REVIEW ARTICLE

Transforaminal endoscopic surgery for symptomatic lumbar discherniations: a systematic review of the literature

Jorm Nellensteijn Æ Raymond Ostelo Æ Ronald Bartels ÆWilco Peul Æ Barend van Royen Æ Maurits van Tulder

Received: 11 March 2009 / Revised: 29 June 2009 / Accepted: 19 August 2009 / Published online: 15 September 2009

� The Author(s) 2009. This article is published with open access at Springerlink.com

Abstract The study design includes a systematic litera-

ture review. The objective of the study was to evaluate the

effectiveness of transforaminal endoscopic surgery and to

compare this with open microdiscectomy in patients with

symptomatic lumbar disc herniations. Transforaminal

endoscopic techniques for patients with symptomatic lum-

bar disc herniations have become increasingly popular. The

literature has not yet been systematically reviewed. A

comprehensive systematic literature search of the MED-

LINE and EMBASE databases was performed up to May

2008. Two reviewers independently checked all retrieved

titles and abstracts and relevant full text articles for inclu-

sion criteria. Included articles were assessed for quality and

outcomes were extracted by the two reviewers indepen-

dently. One randomized controlled trial, 7 non-randomized

controlled trials and 31 observational studies were identi-

fied. Studies were heterogeneous regarding patient selec-

tion, indications, operation techniques, follow-up period

and outcome measures and the methodological quality of

these studies was poor. The eight trials did not find any

statistically significant differences in leg pain reduction

between the transforaminal endoscopic surgery group

(89%) and the open microdiscectomy group (87%); overall

improvement (84 vs. 78%), re-operation rate (6.8 vs. 4.7%)

and complication rate (1.5 vs. 1%), respectively. In con-

clusion, current evidence on the effectiveness of trans-

foraminal endoscopic surgery is poor and does not provide

valid information to either support or refute using this type

of surgery in patients with symptomatic lumbar disc her-

niations. High-quality randomized controlled trials with

sufficiently large sample sizes are direly needed to evaluate

if transforaminal endoscopic surgery is more effective than

open microdiscectomy.

Keywords Lumbar disc herniation � Transforaminal �Endoscopic surgery � Minimally invasive surgery �Systematic review

Introduction

Surgery for lumbar disc herniation can be classified into

two broad categories: open versus minimally invasive

surgery and posterior versus posterolateral approaches.

Mixter and Barr in 1934 were the first authors to treat

lumbar disc herniation surgically by performing an open

laminectomy and discectomy [41]. With the introduction of

the microscope, Caspar and Yasargil refined the original

laminectomy into open microdiscectomy [4, 63]. Lami-

nectomy and microdiscectomy are open procedures using a

posterior approach. Currently, open microdiscectomy is the

most widespread procedure for surgical decompression of

radiculopathy caused by lumbar disc herniation, but

J. Nellensteijn

Department of Orthopaedics, EMGO Institute, VU University

Medical Center, Amsterdam, The Netherlands

R. Ostelo (&) � M. van TulderDepartment of Health Sciences, EMGO Institute, VU University

Medical Center, VU University, De Boelelaan 1085,

room U-430, 1081 HV Amsterdam, The Netherlands

e-mail: r.ostelo@vumc.nl

W. Peul

Leiden University Medical Center, Leiden, The Netherlands

R. Bartels

Department of Neurosurgery, Radboud University Nijmegen

Medical Centre, Nijmegen, The Netherlands

B. van Royen

VU University Medical Center, Amsterdam, The Netherlands

123

Eur Spine J (2010) 19:181–204

DOI 10.1007/s00586-009-1155-x

minimally invasive surgery has gained a growing interest.

The concept of minimally invasive surgery for lumbar disc

herniations is to provide surgical options that optimally

address the disc pathology without producing the iatro-

genic morbidity associated with the open surgical proce-

dures. In the last decades, endoscopic techniques have been

developed to perform discectomy under direct view and

local anaesthesia.

Kambin and Gellmann in 1973 [22] in the United States

and Hijikata in Japan in 1975 [12], independently per-

formed a non-visualised, percutaneous central nucleotomy

for the resection and evacuation of nuclear tissue via a

posterolateral approach. In 1983, Forst and Housman

reported the direct visualization of the intervertebral disc

space with a modified arthroscope [9]. Kambin published

the first intraoperative discoscopic view of a herniated

nucleus pulposus in 1988 [21]. In 1989 and 1991 Schreiber

et al. described ‘percutaneous discoscopy’, a biportal

endoscopic posterolateral technique with modified instru-

ments for direct view [52, 55]. In 1992, Mayer introduced

percutaneous endoscopic laser discectomy combining for-

ceps and laser [40]. With the further improvement of

scopes (e.g. variable angled lenses and working channel for

different instruments), the procedure became more refined.

