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S Y S T E M A T I C R E V I E W Open Access
Remnant preservation technique versus
standard technique for anterior cruciate
ligament reconstruction: a meta-analysis
of randomized controlled trials
Hong-De Wang
1,3
, Fu-Shun Wang
2
, Shi-Jun Gao
1,3
and Ying-Ze Zhang
1,3,4*
Abstract
Background: This meta-analysis was performed to compare the clinical outcomes of primary anterior cruciate
ligament (ACL) reconstruction using the ACL remnant preservation technique versus the standard technique.
Methods: PubMed, Embase, and the Cochrane Library were searched through December 24, 2017, to identify
randomized controlled studies that compared the use of the ACL remnant preservation technique versus the
standard technique for primary ACL reconstruction. Statistical heterogeneity among the trials was evaluated with
chi-square and I-square tests. A sensitivity analysis was conducted to explore sources of heterogeneity. Subgroup
analysis was performed to identify potential differences according to type of ACL remnant tissue (remnant bundle
or remnant fibers).
Results: Seven studies with a combined 412 patients (208 in the remnant preservation technique group and 204
in the standard technique group) were included in the meta-analysis. There was a significant difference between
the groups in Lysholm score (mean difference (MD), 2.20; 95% confidence interval (CI), 0.95–3.45; P= 0.0006) and
side-to-side difference (MD, −0.71; 95% CI, −0.87 to −0.55; P< 0.01). There was no significant difference between
the groups in subjective International Knee Documentation Committee (IKDC) score, complications, pivot shift test,
Lachman test, or overall IKDC score. Subgroup analysis demonstrated that for primary ACL reconstruction with
preservation of remnant fibers, the remnant preservation technique was superior to the standard technique based
on Lysholm scores (P< 0.01) and side-to-side difference (P< 0.01).
Conclusions: Based on the current literature, using the remnant preservation technique showed a better clinical
outcome than using the standard technique for patients undergoing primary ACL reconstruction with respect to
Lysholm score and side-to-side difference. However, it remains unclear that there is a definite advantage to use the
remnant preservation technique compared with the standard technique.
Keywords: Anterior cruciate ligament, Reconstruction, Remnant preservation, Meta-analysis
* Correspondence: profyzzhang@126.com
1
Department of Orthopaedic Surgery, The Third Hospital of Hebei Medical
University, No. 139 Ziqiang Road, Qiaoxi District, Shijiazhuang 050051,
People’s Republic of China
3
Key Laboratory of Biomechanics of Hebei Province, Shijiazhuang 050051,
Hebei, People’s Republic of China
Full list of author information is available at the end of the article
© The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver
(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
Wang et al. Journal of Orthopaedic Surgery and Research (2018) 13:231
https://doi.org/10.1186/s13018-018-0937-4
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Background
Anterior cruciate ligament (ACL) injury is one of the
most common knee injuries with an annual incidence of
68.6 per 100,000 person-years [1,2]. An injured ACL
cannot heal naturally and will lead to an increased risk
of meniscal injury and osteoarthritis [3–5]. Thus, ACL
reconstruction is a conventional surgical technique to
restore function to the knee with a ruptured ACL, and
excellent clinical outcomes have been reported.
Residual ACL remnants are commonly observed during
arthroscopic examination. To identify the ACL attachment,
the ACL remnant is debrided clearly during ACL recon-
struction using standard techniques. In recent years, the
importance of the ACL remnant has been recognized in
terms of biomechanical, vascular, and proprioceptive func-
tion. Some studies reported that mechanoreceptors that
control knee proprioception are located in the inner mem-
brane of the synovium near the tibial attachment of the
ACL [6,7]. In addition, the ACL remnant tissue has good
subsynovial and intrafascicular vascularity [6]. This may ac-
celerate cell repopulation and revascularization in the graft.
However, the clinical outcomes remain controversial as to
the use of the remnant preservation technique versus the
standard technique. Some studies reported good clinical
outcomes following remnant preservation [8–10]. Kondo et
al. [10] reported that the benefit of the remnant preserva-
tion technique can significantly improve postoperative knee
stability. Lee et al. [11]reportedthatpatientswitha
remnant greater than 20% of the length of the ACL had
better proprioceptive function than those with less than
20% length. Conversely, some authors have reported that
there is no significant difference between the two tech-
niques, and even that remnant preservation may increase
the risk of certain complications and subsequently affect
the functional performance of the knee [12,13].
