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Chapter 19 Anatomy of the Anterior Cervicothoracic Spine 353
FIG. 19.28 When posterolateral structures of the transverse process and
pedicle have been removed, exposure should be adequate for discectomy.
costotransversectomy, approximately 12 cm of rib can be
resected with the lateral extracavitary approach. Once cut
laterally, it is gently lied o the underlying parietal pleura
and detached medially from its vertebral body and costal
attachments.
e neurovascular bundle is visualized and traced back to
the neural foramen, allowing for identication of the corre-
sponding pedicle. e pedicle is now very carefully taken
down with a high-speed burr or rongeur while not violating
the underlying dura.
Upon complete pedicle and transverse process resection,
good visualization of the disc space should be achievable (Fig.
19.28). Depending on the indication for the approach, discec-
tomy is then performed followed by corpectomy.
Corpectomy can be performed from pedicle to pedicle with
a combination of curettes, high-speed burr, and pituitary
rongeur. Great caution should be exercised during corpectomy
to avoid injuring the ventral dura and spinal cord. To improve
visualization, the bed can be rotated 20 to 30 degrees away
from the operating surgeon. Additionally, a thin shell of posterior vertebral body cortex can be le behind until central
and ventral corpectomy has been completed. is remaining
shell of bone can then be carefully removed, pushing it away
from the ventral dura.
Aer completion of the corpectomy, the corpectomy cage
and/or gra is placed and positioning conrmed with uoroscopy. If posterior pedicle screw and rod stabilization is to be
performed, a separate, standard, midline fascial incision and
approach is performed medial to the paraspinal muscles,
elevating them in a subperiosteal manner.
Upon completion of corpectomy and stabilization, the
pleura is examined for any breaches. If a breach is identied,
it is repaired. If the breach is considered signicant, chest tube
placement may be necessary.
28
Minimally Invasive Approaches to the Thoracic and Thoracolumbar Spine
Recent advances in techniques have led to the development of
minimally invasive approaches to the thoracic and thoracolumbar spine that exploit the same tissue planes as traditional
open procedures but achieve access through smaller incisions
and less tissue disruption. Potential benets of minimally
invasive approaches include less postoperative pain, quicker
recovery, and avoiding complications and morbidities associated with larger open procedures. Early results are promising,
with complication rates ranging from 4.8% to 13.5%.
28,29
at
being said, they can be technically demanding and, if complications do arise, they can be dicult to manage through the
small access site.
Minimally invasive lateral approaches to the thoracic spine
have been described.
29,30
Similar techniques have been applied
to traumatic fractures requiring corpectomy.31 e patient
is positioned in the true lateral decubitus position similar
to thoracotomy approaches. A transthoracic or retropleural
approach can be utilized. For the transthoracic approach, a
3- to 4-cm oblique incision paralleling and between the ribs
of interest is made. e intercostal muscles and parietal pleura
are incised in line with the skin incision, allowing entry into
the thoracic cavity. Depending on the exposure required,
a portion of the rib can be resected. Care should be taken
to avoid injuring the neurovascular bundle that lies on the
undersurface of the rib.
If a retropleural approach is utilized, a 6-cm oblique incision following the course of the rib is made in the midaxillary
line. Approximately 5 cm of rib is then carefully subperiosteally dissected and resected, with care taken not to violate the
parietal pleura or neurovascular bundle. e plane between
the endothoracic fascia and parietal pleura is developed and
the pleura mobilized anteriorly until the lateral side of the
vertebral body, pedicle, and disc space are exposed. If a lesided approach is performed, the aorta and hemizygos vein
are retracted anteriorly with the pleura. An expandable retractor system is then placed, protecting the surrounding structures and allowing focal access to the surgical pathology.
Standard surgical techniques are employed. For corpectomies,
an expandable cage can be utilized.
KEY POINTS
Low Anterior Cervical and High Transsternal Approach
1. The plane between the midline esophagus and airway and the
carotid sheath laterally is utilized with this approach.
2.
A left-sided approach should be considered given the
predictable course of the recurrent laryngeal nerve on this side.
3.
Turning the head away from the approach side and gently
taping the shoulders downward will improve access and
uoroscopic visualization.
