Journal of the American Academy of Orthopaedic Surgeons
80
Open hemilaminectomy to treat
symptomatic intervertebral disk her-
niation, described by Mixter and
Barr in 1934,
1
set the standard for
subsequent surgical techniques. The
trend since has been to develop less
invasive surgical procedures for the
treatment of radiculopathy second-
ary to herniated disk. The concept
of minimally invasive spine surgery
is to provide surgical options that
optimally address the disk pathol-
ogy without producing the types of
morbidity commonly associated
with open surgical procedures. Min-
imally invasive techniques are not,
however, a panacea for all lumbar
disk pathology. These techniques
are designed to treat nerve root com-
pression alone as the source of ra-
diculopathy in patients with acute
primary disk herniations.
Radiculopathy has been attrib-
uted to the production of chemical
mediators that result from the com-
pression and/or leakage of degen-
erative nuclear material through

lateral, posterior interlaminar, or
foraminal approaches. The stan-
dard for evaluation of percutaneous
techniques became open microdisk-
ectomy, considered the benchmark
for comparison. A recently devel-
oped percutaneous variation of the
standard laminotomy technique is
endoscopic diskectomy. Laparo-
scopic transperitoneal and retroperi-
toneal approaches to herniated
nuclear pathology also have been
introduced.
Dr. Mathews is Associate Clinical Professor,
Department of Orthopaedic Surgery, Virginia
Commonwealth University, Medical College of
Virginia, Richmond, VA. Ms. Long is Clinical
Researcher, MidAtlantic Spine Specialists,
Richmond.
One or more of the authors or the departments
with which they are affiliated has received
something of value from a commercial or other
party related directly or indirectly to the sub-
ject of this article.
Reprint requests: Dr. Mathews, Suite 200,
7650 Parham Road, Richmond, VA 23294.
Copyright 2002 by the American Academy of
Orthopaedic Surgeons.
Abstract
Hemilaminectomy with diskectomy, the original surgical option to address

surgical instrumentation. Better
patient selection has resulted from
experience with individual tech-
niques as well as an appreciation of
technique-related complications and
outcomes. In addition, improved
fluoroscopic imaging and navigation
systems have enhanced the safety
and predictability of minimally inva-
sive techniques when performed by
experienced endoscopic surgeons.
Perhaps the most notable advan-
tage of minimally invasive tech-
niques is the ability they provide to
surgically address and resolve her-
niated nuclear pathology without
the morbidity associated with inci-
sion of the paraspinal muscle in tra-
ditional open techniques. Enhanced
visualization of the surgical field
allows the pathology to be seen and
permits both identification and
avoidance of injury to the neurovas-
cular structures. The surgical field
can be surveyed before conclusion of
the procedure, and the diskectomy
itself can be inspected and docu-
mented on videotape. In addition,
these procedures generally are done
on an outpatient basis. Patients usu-

achieved without significant change
in neural anatomy following the
procedure. The governing factor in
considering a minimally invasive
procedure is patient selection.
5
Indications for Minimally
Invasive Spine Surgery
Except in emergent circumstances,
such as rapidly progressive neuro-
logic deficits or the threat of cauda
equina syndrome, 6 to 8 weeks of
nonsurgical treatment with appro-
priate medication and conservative
care is routine before proceeding
with surgical intervention. The ideal
candidate should have unilateral
radicular pain radiating into the
foot, with leg pain greater than back
pain. Positive straight leg raising is
often present. The radicular pain
may be described as lancinating
and/or aching. Other complaints
can include numbness, tingling, and
weakness, along with decreased sen-
sation to light touch and pin prick.
Because herniation can result in
canal stenosis relative to the size of
the herniation, some patients com-
plain of pseudoclaudication.

also are relative contraindications.
Techniques, Complications,
and Results
Early Techniques
Open microdiskectomy, the
benchmark procedure with which
percutaneous and minimally inva-
sive techniques are compared, uti-
lizes a small incision and a micro-
scope or loupe magnification rather
than an endoscope. The technique is
similar to minimally invasive tech-
niques in regard to patient selection
and indications. Compared with
percutaneous techniques, especially
foraminal epidural endoscopy,
diskectomy is limited in its ability to
address sequestered free fragments
with significant migration. Open
diskectomy allows the surgeon to
visualize the pathology and neu-
rovascular anatomy, but in this tech-
nique, the anatomic structures often
must be gently manipulated (rather
than avoided) for optimal access to
the disk–nerve root compression
interface. The overall rate of suc-
Treatment of Intervertebral Disk Herniation
Journal of the American Academy of Orthopaedic Surgeons
82

