In patients with sciatic neuropathy associated with an acetabular fracture
or previous acetabular surgery, release of the sciatic nerve from scar tissue,
heterotopic bone, or impinging hardware, with the release beginning at the
greater sciatic notch and extending distal to the insertion of the gluteus
maximus tendon, can result in a marked decrease in neurologic symptoms. In our
series, sensory symptoms, including radicular pain, paresthesias, and
diminished sensation, demonstrated marked improvement after sciatic nerve
decompression. While the majority of patients with motor symptoms demonstrated
improvement, footdrop was less likely to completely resolve after nerve
release. None of the patients in our series had worsening of neurologic
function following sciatic nerve release.
Patient Setup and Positioning
Essential instruments to perform sciatic nerve decompression include
pituitary rongeurs, curved and straight osteotomes, microdissecting scissors,
and Kerrison punches (Fig. 1).
The Kocher-Langenbeck approach is used to gain access to the sciatic nerve,
and the patient may be positioned in either the prone or the lateral decubitus
position. In the series of photographs in the present report, the patient is
placed in the prone position. General anesthesia is usually administered as it
does not interfere with intraoperative neurologic monitoring with use of
electromyography or somatosensory evoked potentials. If regional anesthesia
techniques are preferred for the treatment of postoperative pain, the
medications should not be utilized until after the sciatic nerve release as
they can impair somatosensory evoked potentials and electromyography
responses. After the induction of anesthesia, the patient is carefully
positioned on a flat radiolucent Jackson table. A headrest is used to prevent
cervical hyperextension of the spine and to permit ready access to the
patient's endotracheal tube. Two foam rolls are positioned longitudinally to
support the patient's chest and to allow the abdomen to be free of
compression. All osseous prominences are padded with pillows placed beneath
the knees and ankles. The scrotum and the Foley catheter are inspected to
ensure that they are not compressed under the patient's abdomen. The knees
remain flexed throughout the procedure to minimize traction on the sciatic
nerve1. Leads are
then placed to provide for intraoperative spontaneous electromyography and/or
somatosensory evoked potential
monitoring2-5.
The patient is then prepared and draped in the usual sterile fashion
(Fig. 2).
Exposure
The skin incision extends from 5 cm distal to the posterior superior iliac
spine to the greater trochanter and then along the femoral shaft for a
distance of approximately 15 cm (Fig.
2). The subcutaneous tissue is divided in line with the incision
to expose the iliotibial band and the fascia over the gluteus maximus, which
are likewise incised in line with the skin incision. The gluteus maximus
muscle is bluntly divided proximally (Fig.
3). To allow for more effective retraction of the posterior flap,
the distal insertion of the gluteus maximus tendon onto the posterior aspect
of the femoral shaft are identified and partially released. A curved clamp is
placed deep to the insertion of the gluteus maximus tendon
(Fig. 4-A), and the proximal
50% of the tendon is released (Fig.
4-B). The sciatic nerve is most reliably identified distally, by
locating the tendon of the quadratus femoris and following it posteriorly to
the fibers of the sciatic nerve (Fig.
5). Unless heterotopic ossification and/or scarring are widespread
enough to involve the quadratus femoris, the anatomy in this area is
relatively undisturbed. The sciatic nerve can be bluntly dissected from the
overlying tissue and traced proximally. If the anatomy is abnormal in this
region, it may be necessary to identify the sciatic nerve beneath the divided
gluteus maximus tendon or more distally in the thigh.
Sciatic Nerve Release
The sciatic nerve is carefully freed from any overlying scar tissue with
use of microdissecting scissors, with the curve of the scissors always
directed away from the nerve (Figs. 6-A,
6-B, and 6-C). A Penrose drain may be placed around the freed
distal portion of the nerve to help to mobilize it
(Fig. 7). In the presence of
extensive scarring, it is necessary to completely mobilize the nerve extending
from the gluteus maximus tendon to the sciatic notch in order to restore the
excursion necessary to accommodate full range of motion at the hip and knee.