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III
354 SURGICAL ANATOMY AND APPROACHES
Transpleural Transthoracic Third Rib Approach
1. A double-lumen endotracheal tube should be used to allow for
selective lung deation.
2.
The rst rib sits medial and recessed to the second rib. The
second rib is typically the highest palpable rib.
3.
The parietal pleura should be entered over the relatively
avascular disc space as opposed to directly over the vertebral
body in order to avoid inadvertent injury to the intercostal
4.
A chest tube should be placed at the end of the case.
Thoracotomy (Anterior) Approach to the Thoracic Spine
1. A right-sided approach should be considered above T10 to
avoid having to manipulate the aorta. Below T10, a left-sided
approach should be considered to avoid working around the
liver.
2.
Ligation of the segmental vessels should be performed away
from the aorta to minimize the risk of the ties or clips
loosening.
3.
The parietal pleura should be entered over the relatively
avascular disc space as opposed to directly over the vertebral
body in order to avoid inadvertent injury to the intercostal
4.
A double-lumen endotracheal tube should be used to allow for
selective lung deation.
Endoscopic Anterior Approach to the Thoracic Spine
1. A double-lumen endotracheal tube should be used to allow for
selective lung deation.
2.
The initial trocar is placed using blunt dissection on the superior
margin of the intervening rib, avoiding damage to the
neurovascular bundle on the undersurface of the rib.
Subsequent trocars are placed under direct thoracoscopic
visualization.
3.
A chest tube should be placed through the inferiormost trocar
site.
4.
A chest radiograph should be obtained at the end of the case
prior to complete closure to ensure full reexpansion of the lung.
lamina is carefully and gently removed in its entirety. This
minimizes pressure on the spinal cord.
Transpedicular Approach
1. This approach may not be ideal for decompression of central
pathology.
2.
Care should be taken not to retract the spinal cord. If necessary,
additional bone should be resected for visualization.
3.
Turning the bed away from the operating surgeon can aid with
ventral visualization.
4.
Pedicle entry and takedown should be performed under
uoroscopic guidance to aid in proper trajectory and depth.
Costotransversectomy
1. The neurovascular bundle on the undersurface of the rib is
protected during rib resection.
2.
This approach utilizes a more lateral trajectory as compared to
the transpedicular approach.
3.
Additional visualization can be achieved by taking down an
adjacent rib.
Lateral Extracavitary Approach
1. This approach is similar to a costotransversectomy approach.
However, a large portion of the rib is resected, providing
additional exposure.
2.
The ventral dura can be protected during corpectomy by
leaving a thin shell of dorsal vertebral body behind until central
and anterior portions of the corpectomy are complete. This
remnant shell can then be gently pushed away from the dura
into the corpectomy cavity and removed safely.
3.
Improved central and contralateral visualization can be achieved
by rotating the bed away from the operating surgeon 20 to 30
degrees.
4.
Any violation of the parietal pleura should be repaired, if
possible. Consideration should be given to placing a chest tube.
Minimally Invasive Approaches
Anterior Approach to the Thoracolumbar Spine
1. A double-lumen endotracheal tube should be used to allow for
selective lung deation.
2.
The peritoneum is bluntly released from the diaphragm and
abdominal musculature.
3.
Care should be taken to avoid injuring the sympathetic chain in
the thoracic cavity and the lumbar plexus in the abdominal
cavity.
4.
Special attention should be given to closure at the junction of
the diaphragm and abdominal musculature to avoid hernia
formation.
Posterior Approach for Decompressive Laminectomy and Fusion
1. Subperiosteal dissection is employed to minimize bleeding.
2. A high speed burr is used to create bilateral troughs at the
junction of the lamina and facet joints for the laminectomy. The
troughs are completed with small Kerrison rongeurs, and the
1. A transthoracic or retropleural approach can be performed
through a minimally invasive approach.
2.
Early results of minimally invasive lateral approaches to the
thoracic and thoracolumbar spine are promising.
3.
One should be prepared to convert to a traditional open
technique should a complication arise or minimally invasive
access is not achievable.
