to the infecbone,
require blood trans-
CT is routinely
used
to
evaluate acetabular fractures and plan treatment [2, 3J. Threedimensional (3D) image processing also has been shown to be useful
in the
acetabular
fractures
cutaneous
fixation
similar
technique
diastatic
diagnosis and understanding of complex [4]. We report a new technique for per-
of these was recently
sacroiliac
injuries
with
described
CT guidance.
for screw
fixation
A of
joints [5].
David
A. Kahler,2
protocol
for these
workstation
1990 and March
infusion
1991
, six
patients who were admitted to the orthopedic trauma service were treated with CTguided screw fixation of their acetabular fractures. The two women and four men were 23-66 years old. Three of the fractures were in the left acetabulum and three were in the right. Four of the fractures were sagittal in orientation and involved with extension into the posterior column.
the roof of the acetabulum The other two patients had
scans
(Voxel
Flinger,
surgeons
of an epidural of local
C American
Roentgen
slices
through
the acetabula
Imaging,
Solon,
OH), where
participated
regional
catheter
anesthetic;
in the 3D planning
anesthesia
volu-
and was
maintained
an anesthesia
on the CT couch.
team
Pac, Olympic Equipment,
A special
sessions.
was established was
stabilizing
by
by intermittent in attendance.
were placed prone or in the lateral decubitus
(affected
device
(Vac-
Seattle, WA) was placed under the patients
to maintain done with
their position. Preliminary scans at 5-mm intervals were radiopaque catheters taped to the skin. The computer and angle measurement cursors were used to define optimal
distance paths for the screws through the fractures and to trace these back to the skin surface. Marks were made on the skin to indicate appro-
Received June 14, 1991 ; accepted after revision October 11 , 1991. 1 Department of Radiology, Box 170, University of Virginia Hospital, Charlottesville, VA 22908. Address Department of Orthopedics, University of Virginia Hospital, Charlottesville, VA 22908.
April 1992 0361-803X/92/1584-0819
3-mm
Reality
actively
the procedure,
side up) position
2
AJR 158:819-822,
includes
metric rendering and multiplanar reconstruction were used to visualize the geometry of the fracture and plan the procedures. The
The patients August
McHugh,2
and 5-mm contiguous slices through the rest of the pelvis. All the scans were done on a third-generation CT scanner (9800 Quick, General Electric). Image data were transferred via tape to a 3D
means
Between
Nancy
3-1 3 days (mean, 9.5 days). Follow-up was accomplished through review of chart notes from follow-up visits to the orthopedic clinic, chart notes from a rehabilitation center (in two patients), and verbal reports from the orthopedic surgeons involved. Follow-up has ranged from 6 to 15 months (mean, 9 months). Follow-up visits to the orthopedic clinic were made approximately every 6 weeks. Pelvic radiographs were obtained at each visit. All patients had high-resolution CT scans of the pelvis to evaluate the geometry of the fracture and to help plan the procedure. Our
orthopedic
and Methods
Boman,2
coronal fractures through the roof extending into the posterior column. None of the patients had bone fragments within the hip joint itself. The interval between the injury and percutaneous fixation was
Before
Materials
Thomas
with
Ray Society
reprint requests to S. B. Gay.
820
GAY
ET
AL.
AJR:158,
Fig.
1.-A,
Downloaded from www.ajronline.org by 190.3.238.185 on 10/17/15 from IP address 190.3.238.185. Copyright ARRS. For personal use only; all rights reserved
neous screw
April 1992
cT-guided percutafixation of right ace-
tabular fracture. B, 20-gauge scout needle in place. C, Guiding cannula in place with Kirschner wire being drilled across fracture. 0, Pilot hole being drilled over Kirachner wire. A second Kirschner wire has been placed for stabillza-
tio E, Fixation screw being tightened across fracture. F, Final posItion of two screws across
D
E
priate
entry
sites
for
the
needles,
Initially a 20-gauge
removable
F
guidewires,
sterile skin preparation and surgical out by operating room nurses.
and
screws.
draping procedures
hub needle(Cook
Standard
were
carried
Inc., Bloomington,
IN) was placed along the previously defined path down to the bone. CT scans served to confirm the needle position (Fig. 1). When correct placement had been achieved, the hub was removed and the guiding cannula from an Ackerman bone biopsy kit (Cook Inc.) was placed over the needle shaft down to the bone. After removal of the 20gauge needle, a 2.0-mm Kirschner guidewire (Synthes USA, Paoli, PA) was placed through this cannula and drilled by the surgeon through both fracture fragments with a pneumatic drill. The radiologist steadied the guiding cannula during this step. CT scans were used to confirm the correct angle and depth of the Kirschner wire. Usually, a second Kirschner wire was placed parallel to the first, by using the same technique, to stabilize the fragments during the subsequent steps. We found the guiding cannula useful for placement of the Kirschner wires. When the initial skin entry site was not strictly perpendicular to the cortical surface, placing the wire through the cannula
helped
prevent
the tip from
fracture.