Despite the risk of devascularization of the nerve, we have not observed any
deterioration in neurologic function after this dissection. Difficulty arises
when the sciatic nerve is surrounded by, or encased in, heterotopic bone.
Liberating the nerve from heterotopic bone requires careful dissection and
takes a considerable amount of time to avoid iatrogenic injury. Furthermore,
heterotopic bone is very well vascularized, and intraoperative blood loss can
be substantial if resection is performed without meticulous attention to
excellent hemostasis. Much of the bleeding is from the osteotomized bone
surfaces and is therefore difficult to control with electrocautery. Thus, it
is necessary to have available an ample supply of cross-matched blood as well
as cell saver systems to allow for autologous blood reinfusion. Hemostatic
agents such as Gelfoam (Pfizer, New York, NY) and FloSeal (Baxter, Deerfield,
Illinois) may also be helpful to minimize bleeding from osseous surfaces.
A combination of osteotomes, pituitary rongeurs, and Kerrison punches are
used to free the sciatic nerve from encasing heterotopic bone. The nerve
should be retracted when the surrounding bone is being osteotomized in order
to protect the nerve from the osteotome and projectile bone fragments
(Figs. 8-A through 8-D). During
removal of the osteotomized bone fragments, care should be taken to ensure
that they are not scarred to the sciatic nerve
(Figs. 9-A through 9-D). Great
care should be taken when osteotomizing heterotopic bone near the greater
sciatic notch as the superior gluteal vessels can be injured easily; this can
result in massive bleeding. Retraction of the injured vessels into the pelvis
can make control of the bleeding extremely difficult without performing an
osteotomy of the sciatic notch or gaining separate exposure through a
retroperitoneal approach.
Sciatic nerve decompression extends from beneath the gluteus maximus tendon
insertion on the femur distally to the greater sciatic notch proximally.
Decompression is performed until the sciatic nerve can be freely mobilized
within this area (Fig. 10). No
attempt is made to explore the nerve proximal to the greater sciatic notch.
Abnormal somatosensory evoked potential or electromyographic responses require
a brief halt in the dissection, with reassessment of limb positioning and
extension of the hip and flexion of the knee as necessary to relieve tension
on the nerve. Dissection resumes when the somatosensory evoked potentials and
the electromyographic activity return to normal. Acetabular open reduction and
internal fixation and/or total hip arthroplasty are then performed if
indicated.
Postoperatively, the patient receives prophylaxis against heterotopic
ossification with indomethacin and irradiation.
CRITICAL CONCEPTSINDICATIONS:On the basis of the literature, it is unclear whether release of the
sciatic nerve from scar tissue and heterotopic bone improves neurologic
outcomes in comparison with the natural history of this disorder. Reports on
the natural history of posttraumatic or postoperative sciatic nerve palsies
have provided conflicting results, with recovery rates ranging from 60% to
100%1,6-8.
