Treatment Of Intractable Discogenic Low Back Pain. A Systematic Review Of Spinal Fusion And Intradiscal Electrothermal Therapy (Idet)

Abstract

A growing number of patients suffer from severe low back pain of discogenic origin that is not responsive to conservative medical management. These patients must consider the option of surgical spinal fusion or minimally-invasive intradiscal electrothermal therapy (IDET).
To conduct a systematic review of clinical outcomes in patients undergoing spinal fusion or the intradiscal electrothermal therapy (IDET) procedure for intractable discogenic low back pain.
Systematic literature review.
English-language journal articles published from January 1995 to December 2005 were identified through computerized searches of the PubMed database and bibliographies of identified articles and review papers. Articles were selected if disc degeneration or disruption was the primary indication for spinal fusion or the IDET procedure and if follow-up outcome data included evaluations of back pain severity, condition-specific functional impairment and/or health-related quality of life. The literature reviewed encompassed 33 spinal fusion articles: 10 randomized controlled trials, 1 nonrandomized controlled trial, 9 before-after trials, and 13 case series. There were 18 IDET articles: 2 randomized controlled trial, 2 nonrandomized controlled trials, 11 before- after trials, and 3 case series. Data were extracted and summarized on patient characteristics, surgical methods, and clinical outcomes.
Overall, there were similar median percentage improvements realized after spinal fusion and the IDET procedure, respectively, for 2 of the 3 outcomes evaluated: pain severity (50%, 51%), back function (42%, 14%) and quality of life (46%, 43%). There was an identifiable randomized controlled trials trend of both treatments reporting a smaller magnitude of improvement in all 3 primary outcomes (pain severity, back function, quality of life) compared to other types of trials. Perioperative complications were commonly associated with spinal fusion (median: 14%, range: 2% to 54%, n = 31 study groups) whereas adverse events were rarely experienced with the IDET procedure (median: 0%, range: 0% to 16%, n = 14 studies). Randomized controlled trials of spinal fusion, in particular, had important methodological limitations.
The majority of patients reported improvement in symptoms following both spinal fusion and the IDET procedure. The IDET procedure appears to offer sufficiently similar symptom amelioration to spinal fusion without the attendant complications.

Full text

Pain Physician. 2006;9:237-248, ISSN 1533-3159
A Systematic Review
Treatment Of Intractable Discogenic Low Back Pain.
A Systematic Review Of Spinal Fusion And Intradiscal
Electrothermal Therapy (Idet)
Gunnar B. J. Andersson, MD, PhD, Nagy A. Mekhail, MD, PhD, and Jon E. Block, PhD
Background
: A growing number of pa-
tients suffer from severe low back pain of
discogenic origin that is not responsive to
conservative medical management. These
patients must consider the option of surgi-
cal spinal fusion or minimally-invasive in-
tradiscal electrothermal therapy (IDET).
Objective
: To conduct a systemat-
ic review of clinical outcomes in patients
undergoing spinal fusion or the intradiscal
electrothermal therapy (IDET) procedure
for intractable discogenic low back pain.
Design
: Systematic literature review.
Methods
: English-language journal
articles published from January 1995 to
December 2005 were identied through
computerized searches of the PubMed da-
tabase and bibliographies of identied ar-
ticles and review papers. Articles were se-
lected if disc degeneration or disruption
was the primary indication for spinal fu-
sion or the IDET procedure and if follow-
up outcome data included evaluations of
back pain severity, condition-specic func-
tional impairment and/or health-related
quality of life. The literature reviewed en-
compassed 33 spinal fusion articles: 10
randomized controlled trials, 1 nonran-
domized controlled trial, 9 before-after tri-
als, and 13 case series. There were 18 IDET
articles: 2 randomized controlled trial, 2
nonrandomized controlled trials, 11 be-
fore-after trials, and 3 case series. Data
were extracted and summarized on patient
characteristics, surgical methods, and clin-
ical outcomes.
Results
: Overall, there were similar
median percentage improvements realized
after spinal fusion and the IDET procedure,
respectively, for 2 of the 3 outcomes evalu-
ated: pain severity (50%, 51%), back func-
tion (42%, 14%) and quality of life (46%,
43%). There was an identiable random-
ized controlled trials trend of both treat-
ments reporting a smaller magnitude of
improvement in all 3 primary outcomes
(pain severity, back function, quality of life)
compared to other types of trials. Periop-
erative complications were commonly as-
sociated with spinal fusion (median: 14%,
range: 2% to 54%, n=31 study groups)
whereas adverse events were rarely expe-
rienced with the IDET procedure (median:
0%, range: 0% to 16%, n=14 studies). Ran-
domized controlled trials of spinal fusion,
in particular, had important methodologi-
cal limitations.
Conclusion
: The majority of patients
reported improvement in symptoms fol-
lowing both spinal fusion and the IDET
procedure. The IDET procedure appears to
offer sufciently similar symptom amelio-
ration to spinal fusion without the atten-
dant complications.”
Key words:
Spinal fusion, intradiscal
electrothermal therapy, back pain.
From: Department of Orthopedic Surgery, Rush
University, Chicago, IL, and Department of Pain
Management, Cleveland Clinic Foundation,
Cleveland, OH
Address Correspondence: Jon E. Block, PhD, 210
Jackson Street, Suite 401, San Francisco, CA 94115
Email: jonblock@jonblockphd.com
Disclaimer: This study was supported, in part, by
Smith & Nephew Endoscopy (Andover, MA).
Conflict of Interest: None
Manuscript received on 5/20/06
Revision submitted on 6/6/06
Accepted for publication on 6/8/06
A
lmost every individual, at some
point in life, will suffer an episode of
low back pain of sufficient severity to
disrupt normal daily activities includ-
ing work and recreation (1). Fortunate-
ly, the vast majority of patients will ex-
perience complete symptom ameliora-
tion with time and conservative med-
ical management (2). Even refractory
cases of severe back pain respond rea-
sonably well to intensive nonopera-
tive multidisciplinary management (3).