The removal of sequestered non-migrated fragments

became possible using a biportal approach [25]. The con-

cept of posterolateral endoscopic lumbar nerve decom-

pression changed from indirect central nucleotomy (inside

out, in which fragments are extracted through an annular

fenestration outside the spinal canal) to transforaminal

direct extraction of the non-contained and sequestered disc

fragments from inside the spinal canal. In this article, the

technique of direct nucleotomy is described as intradiscal

and the technique directly in the spinal canal is described

as intracanal technique; both are transforaminal approaches

(Fig. 1).

The indications for transforaminal endoscopic treatment

are the same as classical discectomy procedures [6, 24, 38].

To reach the posterior part of the epidural space, the

superior articular process of the facet joint is usually the

obstacle. Yeung and Knight used a holmium-YAG

(yttrium-aluminium-garnet)—laser for ablation of bony

and soft tissue for decompression, enhanced access and to

improve intracanal visualisation [30, 64]. Yeung developed

the commercially available Yeung Endoscopic Spine Sys-

tem (YESS) in 1997 [65] and Hoogland in 1994 developed

the Thomas Hoogland Endoscopic Spine System (THES-

SYS). With this latter system, it is possible to enlarge the

intervertebral foramen near the facet joint with special

reamers to reach intracanal extruded and sequestered disc

fragments and decompress foraminal stenosis [16].

Recently, also another minimally invasive technique,

microendoscopic discectomy (MED), has been developed.

In MED, a microscope is used and the spine is approached

from a posterior direction and not transforaminal. There-

fore, this technique is not considered in the current sys-

tematic review.

Endoscopic surgery for lumbar disc herniations has been

available for more than 30 years, but at present a systema-

tic review of all relevant studies on the effectiveness of

transforaminal endoscopic surgery in patients with symp-

tomatic lumbar disc herniations is lacking.

Methods

Objective

The objective of this systematic review was to assess the

effectiveness of transforaminal endoscopic surgery in

patients with symptomatic lumbar disc herniations. The

main research questions were

1. What is the effectiveness of transforaminal endoscopic

surgery?

a. What is the effectiveness of the older intradiscal

transforaminal technique and the more recently

developed extracanal transforaminal technique?

b. What is the effectiveness of transforaminal endo-

scopic surgery for the different types of hernia-

tions (mere lateral herniations versus central

herniations versus all types of lumbar disc

herniations)?

2. What is the effectiveness of transforaminal endoscopic

surgery when compared with open microdiscectomy?

For this systematic review, we used the method guide-

lines for systematic reviews as recommended by the

Cochrane Back Review Group [61]. Below the searchFig. 1 Different posterolateral approaches to the lumbar disc. a Theintradiscal technique, b the intracanal technique

182 Eur Spine J (2010) 19:181–204

123

strategy, selection of the studies, data extraction, methodo-

logical quality assessment and data analysis are described

in more detail. All these steps were performed by two

independent reviewers and during consensus meetings

potential disagreements between the two reviewers

regarding these issues were discussed. If they were not

resolved, a third reviewer was consulted.

Search strategy

An experienced librarian performed a comprehensive sys-

tematic literature search. The MEDLINE and EMBASE

databases were searched for relevant studies from 1973 to

May 2008. The search strategy consisted of a combination

of keywords concerning the technical procedure and key-

words regarding the anatomical features and pathology

(Table 1). We conducted two reviews, one on lumbar disc

herniation and one on spinal stenosis, and combined the

search strategy for these two reviews for efficiency reasons.

These keywords were used as MESH headings and free text

words. The full search strategy is available upon request.

Selection of studies

The search was limited to English, German and Dutch

studies, because these are the languages that the review

authors are able to read and understand. Two review

authors independently examined all titles and abstracts that

met our search terms and reviewed full publications, when

necessary. In addition, the reference sections of all primary

studies were inspected for additional references. Studies

were included that describe transforaminal endoscopic

surgery for adult patients with symptomatic lumbar disc

herniations. As we expected only a limited number of

randomized controlled trials in this field, we also included

observational studies (non-randomized controlled clinical

trials, cohort studies, case–control studies and retrospective

patient series). To be included, studies had to report on

more than 15 cases, with a follow-up period of more than

6 weeks.

Data extraction

Two review authors independently extracted relevant data

from the included studies regarding design, population (e.g.

age, gender, duration of complaints before surgery, etc),

type of surgery, type of control intervention, follow-up

period and outcomes. Primary outcomes that were con-

sidered relevant are pain intensity (e.g. visual analogue

scale or numerical rating scale), functional status (e.g.

Roland Morris Disability Scale, Oswestry Scale), global

perceived effect (e.g. McNab score, percentage patients

improved), vocational outcomes (e.g. percentage return to

work, number of days of sick leave), and other outcomes

(recurrences, complication, re-operation and patient satis-

faction). We contacted primary authors where necessary

for clarification of overlap of data in different articles.