“walking”
off the desired
bone
site. In addition, the stiff cannula maintained correct angulation during drilling with the Kirschner wire. Once the Kirschner wires had transfixed the fracture, a pilot hole entry
was
drilled
through
both
fragments.
This
cannulated
drill bit, marked in centimeters,
correlating
measurements
on
the
bit with
was
done
with
and a pneumatic distance
a long
drill. By
measurements
from the CT scans, this hole could be precisely drilled to the far cortex of the deep fragment. When the drill bit was removed after making
the pilot hole, the guidewire
tended
to back out of the bone
together with the bit. In two instances, the Kirschner wire did back out of the pilot hole in the bone. It was replaced by pushing the end against the cortical surface until the hole was found again and the wire could be repositioned. The surgeon placed a cannulated self-tapping orthopedic screw (Richards Medical Co., Memphis, TN) of the correct length over the Kirschner wire. The correct length of the screw was estimated by measuring the distance between the proximal and distal cortices and adding approximately 5 mm. The screw was pushed bone surface over the Kirschner wire and screwed fragments
with
a hollow
screwdriver,
thus
down
through fixing the fracture.
to the
both After
AJR:158,
CT-GUIDED
April 1992
optimal placement When there was
was confirmed enough space
made over the second Kirschner
wire
and
another
screw
was
in tandem
indicated,
these
same
steps
with
the first.
In all but one case,
FIXATION
by CT, the guidewire was removed. in the fragments, a pilot hole was
When
repeated to fix the second component
Downloaded from www.ajronline.org by 190.3.238.185 on 10/17/15 from IP address 190.3.238.185. Copyright ARRS. For personal use only; all rights reserved
SCREW
we placed
placed
were
of the fracture (three patients).
two
Kirschner
wires
across
each
fracture so that the second wire could stabilize the fracture fragments during
drilling
and screw
placement
over the first.
If a second
screw
was placed, the first screw served to steady the fragments. Because the screws are 6.5 mm in diameter, we maintained a distance of at least 6.5 mm between the first and second guidewires to avoid entangling
the threads
and weakening
the fixation.
In one patient,
we
placed a screw over a single Kirschner wire into a coronal fracture of the acetabular roof that extended far up into the ileum. Both fragments were large enough to prevent rotation during the drilling or screw placement.
821
percutaneous screw placement, balanced traction was maintamed with femoral pins. The traction interfered with reproducible table positioning. The fragment lodged in the acetabular roof fracture prevented reduction, and in fact led to partial
stripping
of
the
bone
around
the
screws
when
we
attempted to fully tighten them. Nonetheless, no translation of the fragments or widening of the displacement has been
seen on follow-up
pelvic radiographs.
The presence
of con-
tralateral tibial and fibular fractures, together with ipsilateral hip dislocation, prevented ambulation for 2 months. The patient now can walk with a cane and has a leg length discrepancy; the left leg is 1 .3 cm shorter than the right. In retrospect, this patient was not a good candidate for percutaneous screw fixation.
Discussion
Results In all cases,
screws
were
successfully
placed
across
the
fractures chosen for percutaneous fixation (Fig. 2). In our first case, Kirschner wire placement was carried out in the CT suite, and the patient was moved to an operating room for placement
of the screws.
the entire procedure last five procedures mm of this
setting
OF FRACTURES
period
In the last five cases,
we performed
in the CT suite. The time required for the ranged from 1 .5 to 2.0 hr with about 30 devoted
up anesthesia.