However, approximately 5% of patients
will continue to experience severe pain
and functional impairment chronically
(4). Almost 90% of the health care costs
for low back pain are consumed by this
group of patients with intractable pain
(5).
A number of biomechanical and
neurologic components have been pu-
tatively implicated in the etiology of
chronic low back pain (6, 7). Internal
disc disruption is associated directly
with chronic pain in an estimated 40%
of patients reporting persistent symp-
toms of unknown origin (8). Posterior
annular fissuring, the delamination and
degeneration of the intervertebral disc,
in particular, is a potential cause of back
pain because mechanical loading to ar-
eas of degenerated and disrupted lamel-
lae causes sensitization of the annular
receptors (9, 10). Histological studies
suggest that in response to disc degen-
eration and lamellar disruption, neo-
vascularization, neuronal penetration
with unmyelinated nerve fibers, and in-
growth of Schwann cells occur (11-13).
It has been observed that at least a por-
tion of this neoinnervation provides a
sensory function, potentially acting as a
pain generator (12, 13).
Patients with chronic, intractable
low back pain of discogenic origin of-
ten must face the harsh reality that the
prognosis for recovery with conserva-
tive, nonoperative management alone is
not good (4, 14, 15). Consequently, this
patient group is confronted with the op-
tion of living with persistent back pain
and possible narcotic dependency or
electing to undergo open surgical spi-
nal fusion. A number of fusion proce-
dures are available for treatment of de-
generative disc disease (16-19). Because
the intervertebral disc is often the pri-
mary source of pain in these patients, a

238
Pain Physician Vol. 9, No. 3, 2006
Andersson et al • A Systematic Review of Spinal Fusion and IDET
current preference has emerged toward
en masse disc excision combined with
instrumented interbody fusion to pro-
vide stabilization (20, 21). Patients with
imaging and discographic evidence of
internal disc disruption may have an-
other option — percutaneous intradis-
cal electrothermal therapy (IDET), the
minimally-invasive technique which
uses a navigable catheter to provide tar-
geted thermal energy within the disc (2,
22, 23).
The primary purpose of this report
is to present a systematic review of the
published literature regarding clinical
outcomes after spinal fusion and IDET
in patients with intractable discogenic
low back pain. Emphasis was placed on
3 primary outcomes: pain severity, con-
dition-specific functional impairment
and health-related quality of life. Quali-
tative outcome comparisons were made
between spinal fusion and IDET, as well
as between each intervention, and non-
operative conservative management.
Methods
Data Sources
A computerized search of the
PubMed database from January 1995
to December 2005 for English-language
publications was conducted using the
key words disc and interbody coupled
separately with fusion or arthrodesis
for studies of spinal fusion, and intra-
discal or IDET for published reports of
IDET studies. The reference lists of the
retrieved articles were reviewed for ad-
ditional studies, as were review articles
on the subject. The initial article inclu-
sion date of 1995 was chosen based on
the finding that the earliest publication
date for a study of the IDET procedure
was 1996 and spinal fusion articles pub-
lished prior to this date often failed to
provide adequate clinical outcome data
with respect to pain severity or func-
tional impairment. Additionally, spi-
nal fusion articles published subsequent
to 1995 were more likely to include pa-
tients treated with newer pedicle screw
fixation and interbody fusion cage de-
vices for disc disease (24). Only IDET
studies that specifically used the Spin-
eCATH® device (Smith & Nephew En-
doscopy, Andover, MA) were included
in this review. This device is a naviga-
ble intradiscal catheter that can be de-
ployed directly adjacent to the posteri-
or or posterolateral annulus and pro-
vides temperature-controlled conduc-
tive heating using a thermal resistive
coil (23).
Study Selection
All articles were triaged for inclu-
sion by one of the authors (JEB) for
suitability prior to review. Studies were
selected for inclusion in this synthe-
sis if the methods section clearly indi-
cated that disc degeneration or disrup-
tion was the primary indication for spi-
nal fusion or the IDET procedure, and if
follow-up outcome data included evalu-
ations of back pain severity, condition-
specific functional impairment and/or
health-related quality of life. Reports of
patients described as having nonspecif-
ic chronic low back pain were includ-
ed if there was discographic evidence
of concordant pain provocation. Stud-
ies evaluating patients for other back
pain-related indications such as spinal/
foraminal stenosis, spondylolisthesis,
failed back syndrome, scoliosis, frac-
ture, spondylosis or nonspecific degen-
erative instability were excluded.
A total of 229 articles were locat-
ed from all sources and triaged for in-
clusion. Fifty one articles (22%) met the
stated requirements for inclusion in this
systematic review: most excluded arti-
cles were either clinical studies that did
not evaluate at least 1 of the 3 primary
outcomes or were studies that intermin-
gled patients with multiple diagnoses
and failed to report outcomes separate-
ly for cases with disc degeneration. All
published articles of the IDET proce-
dure were included in this review. Three
studies (25-27) were excluded that used
a distinctly different intradiscal device
consisting of a radiofrequency needle
probe inserted directly into the center
of the nucleus. Experimentally this de-
vice has been shown to be unable to ac-
cess the broad expanse of the posteri-
or annular wall, the site of symptomatic
disc disruption (12), and the device also
fails to provide sufficient annular heat-
ing and tissue coagulation to achieve
the desired clinical benefit (28).
Data Extraction
All studies were classified as fol-
lows: randomized controlled trial, non-
randomized controlled trial, before-af-
ter trial (prospective), or case series (ret-
rospective). The literature reviewed en-
compassed 33 spinal fusion articles: 10
randomized controlled trials (29-38), 1
nonrandomized controlled trial (39), 9
before-after trials (40-48), and 13 case
series (49-61). Randomized controlled
trials of spinal fusion were further sub-
categorized as studies comparing spi-
nal fusion with conservative manage-
ment (n=2) (31, 37) and studies com-
paring various fusion techniques (n=8)
(29, 30, 32-36, 38). Six of the spinal fu-
sion articles provided outcomes on sim-
ilar or equivalent patient groups (33, 34,
42, 43, 51, 52).