KEY REFERENCES
1. Tew JM Jr, Mayeld FH. Complications of surgery of the anterior
cervical spine. Clin Neurosurg. 1976;23:424-434.
2.
Kothe R, O’Holleran JD, Liu W, et al. Internal architecture of the
thoracic pedicle: an anatomic study. Spine. 1996;21:
264-270.
3.
Patterson RH Jr, Arbit E. A surgical approach through the pedicle
to protruded thoracic disks. J Neurosurg. 1978;48:
768-772.
4.
Benzel EC. The lateral extracavitary approach to the spine using
the three quarter prone position. J Neurosurg. 1989;71:
837-841.
Chapter 19 Anatomy of the Anterior Cervicothoracic Spine 355
REFERENCES
1. Tew JM Jr, Mayeld FH. Complications of surgery of the
anterior cervical spine. Clin Neurosurg. 1976;23:424-434.
2. Kilburg C, Sullivan HG, Mathiason MA. Eect of approach
side during anterior cervical discectomy and fusion on the
incidence of recurrent laryngeal nerve injury. J Neurosurg
Spine. 2006;4:273-277.
3. Daniels AH, Riew KD, Yoo JU, et al. Adverse events associated
with anterior cervical spine surgery. J Am Acad Orthop Surg.
2008;16:729-738.
4. Hoppenfeld S, DeBoer P, Buckley R, et al. Surgical Exposures
in Orthopedics: e Anatomic Approach. Philadelphia: JB
Lippincott; 2009.
5. Campos JH. Lung isolation techniques. Anesthesiol Clin North
Am. 2001;19:455-474.
6. Fujimaki Y, Kawahara N, Tomita K, et al. How many ligations
of bilateral segmental arteries cause ischemic spinal cord
dysfunction? An experimental study using a dog model. Spine.
2006;31(21):E781-E789.
7. Landreneau RJ, Hazelrigg SR, Mack MJ, et al. Postoperative
pain related morbidity: video-assisted thoracic surgery versus
thoracotomy. Ann orac Surg. 1993;56:1285-1289.
8. Hazelrigg SR, Landreneau RJ, Boley TM, et al. e eect of
muscle-sparing versus standard posterolateral thoracotomy on
pulmonary function, muscle strength, and postoperative pain.
J orac Cardiovasc Surg. 1991;101:394-400.
9. Wang JC. Advanced Reconstruction: Spine. Rosemont, IL:
American Association of Orthopaedic Surgeons; 2011.
10. Kim DH. Surgical Anatomy and Techniques to the Spine.
Philadelphia: WB Saunders; 2006.
11. Whang PG, Vaccaro AR. oracolumbar fracture: posterior
instrumentation using distraction and ligamentotaxis
reduction. J Am Acad Orthop Surg. 2007;15:695-701.
12. Kirkpatrick JS. oracolumbar fracture management: anterior
approach. J Am Acad Orthop Surg. 2003;11:355-363.
13. Magee DJ. Orthopedic Physical Assessment. 4th ed.
Philadelphia.: Saunders; 2002.
14. Kothe R, O’Holleran JD, Liu W, et al. Internal architecture of
the thoracic pedicle: an anatomic study. Spine. 1996;21:264-270.
15. Banta CJ 2nd, King AG, Dabezies EJ, et al. Measurement of
eective pedicle diameter in the human spine. Orthopedics.
1989;12:939-942.
16. Berry JL, Moran JM, Berg WS, et al. A morphometric study
of the human lumbar and selected thoracic vertebrae. Spine.
1987;12:362-367.
17. Krag MH, Weaver DL, Beynonn BD, et al. Morphometry
of the thoracic and lumbar spine related to transpedicular
screw placement for surgical spine xation. Spine. 1988;
13:27-32.
18. Panjabi MM, Takata K, Goel V, et al. oracic human
vertebrae: quantitative three-dimensional anatomy. Spine.
1991;16:888-901.
19. Zindrick MR, Wiltse LL, Doornik A, et al. Analysis of the
morphometric characteristics of the thoracic and lumbar
pedicles. Spine. 1987;12:160-166.