to transferring
the
patient
and
Two screws
Three screws were placed coronal or sagittal fractures
were used in five cases. in one patient. All six patients had through
the acetabular
roof;
all
fractures were fixed with at least one screw. Four patients also had fractures of the posterior column; three of these were fixed. Although two patients had fractures of the anterior column, we did not attempt to fix either of these because intervening
structures
(i.e.,
the common
femoral
vessels)
pre-
Currently, patients who have had acetabular fractures are treated with either open reduction and internal fixation or bed rest. When there is a widely displaced complex fracture, fragments in the hip joint, or fragments displaced into the fracture, open reduction is the procedure of choice. Con-
versely,
a simple,
minimally
displaced
acetabular
fracture
without free fragments in the joint may still be treated with bed rest and careful rehabilitation alone. The procedure we describe offers a third option. It is yet unclear which subset of patients will benefit most from percutaneous screw fixation. It would seem that mildly displaced (perhaps less than 1.0 cm) fractures through the acetabular roof and the posterior column may be best treated by this technique. Also, the alignment of the fracture fragments must be such that a smooth acetabulum can result from reduction [6].
Percutaneous
fixation
offers several advantages
over open
cluded a safe path for the hardware. Both of these fractures were of an orientation that would have required placing a very long screw through the superior pubic ramus at an awkward angle. Additionally, the cortex of the deep fragment was
reduction of acetabular fractures. Soft-tissue disruption with the potential for devasculanzation or denervation is virtually eliminated. Blood loss is also significantly decreased, and a
contiguous
patient had a nondisplaced fracture. None of the patients had any significant blood loss. Five patients began to walk with crutches within 3 weeks of the
tissue trauma and the lack of an open wound. Patients can often begin weight-bearing within 2 weeks after percutaneous fixation and do not have to recuperate from an operation. Regional anesthetic risks are equal for both procedures. It should be noted that complete reduction was not achieved in all patients, but was not considered mandatory because
procedure.
fixation
with the joint
have projected reduction
space,
and the tip of a screw
into the joint. Five of six patients
of displacement
All the
of the
patients
are
fracture,
now
while
walking,
five
would
had some the
with
other
full
weight-bearing and one with a cane. No evidence of degenerative change, shifting of the fragments, or dystrophic calcification about the hip joint has been seen on any of the followup pelvic radiographs. A small amount of lucency was seen around a single screw in one patient on a 5-month follow-up film. Subsequently, the patient became febrile, and the screw was removed surgically. It proved to be infected with Staphylococcus aureus. The patient is still walking without difficulty. One patient had a poor technical result and did not progress to crutch-assisted walking until 2 months after the procedure.
He had had a complex hip dislocation.
This
left acetabular fracture
was
fracture more
with posterior
displaced
than
the
others, with a 1 .2-cm maximum gap between the fragments of the sagittal acetabular roof fracture. In addition, a small bone fragment was lodged between the fragments. During
lower risk of infection
permitted
may be anticipated
walking
during
owing to decreased
recovery,
which
in itself
promotes healing [7]. Thin-section CT scans were useful in evaluating the severity and geometry ofthe fractures. Such imaging is vitalto exclude the presence of small free fragments of bone within the hipjoint space. When such fragments are identified, an open procedure is necessary because even small chips can cause significant
damage
to the joint
ment [8]. Three-dimensional
with
weight-bearing
reconstruction
and
move-
was used to plan
the fixation procedure in all cases and was found to be valuable in delineating the complex bony relationships. In our opinion, 3D surface rendition and multiplanar reconstruction in coronal and sagittal planes showed the relationship of all fragments more clearly. The orthopedists, who joined the planning sessions with radiologists, found the real-time interactive nature of such displays particularly helpful. Such co-
822
GAY
ET AL.
AJR:158,
Fig. 2.-Axial CT scans through tabular reef during screw placement
April 1992
right acewith pa-
tient prone. A, 20-gauge
its tip contacting
Downloaded from www.ajronline.org by 190.3.238.185 on 10/17/15 from IP address 190.3.238.185. Copyright ARRS. For personal use only; all rights reserved
B, Guiding
scout needle in position with posterior fragment. cannula in place after removal of
scout needle. C, Two Kirschner fracture.
wires in place bridging
D, Final position of two screws. partial reduction has been achieved.
A
Note
that
B
r
I
.
#{149}1#{149} ..
D
C
operation in planning for optimal outcome.
and performing
these
We have shown that it is technicallyfeasible
procedures
is vital
to place screws
across acetabular fractures under CT guidance. A combination of standard removable hub needles, a percutaneous bone biopsy set, and orthopedic guidewire and screw hardware
were used. The pneumatic
drills, cannulated
bits, and screw-
drivers used are available in most hospitals where orthopedic surgery is performed. Two radiologists, two orthopedic surgeons, and three orthopedic residents participated in the six procedures at various times, and only one technical failure occurred. The successful result suggests that the technique
can be performed
easily and reproducibly.