There were 18 IDET articles: 2 ran-
domized controlled trials (62, 63), 2
nonrandomized controlled trials (64,
65), 11 before-after trials (66-76), and 3
case series (77-79). The 2 nonrandom-
ized controlled trials reported outcomes
on the same patient population with dif-
ferent lengths of follow-up (64, 65). Five
of the before-after trials likewise report-
ed outcomes on the same patient popu-
lation with different lengths of follow-
up (67, 68, 70-72).
The quality of all reports of ran-
domized controlled trials was graded us-
ing the 5-point Jadad Score with a score
of “1” representing poor quality and a
score of “5” reflecting excellent quali-
ty (80). This scoring system rates study
quality on 3 fundamental methodolog-
ical criteria: randomization, blinding,
and completeness of follow-up. Results
of randomized controlled trials of spi-
nal fusion versus conservative manage-
ment, and of the IDET procedure versus
sham control were analyzed per proto-
col. Post hoc intention-to-treat analyses

Andersson et al • A Systematic Review of Spinal Fusion and IDET 239
Pain Physician Vol. 9, No. 3, 2006
were not conducted.
The following information was ab-
stracted from each of the selected arti-
cles: age, gender distribution, duration
of symptoms, length of follow-up, indi-
cation, type of procedure, sample size,
outcome(s), and complication rate. For
spinal fusion, the type of procedure was
recorded as posterolateral (PLF), poste-
rior lumbar interbody (PLIF), anterior
lumbar interbody (ALIF), or circumfer-
ential (360º) (CF) fusion.
This synthesis focused on 3 pri-
mary clinical outcomes: pain severi-
ty as measured by visual analog scale
(normally 10-point), condition-specif-
ic functional impairment as measured
by the Oswestry disability index (100-
point), and health-related quality of life
as measured by the SF-36 questionnaire
instrument (100-point) (81). Find-
ings from the Roland-Morris disability
questionnaire were included only if the
Oswestry was not used, and results for
the physical functioning domain of the
SF-36 were summarized. For spinal fu-
sion studies, results with respect to the
percentage of patients achieving good
or excellent clinical results (or highest
equivalent rating) also were included.
This outcome was defined variously but
generally reflected moderate to com-
plete pain relief (54, 82, 83). For studies
of the IDET procedure, results for the
percentage of patients demonstrating at
least a 2-point improvement in pain se-
verity were included as an improvement
of this magnitude has been shown to be
clinically significant (84).
Statistical Methods
For the three primary outcomes,
the estimated percentage improvement
from baseline to final follow-up was
computed from mean values report-
ed in each article (85). For pain sever-
ity and back impairment, decreases in
scores reflected improvement where-
as for quality of life, increases in scores
reflected improvement. In all cases, the
median percentage improvement and
associated range for each outcome was
presented for all studies by type of treat-
ment (i.e., spinal fusion or IDET). For
spinal fusion articles, the median per-
centage improvement in each outcome
also was provided for each type of fu-
sion procedure (e.g., PLF, PLIF, ALIF,
etc.) separately. Lastly, the median per-
centage improvement in each outcome
grouped by hierarchy of study design
was presented for both types of treat-
ments separately. No adjustments were
made to median summary scores for
sample size, length of followup, or oth-
er factors. Significance values were ab-
stracted directly from the text and not
computed post hoc. For controlled tri-
als, P values reflect comparisons in im-
provement between study groups. For
single-arm before-after trials and case
series, P values reflect paired compar-
isons within study groups. If provided,
the major complication or adverse event
rate was abstracted directly from each
report. If complications were only list-
ed, then the total number of complica-
tions was divided by the number of pro-
cedures to arrive at percentage estimate
for adverse events.
Results
Table 1 summarizes selected de-
mographic and study-related character-
istics for all investigations of spinal fu-
sion and the IDET procedure separate-
ly. While there were no noteworthy dif-
ferences between treatments for age or
gender distribution, the median dura-
tion of symptoms and the length of fol-
low-up were somewhat longer for pa-
tients treated with spinal fusion com-
pared to patients treated with the IDET
procedure. The primary presenting clin-
ical symptom, back pain severity, also
was fairly similar between treatments.
Adjusted to a 10-point scale, the medi-
an baseline pain severity scores were 7.9
(range: 6.2 to 8.9) and 6.6 (range: 5.9 to
8.0) for studies of spinal fusion and the
IDET procedure, respectively.
Complete findings grouped by
study design into the categories of in-
dication, type of procedure, baseline, fi-
nal follow-up values for 3 primary out-
comes, the percentage good or excellent
results, and complication rates are all
presented in Table 2 for spinal fusion.
There were 10 reports (30%) of patients
treated with PLF, 7 (21%) with PLIF, 12
(36%) with ALIF, and 6 (18%) with CF.
There were 28 studies (85%) reporting
pain severity results, 17 studies (52%)
reporting Oswestry results and 5 stud-
ies (15%) reporting SF-36 results. The
overall median percentage improve-
ment after spinal fusion in pain sever-
ity was 50% (range: 24% to 77%), in Os-
westry was 42% (range: 17% to 77%),
and in SF-36 was 46% (range: 21% to
123%).