Based on the current evidence, the purpose of this
meta-analysis of randomized controlled trials (RCTs) on
the clinical outcomes following either the remnant preser-
vation or the standard technique of ACL reconstruction
was to lead to the appropriate selection of technique to
provide the greatest benefit to patients. The clinical out-
comes that were assessed included knee functionality, sta-
bility, subjective evaluation, and complication rate.
Methods
This meta-analysis was performed according to the
guidelines outlined in the Preferred Reporting Items for
Systematic Reviews and Meta-Analyses (PRISMA) state-
ment [14].
Study eligibility
Two reviewers independently decided which studies to
include based on the selection criteria. The inclusion cri-
teria were as follows: (1) the article described a RCT
(level of evidence, I or II), (2) only the isolated ACL in-
jury, (3) primary ACL reconstruction was performed, (4)
reconstruction was performed with the remnant preser-
vation technique or the standard technique, and (5) the
study included clinically relevant subjective and object-
ive outcomes, such as subjective patient evaluation,
complications, stability, and function.
The exclusion criteria were as follows: (1) the article
described a case-control study, retrospective cohort
study, case series, review article, letter to the editor, or
technique note, (2) injury to multiple knee ligaments,
meniscal injury, and/or cartilage injury requiring surgery,
(3) the study included the same patients from the same
center undergoing the same technique with different
follow-up intervals.
Literature search
We searched PubMed, Embase, and the Cochrane Li-
brary to identify RCTs published from the initial date to
24 December 2017 that compared the remnant preserva-
tion technique with the standard technique for primary
ACL reconstruction. The title and abstract fields were
searched for the following terms in each database: anter-
ior cruciate ligament, remnant, preservation. A manual
search was also performed for articles potentially missed
by the electronic search. The search history of each data-
base is supplied in Additional file 1, Additional file 2,
and Additional file 3.
Study selection and data extraction
Two reviewers independently decided which studies to
include based on the selection criteria. Studies were se-
lected in two levels of screening: screening of the titles
and abstracts and screening of the full texts. Disagree-
ment between the reviewers was resolved by consensus
or by discussion with the senior author if a consensus
could not be reached.
The extracted data were assessed by two independent
reviewers who reviewed basic information including first
author, publication year, study type, sample size, mean
age, sex ratio, graft type, fixation method, mean
follow-up, and quality assessment score in standardized
forms. The primary outcomes were subjective patient
evaluation, including subjective International Knee
Documentation Committee (IKDC) score and Lysholm
score, and complications. The secondary outcomes were
knee stability, including the pivot shift test, Lachman
test, and side-to-side difference, and knee function, in-
cluding overall IKDC score. The side-to-side difference
was measured with a KT-1000/2000 arthrometer. The
mean and standard deviation were not reported in some
studies and were calculated by using statistical formulas
if the related data was provided [15]. Disagreements
were resolved by discussion among the authors.
Wang et al. Journal of Orthopaedic Surgery and Research (2018) 13:231 Page 2 of 11
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Risk of bias assessment
Two authors independently graded the methodological
quality of each eligible study using the Cochrane Collab-
oration tool to assess the risk of bias for RCTs [16]. The
authors assessed random sequence generation, allocation
concealment, blinding of participants and personnel,
blinding of outcome assessors, incomplete outcome data,
selective outcome reporting, and other bias (baseline
balance and funding). All fields were judged as having a
low risk of bias, high risk of bias, or unclear risk of bias.
Data analysis
Data analysis was performed with RevMan (Version 5.3;
Copenhagen: The Nordic Cochrane Centre, The
Cochrane Collaboration, 2014). A random-effects model
was adopted to pool the results. The risk ratio (RR) was
used as a summary statistic for dichotomous variables,
and the mean difference (MD) was used to analyze con-
tinuous variables. Both were reported with 95% confi-
dence intervals (CIs), and a Pvalue of 0.05 was used as
the level of statistical significance. Statistical heterogen-
eity between trials was evaluated with the chi-square
and I-square tests (I
2
:0–30% was considered homogen-
eity, 30–60% was considered moderated heterogeneity,
and > 60% was considered substantial heterogeneity),
with significance set at P< 0.10. A sensitivity analysis
was conducted to explore sources of heterogeneity. We
also performed a subgroup analysis to identify potential
differences according to the type of ACL remnant tissue
(remnant bundle or remnant fibers).
