Knee Surg Sports Traumatol Arthrosc DOI 10.1007/s00167-013-2811-6
KNEE
Anatomic single- versus double-bundle ACL reconstruction: a meta-analysis Neel Desai • Haukur Bjo¨rnsson • Volker Musahl • Mohit Bhandari • Max Petzold • Freddie H. Fu • Kristian Samuelsson
Received: 19 October 2013 / Accepted: 30 November 2013 Ó Springer-Verlag Berlin Heidelberg 2013
Abstract Purpose To determine whether anatomic double-bundle anterior cruciate ligament (ACL) reconstruction compared to anatomic single-bundle ACL reconstruction more effectively restored antero–posterior (A–P) laxity, rotatory laxity and reduced frequency of graft rupture. Our hypothesis was that anatomic double-bundle ACL reconstruction results in superior rotational knee laxity and fewer graft ruptures due to its double-bundle tension pattern, compared with anatomic single-bundle ACL reconstruction. Methods An electronic search was performed using the PubMed, EMBASE and Cochrane Library databases. All therapeutic trials written in English reporting knee kinematic outcomes and graft rupture rates of primary anatomic double- versus single-bundle ACL reconstruction were included. Only clinical studies of levels I–II evidence were included. Data regarding kinematic tests were extracted and included pivot-shift test, Lachman test, anterior drawer test, KT-1000 measurements, A–P laxity measures using
N. Desai H. Bjo¨rnsson K. Samuelsson (&) Department of Orthopaedics, Sahlgrenska University Hospital, 431 80 Mo¨lndal, Sweden e-mail: [email protected] V. Musahl F. H. Fu Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA M. Bhandari Division of Orthopaedic Surgery, Department of Surgery, McMaster University, Hamilton, ON, Canada M. Petzold Centre for Applied Biostatistics, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
navigation and total internal–external (IRER) laxity measured using navigation, as well as graft failure frequency. Results A total of 7,154 studies were identified of which 15 papers (8 randomized controlled trials and 7 prospective cohort studies, n = 970 patients) met the eligibility criteria. Anatomic ACL double-bundle reconstruction demonstrated less anterior laxity using KT-1000 arthrometer with a standard mean difference (SMD) = 0.36 (95 % CI 0.214–0.513, p \ 0.001) and less A–P laxity measured with navigation (SMD = 0.29 95 % CI 0.01–0.565, p = 0.042). Anatomic double-bundle ACL reconstruction did not lead to significant improvements in pivot-shift test, Lachman test, anterior drawer test, total IRER or graft failure rates compared to anatomic single-bundle ACL reconstruction. Conclusion Anatomic double-bundle ACL reconstruction is superior to anatomic single-bundle reconstruction in terms of restoration of knee kinematics, primarily A–P laxity. Whether these improvements of laxity result in long-term improvement of clinical meaningful outcomes remains uncertain. Level of evidence II. Keywords Anterior cruciate ligament ACL Reconstruction Single-bundle Double-bundle Anatomic Meta-analysis
Introduction Anterior cruciate ligament (ACL) injuries can lead to longterm functional deficits of knee function, often significantly limiting the patients’ partaking in sporting activities, particularly those involving rapid changes of direction and pivoting. One of the goals of ACL reconstruction is the
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restoration of native anatomy and kinematics. Up to recently, transtibial single-bundle ACL reconstruction has been the standard surgical option to treat ACL-deficient knees [7]. It was developed during an era where isometric graft placement was the norm [37]. The concept of isometric placement denotes that the distance between ACL graft origin and insertion remains constant during flexion and extension. The reasons for the adherence to the isometric concept were that biomechanical studies had shown irreversible elongation of the graft if stretched repetitively more than four per cent, and surgeons believed that this elongation was prevented when placing the graft isometrically [35, 46]. In addition to this, to achieve effective isometry, optimal graft placement was high in the intercondylar notch of the femur close to the proximal limit of Blumensaat’s line, and this graft position was outside the native femoral ACL footprint. Recent biomechanical and clinical studies have shown suboptimal restoration of knee kinematics and sustained pivot-shift with isometrically placed grafts in comparison with those placed in the native ACL footprints [22, 30, 33]. Today, it is known that native ACL is in not isometric, owing largely to its complex, non-uniform multiple-bundle anatomy, with each bundle exhibiting different tensile properties [2]. The antero-medial (AM) bundle is taut predominantly during knee flexion with a maximum at 45°–60°, whereas the postero-lateral (PL) bundle is maximally