Methodological quality assessment

Two review authors independently assessed the methodo-

logical quality of the included studies. Controlled trials

were assessed using a criteria list recommended by the

Cochrane Back review group as listed in Table 2 [61]. If

studies met at least 6 out of the 11 criteria, the study was

considered to have a low risk of bias (RoB). If only 5 or

less of the criteria were met, the study was labelled as high

RoB Non-controlled studies were assessed using a modi-

fied 5-point assessment score as listed in Table 3. Dis-

agreements were resolved in a consensus meeting and a

third review author was consulted when necessary.

Data analysis

To assess the effectiveness of transforaminal endoscopic

surgery and to compare it to open microdiscectomy, the

results of outcome measures were extracted from the ori-

ginal studies. The outcome data of some studies were

recalculated, because the authors of the original papers did

not handle drop outs, lost to follow-up and/or failed oper-

ations adequately. If a study reported several follow-up

intervals, the outcome of the longest follow-up moment

was used.

Because only one randomized trial was identified and

the controlled trials were heterogeneous regarding study

populations, endoscopic techniques, outcome measures,

measurement instruments and follow-up moments, statis-

tical pooling was not performed. The median and range

(min–max) of the results of the individual studies for each

outcome measure are presented.

Table 1 Selection of terms used in our search strategy

Technical procedure Anatomical features/disorder

Endoscopy Spine

Arthroscopy Back

Video-assisted surgery Back pain

Surgical procedures, minimally

invasive

Spinal diseases

Microsurgery Disc displacement

Transforaminal Intervertebral disc

displacement

Discectomy Spinal cord compression

Percutaneous Sciatica

Foraminotomy, foraminoplasty

discoscopy

Radiculopathy

Eur Spine J (2010) 19:181–204 183

123

Results

Search and selection

Two thousand five hundred and thirteen references were

identified in MEDLINE and EMBASE that were

potentially relevant for the reviews on lumbar disc herni-

ation and spinal stenosis. After checking the titles and

abstracts, a total of 123 full text articles were retrieved that

were potentially eligible for this review on lumbar disc

herniation. Reviewing the reference lists of these articles

resulted in an additional 17 studies. Some patient cohorts

Table 2 Criteria list for quality assessment of controlled studies

A Was the method of randomization adequate? Y N ?

B Was the treatment allocation concealed? Y N ?

C Were the groups similar at baseline regarding the most important prognostic indicators? Y N ?

D Was the patient blinded to the intervention? Y N ?

E Was the care provider blinded to the intervention Y N ?

F Was the outcome assessor blinded to the intervention? Y N ?

G Were co-interventions avoided or similar? Y N ?

H Was the compliance acceptable in all groups? Y N ?

I Was the drop out rate described and acceptable? Y N ?

J Was the timing of the outcome assessment in all groups similar? Y N ?

K Did the analysis include an intention to treat analysis? Y N ?

? score unclear

A: A random (unpredictable) assignment sequence. Examples of adequate methods are computer generated random number table and use of

sealed opaque envelopes. Methods of allocation using date of birth, date of admission, hospital numbers or alternation should not be regarded as

appropriate

B: Assignment generated by an independent person not responsible for determining the eligibility of the patients. This person has no information

about the persons included in the trial and has no influence on the assignment sequence or on the decision about eligibility of the patient

C: In order to receive a ‘yes’, groups have to be similar at baseline regarding demographic factors, duration and severity of complaints,

percentage of patients with neurological symptoms and value of main outcome measure(s)

D: The reviewer determines if enough information about the blinding is given in order to score a ‘yes

E: The reviewer determines if enough information about the blinding is given in order to score a ‘yes’

F: The reviewer determines if enough information about the blinding is given in order to score a ‘yes’

G: Co-interventions should either be avoided in the trial design or similar between the index and control groups

H: The reviewer determines if the compliance to the interventions is acceptable, based on the reported intensity, duration, number and frequency

of sessions for both the index intervention and control intervention(s)

I: The number of participants who were included in the study but did not complete the observation period or were not included in the analysis

must be described and reasons given. If the percentage of withdrawals and drop outs does not exceed 20% for short-term follow-up and 30% for

long-term follow-up and does not lead to substantial bias a ‘yes’ is scored. (N.B. these percentages are arbitrary, not supported by literature)

J: The timing of outcome assessment should be identical for all intervention groups and for all important outcome assessments

K: All randomized patients are reported/analysed in the group they were allocated to by randomization for the most important moments of effect

measurement (minus missing values) irrespective of non-compliance and co-interventions

Table 3 Criteria list for quality assessment of non-controlled studies

A Patient selection/inclusion adequately described? Y N ?

B Drop out rate described? Y N ?

C Independent assessor? Y N ?