Mild peroneal or tibial nerve injury and severe tibial nerve injury
demonstrate substantial recovery at two
years9. However,
only 30% of patients with a severe peroneal nerve injury demonstrate
satisfactory
recovery9. On the
basis of the natural history and our experience suggesting that release can be
performed safely and effectively with early return of sensory and motor
function, we identify two indications for sciatic nerve decompression.The first indication is posttraumatic sciatic sensory or motor neuropathy
in a patient with an acetabular fracture. The nerve dysfunction may be acute,
as in a patient with a posterior wall fracture associated with hip
dislocation, in which case the nerve decompression can be performed prior to
open reduction and internal fixation of the acetabulum. The nerve dysfunction
also may develop in a delayed fashion, weeks to months after the injury,
because of progressive scarring or heterotopic ossification in a patient with
a head injury or a patient who had closed treatment after an acetabular
fracture (Figs. 11-A, 11-B, and
11-C).The second indication is sciatic sensory or motor neuropathy that develops
months after reconstructive surgery as a result of wear debris, implant
migration, capsular or muscular scarring, or heterotopic ossification.CONTRAINDICATIONS:Sciatic nerve decompression should not be performed in the absence of
neurologic symptoms; asymptomatic patients are not considered to be candidates
for surgery.PITFALLS:The sciatic nerve should be identified in normal tissue distal to
heterotopic bone and scar tissue. It is most reliably identified over the
posterior aspect of the quadratus femoris muscle. Attempting to identify the
nerve more proximally within scar risks injury to or even transection of the
sciatic nerve.The nerve should be identified in a region of normal anatomy and bluntly
dissected free. A Penrose drain placed around this portion of the nerve helps
to identify it throughout the nerve release as well as the remainder of the
operation. We typically link the ends of the Penrose drain with a suture
instead of a clamp to avoid traction injury to the nerve from the weight of
the clamp.Dissection is performed carefully with the curve of the scissors facing
away from the nerve. The nerve is mobilized proximally by opening the
scissors, the scissors are retracted without closing the blades, and only the
mobilized area is cut under direct vision.Blunt finger dissection, performed by sweeping a finger longitudinally on
either side of the nerve, should be used whenever possible as it minimizes the
potential risk of nerve injury.In the region of the piriformis muscle, one should be aware of nerve
variants. In 14.3% of patients, the nerve separates into two divisions, with
one passing through the piriformis and the other passing anterior and distal
to the muscle. In 4.4% of patients, the nerve separates into two divisions,
with one passing posterior and proximal to and the other passing anterior and
distal to the piriformis. In 2.2% of patients, an unsplit nerve passes through
the piriformis
muscle10. Early
release of the piriformis tendon will facilitate more proximal nerve
decompression.When resecting heterotopic bone, one should protect the sciatic nerve by
retracting it gently away from the area to be osteotomized. An osteotomy of
heterotopic bone should not be performed directly over the nerve. Rather, the
ectopic bone should be osteotomized lateral to the sciatic nerve and split in
the coronal plane, and then the anterior and posterior segments can be
carefully pried open to release the nerve. Kerrison punches are very helpful
for removing bone from around the nerve. During removal of the bone, extra
care should be taken to ensure that the mobilized bone is not scarred to the
nerve.Great care should be taken when approaching the sciatic notch. It is not
necessary to free the nerve proximal to the notch. Performing an osteotomy at
the greater sciatic notch or resecting heterotopic bone in the notch risks
injury to the superior gluteal vessels. These vessels may retract into the
pelvis and become inaccessible, resulting in massive bleeding.One should be prepared for the possibility of substantial blood loss when
resecting extensive heterotopic bone. Heterotopic bone is very vascular, and
the osteotomized surfaces tend to persistently ooze; this bleeding is
difficult to control with electrocautery. Ample cross-matched blood as well as
cell saver systems to allow for autologous blood reinfusion should be
available. Hemostatic agents such as Gelfoam (Pfizer) and FloSeal (Baxter)
also can help to control bleeding from osseous surfaces.AUTHOR UPDATE:The technique continues to be performed exactly as described since it was
published in the original article.
CRITICAL CONCEPTS
INDICATIONS:
On the basis of the literature, it is unclear whether release of the
sciatic nerve from scar tissue and heterotopic bone improves neurologic
outcomes in comparison with the natural history of this disorder. Reports on
the natural history of posttraumatic or postoperative sciatic nerve palsies
have provided conflicting results, with recovery rates ranging from 60% to
100%1,6-8.