Procedures involving an interbody
fusion showed somewhat greater me-
dian percentage improvement in pain
severity than PLF although the ranges
were overlapping: PLF (median: 37%,
range: 30% to 77%, n=9 study groups),
PLIF (median: 57%, range: 52% to 61%,
n=4 study groups), ALIF (median: 50%,
range: 31% to 75%, n=11 study groups),
and CF (median: 41%, range: 24% to
70%, n=6 study groups). Similar results
by type of fusion procedure also were
observed for the median percentage im-
provement in the Oswestry disability
index: PLF (median: 38%, range: 21%
to 73%, n=7 study groups), PLIF (medi-
an: 54%, range: 24% to 58%, n=3 study
Table 1. Summary of Selected Demographic and Study-Related Characteristics
IDET indicates intradiscal electrothermal therapy.
Characteristic Spinal Fusion IDET*
no. of 33 median (range) no. of 18 median (range)
Age (years) 32 44 (37-58) 16 41 (35-45)
Female (%) 30 47 (24-92) 18 47 (13-59)
Duration of Symptoms (months) 20 43 (3-115) 16 38 (6-92)
Length of Follow-up (months) 33 24 (12-68) 18 12 (3-28)

240
Pain Physician Vol. 9, No. 3, 2006
Andersson et al • A Systematic Review of Spinal Fusion and IDET
Table 2. Study Background Characteristics and Clinical Findings of Published Reports of Spinal Fusion for the
Treatment of Discogenic Low Back Pain
Reference
Study Characteristics
Outcome
§
Baseline
Value
Final
Follow-up
Value
∆ from Baseline
% GE
||
% AE
¶
Design
*
Indication
†
Procedure
‡
Sample
Size value (%)
P
value
France et al
1999
RCT
J.S. = 1
DDD PLF
PLF
#
41
42
PS NR
NR
4.0
4.0
NR
NR
NS 63
73
NR
Boden et al
2000
RCT
J.S. = 3
DDD
ALIF
**
ALIF
††
11
3
OS 39
35
14
20
25
15
(64)
(43)
.12 100
67
21
SF 48
30
86
67
38
37
(79)
(123)
NR
Fritzell et al
2001
RCT
J.S. = 3
DDD/DH V
CM
222
72
PS 64
63
43
58
21
5
(33)
(8)
.0002 NR 17
OS 47
48
36
46
11
2
(24)
(6)
.015
Boden et al
2002
RCT
J.S. = 2
DDD
PLF
††
PLF
**
PLF
**#
5
11
9
PS 17
16
13
11
11
3
6
5
10
(35)
(31)
(77)
.025 60
60
100
12
OS 54
49
40
31
36
11
23
13
29
(43)
(27)
(73)
NR
SF
‡‡
26
29
31
32
35
48
6
6
17
(23)
(21)
(55)
.07
Burkus et al
2002
RCT
J.S. = 2
DDD
ALIF
**
ALIF
††
143
136
PS 16
16
7
8
9
8
(56)
(50)
NR NR 10
OS 54
55
24
24
29
30
(54)
(55)
NR
Burkus et al
2002
RCT
J.S. = 2
DDD
ALIF
**
ALIF
††
24
22
PS 16.3
16.3
7.4
10.9
9
5
(56)
(31)
.05 83
55
4
18
OS 52
55
19
33
33
22
(63)
(40)
.04
SF
‡‡
30
30
45
40
15
10
(50)
(33)
NS
Fritzell et al
2002
RCT
J.S. = 3
DDD
PLF
#
PLF
CF
73
74
75
PS 64
63
66
45
40
46
19
23
20
(30)
(36)
(30)
NS 41
50
46
6
16
31
OS 47
48
47
37
34
39
10
14
8
(21)
(29)
(17)
NS
Gibson et al
2002
RCT
J.S. = 1
DDD
PLF
††
PLF
§§
32
37
RM 18
17
11
15
7
2
(39)
(12)
.04 NR NR
Ivar Brox et al
2003
RCT
J.S. = 3
CNLBP/ DDD PLF
CM
37
27
PS 62
64
39
49
23
15
(37)
(23)
.14 NR 18
OS 42
43
26
30
16
13
(38)
(30)
.33
Sasso et al
2004
RCT
J.S. = 2
DDD
ALIF
||||
ALIF
§§
77
62
OS 51
53
30
32
21
21
(41)
(40)
NS NR 44
36
SF
‡‡
28
29
40
37
12
8
(43)
(28)
NS
Madan et al
2003
NCT IDD PLF
PLIF
36
35
PS 8.4
8.4
5.3
4
3.1
4.4
(37)
(52)
NS 64
80
8
11
OS 64
67
39
31
25
36
(39)
(54)
NS
Gertzbein
et al
1996
BA DDD CF 67 PS 7.1 2.1 5 (70) .006 NR 10
Hall et al
1996
BA DDD PLF 120 PS NR NR 2.6 NR <.0001 65 13
Kuslich et al
1998
BA DDD ALIF/PLIF 947 PS 5.0 2.9 2.1 (42) .001 NR 2
Simmons
et al
1998
BA DDD PLF 213 PS 3.7 2.0 1.7 (46) <.0001 NR 22
Table 2 continued to p. 171.