D Co-interventions described? Y N ?

E Was the timing of the outcome assessment similar? Y N ?

? score unclear

A: All the basic elements of the study population are adequately described; i.e. demography, type and level of disorder, physical and radiological

inclusion and exclusion criteria, pre-operative treatment and duration of disorder

B: Are the patients of whom no outcome was obtained, described in quantity and reason for drop out

C: The data were assessed by an independent assessor

D: All co-interventions in the population during and after the operation are described

E: The timing of outcome assessment should be more or less identical for all intervention groups and for all important outcome assessments

184 Eur Spine J (2010) 19:181–204

123

were described in more than one article. In these cases, all

articles were used for the quality assessment of the study,

but outcome data reporting the longest follow-up was used.

After scrutinising all full text papers, 39 studies reported in

45 articles were included in this review. Sixteen studies

(41%) had a mean follow-up of more than 2 years. The

characteristics and outcomes of the included studies are

presented in Tables 4, 5, 6 and 7.

Type of studies and methodological quality

A total of six prospective controlled studies and two ret-

rospective controlled studies were included. Of the six

prospective controlled studies, only the study by Hermantin

et al. [11] was considered to have a low RoB. The other

five prospective controlled studies and two retrospective

controlled were labelled as a high RoB (the full RoB

assessment is available upon request).

Furthermore, 12 studies were designed as prospective

cohort (without control group) and there were 19 retro-

spective studies (also without control group). When it was

unclear whether the study was prospective or retrospective,

the study was considered retrospective.

Of the six prospective controlled studies, four compared

transforaminal endoscopic surgery with open discectomy

or microdiscectomy. All four were reported as randomized

trials, but in three of them the method of randomization

was inadequate. Mayer and Brock [39] did not describe the

randomization method at all, and Krappel et al. [31] and

Ruetten et al. [47] did not randomize, but allocated patients

alternately to transforaminal endoscopic surgery or

microdiscectomy. Only in the low RoB study by Hermantin

et al. [11] randomization was adequately performed in 60

patients with non-sequestered lumbar disc herniations.

However, the generalizability of this study is poor because

patients with a specific type of herniated disc were selected

and results are consequently not directly transferable to all

patients with lumbar disc herniations.

Outcomes

1. What is the effectiveness of transforaminal endoscopic

surgery?

No randomized controlled trials were identified. Outcomes

of 31 observational, non-controlled studies are presented in

Table 8. The median overall improvement of leg pain

(VAS) was 88 (range 65–89%), global perceived effect

(MacNab) 85 (72–94%), return to work of 90%, recurrence

rate 1.7%, complications 2.8% and re-operations 7%.

1a. What is the effectiveness of the older intradiscal

technique and the more recently developed intra-

canal technique?

No randomized controlled trials were identified. In Table 9

the results of 14 non-controlled studies describing the

intradiscal technique and 16 non-controlled studies

describing the intracanal technique are presented. The

median leg pain improvement (VAS) was 83% (78–88%)

for the intradiscal versus 88% (65–89%) for the intracanal

technique and the results for global perceived effect were

(MacNab) 85% (78–89%) versus 86% (72–93%), respec-

tively; and other outcomes are listed in Table 9.

1b. What is the effectiveness of transforaminal endo-

scopic surgery for the different types of hernia-

tions (mere lateral herniations versus central

herniations versus all types of lumbar disc

herniations)?

No randomized controlled trials were identified. Six non-

controlled studies described surgery for far-lateral hernia-

tions, one for central herniations and in 15 studies all types

of herniations were included. The median GPE (MacNab)

was 86% (85–86%) for lateral herniations, 91% for central

herniations and 83% (79–94%) for all types of herniations.

Other outcomes are listed in Table 10.

2. What is the effectiveness of transforaminal endoscopic

surgery compared to open microdiscectomy?

Six controlled studies (n = 720) were identified that

compared transforaminal endoscopic to open microdiscec-

tomy. Four of them were prospective and two retrospective

studies.

Only one randomized controlled trial (n = 60) with a

low RoB was identified that compared pure intradiscal

technique with open laminotomy [11]. There were no sta-

tistically significant differences between the two groups.

The pain reduction in the transforaminal endoscopic sur-

gery group was 71 versus 82% in the open laminotomy

group after on average 32 months follow-up. The overall

improvement was 97 versus 93%, re-operation rate 6.7

versus 3.3% and complication rate 6.7 versus 0%, respec-

tively. Overall, the controlled studies found no differences

in outcomes: leg pain reduction in the transforaminal

endoscopic surgery group was 89 versus 87% in the open

microdiscectomy group, overall improvement (GPE) was

84 versus 78%, re-operation rate 6.8 versus 4.7% and

complication rate 1.5 versus 1.0%, respectively (Table 11).