ization and relief of tension on annu-
lar fibers as well as involution of the
nucleus, essentially withdrawing the
compressive nerve pathology back
into the annular confines.
10
Chemonucleolysis caused dena-
turization of the intervertebral
nucleus and a relative disk debulk-
ing. Allergic reactions and even
anaphylaxis occurred in approxi-
mately 1% of patients treated with
chymopapain.
11
Postoperatively,
radiographs of treated patients
often demonstrated disk space col-
lapse.
12
In some centers, chemo-
nucleolysis currently is used in con-
junction with epiduroscopy in the
treatment of migrated or seques-
tered free fragments. The technique
is more popular in Europe than in
the United States.
11
Gogan and
Fraser
13

these results are less satisfactory
than those achieved with other tech-
niques, this procedure has largely
fallen out of favor.
Laser disk decompression is a
blind, nonspecific disk depressur-
ization procedure resulting in grad-
ual withdrawal of disk compression
on the nerve root. Because it is a
blind procedure, complications have
paralleled those of the blind nu-
cleotomy techniques. An additional
concern related to complications
early in the use of laser disk decom-
pression was the heat associated
with direct-firing wavelengths
delivered by probes in proximity to
neurovascular structures.
16
In cen-
ters where this technique is still in
use, successful outcomes have
ranged from 50% to 89%,
10,17
imply-
ing various outcomes in nonprospec-
tive, nonrandomized studies with
resulting inconsistent data. Recent
application of the holmium:YAG
cool, side-firing laser in conjunction

L
Hallett H. Mathews, MD, and Brenda H. Long, MS, RN
Vol 10, No 2, March/April 2002
83
site. Complications with this tech-
nique are minimal, but infection
(two cases), transient peroneal neu-
ropraxia (two cases), and transient
skin hypersensitivity (five cases)
have been reported, for a complica-
tion rate of 3% in one large series of
patients spanning 10 years.
18
Theo-
retic complications related to trau-
ma to neurovascular structures and
perineural/intraneural fibrosis have
not been reported. The success rate
for this technique ranges from 75%
to 98%.
18-21
The laparoscopic anterior ap-
proach to the lumbar spine for pri-
mary disk herniations began to be
used in the mid-1980s and early
1990s. This technique allows access
to contained disk herniations, as
well as to some extruded and mi-
grated fragments, through either a
transperitoneal or retroperitoneal

questered free fragments in the
epidural space when they are limit-
ed to confines of the axilla and the
pedicle. Such access is facilitated by
appropriately sized endoscopes
with varied lens angles; foraminal
and extraforaminal disk herniations
are technically demanding for stan-
dard microscopic techniques. The
foraminal endoscopic technique
allows visualization of the patholo-
gy and avoidance of neurovascular
structures at risk, as well as visual-
ization of the selective diskectomy
and documentation of the surgical
effect at the time of the procedure
(Fig. 3). As with arthroscopic micro-
diskectomy, manual and automated
instrumentation sized to the work-
ing channel of the endoscope allows
Figure 2 Laparoscopic diskectomy technique. R = retroperitoneal space. The instruments
are inserted on the left side, with the smooth pituitary instrument traversing the retroperi-
toneum through the psoas muscle. The trochar needle is placed through the posterolateral
approach. (Adapted with permission.
22
)
Figure 3 Foraminal endoscopic diskectomy technique compared with the extraforaminal
approach. The foraminal approach allows direct dissection and removal of herniated
material. (Adapted with permission.
12

mized by the excellent visualization.
The success rate has recently been
reported at 78%.
25
Key to the suc-
cess of foraminal epidural endo-
scopic surgery are patient selection
and, at surgery, familiarity with the
spatial orientation and with the
anatomy at risk. The learning curve
is steep, and success with this tech-
nique requires regular use.
26
For-
aminal epidural endoscopic surgery
has been equated to open micro-
diskectomy as “microdiscectomy
through a cannula.”
26
Microendoscopic diskectomy
through the interlaminar approach
allows endoscopic intervention for a
broad range of disk pathology. This
technique is indicated for all forms
of disk herniation (Fig. 4) as well as
for associated pathology, such as lat-
eral recess or central canal stenosis.
Microendoscopic diskectomy is per-
formed through a slightly larger
tubular distractor and thus closely

ria.
27
This series included patients
who underwent surgery for lateral
herniations, herniations within the
spinal canal, and free-fragment
pathology.
27
Summary
Early blind, nonspecific intradiscal
techniques have been superseded
by a variety of low-morbidity, min-
imally invasive surgical options
that offer treatment for patients
with radiculopathy secondary to
disk pathology tailored to their re-
spective pathologies. These proce-
dures provide results comparable
to those of microdiskectomy done
with magnification and may poten-
tially have advantages for some
specific indications.
Dural sac
Exiting
nerve root
Intervertebral
disk
L5
Herniation
Central

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