Mild peroneal or tibial nerve injury and severe tibial nerve injury
demonstrate substantial recovery at two
years9. However,
only 30% of patients with a severe peroneal nerve injury demonstrate
satisfactory
recovery9. On the
basis of the natural history and our experience suggesting that release can be
performed safely and effectively with early return of sensory and motor
function, we identify two indications for sciatic nerve decompression.The first indication is posttraumatic sciatic sensory or motor neuropathy
in a patient with an acetabular fracture. The nerve dysfunction may be acute,
as in a patient with a posterior wall fracture associated with hip
dislocation, in which case the nerve decompression can be performed prior to
open reduction and internal fixation of the acetabulum. The nerve dysfunction
also may develop in a delayed fashion, weeks to months after the injury,
because of progressive scarring or heterotopic ossification in a patient with
a head injury or a patient who had closed treatment after an acetabular
fracture (Figs. 11-A, 11-B, and
11-C).The second indication is sciatic sensory or motor neuropathy that develops
months after reconstructive surgery as a result of wear debris, implant
migration, capsular or muscular scarring, or heterotopic ossification.
On the basis of the literature, it is unclear whether release of the
sciatic nerve from scar tissue and heterotopic bone improves neurologic
outcomes in comparison with the natural history of this disorder. Reports on
the natural history of posttraumatic or postoperative sciatic nerve palsies
have provided conflicting results, with recovery rates ranging from 60% to
100%1,6-8.
Mild peroneal or tibial nerve injury and severe tibial nerve injury
demonstrate substantial recovery at two
years9. However,
only 30% of patients with a severe peroneal nerve injury demonstrate
satisfactory
recovery9. On the
basis of the natural history and our experience suggesting that release can be
performed safely and effectively with early return of sensory and motor
function, we identify two indications for sciatic nerve decompression.
The first indication is posttraumatic sciatic sensory or motor neuropathy
in a patient with an acetabular fracture. The nerve dysfunction may be acute,
as in a patient with a posterior wall fracture associated with hip
dislocation, in which case the nerve decompression can be performed prior to
open reduction and internal fixation of the acetabulum. The nerve dysfunction
also may develop in a delayed fashion, weeks to months after the injury,
because of progressive scarring or heterotopic ossification in a patient with
a head injury or a patient who had closed treatment after an acetabular
fracture (Figs. 11-A, 11-B, and
11-C).
The second indication is sciatic sensory or motor neuropathy that develops
months after reconstructive surgery as a result of wear debris, implant
migration, capsular or muscular scarring, or heterotopic ossification.
CONTRAINDICATIONS:
Sciatic nerve decompression should not be performed in the absence of
neurologic symptoms; asymptomatic patients are not considered to be candidates
for surgery.
PITFALLS:
The sciatic nerve should be identified in normal tissue distal to
heterotopic bone and scar tissue. It is most reliably identified over the
posterior aspect of the quadratus femoris muscle. Attempting to identify the
nerve more proximally within scar risks injury to or even transection of the
sciatic nerve.The nerve should be identified in a region of normal anatomy and bluntly
dissected free. A Penrose drain placed around this portion of the nerve helps
to identify it throughout the nerve release as well as the remainder of the
operation. We typically link the ends of the Penrose drain with a suture
instead of a clamp to avoid traction injury to the nerve from the weight of
the clamp.Dissection is performed carefully with the curve of the scissors facing
away from the nerve. The nerve is mobilized proximally by opening the
scissors, the scissors are retracted without closing the blades, and only the
mobilized area is cut under direct vision.Blunt finger dissection, performed by sweeping a finger longitudinally on
either side of the nerve, should be used whenever possible as it minimizes the
potential risk of nerve injury.In the region of the piriformis muscle, one should be aware of nerve
variants. In 14.3% of patients, the nerve separates into two divisions, with
one passing through the piriformis and the other passing anterior and distal
to the muscle. In 4.4% of patients, the nerve separates into two divisions,
with one passing posterior and proximal to and the other passing anterior and
distal to the piriformis. In 2.2% of patients, an unsplit nerve passes through
the piriformis
muscle10. Early
release of the piriformis tendon will facilitate more proximal nerve
decompression.When resecting heterotopic bone, one should protect the sciatic nerve by
retracting it gently away from the area to be osteotomized. An osteotomy of
heterotopic bone should not be performed directly over the nerve. Rather, the
ectopic bone should be osteotomized lateral to the sciatic nerve and split in
the coronal plane, and then the anterior and posterior segments can be
carefully pried open to release the nerve. Kerrison punches are very helpful
for removing bone from around the nerve. During removal of the bone, extra
care should be taken to ensure that the mobilized bone is not scarred to the
nerve.Great care should be taken when approaching the sciatic notch. It is not
necessary to free the nerve proximal to the notch. Performing an osteotomy at
the greater sciatic notch or resecting heterotopic bone in the notch risks
injury to the superior gluteal vessels. These vessels may retract into the
pelvis and become inaccessible, resulting in massive bleeding.One should be prepared for the possibility of substantial blood loss when
resecting extensive heterotopic bone. Heterotopic bone is very vascular, and
the osteotomized surfaces tend to persistently ooze; this bleeding is
difficult to control with electrocautery. Ample cross-matched blood as well as
cell saver systems to allow for autologous blood reinfusion should be
available. Hemostatic agents such as Gelfoam (Pfizer) and FloSeal (Baxter)
also can help to control bleeding from osseous surfaces.