Andersson et al • A Systematic Review of Spinal Fusion and IDET 241
Pain Physician Vol. 9, No. 3, 2006
Reference
Study Characteristics
Outcome
§
Baseline
Value
Final
Follow-up
Value
∆ from Baseline
% GE
||
% AE
¶
Design
*
Indication
†
Procedure
‡
Sample
Size value (%)
P
value
Kuslich et al
2000
BA DDD ALIF/PLIF 196 PS 5.1 2.8 2.3 (45) <.05 NR 14
Kleeman et al
2001
BA DDD ALIF 22 PS
OS
SF
7.7
47
40
1.9
11
84
5.8
36
44
(75)
(77)
(110)
<.001
<.001
NR
NR 9
Lowe et al
2002
BA DDD/DH PLIF 40 PS 8.3 3.2 5.1 (61) <.0001 80 10
Pellise et al
2002
BA DDD ALIF 12 PS 7.2 2.2 5 (69) <.01 92 NR
Folman et al
2003
BA DDD PLIF 87 PS
OS
8.5
31
3.3
13
5.2
18
(61)
(58)
<.01
<.01
NR 3
Buttermann
et al
1998
CS DDD V 35 PS
OS
8.5
63
4.5
32
4
31
(47)
(49)
<.05
<.05
NR NR
Gertzbein
et al
1998
CS DDD CF 51 PS 7.4 4.4 3 (41) <.001 17 27
Grob and
Humke
1998
CS IDD/DH PLF 173 PS 7.6 2.9 4.7 (62) NR 76 10
Humke et al
1998
CS DH PLF 173 PS 7.6 2.9 4.7 (62) NR 76 10
Whitecloud
et al
1998
CS DDD CF 35 PS 7.2 5.5 1.7 (24) .0002 NR 54
Leufven and
Nordwall
1999
CS DDD PLIF 29 PS 8.6 4.0 4.6 (53) <.001 52 7
Tandon et al
1999
CS CNLBP PLIF 53 OS 51 39 12 (24) <.001 NR 13
Barrick et al
2000
CS DDD/DH ALIF 18 PS
OS
7.9
56
4.7
48
3.2
8
(41)
(17)
<.001
.03
NR NR
algott et al
2000
CS DDD/IDD CF 46 PS NR NR NR (56) NR 76 NR
Madan and
Boeree
2001
CS DDD ALIF 27 PS
OS
8.2
60
4.1
34
4.1
26
(50)
(43)
<.0001
<.0001
NR 11
algott et al
2002
CS DDD/IDD ALIF 50 PS 8.9 3.8 5.1 (57) NR 90 16
algott et al
2002
CS DDD CF 20 PS
OS
8.9
64
3.4
35
5.5
29
(62)
(45)
NR 80 15
Beutler and
Peppelman
2003
CS DDD ALIF 104 OS 58 34 24 (41) NR NR NR
NS, not signicant; NR, not reported.
*
RCT indicates randomized controlled trial; NCT, nonrandomized controlled trial; BA, prospective before-after trial; CS, retrospective case series. J.S.
indicates Jadad score (1 to 5) for methodological quality.
†
DDD indicates degenerative disc disease; IDD, internal disc disruption; DH, disc herniation; CNLBP, chronic nonspecic low back pain.
‡
PLF indicates posterolateral fusion; PLIF, posterior lumbar interbody fusion; ALIF, anterior lumbar interbody fusion; IF, interbody fusion; CF, combined
anterior-posterior or 360°
fusion; CM, conservative management; V, various fusion techniques.
§
PS indicates pain severity; OS, Oswestry disability index; SF, SF-36 physical functioning domain (unless otherwise indicated); RM, Roland-Morris dis-
ability questionnaire.
||
GE indicates good or excellent clinical results.
¶
AE indicates adverse events.
#
Fusion procedure performed without instrumentation.
**
Graft material consisted of rhBMP-2.
† †
Graft material consisted of autologous bone.
‡‡
Results provided for the SF-36 physical component summary score.
§§
Graft material consisted of allogeneic bone or femoral ring allograft.
||||
Cylindrical threaded titanium cage device.
Table 2 continued

242
Pain Physician Vol. 9, No. 3, 2006
Andersson et al • A Systematic Review of Spinal Fusion and IDET
ventions, the patient was generally un-
blinded to treatment assignment in ran-
domized controlled trials and this ad-
versely affected the methodological
quality ratings of these studies.
Table 3 provides comparable find-
ings for the IDET procedure regarding
indication, type of procedure as well as
baseline and final follow-up values for
the 3 primary outcomes and complica-
tion rates. There were 15 studies (83%)
reporting pain severity results, 5 stud-
ies (28%) reporting Oswestry results
and 8 studies (44%) reporting SF-36 re-
sults. The overall median percentage
improvement after the IDET procedure
in pain severity was 51% (range: 22% to
71%), in Oswestry was 14% (range: 4%
to 35%), and in SF-36 was 43% (range:
7% to 76%). In 5 IDET studies (28%)
the median percentage of patients ex-
periencing at least a 2-point improve-
ment in pain severity on a 10-point vi-
sual analog scale was 65% (range: 52%
to 72%).
The two randomized controlled
trials of the IDET procedure versus a
sham control also had conflicting find-
ings (62, 63). Pauza et al (62) demon-
strated significantly better improve-
ment in pain severity (36% vs. 17%, P
= 0.045) and back function (35% vs.
12%, P < 0.05) among patients treat-
ed with the IDET procedure compared
to patients randomly assigned to sham
control. These improvements were re-
alized in spite of a notable placebo re-
sponse among sham-treated patients
(Table 3). Alternatively, Freeman et al
(63) reported an almost uniform lack of
effectiveness in either treatment group
on any outcome over 6 months. For ex-
ample, subjects randomly treated with
the IDET procedure experienced an ap-
proximate 4% average improvement in
back function compared to their sham-
treated counterparts who had an ap-
proximate 2% decline (P = 0.50).
Adverse events were rarely expe-
rienced with the IDET procedure. Of
14 IDET studies reporting periopera-
tive complications, 11 studies (79%) re-
ported no complications. In the 3 IDET
studies reporting adverse events, the
rate was comparatively low (range: 9%
to 16%). Both randomized controlled
trials of the IDET procedure were rat-
ed as having excellent methodological
quality (Jadad score: 5) and a success-
fully executed blinded sham control
(62, 63).