20. Oda I, Abumi K, Cunningham BW, Kaneda K, McAfee PC. An
in vitro human cadaveric study investigating the biomechanical
properties of the thoracic spine. Spine. 2002;27(3):E64-E70.
21. Patterson RH Jr, Arbit E. A surgical approach through the
pedicle to protruded thoracic disks. J Neurosurg. 1978;48:
768-772.
22. Metcalfe S, Gbejuade H, Patel NR. e posterior transpedicular
approach for circumferential decompression and instrumented
stabilization with titanium cage vertebrectomy reconstruction
for spinal tumors: consecutive case series of 50 patients. Spine.
2012;37(16):1375-1383.
23. Wong ML, Lau HC, Kaye AH. A modied posterolateral
transpedicular approach to thoracolumbar corpectomy with
nerve preservation and bilateral cage reconstruction. J Clin
Neurosci. 2014;21(6):988-992.
24. Campbell WC, Edmonson AS, Crenshaw AH. Infections of the
spine. In: Campbell’s Operative Orthopaedics. 13th ed. St. Louis:
Elsevier; 2017.
25. Daubs M, Fernandez ML. e costotransversectomy approach
for vertebrectomy. In: Wang JC, ed. Advanced Reconstruction:
Spine. Rosemont, IL: American Academy of Orthopaedic
Surgeons; 2011:243-249.
26. Lifshutz J, Lidar Z, Maiman D. Evolution of the lateral
extracavitary approach to the spine. Neurosurg Focus.
2004;16:E12.
27. Benzel EC. e lateral extracavitary approach to the
spine using the three quarter prone position. J Neurosurg.
1989;71:837-841.
28. Vacarro AR. Fractures of the Cervical, oracic and Lumbar
Spine. New York: Marcel Dekker; 2003.
29. Uribe JS, Dakwar E, Le TV, et al. Minimally invasive
surgery treatment for thoracic spine tumor removal. Spine.
2010;35(26):347-354.
30. Serak J, Vanni S, Levi AD. e extreme lateral approach for the
treatment of thoracic and lumbar vertebral body metastasis.
J Neurosurg Sci. 2015. Epub ahead of print.
31. Smith WD, Dakwar E, Le TV, et al. Minimally invasive surgery
for traumatic spinal pathologies. Spine. 2010;35(26):338-346.
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Lateral and Posterior Approaches to
SECTION
20
CHAPTER
Selection of Approach to the Lumbar Spine
Once the decision has been made to operate, the surgeon must
choose the best procedure and approach. When considering
the options in the lumbar spine, many factors must be taken
into account. First is the location of the pathology. Disease or
deformity that primarily involves the vertebral bodies may be
most easily approached through the abdomen or ank. e
posterior elements are most easily approached through a
posterior, midline incision. Second, the morbidity of each
approach must t the risk tolerance of each individual patient.
For example, it may be preferable to avoid an anterior approach
in a young male who has pathology at L5–S1 to avoid the risk
of retrograde ejaculation.
invasive techniques, decreasing overall morbidity from tissue
dissection must be weighed against more complete visualization that the more traditional open approaches provide.
Chapter 21 discusses lateral and posterior approaches to the
lumbar spine and their pros and cons.
Minimally Invasive Lateral Approach to the Spine
e concept of minimally invasive spine surgery is attractive
to both patients and surgeons alike. Decreased postoperative
pain, shorter hospital stay, and quicker return to activities
support the use of minimally invasive techniques whenever
possible.
is can be used for multilevel interbody fusions to correct
kyphoscoliosis, for interbody support when treating adjacent
segment degeneration or multilevel fusions, or to drain a
psoas abscess (Fig. 20.1). With this approach, access to the
spine from T7 down to L4–L5 is possible. However, L4–L5 is
oen dicult to reach due to a high-riding iliac crest, and a
lateral interbody fusion at this level is controversial at this
time. e means to accessing L5–S1 laterally has not been
developed.
Technique
Once the patient has been intubated and prophylactic antibiotics given, the patient is placed in the lateral decubitus position.