The sciatic nerve should be identified in normal tissue distal to
heterotopic bone and scar tissue. It is most reliably identified over the
posterior aspect of the quadratus femoris muscle. Attempting to identify the
nerve more proximally within scar risks injury to or even transection of the
sciatic nerve.
The nerve should be identified in a region of normal anatomy and bluntly
dissected free. A Penrose drain placed around this portion of the nerve helps
to identify it throughout the nerve release as well as the remainder of the
operation. We typically link the ends of the Penrose drain with a suture
instead of a clamp to avoid traction injury to the nerve from the weight of
the clamp.
Dissection is performed carefully with the curve of the scissors facing
away from the nerve. The nerve is mobilized proximally by opening the
scissors, the scissors are retracted without closing the blades, and only the
mobilized area is cut under direct vision.
Blunt finger dissection, performed by sweeping a finger longitudinally on
either side of the nerve, should be used whenever possible as it minimizes the
potential risk of nerve injury.
In the region of the piriformis muscle, one should be aware of nerve
variants. In 14.3% of patients, the nerve separates into two divisions, with
one passing through the piriformis and the other passing anterior and distal
to the muscle. In 4.4% of patients, the nerve separates into two divisions,
with one passing posterior and proximal to and the other passing anterior and
distal to the piriformis. In 2.2% of patients, an unsplit nerve passes through
the piriformis
muscle10. Early
release of the piriformis tendon will facilitate more proximal nerve
decompression.
When resecting heterotopic bone, one should protect the sciatic nerve by
retracting it gently away from the area to be osteotomized. An osteotomy of
heterotopic bone should not be performed directly over the nerve. Rather, the
ectopic bone should be osteotomized lateral to the sciatic nerve and split in
the coronal plane, and then the anterior and posterior segments can be
carefully pried open to release the nerve. Kerrison punches are very helpful
for removing bone from around the nerve. During removal of the bone, extra
care should be taken to ensure that the mobilized bone is not scarred to the
nerve.
Great care should be taken when approaching the sciatic notch. It is not
necessary to free the nerve proximal to the notch. Performing an osteotomy at
the greater sciatic notch or resecting heterotopic bone in the notch risks
injury to the superior gluteal vessels. These vessels may retract into the
pelvis and become inaccessible, resulting in massive bleeding.
One should be prepared for the possibility of substantial blood loss when
resecting extensive heterotopic bone. Heterotopic bone is very vascular, and
the osteotomized surfaces tend to persistently ooze; this bleeding is
difficult to control with electrocautery. Ample cross-matched blood as well as
cell saver systems to allow for autologous blood reinfusion should be
available. Hemostatic agents such as Gelfoam (Pfizer) and FloSeal (Baxter)
also can help to control bleeding from osseous surfaces.
AUTHOR UPDATE:
The technique continues to be performed exactly as described since it was
published in the original article.