The risks of the
procedure are primarily those related to damage to structures found adjacent to the posteroinferior aspect of the acetabulum: the sciatic nerve and the superior and inferior gluteal artery and vein. The procedure must be planned so that the path of the hardware will not injure these structures. The small number of patients and the relatively short followup preclude definitive conclusions about the indications for
and the success rate of this technique. We are continuing to follow our first six patients and will perform further procedures in order to better define the role of this method in patients with acetabular fractures. REFERENCES 1 . Judet R, Judet J, Letoumel E. Fractures of the acetabulum: classification and surgical approaches for open reduction. J Bone Joint Surg (Am) 1964;46-A: 1615-1646 2. Sauser DD, Billimona PE, Rouse GA, Mudge K. CT evaluation of hip trauma. AiR 1980;135:269-274 3. Mack LA, Harley JO, Winquist RA. CT of acetabular fractures: analysis of fracture pattems. AJR 1982;1 38:407-412 4. Burk DL Jr, Mears DC, Kennedy WH, et at. Three-dimensional computed tomography of acetabular fractures. Radio!ogy 1985;1 55:183-186 5. Nelson DW, Duwelius PJ. CT-guided fixation of sacral fractures and sacroiliac joint disruptions. Radiology 1991;1 80: 527-532 6. Matta J, Merritt P. Displaced acetabular fractures. C!in Orthop 1988;230:83-97 7. Mayo KA. Fractures of the acetabulum. Orthop C!in North Am 1987;1 8:
43-57 8. Epstein
1980
HC. Traumatic
dislocation
of the hip. Baltimore:
Williams
& Wilkins,
Percutaneous CT Guidance:
Screw Fixation of Acetabular Fractures Preliminary Results of a New Technique
Spencer B. Gay,1 Christopher and Henry T. Goitz2
Sistrom,1
Gwo-Jaw
Wang,2
Treatment of acetabular fractures generally consists of either bed rest and traction for simple minimally displaced fractures, or open reduction and internal fixation for complex or significantly displaced fractures. Internal fixation permits
early ambulation and can significantly time spent in bed [1]. Open reduction
ture,
however,
is a significant
reduce the amount of of an acetabular frac-
physiological
trauma
patient and has the associated risks of postoperative tion, wound healing problems, formation of heterotopic
and neurologic fusion,
during
injury. Many such patients or after
the procedure.
to the infecbone,
require blood trans-
CT is routinely
used
to
evaluate acetabular fractures and plan treatment [2, 3J. Threedimensional (3D) image processing also has been shown to be useful
in the
acetabular
fractures
cutaneous
fixation
similar
technique
diastatic
diagnosis and understanding of complex [4]. We report a new technique for per-
of these was recently
sacroiliac
injuries
with
described
CT guidance.
for screw
fixation
A of
joints [5].
David
A. Kahler,2
protocol
for these
workstation
1990 and March
infusion
1991
, six
patients who were admitted to the orthopedic trauma service were treated with CTguided screw fixation of their acetabular fractures. The two women and four men were 23-66 years old. Three of the fractures were in the left acetabulum and three were in the right. Four of the fractures were sagittal in orientation and involved with extension into the posterior column.
the roof of the acetabulum The other two patients had
scans
(Voxel
Flinger,
surgeons
of an epidural of local
C American
Roentgen
slices
through
the acetabula
Imaging,
Solon,
OH), where
participated
regional
catheter
anesthetic;
in the 3D planning
anesthesia
volu-
and was
maintained
an anesthesia
on the CT couch.
team
Pac, Olympic Equipment,
A special
sessions.
was established was
stabilizing
by
by intermittent in attendance.
were placed prone or in the lateral decubitus
(affected
device
(Vac-
Seattle, WA) was placed under the patients
to maintain done with
their position. Preliminary scans at 5-mm intervals were radiopaque catheters taped to the skin. The computer and angle measurement cursors were used to define optimal
distance paths for the screws through the fractures and to trace these back to the skin surface. Marks were made on the skin to indicate appro-
Received June 14, 1991 ; accepted after revision October 11 , 1991. 1 Department of Radiology, Box 170, University of Virginia Hospital, Charlottesville, VA 22908. Address Department of Orthopedics, University of Virginia Hospital, Charlottesville, VA 22908.