In none of the studies, there were any statistically signifi-

cant differences between the intervention groups on pain

improvement and global perceived effect. Ruetten et al.

[47] (n = 200) reported statistically significant differences

on return to work, but this was a secondary outcome and it

was unclear how many subjects in each group had work

and if groups were comparable regarding work status and

history of work absenteeism at baseline.

In one study, transforaminal endoscopic surgery was

compared with the same operation combined with

Eur Spine J (2010) 19:181–204 185

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urn

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I:9

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ol:

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y,

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14

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42

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ge

19

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or

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rolo

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me

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men

tal

inst

abil

ity

Eur Spine J (2010) 19:181–204 187

123

Ta

ble

4co

nti

nu

ed

Stu

dy/a

uth

or,

met

ho

do

log

yM

ain

incl

usi

on

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eria

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ain

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usi

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tech

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ow

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om

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men

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ette

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ized

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eno

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index

[38]

188 Eur Spine J (2010) 19:181–204

123

Ta

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test

)

Eur Spine J (2010) 19:181–204 189

123

Ta

ble

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]In

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ecifi

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om

pli

cati

on

s:1

.5%

Re-

oper

atio

ns:

4.6

%

Kaf

adar

etal

.[2

0]

Incl

usi

on

crit

eria

n=

42

$2#

40

,ra

ng

e1

8–

74

yea

rsP

ercu

tan

eou

sen

do

sco

pic

tran

sfora

min

aldis

cect

om

y(P

ET

D)

Fo

llo

w-u

p:

mea

n1

5m

on

ths

(ran

ge

6–

24

)(S

D4

),0

%lo

stto

foll

ow

-up

Au

tho

rsex

clu

ded

n=

8fr

om

anal

yse

sd

ue

tost

op

ped

pro

ced

ure

s.T

hes

ew

ere

tak

enin

toac

cou

nt

inth

isre

vie

wR

adic

ulo

pat

hy

Type:

all

LD

HP

ure

intr

adis

cal

tech

niq

ue

GP

E(S

/S-s

core

):14%

exce

llen

t,36%

good

36

%p

oo

r

Po

st-t

ensi

on

sign

Lev

el:

sin

gle

lev

el,

L4

–L

5K

arl

Sto

rzin

stru

men

tati

on

Rec

urr

ence

:0

%

Neu

rolo

gic

aldefi

cit

Co

mpli

cati

on

s:4

5%

Ex

clu

sio

ncr

iter

iaR

e-o

per

atio

ns:

17

%

Pre

vio

us

surg

ery

(sam

ele

vel

)

Spin

alst

enosi

s

Seg

men

tal

inst

abil

ity

Cal

cifi

edL

DH

190 Eur Spine J (2010) 19:181–204

123

Ta

ble

6co

nti

nu

ed

Stu

dy

Mai

nin

clu

sio

ncr

iter

ia,

mai

nex

clu

sio

ncr

iter

iaN

um

ber

of

par

tici

pan

tsty

pe/

lev

elL

DH

Inte

rven

tions/

tech

niq

ue/

inst

rum

enta

tio

nF

oll

ow

-up

:d

ura

tio

nan

do

utc

om

eC

om

men

t

Kam

bin

[23];

Kam

bin

Incl

usi

on

crit

eria

n=

17

5$7

6#

99

Art

hro

sco

pic

mic

rod

isce

cto

my

and

sele

ctiv

efr

agm

ente

ctom

yF

oll

ow

-up

:m

ean

48

mo

nth

s(r

ang

e2

4–

78

),3

.4%

lost

tofo

llo

w-u

p

Rad

icu

lop

ath

yT

yp

e:al

lL

DH

Pu

rein

trad

isca

lte

chniq

ue

GP

E(M

od

ified

Pre

sby,

St

Lu

ke

sco

re):

77

%ex

cell

ent,

11

%g

oo

d,

12

%fa

iled

Po

st-t

ensi

on

sign

Lev

el:

sin

gle

lev

el,

L2

-S

1K

amb

inte

chn

ique

Ret

urn

tow

ork

(3w

eek

s):

95

%

Neu

rolo

gic

aldefi

cit

Bip

ort

aln

=5

9C

om

pli

cati

on

s:5

.3%

Ex

clu

sio

ncr

iter

iaR

e-o

per

atio

ns:

7.7

%

Lar

ge

extr

alig

amen

tal

LD

H

Pre

vio

us

surg

ery

(sam

ele

vel

)

Cau

da

syn

dro

me

Deg

ener

ativ

ed

isc

Kn

igh

tet

al.

[27];

Kn

igh

tet

al.