Results
Characteristics of included studies
A summary of the study selection process is presented in
Fig. 1. Our search identified 415 records. A total of 284 ci-
tations were discarded because they were duplicates or did
not fit the eligibility criteria. After full-text verification of
the remaining 15 articles, seven studies with a combined
412 patients (208 in the remnant preservation technique
group and 204 in the standard technique group) were in-
cluded in the meta-analysis [17–23].
All included studies randomized patients to primary
ACL reconstruction using hamstring tendon autografts
or allografts. All seven studies used the same fixation
Fig. 1 Selection process for the meta-analysis of studies comparing the ACL remnant preservation technique with the standard technique for
ACL reconstruction
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method for both the remnant preservation technique
group and the standard technique group. However, the
fixation methods differed between studies. Femoral fix-
ation was obtained with an EndoButton in three studies,
RigidFix in two studies, Cross-pin in one study, and
Interference screw in one study. Tibial fixation was
obtained with a bioabsorbable interference screw in
sixstudiesandwithanIntrafixinonestudy.Among
the 412 patients, 404 patients used soft-tissue grafts
including hamstring tendons and tibialis anterior ten-
dons for ACL reconstruction. Only eight patients
used bone-patellar tendon-bone grafts in the study of
Pujol et al. Both of the two groups of patients re-
ceived the same rehabilitation protocols in each in-
cluded RCT. The characteristics of the included
studies are shown in Table 1.
Meta-analysis of clinical outcomes
Primary outcomes
The results of the Lysholm scores (MD, 2.20; 95% CI,
0.95–3.45; P= 0.0006) (P= 0.40 and I
2
= 1% for hetero-
geneity) showed a statistically significant difference be-
tween the remnant preservation technique and the
standard technique in favor of the remnant preservation
technique. There was no significant difference between
the groups in subjective IKDC scores (MD, −0.34; 95%
CI, −2.34–1.67; P= 0.74) (P= 0.68 and I
2
= 0% for het-
erogeneity) or complications (RR, 0.95; 95% CI, 0.62–
1.46; P= 0.81) (P= 0.15 and I
2
= 41% for heterogeneity).
The results of the primary outcomes are illustrated in
Table 2and Fig. 2. In addition, there was no significant
difference between the groups in any individual compli-
cation (including revision rate, cyclops lesion or arthrofi-
brosis) except for impingement (RR, 0.50; 95% CI, 0.30–
0.84; P= 0.009). The individual complication results are
illustrated in Table 3.
Secondary outcomes
Except for side-to-side difference (MD, −0.71; 95% CI,
−0.87−− 0.55; P< 0.01) (P< 0.01 and I
2
= 91% for het-
erogeneity), which was in favor of the remnant preserva-
tion technique, there was no significant difference
between the remnant preservation technique and the
standard technique with respect to secondary stability
outcomes, including the pivot shift test and the Lach-
man test. Moreover, there were no significant differences
in secondary functional outcomes on overall IKDC
scores. The secondary outcome results are illustrated in
Table 2and Fig. 3.
Sensitivity analysis and subgroup analysis
Sensitivity analysis was conducted to explore the possi-
bility of heterogeneity in stability outcomes. The results
showed that there was no particularly influential study
among the included studies, except for the effects of the
studies of Andonovski on side-to-side difference [23].
The mean follow-up time in this trial was 7 months. Ex-
clusion of this trial did not alter the results of the
side-to-side difference. (MD, −0.45; 95% CI, −0.64 to −
0.26; P< 0.01) (P= 0.39 and I
2
= 0% for heterogeneity).
Subgroup analysis was performed according to type of
remnant tissue (remnant bundle or remnant fibers), as
displayed in Table 4. Significant differences were found
in both subgroups between the remnant preservation
technique and the standard technique in side-to-side dif-
ference, and in the subgroup of remnant fibers between
the remnant preservation technique and the standard
technique in Lysholm scores.