April 1992 0361-803X/92/1584-0819
3-mm
Reality
actively
the procedure,
side up) position
2
AJR 158:819-822,
includes
metric rendering and multiplanar reconstruction were used to visualize the geometry of the fracture and plan the procedures. The
The patients August
McHugh,2
and 5-mm contiguous slices through the rest of the pelvis. All the scans were done on a third-generation CT scanner (9800 Quick, General Electric). Image data were transferred via tape to a 3D
means
Between
Nancy
3-1 3 days (mean, 9.5 days). Follow-up was accomplished through review of chart notes from follow-up visits to the orthopedic clinic, chart notes from a rehabilitation center (in two patients), and verbal reports from the orthopedic surgeons involved. Follow-up has ranged from 6 to 15 months (mean, 9 months). Follow-up visits to the orthopedic clinic were made approximately every 6 weeks. Pelvic radiographs were obtained at each visit. All patients had high-resolution CT scans of the pelvis to evaluate the geometry of the fracture and to help plan the procedure. Our
orthopedic
and Methods
Boman,2
coronal fractures through the roof extending into the posterior column. None of the patients had bone fragments within the hip joint itself. The interval between the injury and percutaneous fixation was
Before
Materials
Thomas
with
Ray Society
reprint requests to S. B. Gay.
820
GAY
ET
AL.
AJR:158,
Fig.
1.-A,
Downloaded from www.ajronline.org by 190.3.238.185 on 10/17/15 from IP address 190.3.238.185. Copyright ARRS. For personal use only; all rights reserved
neous screw
April 1992
cT-guided percutafixation of right ace-
tabular fracture. B, 20-gauge scout needle in place. C, Guiding cannula in place with Kirschner wire being drilled across fracture. 0, Pilot hole being drilled over Kirachner wire. A second Kirschner wire has been placed for stabillza-
tio E, Fixation screw being tightened across fracture. F, Final posItion of two screws across
D
E
priate
entry
sites
for
the
needles,
Initially a 20-gauge
removable
F
guidewires,
sterile skin preparation and surgical out by operating room nurses.
and
screws.
draping procedures
hub needle(Cook
Standard
were
carried
Inc., Bloomington,
IN) was placed along the previously defined path down to the bone. CT scans served to confirm the needle position (Fig. 1). When correct placement had been achieved, the hub was removed and the guiding cannula from an Ackerman bone biopsy kit (Cook Inc.) was placed over the needle shaft down to the bone. After removal of the 20gauge needle, a 2.0-mm Kirschner guidewire (Synthes USA, Paoli, PA) was placed through this cannula and drilled by the surgeon through both fracture fragments with a pneumatic drill. The radiologist steadied the guiding cannula during this step. CT scans were used to confirm the correct angle and depth of the Kirschner wire. Usually, a second Kirschner wire was placed parallel to the first, by using the same technique, to stabilize the fragments during the subsequent steps. We found the guiding cannula useful for placement of the Kirschner wires. When the initial skin entry site was not strictly perpendicular to the cortical surface, placing the wire through the cannula
helped
prevent
the tip from
fracture.
“walking”
off the desired
bone
site. In addition, the stiff cannula maintained correct angulation during drilling with the Kirschner wire. Once the Kirschner wires had transfixed the fracture, a pilot hole entry
was
drilled
through
both
fragments.
This
cannulated
drill bit, marked in centimeters,
correlating
measurements
on
the
bit with
was
done
with
and a pneumatic distance
a long
drill. By
measurements
from the CT scans, this hole could be precisely drilled to the far cortex of the deep fragment. When the drill bit was removed after making
the pilot hole, the guidewire
tended
to back out of the bone
together with the bit. In two instances, the Kirschner wire did back out of the pilot hole in the bone. It was replaced by pushing the end against the cortical surface until the hole was found again and the wire could be repositioned. The surgeon placed a cannulated self-tapping orthopedic screw (Richards Medical Co., Memphis, TN) of the correct length over the Kirschner wire. The correct length of the screw was estimated by measuring the distance between the proximal and distal cortices and adding approximately 5 mm. The screw was pushed bone surface over the Kirschner wire and screwed fragments
with
a hollow
screwdriver,
thus
down
through fixing the fracture.
to the
both After
AJR:158,
CT-GUIDED
April 1992
optimal placement When there was
was confirmed enough space
made over the second Kirschner
wire
and
another
screw
was
in tandem
indicated,
these
same
steps
with
the first.