The median percentage improve-
ment from baseline and the associated
range for the 3 primary outcomes cate-
gorized by study design are presented in
Table 4. There was an identifiable trend
for randomized controlled trials to re-
port a smaller magnitude of improve-
ment in all outcomes compared to oth-
er types of trials. This trend was appar-
ent for studies of both spinal fusion and
the IDET procedure. For example, there
was an approximate 36% median reduc-
tion in pain severity realized after spinal
fusion in randomized controlled trials
compared to a median reduction of 61%
reported in before-after trials. The me-
dian pain severity reduction (36%) for
one of the randomized controlled trials
of the IDET procedure compared favor-
ably with trials of spinal fusion. Similar-
ly, the median percentage improvement
in pain severity was higher (50%) in be-
fore-after trials of IDET (Table 4).
discussion
This systematic review provides a
comparative evaluation of clinical out-
come and complication rates for pub-
lished studies of spinal fusion and the
IDET procedure. Patients included in
these studies suffered from severe in-
tractable back pain of discogenic ori-
gin. These patients uniformly experi-
enced inadequate pain amelioration,
exhausting the entire range of conser-
vative medical interventions includ-
ing pain medications, physical thera-
py, epidural injections, and psycholog-
ical interventions. Patients eligible for
the IDET procedure have specific im-
aging and discographic evidence of in-
ternal disc disruption. These patients
represent a subset of cases presenting
with the more general diagnosis of se-
vere disc degeneration that are man-
aged operatively with spinal fusion and,
groups), ALIF (median: 43%, range:
17% to 77%, n=12 study groups), and
CF (median: 31%, range: 17% to 45%,
n=2 study groups). There were too few
studies reporting SF-36 results to sub-
categorize the findings by spinal fusion
procedure.
Sixteen of 33 (48%) spinal fusion
studies reported on the percentage of
patients achieving good or excellent re-
sults (Table 2). The overall median per-
centage value of good or excellent re-
sults was 67% but the range was wide
(17% to 100%). There was a somewhat
lower median percentage of good or ex-
cellent results for patients treated with
PLF or CF although the ranges were
overlapping: PLF (median: 64%, range:
41% to 100%, n=10 study groups), PLIF
(median: 80%, range: 52% to 80%, n=3
study groups), ALIF (median: 85%,
range 55% to 100%, n=6 study groups),
and CF (median: 61%, range: 17% to
80%, n=4 study groups).
The 2 randomized controlled tri-
als of spinal fusion versus conserva-
tive management had conflicting find-
ings (31, 37). Fritzell et al (31) dem-
onstrated significantly better improve-
ment in pain severity (33% vs. 8%, P =
0.0002) and back function (24% vs. 6%,
P = 0.015) among patients treated with
fusion compared to patients assigned
to nonoperative management. On the
other hand, Ivar Brox et al (37) failed
to show a difference in improvement in
pain severity (37% vs. 23%, P = 0.14) or
back function (38% vs. 30%, P = 0.33)
between fusion and conservative man-
agement, respectively.
Perioperative complications were
commonly associated with spinal fu-
sion (median: 14%, range: 2% to 54%,
n=31 study groups) with a tendency for
a higher percentage of adverse events
among patients treated with circum-
ferential (360º) fusion. Two random-
ized controlled trials of spinal fusion
were rated as having poor methodolog-
ical quality (Jadad score: 1) (29, 36), 4
were rated fair (Jadad score: 2) (32-34,
38), and 4 were rated good (Jadad score:
3) (30, 31, 35, 37). Due to the distinct
characteristics of these surgical inter-

Andersson et al • A Systematic Review of Spinal Fusion and IDET 243
Pain Physician Vol. 9, No. 3, 2006
Table 3. Study Background Characteristics and Clinical Findings of Published Reports of Intradiscal Electrothermal
Therapy (IDET) for the Treatment of Discogenic Low Back Pain
Reference Study Characteristics
Outcome
§
Baseline
Value
Final
Follow-up
Value
∆ from Baseline % ∆ PS
≥ 2
points||
% AE
¶
Design
*
Indication
†
Procedure
‡
Sample
Size value (%)
P
value
Pauza et al
2004
RCT
J.S. = 5
IDD SC
sSC
37
27
PS 6.6
6.5
4.2
5.4
2.4
1.1
(36)
(17)
.045 56 0
OS 31
33
20
28
11
4
(35)
(12)
.05
SF 56
49
71
60
15
11
(27)
(22)
.55
Freeman et al
2005
RCT
J.S. = 5
DDD SC
sSC
38
19
OS 41
41
40
42
1
1
(4)
(2)
.5 NR 0
SF 42
35
45
37
3
2
(7)
(6)
.8
Karasek and Bogduk
2000
NCT IDD SC
CM
36
17
PS 8.0
8.0
3.0
8.0
5
0
(63)
(0)
<.0001 NR 0
Bogduk and Karasek
2002
NCT IDD SC
CM
36
17
PS 8.0
8.0
3.0
7.5
5
.5
(63)
(6)
.03 NR 0
Derby et al
2000
BA IDD/DDD SC 32 PS
RM
NR
NR
NR
NR
1.84
4.03
NR
NR
NR
NR
NR 0
Saal and Saal
2000
BA CNLBP SC 62 PS
SF
6.6
39
3.7
59
3.0
20
(45)
(51)
<.001
<.001
NR 0
Saal and Saal
2000
BA CNLBP SC 25 PS
SF
7.3
40
3.6
55
3.7
15
(51)
(38)
<.0001
.001
NR 0
Singh
2000
BA IDD SC 21 PS 6.2 3.9 2.3 (37) .0001 NR NR
Welch et al
2001
BA DDD SC 23 OS
SF
34
31
26
47
8
16
(24)
(52)
NR
NR
NR 8.6
Gerszten et al
2002
BA DDD SC 27 OS
SF
34
32
30
47
4
15
(7)
(47)
NR
NR
NR 0
Saal and Saal
2002
BA CNLBP SC 58 PS
SF
6.6
41
3.4
72
3.2
31
(48)
(76)
.0001
<.0001
72 0
Spruit and Jacobs
2002
BA DDD SC 20 PS
OS
SF
65
43
45
51
37
55
14
6
10
(22)
(14)
(22)
<.05
NS
NS
NR NR
Lutz et al
2003
BA CNLBP SC 33 PS
RM
7.5
13.9
3.9
6.6
3.9
7.3
(52)
(53)
<.001
<.001
70 0
Kapural et al
2004
BA DDD SC 17 PS 7.4 2.5 4.9 (66) <.001 NR NR
Mekhail and Kapural
2004
BA IDD SC 32 PS 8.0 2.3 5.7 (71) <.001 NR NR
Endres et al
2002
CS DDD SC 54 PS NR NR NR <.001 65 0
Cohen et al
2003
CS DDD SC 79 PS 5.9 2.1 3.8 (64) NR NR 10
Freedman et al
2003
CS CNLBP SC 31 PS NR NR NR NR 52 16
NS, not signicant; NR, not reported.