[29

]In

clu

sio

ncr

iter

ian

=2

50

$?#

?,m

ean

48

yea

rs,

ran

ge

21

–86

En

dosc

op

icla

ser

fora

min

opla

sty

(EL

F)

Fo

llo

w-u

p:

mea

n3

0m

on

ths

(ran

ge

24

–4

8)

(SD

5.8

7),

3.2

%lo

stto

foll

ow

-up

Au

tho

rsin

clu

ded

also

deg

ener

ativ

ean

dla

tera

lst

enosi

sin

this

study

Pri

or

dis

csu

rger

yn

=7

5T

yp

e:A

llL

DH

Intr

adis

cal

and

intr

acan

alte

chniq

ue

Pai

n(V

AS

[5

0%

imp

rovem

ent)

:5

6%

Bac

kp

ain

Lev

el:

sin

gle

and

mult

iple

lev

el,

L2

–S

1R

ich

ard

Wo

lfin

stru

men

tati

on

Fu

nct

ion

alst

atu

s(O

DI)

:6

0%

imp

rov

edC

50

%

Leg

pai

nC

om

pli

cati

on

s:0

.8%

Rad

icu

lop

ath

yR

e-o

per

atio

ns:

5.2

%

Ex

clu

sio

ncr

iter

ia

Cau

da

syn

dro

me

Pai

nle

ssm

oto

rd

efici

t

Lee

etal

.[3

3]

Incl

usi

on

crit

eria

n=

11

6$4

3#

73

,m

ean

36

yea

rs,

ran

ge

18

–65

Per

cuta

neo

us

end

osc

op

iclu

mb

ard

isce

cto

my

(PE

LD

)F

oll

ow

-up

:m

ean

14

.5m

on

ths

(ran

ge

9–

20),

0%

lost

tofo

llo

w-u

p

Rad

icu

lop

ath

yT

yp

e:n

ot

spec

ified

Intr

adis

cal

and

intr

acan

alte

chniq

ue

Pai

nle

g(V

AS

):p

re-o

p.

7.5

,fo

llo

w-u

p2

.6,

dif

fere

nce

4.9

=6

5%

Neu

rolo

gic

aldefi

cit

Lev

el:

single

level

,L

2–S

1Y

ES

S,

Ric

har

dW

olf

inst

rum

enta

tio

nG

PE

(Mo

difi

edM

acN

ab):

45

%ex

cell

ent,

47

%g

oo

d,

6.0

%p

oo

r

No

n-c

onta

ined

or

seq

ues

tere

dL

DH

Ret

urn

tow

ork

:av

erag

e1

4d

ays,

ran

ge

1–

48

day

s

Ex

clu

sio

ncr

iter

iaR

ecu

rren

ce:

0%

Pre

vio

us

surg

ery

(sam

ele

vel

)C

om

pli

cati

on

s:0

%

Cen

tral

or

late

ral

sten

osi

sR

e-o

per

atio

ns:

0%

Seg

men

tal

inst

abil

ity

Eur Spine J (2010) 19:181–204 191

123

Ta

ble

6co

nti

nu

ed

Stu

dy

Mai

nin

clu

sio

ncr

iter

ia,

mai

nex

clu

sio

ncr

iter

iaN

um

ber

of

par

tici

pan

tsty

pe/

lev

elL

DH

Inte

rven

tions/

tech

niq

ue/

inst

rum

enta

tio

nF

oll

ow

-up

:d

ura

tio

nan

do

utc

om

eC

om

men

t

Mo

rgen

ster

net

al.

[42

]In

clu

sio

ncr

iter

ian

=1

44

$48

#9

6,

mea

n4

6y

ears

,ra

ng

e1

8–

76

En

dosc

op

icsp

ine

surg

ery

Fo

llo

w-u

p:

mea

n2

4m

on

ths

(ran

ge

3–

48

),0

%lo

stto

foll

ow

-up

Pri

mar

yo

utc

om

eo

fth

isst

ud

yw

asto

com

par

en

orm

alv

ersu

sin

ten

siv

ep

hy

sica

lth

erap

yp

ost

op

erat

ive

rev

alid

atio

n

Rad

iculo

pat

hy

Type:

all

LD

HIn

trad

isca

lan

din

trac

anal

tech

niq

ue

GP

E(M

acN

ab):

83%

exce

llen

tan

dgood,

3%

po

or

Neu

rolo

gic

aldefi

cit

Lev

el:

mult

iple

level

n=

60

,L

1–

S1

YE

SS

,R

ich

ard

Wo

lfin

stru

men

tati

on

Co

mpli

cati

on

s:9

%

Ex

clu

sio

ncr

iter

iaR

e-o

per

atio

ns:

5.6

%

Seq

ues

trat

ion

Ram

sbac

her

etal

.[4

5]

Incl

usi

on

crit

eria

n=

39

$21

#1

8,

mea

n5

0y

ears

Tra

nsf

ora

min

alen

do

sco

pic

seq

ues

trec

tom

y(T

ES

)F

oll

ow

-up

:6

wee

ks,

0%

lost

tofo

llo

w-u

p

Rad

icu

lop

ath

yT

yp

e:al

lL

DH

Intr

acan

alte

chn

ique

Pai

nle

g(V

AS

):p

re-o

p.