In all but one case,
FIXATION
by CT, the guidewire was removed. in the fragments, a pilot hole was
When
repeated to fix the second component
Downloaded from www.ajronline.org by 190.3.238.185 on 10/17/15 from IP address 190.3.238.185. Copyright ARRS. For personal use only; all rights reserved
SCREW
we placed
placed
were
of the fracture (three patients).
two
Kirschner
wires
across
each
fracture so that the second wire could stabilize the fracture fragments during
drilling
and screw
placement
over the first.
If a second
screw
was placed, the first screw served to steady the fragments. Because the screws are 6.5 mm in diameter, we maintained a distance of at least 6.5 mm between the first and second guidewires to avoid entangling
the threads
and weakening
the fixation.
In one patient,
we
placed a screw over a single Kirschner wire into a coronal fracture of the acetabular roof that extended far up into the ileum. Both fragments were large enough to prevent rotation during the drilling or screw placement.
821
percutaneous screw placement, balanced traction was maintamed with femoral pins. The traction interfered with reproducible table positioning. The fragment lodged in the acetabular roof fracture prevented reduction, and in fact led to partial
stripping
of
the
bone
around
the
screws
when
we
attempted to fully tighten them. Nonetheless, no translation of the fragments or widening of the displacement has been
seen on follow-up
pelvic radiographs.
The presence
of con-
tralateral tibial and fibular fractures, together with ipsilateral hip dislocation, prevented ambulation for 2 months. The patient now can walk with a cane and has a leg length discrepancy; the left leg is 1 .3 cm shorter than the right. In retrospect, this patient was not a good candidate for percutaneous screw fixation.
Discussion
Results In all cases,
screws
were
successfully
placed
across
the
fractures chosen for percutaneous fixation (Fig. 2). In our first case, Kirschner wire placement was carried out in the CT suite, and the patient was moved to an operating room for placement
of the screws.
the entire procedure last five procedures mm of this
setting
OF FRACTURES
period
In the last five cases,
we performed
in the CT suite. The time required for the ranged from 1 .5 to 2.0 hr with about 30 devoted
up anesthesia.
to transferring
the
patient
and
Two screws
Three screws were placed coronal or sagittal fractures
were used in five cases. in one patient. All six patients had through
the acetabular
roof;
all
fractures were fixed with at least one screw. Four patients also had fractures of the posterior column; three of these were fixed. Although two patients had fractures of the anterior column, we did not attempt to fix either of these because intervening
structures
(i.e.,
the common
femoral
vessels)
pre-
Currently, patients who have had acetabular fractures are treated with either open reduction and internal fixation or bed rest. When there is a widely displaced complex fracture, fragments in the hip joint, or fragments displaced into the fracture, open reduction is the procedure of choice. Con-
versely,
a simple,
minimally
displaced
acetabular
fracture
without free fragments in the joint may still be treated with bed rest and careful rehabilitation alone. The procedure we describe offers a third option. It is yet unclear which subset of patients will benefit most from percutaneous screw fixation. It would seem that mildly displaced (perhaps less than 1.0 cm) fractures through the acetabular roof and the posterior column may be best treated by this technique. Also, the alignment of the fracture fragments must be such that a smooth acetabulum can result from reduction [6].
Percutaneous
fixation
offers several advantages
over open
cluded a safe path for the hardware. Both of these fractures were of an orientation that would have required placing a very long screw through the superior pubic ramus at an awkward angle. Additionally, the cortex of the deep fragment was
reduction of acetabular fractures. Soft-tissue disruption with the potential for devasculanzation or denervation is virtually eliminated. Blood loss is also significantly decreased, and a
contiguous
patient had a nondisplaced fracture. None of the patients had any significant blood loss. Five patients began to walk with crutches within 3 weeks of the
tissue trauma and the lack of an open wound. Patients can often begin weight-bearing within 2 weeks after percutaneous fixation and do not have to recuperate from an operation. Regional anesthetic risks are equal for both procedures. It should be noted that complete reduction was not achieved in all patients, but was not considered mandatory because
procedure.
fixation
with the joint
have projected reduction
space,
and the tip of a screw
into the joint. Five of six patients
of displacement
All the
of the
patients
are
fracture,
now
while
walking,
five
would
had some the
with
other
full
weight-bearing and one with a cane. No evidence of degenerative change, shifting of the fragments, or dystrophic calcification about the hip joint has been seen on any of the followup pelvic radiographs. A small amount of lucency was seen around a single screw in one patient on a 5-month follow-up film. Subsequently, the patient became febrile, and the screw was removed surgically. It proved to be infected with Staphylococcus aureus. The patient is still walking without difficulty. One patient had a poor technical result and did not progress to crutch-assisted walking until 2 months after the procedure.