4–8
One such technique is lateral access to the spine.9
1–3
With the advent of minimally
the Lumbosacral Spine
Yu-Po Lee
Saif Aldeen Farhan
Nitin N. Bhatia
When correcting a kyphoscoliosis, it is oen easier to perform
the lateral approach on the side of the concavity. When planning to perform a lateral interbody fusion, we advise studying
the preoperative anteroposterior (AP) and lateral radiographs
and the axial magnetic resonance images (MRIs) to determine
if this procedure is feasible. e AP and lateral radiographs
will show if the iliac crests are too high (see Figs. 20.1A–B).
e axial MRI should also be evaluated to see where the nerves
are preoperatively (Fig. 20.2). If the nerve is in the middle of
the disc space, the surgeon may attempt to approach from the
other side or plan for a dierent procedure.
e table should be exed slightly to increase the distance
between the iliac crest and the rib cage, and the patient secured
with tape over the greater trochanter and chest wall (Fig. 20.3).
Care should be taken not to ex the table too much, as that
may put increased strain on the psoas and lumbar plexus. e
leg on top should also be exed, abducted with pillows, and
externally rotated to relax the psoas. A cross-table AP should
be taken and the table should be rotated to place the patient
in a true AP position (Fig. 20.4A). A corresponding lateral
uoroscopic image should also be taken to verify that access
to the disc space is possible (Fig. 20.4B). Minor adjustments
should be made to the table to obtain a true lateral.
Once the patient has been prepped and draped, start with
the lateral image. A radiopaque marker is placed over the
center of the aected disc space (Fig. 20.5). Once this point
has been identied, a mark is made. rough this mark, a
small incision will be made for insertion of the dilators and
an expandable retractor, which will provide access to the
lateral spine. A second mark is made posterior to this rst
mark at the border between the erector spinae muscles and
the abdominal obliques (Fig. 20.6). At this second mark, a
transverse incision about 2 cm long is made to accommodate
the surgeon’s index nger. Finger dissection is used down to
the lumbodorsal fascia. A clamp, or scissors, can be used to
spread the fascia and muscle bers and provide entry into the
retroperitoneal space. Once an opening is created, the index
nger is used to sweep the peritoneum anteriorly and to
palpate the psoas muscle (Fig. 20.7AB). Sweep the index nger
inferiorly to feel the inner table of the iliac crest (if in the lower
lumbar spine) to verify that you are in the abdominal cavity.
III
357
A
FIG. 20.1 (A–B) Anteroposterior and lateral radiographs of a 71-year-old woman with degenerative scoliosis.
(C–D) Anteroposterior and lateral radiographs after L3–L4 and L4–L5 lateral interbody fusions and minimally
invasive transforaminal lumbar interbody fusion at L5–S1.
FIG. 20.2 Axial magnetic resonance image showing nerve roots in the axial
plane. Arrow is pointing to the ventral nerve root. In this case, the surgeon
may wish to approach from the right side to avoid the nerve root here.
B
C
FIG. 20.3 Patient placed in right lateral decubitus position with table exed
to increase the distance between his ribs and iliac crest.
D
A
FIG. 20.4 (A) Cross-table anteroposterior (AP) position showing a true AP view. The endplates are parallel and
the spinous process is midline. (B) Corresponding lateral uoroscopic image showing parallel endplates and
superimposed pedicles.
B
Chapter 20 Lateral and Posterior Approaches to the Lumbosacral Spine 359
SECTION
III
FIG. 20.5 Fluoroscopic image showing center positioning over the disc
space. A mark is made on the skin here.
FIG. 20.6 Two-incision technique shown with lateral and posterolateral
marks. The posterolateral incision is made about the length of the surgeon’s
index nger away from the lateral incision. From this mark, the surgeon
should also measure the distance to the spine to make sure to be able to
reach the psoas from this incision.
A
C
FIG. 20.7 (A–B) The surgeon uses digital palpation to sweep the abdominal
contents anteriorly and create a cavity in the retroperitoneal space. (C) The
index nger guides the initial dilator down to the psoas. (D) Once the initial
dilator is secured in place with a K-wire, larger dilators are used to spread
the psoas under neuromonitoring, and a retractor is placed over the
dilators.