6.7

,fo

llo

w-u

p0

.8,

dif

fere

nce

5.9

=8

8%

Neu

rolo

gic

aldefi

cit

Lev

el:

single

level

,L

3–S

1S

ofa

mor–

Dan

eken

dosc

ope

Pai

nbac

k(V

AS

):pre

-op.

5.1

,fo

llow

-up

1.3

,d

iffe

ren

ce3

.8=

74

%

Ex

clu

sio

ncr

iter

iaP

S:

77%

(ver

ysa

tisfi

ed?

sati

sfied

)

Far

mig

rate

dse

qu

este

rsC

om

pli

cati

on

s:5

.1%

Cen

tral

or

late

ral

sten

osi

sR

e-o

per

atio

ns:

10

%

Hig

hil

iac

cres

t

Ru

ette

net

al.

[46]

Incl

usi

on

crit

eria

n=

51

7$2

77

#2

40

,m

ean

38

yea

rs,

ran

ge

16

–78

Extr

eme-

late

ral

tran

sfora

min

alap

pro

ach

Fo

llo

w-u

p:

12

mo

nth

s,1

0%

lost

tofo

llo

w-

up

Rad

icu

lop

ath

yT

yp

e:al

lL

DH

Intr

acan

alte

chniq

ue,

Ric

har

dW

olf

inst

rum

enta

tio

n,

n=

27

bil

ater

alP

ain

leg

(VA

S):

pre

-op

.7

.1,

foll

ow

-up

0.8

,d

iffe

ren

ce6

.3=

89

%

Neu

rolo

gic

aldefi

cit

Lev

el:

mult

iple

level

n=

46

,L

1–

L5

Pai

nb

ack

(VA

S):

pre

-op

.1

.8,

foll

ow

-up

1.6

,d

iffe

ren

ce0

.2=

13

%

Ex

clu

sio

ncr

iter

iaF

un

ctio

nal

stat

us

(OD

I):

pre

-op

.7

8,

foll

ow

-u

p2

0,

dif

fere

nce

58

=7

4%

Far

cran

ial/

caudal

mig

rate

dse

qu

este

rR

ecu

rren

ce:

6.9

%

Pre

vio

us

surg

ery

(sam

ele

vel

)C

om

pli

cati

on

s:0

%

Spin

alst

enosi

sR

e-o

per

atio

ns:

6.9

%

192 Eur Spine J (2010) 19:181–204

123

Ta

ble

6co

nti

nu

ed

Stu

dy

Mai

nin

clu

sio

ncr

iter

ia,

mai

nex

clu

sio

ncr

iter

iaN

um

ber

of

par

tici

pan

tsty

pe/

lev

elL

DH

Inte

rven

tions/

tech

niq

ue/

inst

rum

enta

tio

nF

oll

ow

-up

:d

ura

tio

nan

do

utc

om

eC

om

men

t

Sas

ani

etal

.[4

8]

Incl

usi

on

crit

eria

n=

66

$36

#3

0,

med

ian

52

yea

rs,

ran

ge

35

–73

Per

cuta

neo

us

end

osc

op

icd

isce

cto

my

(PE

D)

Fo

llo

w-u

p:

12

mo

nth

s,0

%lo

stto

foll

ow

-up

Rad

icu

lop

ath

yT

yp

e:fo

ram

inal

?ex

traf

ora

min

alL

DH

Pu

rein

trad

isca

lte

chniq

ue

Kar

lS

torz

inst

rum

enta

tio

nP

ain

(VA

S):

pre

-op

.8

.2,

foll

ow

-up

1.2

,d

iffe

ren

ce7

.0=

85

%

Po

st-t

ensi

on

sign

Lev

el:

sin

gle

lev

el,

L2

–L

5F

un

ctio

nal

stat

us

(OD

I):

pre

-op

.7

8,

foll

ow

-u

p8

,d

iffe

ren

ce7

0=

90

%

Neu

rolo

gic

aldefi

cit

Co

mpli

cati

on

s:6

.1%

Ex

clu

sio

ncr

iter

iaR

e-o

per

atio

ns:

7.6

%

Pre

vio

us

surg

ery

(sam

ele

vel

)

Sch

ub

ert

and

Ho

og

lan

d[5

4]

Incl

usi

on

crit

eria

n=

55

8$1

79

#3

79

,m

ean

44

yea

rs,

ran

ge

18

–65

Tra

nsf

ora

min

aln

ucl

eoto

my

wit

hfo

ram

ino

pla

sty

Fo

llo

w-u

p:

12

mo

nth

s,8

.7%

lost

tofo

llo

w-

up

Rad

iculo

pat

hy

Type:

all

LD

HIn

trac

anal

tech

niq

ue,

Thes

sys

inst

rum

enta

tio

nP

ain

leg

(VA

S):

pre

-op

.8

.4,

foll

ow

-up

1.0

,d

iffe

ren

ce7

.4=

88

%

Po

st-t

ensi

on

sign

Lev

el:

sin

gle

lev

el,

L2

–S

1P

ain

bac

k(V

AS

):p

re-o

p.