He had had a complex hip dislocation.
This
left acetabular fracture
was
fracture more
with posterior
displaced
than
the
others, with a 1 .2-cm maximum gap between the fragments of the sagittal acetabular roof fracture. In addition, a small bone fragment was lodged between the fragments. During
lower risk of infection
permitted
may be anticipated
walking
during
owing to decreased
recovery,
which
in itself
promotes healing [7]. Thin-section CT scans were useful in evaluating the severity and geometry ofthe fractures. Such imaging is vitalto exclude the presence of small free fragments of bone within the hipjoint space. When such fragments are identified, an open procedure is necessary because even small chips can cause significant
damage
to the joint
ment [8]. Three-dimensional
with
weight-bearing
reconstruction
and
move-
was used to plan
the fixation procedure in all cases and was found to be valuable in delineating the complex bony relationships. In our opinion, 3D surface rendition and multiplanar reconstruction in coronal and sagittal planes showed the relationship of all fragments more clearly. The orthopedists, who joined the planning sessions with radiologists, found the real-time interactive nature of such displays particularly helpful. Such co-
822
GAY
ET AL.
AJR:158,
Fig. 2.-Axial CT scans through tabular reef during screw placement
April 1992
right acewith pa-
tient prone. A, 20-gauge
its tip contacting
Downloaded from www.ajronline.org by 190.3.238.185 on 10/17/15 from IP address 190.3.238.185. Copyright ARRS. For personal use only; all rights reserved
B, Guiding
scout needle in position with posterior fragment. cannula in place after removal of
scout needle. C, Two Kirschner fracture.
wires in place bridging
D, Final position of two screws. partial reduction has been achieved.
A
Note
that
B
r
I
.
#{149}1#{149} ..
D
C
operation in planning for optimal outcome.
and performing
these
We have shown that it is technicallyfeasible
procedures
is vital
to place screws
across acetabular fractures under CT guidance. A combination of standard removable hub needles, a percutaneous bone biopsy set, and orthopedic guidewire and screw hardware
were used. The pneumatic
drills, cannulated
bits, and screw-
drivers used are available in most hospitals where orthopedic surgery is performed. Two radiologists, two orthopedic surgeons, and three orthopedic residents participated in the six procedures at various times, and only one technical failure occurred. The successful result suggests that the technique
can be performed
easily and reproducibly.
The risks of the
procedure are primarily those related to damage to structures found adjacent to the posteroinferior aspect of the acetabulum: the sciatic nerve and the superior and inferior gluteal artery and vein. The procedure must be planned so that the path of the hardware will not injure these structures. The small number of patients and the relatively short followup preclude definitive conclusions about the indications for
and the success rate of this technique. We are continuing to follow our first six patients and will perform further procedures in order to better define the role of this method in patients with acetabular fractures. REFERENCES 1 . Judet R, Judet J, Letoumel E. Fractures of the acetabulum: classification and surgical approaches for open reduction. J Bone Joint Surg (Am) 1964;46-A: 1615-1646 2. Sauser DD, Billimona PE, Rouse GA, Mudge K. CT evaluation of hip trauma. AiR 1980;135:269-274 3. Mack LA, Harley JO, Winquist RA. CT of acetabular fractures: analysis of fracture pattems. AJR 1982;1 38:407-412 4. Burk DL Jr, Mears DC, Kennedy WH, et at. Three-dimensional computed tomography of acetabular fractures. Radio!ogy 1985;1 55:183-186 5. Nelson DW, Duwelius PJ. CT-guided fixation of sacral fractures and sacroiliac joint disruptions. Radiology 1991;1 80: 527-532 6. Matta J, Merritt P. Displaced acetabular fractures. C!in Orthop 1988;230:83-97 7. Mayo KA. Fractures of the acetabulum. Orthop C!in North Am 1987;1 8:
43-57 8. Epstein
1980
HC. Traumatic
dislocation
of the hip. Baltimore:
Williams
& Wilkins,