Risk of bias in the included studies
Information about the risk of bias in each study is pre-
sented in Fig. 4. All seven studies had an unclear risk of
bias. Random sequence generation was not reported in
these seven studies. All of these studies lacked blinding
of the participants except for the study by Andonovski.
Allocation concealment was carried out adequately in
three studies.
Discussion
This meta-analysis that included seven RCTs suggested
that the remnant preservation technique during ACL re-
construction showed a better clinical outcome compared
with the standard technique with respect to Lysholm
score and side-to-side difference.
Remnant preservation has been recognized to have an
important role in ACL reconstruction. However, its ac-
tual effectiveness remains controversial. For patients
with ACL injury, the first concern is subjective patient
evaluation and complications. The differences in subject-
ive evaluation and complications between the use of the
remnant preservation technique and the standard tech-
nique play an important role in patient choice.
Some previous studies reported that there are mechano-
receptors located in the subsynovial layer near the tibial site
of ACL fibers [24,25]. Moreover, many authors showed
that the regeneration of mechanoreceptors may be acceler-
ated by revascularization of the graft and that the recovery
ofkneeproprioceptivefunctioncouldbepromotedbythe
surviving mechanoreceptors of the ACL remnant and the
regenerated mechanoreceptors [11,25–29]. Therefore,
some authors have preserved the ACL remnant during
ACL reconstruction, assuming that remnant preservation
can better restore proprioceptive and functional outcomes
of the knee joint [8,10,11,27,30–32]. Kondo et al. [10]re-
ported that remnant preservation significantly improved
postoperative knee stability and arthroscopic evaluation
than using the remnant resecting technique during ACL re-
construction. Lee et al. [11] reported in a group of 16
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Table 1 Characteristics of included studies
Study Year Study
type
Sample
(RP/ST)
Mean age
(RP/ST)
Gender M,F
(RP/ST)
Surgical
technique
Graft type Fixation method (F/T) Follow-up interval
(mo)(RP/ST)
Quality
assessment
a
Andonovski
et al.
2017 RCT 33/33 28/28 NR/NR A, SB HT Endobutton/Interfernce screw 7/7 Unclear risk
Lu et al. 2015 RCT 36/36 29.3/31.4 36,0/36,0 A, DB HT Endobutton/Interfernce screw 34.7/39.6 Unclear risk
Hong et al. 2012 RCT 39/41 31/31 33,12/34,11 A, SB TA/HT
allograft
RigidFix/IntraFix 25.8/25.5 Unclear risk
Pujol et al. 2012 RCT 29/25 31.24/28.56 16,13/17,8 A, SB HT/BPTB Interference screw, cortical button/Interference
screw, double fixation
12/12 Unclear risk
Demirağ
et al.
2012 RCT 20/20 31/28 18,2/18,2 A, SB HT Cross-pin/Screw 24.3/24.3 Unclear risk
Zhang et al. 2014 RCT 27/24 23.5/25.3 19,4/21,5 A, SB HT RigidFix/Interference screw 24.4 ± 25.2 Unclear risk
Gohil et al. 2007 RCT 24/25 30.5/35.5 14,10/13,12 A, SB HT Endobutton/Interfernce screw 12/12 Unclear risk
RCT, randomized controlled trial; M, male; F, female; mo, month; NR, not reported; RP, remnant preservation; ST, standard; A, anatomic reconstruction; SB, single-bundle reconstruction; DB, double-bundle
reconstruction; HT, hamstring tendon; TA, tibialis anterior; BPTB, bone-patellar tendon-bone
a
Cochrane Collaboration Risk of Bias for RCTs (graded as low risk of bias, high risk of bias, or unclear risk of bias)
Wang et al. Journal of Orthopaedic Surgery and Research (2018) 13:231 Page 5 of 11
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patients that better proprioceptive and functional outcomes
occurred in those with a preserved remnant greater than
20% of the length of the ACL than in those where the
remnant was less than 20%. Yanagisawa et al. [8]reported
that the remnant preservation technique reduces the
amount of bone tunnel enlargement. Kitamura et al. [32]
demonstrated that the preservation of ACL remnant tissue
in anatomic double-bundle ACL reconstruction appears to
improve the control of pivot-shift laxity at a minimum of
12 months after surgery. However, one study that was in-
cluded in our analysis demonstrated that remnant preserva-
tion had no significant advantage over the standard
technique in terms of proprioception function. The other
six RCTs included in our analysis did not assess this out-
come, so the proprioception between the two techniques
cannot be compared. In addition, the proprioceptive func-
tion of the knee joint does not depend solely on the ACL.