8.6

,fo

llo

w-u

p1

.4,

dif

fere

nce

7.2

=8

4%

Neu

rolo

gic

aldefi

cit

GP

E(M

acN

ab):

51%

exce

llen

t,43%

good,

0.3

%p

oo

r

Seq

ues

trat

ion

Rec

urr

ence

:3

.6%

Ex

clu

sio

ncr

iter

iaC

om

pli

cati

on

s:0

.7%

Pre

vio

us

surg

ery

(sam

ele

vel

)R

e-o

per

atio

ns:

3.6

%

Su

ess

etal

.[5

7]

Incl

usi

on

crit

eria

n=

25

$11

#1

4,

mea

n4

8y

ears

,ra

ng

e2

6–

72

Per

cuta

neo

us

tran

sfora

min

alen

do

sco

pic

seq

ues

trec

tom

y(P

TF

ES

)

Fo

llo

w-u

p:

6w

eeks,

0%

lost

tofo

llo

w-u

pA

llp

atie

nts

op

erat

edu

nd

erg

ener

alan

aest

hes

iaan

dE

MG

mo

nit

ori

ng

Rad

icu

lop

ath

yT

yp

e:fo

ram

inal

?ex

traf

ora

min

alL

DH

Pu

rein

trad

isca

lte

chniq

ue,

inst

rum

enta

tio

nn

ot

spec

ified

Pai

nle

g(V

AS

):p

re-o

p.

6.7

,fo

llo

w-u

p0

.8,

dif

fere

nce

5.9

=8

8%

Neu

rolo

gic

aldefi

cit

Lev

el:

single

level

,L

2–L

5P

ain

bac

k(V

AS

):pre

-op.

5.1

,fo

llow

-up

1.3

,d

iffe

ren

ce3

.8=

75

%

Ex

clu

sio

ncr

iter

iaC

om

pli

cati

on

s:4

%

Cau

da

syn

dro

me

Re-

oper

atio

ns:

8%

Spin

alst

enosi

s

Inte

rven

tio

nas

qu

ote

din

ori

gin

alar

ticl

e.P

ost

-ten

sion

sig

ns

den

ote

sp

osi

tiv

ete

nsi

on

sig

ns

(str

aig

ht

leg

rais

ing

test

or

con

tral

ater

alst

raig

ht

leg

rais

ing

test

)

Outc

om

es:

Sst

atis

tica

lly

signifi

cant,

NS

not

stat

isti

call

ysi

gnifi

cant,

PS

pat

ien

tsa

tisf

acti

on

,M

acN

ab

Mac

Nab

sco

reas

des

crib

edb

yM

acN

ab[3

9].

Th

esu

mo

f‘e

xce

llen

t’an

d‘g

oo

d’

ou

tco

mes

are

lab

elle

d‘s

atis

fact

ory

’,G

PE

glo

bal

per

ceiv

edef

fect

,S

/S-s

core

Su

ezaw

aan

dS

chre

iber

sco

re[4

0],

Pre

sby.

St

Luke

score

Rush

-Pre

sby

teri

an-S

tL

uk

esc

ore

[23],

OD

IO

swes

try

dis

abil

ity

ind

ex[3

8]

Eur Spine J (2010) 19:181–204 193

123

Ta

ble

7R

etro

spec

tiv

eco

ho

rtst

ud

ies

Stu

dy

Mai

nin

clu

sio

ncr

iter

ia,

mai

nex

clusi

on

crit

eria

Type

/lev

elL

DH

Inte

rven

tions/

tech

niq

ue/

inst

rum

enta

tio

nF

oll

ow

-up

:d

ura

tio

nan

do

utc

om

eC

om

men

t

Ah

net

al.

[3]

Incl

usi

on

crit

eria

n=

43

$11

#3

2,

mea

n4

6y

ears

,ra

ng

e2

2–

72

Per

cuta

neo

us

endosc

opic

lum

bar

dis

cect

om

y(P

EL

D)

Fo

llo

w-u

p:

rang

e2

4–

39

mon

ths,

0%

no

n-

resp

on

der

sA

uth

ors

incl

ud

edo

nly

pat

ien

tsw

ith

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59

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Cal

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194 Eur Spine J (2010) 19:181–204

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Hoch

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13

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31

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trat

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Hig

hil

iac

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Eur Spine J (2010) 19:181–204 195

123

Ta

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