* RCT indicates randomized controlled trial; NCT, nonrandomized controlled trial; BA, prospective before-after trial; CS, retrospective case
series. J.S. indicates Jadad score (1 to 5) for methodological quality.
† DDD indicates degenerative disc disease; IDD, internal disc disruption; CNLBP, chronic nonspecic low back pain.
‡ SC, SpineCATH device; sSC, sham SpineCATH device; CM, conservative management.
§ PS indicates pain severity; OS, Oswestry disability index; SF, SF-36 physical functioning domain; RM, Roland-Morris disability question-
naire.
|| Adjusted to a standard 10-point visual analog scale (VAS).
¶ AE indicates adverse events.
consequently, may have somewhat dif-
ferent clinical characteristics at base-
line. Inspection of comparative median
pain severity scores (and ranges) sug-
gests that the severity of back pain suf-
fered by patients prior to spinal fusion
was somewhat higher but with general-
ly similar overlapping ranges, to the se-
verity reported by patients undergoing
the IDET procedure. Thus, the present-
ing symptomatology of patients includ-
ed in both types of studies was fairly ho-
mogeneous. A primary goal of this lit-
erature review was to evaluate wheth-
er highly-selected patients with defini-
tive evidence of internal disc disruption
could benefit from the IDET procedure
at a stage prior to undergoing operative
intervention and, thus, markedly delay
or obviate the need for subsequent spi-
nal fusion.
The median percentage of patients
reporting good or excellent results after
spinal fusion surgery for discogenic low

244
Pain Physician Vol. 9, No. 3, 2006
Andersson et al • A Systematic Review of Spinal Fusion and IDET
back pain in the current synthesis was
67% (range: 17% to 100%). This finding
is similar to results reported by Turner
et al (86) in 1992, for the percentage of
satisfactory outcomes after fusion for all
indications (mean: 68%, range: 16% to
95%). Bono and Lee (24) likewise found
no difference in good or excellent per-
centages in fusion studies of degenera-
tive disc disease published in the 1980s
(78%) and the 1990s (74%). This appar-
ent lack of improvement in clinical out-
come following spinal fusion is note-
worthy in light of the significant tech-
nical and device-related advances in
the surgical procedure during the last
decade including pedicle screw instru-
mentation and interbody cage systems.
The current literature review in-
cluded only studies of patients where
disc degeneration was implicated as the
primary cause of chronic pain and was
stated as the indication for more aggres-
sive intervention beyond nonopera-
tive conservative medical management.
While previous studies have generally
found little association between surgical
indication and outcome (49, 86), the fo-
cus on a single indication in this review
allowed for a direct comparison of out-
comes following spinal fusion and the
IDET procedure. This report also has
the advantage of providing results for
both spinal fusion and the IDET pro-
cedure on a set of well-described clin-
ical outcomes including pain severity,
condition-specific functional impair-
ment and health-related quality of life
that previous reviews have not includ-
ed (81, 87).
It remains unclear whether spinal
fusion provides an advantage over con-
servative medical management with
respect to symptomatic improvement
among patients with intractable disco-
genic low back pain. The two random-
ized controlled trials comparing spi-
nal fusion with conservative manage-
ment provided conflicting findings in
this regard for both pain severity and
functional impairment of the back (31,
37). The subjects in these trials were
unblinded to treatment assignment,
subjecting them to ascertainment bias.
This methodological shortcoming re-
duced the quality rating of these stud-
ies. Inadequate treatment allocation
concealment and lack of double blind-
ing can substantially inflate treatment
effects, particularly with respect to psy-
chologically-linked and subjective out-
comes such as the perception of pain,
its severity and the degree of associated
functional impairment (88-90). Thus, it
is impossible to estimate the contribu-
tion of nonspecific study effects, par-
ticularly placebo effect, on the report-
ed improvements realized with spinal
fusion (91). This may also explain, in
large part, the often weak association
shown between symptomatic improve-
ment and whether the fusion surgery
was technically successful in achieving
a solid arthrodesis (91).
Previous reviews of the clinical lit-
erature regarding the IDET procedure
have noted encouraging findings but
cautioned that lack of controlled tri-
als prevented definitive conclusions re-
garding treatment effectiveness (92, 93).
Both randomized controlled trials of the
IDET procedure included in this review
were methodologically sound with ap-
propriate treatment allocation conceal-
ment and the successful execution of a
blinded sham control. Indeed, Pauza et
al (62) reported that patients in either
study group were unable to accurate-
ly guess whether they received the true
intervention or the sham. Consequent-
ly, a placebo response amounting to an
approximate 20% reduction in pain se-
verity was demonstrated in this study.
Nonetheless, Pauza et al (62) showed a
significant improvement in back pain
severity and functional impairment be-
yond the placebo response.