Other factors such as muscles, ligaments, menisci, the joint
capsule, and even skin can influence proprioception and
make it difficult to directly compare the studies. Therefore,
more accurate measurements and clinical outcome scores
should be introduced to assess proprioceptive function.
The remnant ACL tissue has good subsynovial and
intrafascicular vascularity [6]. Wu et al. [33]reportedin
an experimental study that blood flow to the grafts was
significantly higher in the remnant-preserved group than
in the remnant-resected group. Therefore, many authors
believed that as the remnant was preserved, a portion of
blood vessels from the tibial attachment were also pre-
served, which may accelerate cell repopulation and
Table 2 Clinical outcomes
Number of
included studies
Number of
included patients
MD/RR 95% CI Heterogeneity
(P/I
2
)
Pvalue
Primary outcomes
Subjective IKDC 3 143 MD −0.34 [−2.34, 1.67] 0.68/0% 0.74
Lysholm score 5 297 MD 2.20 [0.95, 3.45] 0.40/1% 0.0006
Complications 5 295 RR 0.95 [0.62, 1.46] 0.15/41% 0.81
Secondary outcomes
Pivot shift test 4 246 RR 1.06 [0.97, 1.17] 0.80/0% 0.20
Lachman test 2 120 RR 1.04 [0.87, 1.23] 0.81/0% 0.69
Side-to-side difference 4 269 MD −0.71 [−0.87, −0.55] < 0.01/91% < 0.01
Overall IKDC 3 206 RR 1.05 [0.96, 1.14] 0.34/8% 0.27
IKDC, International Knee Documentation Committee
Fig. 2 Primary outcomes after anterior cruciate ligament (ACL) reconstruction. RP-group, Remnant preservation technique group; St-group, Standard
technique group. aSubjective International Knee Documentation Committee scores after ACL reconstruction. bLysholm scores after ACL reconstruction.
cComplications after ACL reconstruction
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revascularization in the graft, resulting in acceleration of
graft remodeling and early restoration of the mechanical
properties of the graft [34][35–37]. Ahn et al. [34]re-
ported that magnetic resonance imaging showed signifi-
cantly larger ACL grafts in the remnant bundle
preservation group than in the standard procedure group,
and these preserved remnant bundles showed progressive
remodeling in the ACL graft. In addition, improved graft
remodeling was confirmed by using arthroscopic
second-look evaluation [27,31]. Ahn et al. [27]performed
a second-look evaluation in 62% patients who underwent
ACL reconstruction with remnant preservation and re-
ported that 91% had fair synovialization of the ACL graft.
Kondo et al. [10] demonstrated on second-look evaluation
that the remnant-preserving procedure was significantly
better than the remnant-resecting procedure with regard
to postoperative laceration or tear of the grafts as well as
synovial and fibrous tissue coverage of the grafts. Two
RCTs included in our study reported the second-look
evaluation [20,22]. Lu et al. [22] showed that the grafts in
the remnant preservation group had a better quality in
terms of synovium coverage, apparent tension, and thick-
ness compared with the standard group. However, Hong
et al. [20] observed no significant difference between the
two groups on second-look evaluation. Allograft was used
in Hong’s study, and the follow-up time was 26 months.
Previous studies demonstrated that the incorporation of
allografts was delayed and that complete remodeling and
cellular replacement of the entire graft may require 3 years
or longer [38,39]. This may be a potential cause for
Table 3 Complications
Number of
included studies
Number of
included patients
RR 95% CI Heterogeneity
(P/I
2
)
Pvalue
Revision 1 72 0.20 [0.01, 4.03] –0.29
Cyclops lesion 4 223 1.51 [0.84, 2.70] 0.92/0% 0.17
Arthrofibrosis 1 40 1.00 [0.43, 2.33] –1.00
Impingement 1 72 0.50 [0.30, 0.84] –0.009
Fig. 3 Secondary outcomes after anterior cruciate ligament (ACL) reconstruction. RP-group, Remnant preservation technique group; St-group,
Standard technique group. aPivot-shift test (Grade 0) after ACL reconstruction. bLachman test (Grade 0) after ACL reconstruction. cSide-to-side
difference after ACL reconstruction. dOverall International Knee Documentation Committee score (Normal, Nearly normal) after ACL reconstruction
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increased side-to-side difference especially in the early
follow-up. Thus, the graft type (autografts or allografts)
and the short follow-up time may have contributed to no
significant difference being observed on second-look
evaluation between the two groups.