B
D
Once the psoas is identied, the index nger is swept up to
the previously made direct lateral mark. A 2-cm incision is
made and the external and internal oblique muscles and the
transverses abdominis muscles are split; dilators are placed
through this opening. e index nger, which is already in the
retroperitoneal space, guides the initial dilator onto the psoas
(Fig. 20.7C). e bers of the psoas are then split with the
dilator, using neuromonitoring as a safety measure, if desired.
A lateral radiograph should be taken to verify the central
position of the dilator at the desired disc space. Once the
position of the initial dilator is secured by placing a Kirschner
wire (K-wire) through the dilator and into the disc space,
larger dilators are used to spread the psoas under neuromonitoring. en, an expandable retractor is placed over the dila-
tors (Fig. 20.7D). Once the retractor is secured to the table,
the dilators are removed to provide lateral access to the disc
(Figs. 20.8). A neuromonitoring probe can be used to check
for any nerves that may be crossing the working window of
the retractor. If a nerve is detected, the K-wire should be
repositioned away from the nerve and the psoas redilated. If
this fails, conversion to another means of interbody fusion
should be considered, as repeated positioning of the retractor,
or pressure on the nerve, could result in postoperative paresthesias or palsies.
AP and lateral radiographs should be taken at this point
to verify that the retractor is docked on the disc space and
that the retractor is positioned over the center of the disc.
Once appropriate positioning has been conrmed, the retrac-
tor should be secured in place. A lateral discectomy is then
performed in standard fashion with shavers, curettes, and
rasps. Care must be taken not to violate the endplates because
much of the correction from a lateral interbody fusion is based
360 SURGICAL ANATOMY AND APPROACHES
A
FIG. 20.8 (A) Once the retractor is deployed, soft tissue over the disc space must be cleared away. Use a probe
to detect any nerves that may cross the eld. (B) The disc can be visualized after the psoas muscle has been
cleared from the eld of view.
A
FIG. 20.9 (A) A Cobb elevator is used to release the contralateral anulus. This aids in the coronal correction of
the deformity. (B) Rotating the Cobb elevator 90 degrees will further release the contralateral anulus.
B
B
on distraction and a compromised endplate will allow the
endplate to subside. A Cobb elevator should be used to release
the contralateral anulus (Fig. 20.9). Releasing the contralateral
anulus loosens the spine in the coronal plane and aids in
the correction of coronal plane deformities. Sizers and trials
are then used to determine the optimal implant size (Fig.
20.10). e implant is then lled with the surgeon’s gra or
fusion enhancer of choice and impacted across (Fig. 20.11).
e wound is then closed in layers. No drains are typically
necessary.
Complications
Since minimally invasive lateral access to the spine is a relatively new procedure, publications regarding the ecacy and
complication rates are sparse. Numbness in the lateral thigh
and psoas weakness have been noted by some physicians;
however, the rate still remains unknown.
10–12
To minimize this
risk, open the retractor just enough to perform the lateral
discectomy. Exuberant deployment of the retractor may place
undue pressure on the nerve roots and/or the psoas itself.
Limiting the amount of time that the retractor is open is also
advised to decrease the length of time that the nerves are
under pressure. In addition, neuromonitoring is advised to
decrease the possibility of nerve injury.
Injury to the bowel and vessels have also been reported.13
It is recommended that this procedure be done at a facility
where a general or vascular surgeon is available. One method
to decrease the rate of bowel or vascular injury is to place the
initial dilator under direct visualization. Aer the lateral inci-
sion has been made, the retractor can be passed down to the
psoas. en, the initial dilator is placed through the psoas
under direct visualization.
Chapter 20 Lateral and Posterior Approaches to the Lumbosacral Spine 361
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III
A
FIG. 20.10 Trialing of the disc space with a (A) paddle trial and (B) implant trial.
A
B
B
FIG. 20.11 Final (A) anteroposterior and (B) lateral radiographs after two-level lateral interbody fusion.