In sharp contrast, Freeman et al
(63) failed to demonstrate either a treat-
ment or a placebo response in their
sham-controlled trial of the IDET pro-
cedure. These idiosyncratic results are
particularly notable given the large
body of evidence describing an iden-
tifiable placebo effect associated with
sham procedures where the primary
outcomes involve subjectivity, such as
pain severity and its surrogates (91). It
is plausible that inappropriate patient
selection criteria may explain these
Table 4. Summary of Percentage Improvement in Outcomes by Study Design for each
Treatment Type
Outcomes
*
Spinal Fusion
IDET
†
% %
no. of 33 median (range) no. of 18 median (range)
Pain Severity
‡
RCT 6 36 (30-77) 1 36 (NA)
NCT 1 NA (37-52) 2 63 (NA)
BA 8 61 (42-75) 8 50 (22-71)
CS 11 53 (24-62) 1 64 (NA)
Back-Specic Impairment
§
RCT 8 40 (17-73) 2 20 (4-35)
NCT 1 NA (39-54) 0 NA
BA 2 NA (58-77) 3 14 (7-24)
CS 6 42 (17-49) 0 NA
Quality of Life
||
RCT 5 43 (21-123) 2 17 (7-27)
NCT 0 NA 0 NA
BA 1 110 (NA) 6 49 (22-76)
CS 0 NA 0 NA
NA, not applicable.
*
Categorized by study design: RCT indicates randomized control trial; NCT, nonrandomized control
trial; BA, prospective before-after trial; CS, retrospective case series.
†
IDET indicates intradiscal electrothermal therapy.
‡
Measured by visual analog scale (VAS).
§
Measured by Oswestry disability index.
||
Measured by either SF-36 physical functioning domain or physical component summary score.

Andersson et al • A Systematic Review of Spinal Fusion and IDET 245
Pain Physician Vol. 9, No. 3, 2006
findings. Specifically, study subjects had
markedly severe disc degeneration with
up to 50% disc height loss, full thickness
annular tears, and a maximum duration
of symptoms of 20 years. Also, greater
than 50% of the subjects were recipients
of worker’s compensation, a group with
a notoriously high rate of recidivism and
poor outcomes (94). The IDET proce-
dure is considered more appropriate in
the acute phase of injury with pain lo-
calized to the annulus and not the end-
plates or facet joints, as commonly oc-
curs with advanced disc degeneration
(75).
Spinal fusion is a complex and ar-
duous surgical intervention. This re-
view found that perioperative compli-
cations occur frequently. Deyo et al (95,
96) estimated that the complication rate
associated with fusion surgery was more
than 2 times greater than for back sur-
gery without fusion. Likewise, in a ran-
domized controlled trial, Fritzell et al
(97) reported a relatively high compli-
cation rate for instrumented PLF (22%)
and CF (40%) with a significantly lower
complication rate among subjects treat-
ed with uninstrumented PLF (12%). In
sharp contrast, this review found few
complications associated with the IDET
procedure with most studies reporting
no adverse events at all. There have been
several isolated case reports of IDET-re-
lated complications which included a
herniated disc (98), cauda equina syn-
drome (99, 100) and vertebral osteone-
crosis (101, 102).
IDET is a minimally-invasive per-
cutaneous procedure that has the ad-
vantage of preserving the native disc
structure (103). Consequently, undergo-
ing the IDET procedure does not elimi-
nate the possibility for surgery at a later
time if severe symptoms persist. How-
ever, among a subset of properly select-
ed chronic back pain sufferers with de-
finitive imaging and discographic ev-
idence of internal disc disruption, the
IDET procedure may obviate the need
for surgery completely.
The overall median percentage of
patients exhibiting a clinically signifi-
cant 2-point reduction in pain severi-
ty in this synthesis was 65%. In a ran-
domized controlled trial, Pauza et al
(62) likewise found that 56% of subjects
treated with the IDET procedure re-
ported a reduction in pain severity of at
least 2 points. In this same trial, 22% of
IDET subjects reported a 75% or greater
pain severity reduction with 9% of sub-
jects reported to be pain free. In a non-
randomized controlled trial, Bogduk
and Karasek (65) reported that 20% of
patients were pain free 24 months af-
ter treatment with the IDET procedure.
The 36-month follow-up in a registry of
approximately 400 patients treated with
IDET showed that only 17% of patients
required spinal fusion surgery due to
persistent symptoms (104). Assuming
a clinically relevant reduction in pain
severity following the IDET procedure
would obviate the need for spinal fu-
sion, it could be postulated that be-
tween 56% and 65% of properly select-
ed patients with intractable discogenic
low back pain would be spared fusion
surgery with its attendant costs, compli-
cations and risks.
The direct periprocedural costs as-
sociated with the IDET procedure have
been estimated at $7,000 US (77). In
contrast, estimates of the direct peri-
operative costs associated with spinal
fusion have been reported in excess of
$50,000 US with more complex proce-
dures involving greater costs (105, 106).
Importantly, these estimates do not in-
clude costs associated with the man-
agement of postoperative complica-
tions which can be substantial in spi-
nal fusion. Thus, based on the compa-
rable clinical improvements realized
with either spinal fusion or the IDET
procedure, particularly with respect to
pain severity and functional impair-
ment, and with the estimate that more
than half of IDET-treated patients could
avoid surgery, it may be prudent to offer
the IDET procedure prior to spinal fu-
sion among all patients who meet strict
eligibility criteria for this procedure.
Gunnar B. J. Andersson, MD, PhD
Professor and Chairman
Department of Orthopedic Surgery
Rush University Medical Center
1653 West Congress Parkway
Chicago, IL 60612
Gunnar_Andersson@rush.edu
Nagy A. Mekhail, MD, PhD
Chairman
Department of Pain Management
Cleveland Clinic Foundation
9500 Euclid Avenue
Cleveland, OH 44195
MEKHAIN@ccf.org
Jon E. Block, PhD
2210 Jackson Street, Suite 401
San Francisco, CA 94115
jonblock@jonblockphd.com
Author AffiliAtion:
AcknowledgMent
This study was supported, in part,
by Smith & Nephew Endoscopy (Ando-
ver, MA).
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