Several studies confirmed that preservation of the
remnant during ACL reconstruction can influence the sta-
bility of the knee joint, particularly the anterior-posterior
stability [27,30,40]. Adachi et al. [40]reportedthat
KT-1000 results in remnant-preserved group were 0.7 ±
1.8 mm versus 1.8 ± 2.1 mm in the standard technique
group (P< 0.05). Kim et al. [11]reportedthatthepostoper-
ative mean side-to-side difference was 1.67 mm on
KT-2000 in patients who underwent double-bundle ACL
reconstruction with the remnant-preserved technique. Ac-
cording to our meta-analysis, the side-to-side difference re-
sults in both groups were comparable to previous cohort
studies. There are likely several reasons why postoperative
knee stability was significantly improved by sufficient pres-
ervation of the ACL remnant tissue. The biology of graft
healing is a process of creeping substitution [36,37]. The
ACL remnant has good subsynovial and intrafascicular vas-
cularity. Therefore, first, the preserved remnant may accel-
erate the revascularization and ligamentation of the grafts,
as well as its incorporation and stability. Second, the
present study showed that in remnant-preserved recon-
struction, the tibial attachment of the ACL remnant tissue,
which appeared to be almost normal, was maintained
around the tibial tunnel site. In contrast, Tomita et al. [41]
reported that the tibial attachment in the remnant-resected
ACL reconstruction was narrow and had a different shape
in comparison with the normal attachment. This may ex-
plain the finding that the impingement rate was signifi-
cantly higher in the standard technique group compared
with the remnant preservation group (P=0.009).
A potential complication of ACL reconstruction using
remnant preservation is cyclops syndrome or a cyclops
lesion [28]. The incidence of cyclops syndrome, which
involves serious loss of knee extension caused by a hard
nodule around the reconstructed ACL, has been re-
ported to range from 2 to 11% [42,43]. The incidence of
a cyclops lesion, which is a soft synovial tissue mass
without any clinical symptoms around the reconstructed
ACL, has been reported to range from 2 to 47% [27,42,44].
Four RCTs included in our meta-analysis reported cyclops
lesion occurrence (18 of 112 in the remnant preservation
technique group, 12 of 111 in the standard technique group)
[17,19–21]. Only one patient required arthroscopic arthroly-
sis for cyclops syndrome [21]. Some magnetic resonance im-
aging studies showed that there was no significant difference
in the prevalence of cyclops lesion after single-bundle ACL
reconstruction between the remnant-preserved and
remnant-resected techniques (12.2% and 15.0%, respectively).
The results of our meta-analysis showed no significant differ-
ence in the occurrence of cyclops lesions between the
remnant preservation technique and the standard technique
(16.1% and 10.8%, respectively. P= 0.17). Thus, we hypothe-
sized that the preservation of ACL remnant tissue does not
increase the incidence of cyclops lesions.