Posterior Approach to the Lumbar Spine
e posterior approach through a midline, longitudinal incision is the most common approach to the lumbar spine. It
provides direct access to the spinous processes, laminae,
facets, and even the pedicles, as well as lateral aspects of the
vertebral bodies at all levels of the lumbar spine. e pedicle
starting holes and transverse processes can be reached by
dissecting and retracting the paraspinal muscles laterally.
rough this approach, it is possible to perform most of the
spine procedures currently practiced today, including microdiscectomies, laminectomies, and most fusion procedures.
e posterior aspect of the vertebral body and disc space over
the lower lumbar levels can be reached following laminectomy
by retracting the dura; however, the exposure is limited.
It is important to bear in mind that anatomic variations
exist among individuals, which must be taken into account
when planning surgery. e intercrestal line typically crosses
at L4–L5; however, this is not a rigid anatomic nding. A
lateral radiograph will show where the intercrestal line is.
Also, lumbarization or sacralization of the last vertebral
segment can confuse the surgeon when localizing the level of
pathology. Additionally, a spina bida occulta or an unusually
wide interlaminar space may exist. To avoid inadvertent injury
to the dura or nerve roots with a Bovie or periosteal elevator
during the exposure, the surgeon should study radiographs
prior to surgery to look for these abnormalities.
362 SURGICAL ANATOMY AND APPROACHES
FIG. 20.12 Patient in standard prone position. Note how the area beneath
the patient is cleared of wires to accommodate imaging.
Technique
Position the patient prone to allow the abdomen to hang free
of pressure (Fig. 20.12). is will reduce venous plexus lling
around the cauda equina by permitting the venous plexus to
drain directly into the inferior vena cava. Also, the anesthesiologist should check the patient’s eyes and the surgeon and
nurses should assess the bony prominences to ensure that they
are well padded. If a microdiscectomy or decompression is to
be performed, exing the lumbar spine on a Wilson frame or
similar table is recommended to open up the interspinous
spaces. If a fusion is also to be performed, placing the patient
on a Jackson table is recommended to maintain the lumbar
lordosis. A solution containing epinephrine in a 1 : 500,000
concentration may be injected into the subcuticular tissues
and muscles to decrease blood loss.
A midline incision is made between the spinous processes
of the levels to be exposed, and the erector spinae and multidus muscles are dissected from the bony elements (spinous
processes, interspinous ligaments, laminae, facet joints, and
transverse processes) as needed for the levels that must be
visualized, using electrocautery or sharp dissection (Fig.
20.13). e paraspinal muscles should be elevated subperios-
teally to minimize blood loss. Care should be taken not to
injure the facet joint capsules and interspinous ligaments in
areas where motion will be expected following the operation.
If the transverse processes must be reached, continue dissecting down the lateral side of the facet joints and onto the
transverse process itself. Close to the facet joints and the pars
interarticularis are the vessels supplying the paraspinal muscles
segmentally.
If these vessels are cut, they can bleed vigorously. Cauterization is necessary to stop these bleeders. e posterior
primary rami of the lumbar nerves run with these vessels.
In order to perform a decompression or a discectomy, it
may be necessary to remove the ligamentum avum. e
supercial ligamentum avum blends laterally into the facet
joint capsule. Use a forward-angled or small straight curette
to detach the supercial and deep layers of the ligamentum
FIG. 20.13 Exposure of the lumbar spine.
FIG. 20.14 Removal of the ligamentum avum. (From Benzel E. Spine
Surgery: Techniques, Complication Avoidance, and Management. Philadelphia:
Churchill Livingstone; 2004.)
avum from the caudal edge of the cephalad lamina. Sweep
the curette medial to lateral and advance the curette with each
successive sweep to detach the ligamentum avum from the
lamina. e ligamentum avum typically inserts over the
caudal 50% of the undersurface of the lamina. Place a small,
angled elevator under the ligamentum avum to li it o the
dura and protect the latter. A Kerrison rongeur, pituitary
rongeur, or knife can be used to remove the ligamentum
avum. e epidural fat, the dura, the nerve root, and the
epidural veins can be seen once the ligamentum avum has
been removed (Fig. 20.14).
If a discectomy or exploration of the disc space is required,
it can typically be performed through this opening. Removal
of a portion of the lamina (laminotomy) may need to be done
to adequately access the disc space. A Peneld 4 can then be
used to help mobilize the traversing nerve root and a nerve
root retractor can be used to gently retract the nerve roots