The types of remnant preservation used in the seven
RCTs were either remnant bundle preservation or
remnant fiber preservation. The former type can be de-
fined as a single-bundle rupture (anteromedial bundle or
posterolateral bundle) with the other bundle remnant pre-
served. The latter type can be defined as a double-bundle
rupture with the remnant fiber preserved. According to
the results of the subgroup analysis, there were significant
differences in terms of side-to-side difference between the
subgroup and the standard technique group. This finding
suggests that if the remnant tissue is a bundle, surgeons
should attempt to preserve the remnant bundle, while if
the remnant tissue is only fibers, the remnant fibers
should be preserved. Interestingly, there was a significant
difference in Lysholm scores between the subgroup of
Table 4 Results of subgroup analysis
Remnant bundle Remnant fibers
MD/RR 95% CI Heterogeneity
(P/I
2
)
Pvalue MD/RR 95% CI Heterogeneity
(P/I
2
)
Pvalue
Primary outcomes
Subjective IKDC MD −0.59 [−2.69, 1.50] 0.76/0% 0.58 MD 2.40 [−4.44, 9.24] –0.49
Lysholm score MD −0.42 [−3.82, 2.98] 0.92/0% 0.81 MD 2.61 [1.27, 3.96] 0.49/0% < 0.01
Complication RR 1.25 [0.57, 2.73] 0.61/0% 0.58 RR 0.85 [0.51, 1.42] 0.04/70% 0.54
Secondary outcomes
Pivot shift test RR 1.05 [0.85, 1.29] 0.34/0% 0.63 RR 1.07 [0.97, 1.18] 0.87/0% 0.16
Lachman test RR 1.08 [0.70, 1.66] –0.74 RR 1.02 [0.86, 1.22] –0.81
Side-to-side difference MD −1.50 [−1.82, −1.18] –< 0.01 MD −0.45 [−0.64, −0.26] 0.39/0% < 0.01
Overall IKDC RR 1.07 [0.86, 1.32] –0.55 RR 1.04 [0.96, 1.14] 0.28/45% 0.35
IKDC, International Knee Documentation Committee
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remnant fiber preservation and the standard technique
group in favor of the subgroup.
Limitation
This study had several limitations. First, all seven studies
were rated as having an unclear risk of bias because the
method of blinding patients was not reported or blinding
was not used. Blinding is rarely possible in surgical stud-
ies, which is an inherent limitation of conducting random-
ized trials. Second, the standard deviation was unavailable
in some studies, so the imputed standard deviation was
used for pooling of the data. Third, the duration of final
follow-up was substantially different among the included
studies, ranging from 7 to 49 months, and this difference
may have obscured the reporting of differences between
the two groups. Finally, the grafts used for ACL recon-
struction were not of the same type and included auto-
graft and allograft, which might influence the
incorporation between the remnant and graft.
Conclusion
Based on the current literature, using the remnant pres-
ervation technique showed a better clinical outcome
than using the standard technique for patients undergo-
ing primary ACL reconstruction with respect to Lysholm
score and side-to-side difference. However, it remains
unclear that there is a definite advantage to use the
remnant preservation technique compared with the
standard technique.
Additional files
Additional file 1: PubMed. (DOCX 125 kb)
Additional file 2: Embase. (DOCX 63 kb)
Additional file 3: Cochrane. (DOCX 81 kb)
Abbreviations
ACL: Anterior cruciate ligament; CIs: Confidence intervals; IKDC: International
Knee Documentation Committee; MD: Mean difference; PRISMA: Preferred
Reporting Items for Systematic Reviews and Meta-Analyses;
RCTs: Randomized controlled trials; RR: Risk ratio
Availability of data and materials
The data of the manuscript was presented in the paper and supplemental
files.
Authors’contributions
HDW and FSW performed the literature search, screened the potential
subject, and extracted and integrated the data independently at the same
time; HDW and FSW checked the data; HDW designed the study and drafted
the initial manuscript; SJG and YZZ critically revised the manuscript; YZZ
provided final approval of the version to be published. All authors read and
approved the final manuscript.
Ethics approval and consent to participate
Not applicable.
Consent for publication
Not applicable.
Competing interests
The authors declare that they have no competing interests.
Publisher’sNote
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
Author details
1
Department of Orthopaedic Surgery, The Third Hospital of Hebei Medical
University, No. 139 Ziqiang Road, Qiaoxi District, Shijiazhuang 050051,
People’s Republic of China.
2
Department of Orthopaedic Surgery,
XinHuaFuShun Clinic of Traditional Chinese and Western Medicine, No. 398
Youyi North Street, Xinhua District, Shijiazhuang 050051, People’s Republic of
China.
3
Key Laboratory of Biomechanics of Hebei Province, Shijiazhuang
Fig. 4 Risk of bias for each randomized controlled trial (RCT). a
Graph depicting risk of bias. bSummary of risk of bias in the
included studies
Wang et al. Journal of Orthopaedic Surgery and Research (2018) 13:231 Page 9 of 11
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
050051, Hebei, People’s Republic of China.
4
Chinese Academy of
Engineering, Beijing 100088, People’s Republic of China.
Received: 5 June 2018 Accepted: 3 September 2018
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