taut with the knee in full extension. Efforts have been made to develop techniques to reconstruct AM and PL bundles separately, as well as focusing increased emphasis on the positioning of the individual grafts to as closely as possible resemble that of the native ACL bundles, the so-called anatomic double-bundle reconstruction. Recent biomechanical and clinical trials have shown superior results in support of this technique [19, 31, 44]. The theoretical advantage is that the two bundles can be tensioned separately, therefore mimicking more of the native tension patterns of the ACL bundles. As a result, in addition to restoring A–P laxity by reconstructing the AMbundle, it is believed that double-bundle ACL reconstruction more effectively re-establishes rotational laxity of which primarily the PL bundle contributes. Striving for anatomically placed single-bundled reconstruction with the goal of placing the graft both in the centres of the tibial and femoral footprints demands high technical ability of the orthopaedic surgeon. Results from previous biomechanical studies on elongation still stand true; thus, if single-bundle reconstruction is performed with graft placement off-centre with regard to ACL footprints, this poses a risk of elongation and graft rupture [46]. A number of systematic reviews and meta-analyses have recently emerged focusing on single-bundle and double-bundle ACL reconstruction. A
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shortcoming common to all these are that there are no strict distinctions between anatomic and non-anatomic techniques. In the clinical setting, this analysis is of great importance as there is a growing interest in both techniques as promising surgical intervention options. Current comparative studies on anatomic single-bundle and double-bundle ACL reconstruction with focus on knee kinematics and graft ruptures were investigated. To obtain true homogeneity, only studies comparing anatomically placed single- and double-bundle ACL reconstruction were included. Kinematic variables was the main focus of analysis, as we believe they are the most significant contributors to subjective and objective outcomes in the long term and that subjective short-term outcome measures are too coarse a tool to detect differences between the two techniques. It was hypothesized that anatomic single-bundle ACL reconstruction was less effective than anatomic doublebundle reconstruction in terms of restoration of knee kinematics and leads to higher graft failure frequency.
Materials and methods This systematic review was conducted in accordance with the PRISMA guidelines (preferred reporting items of systematic reviews and meta-analyses) [27]. PRISMA is comprised of a checklist including 27 items relating to the content of systematic reviews and meta-analyses and a four-phase flow diagram depicting the processing of this content. Eligibility criteria Inclusion criteria were clinical studies comparing anatomic single- and double-bundle primary ACL reconstruction. Only studies on human adults with isolated total ACL rupture were eligible for inclusion. Studies on patients with open physes and cadavers were not included. Only therapeutic studies were included, whereas prognostic and diagnostic studies were excluded unless the authors reported a clear relation between the outcome measures and the surgical technique. No Economical and Decision analysis studies were included. Concomitant meniscus and minor cartilage injuries were not grounds for exclusion [36]. Information sources and search Electronic search A systematic electronic search was performed from PubMed (MEDLINE), EMBASE and Cochrane Library
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databases. Publication dates set for inclusion were from January 1995 to August 2011. An additional updated search was performed in July 2012 only from the PubMed (MEDLINE) database and relevant publications between August 2011 and July 2012 were included. Two experts in electronic search methods at the **MASKED** Library performed and validated the search. The following search strings were used in the fields Title, Abstract and Keywords: (‘‘Anterior Cruciate Ligament’’ [Mesh] OR ‘‘anterior cruciate ligament’’ [tiab] OR ACL [tiab]) AND (‘‘Surgical Procedures, Operative’’ [Mesh] OR surgical [tiab] OR surgery [tiab] OR reconstruction [tiab] OR reconstructive [tiab] OR reconstructed [tiab]) AND (English [lang] AND (‘‘1995’’ [PDAT]: ‘‘3000’’ [PDAT])). Only papers written in English were included [36]. Data collection and analysis Study selection All the studies yielded from the electronic search were sorted based on abstracts by three reviewers, each reviewer sorting one database each that in turn was validated twice by the other reviewers. The included studies were then categorized into study types proposed by the Oxford Centre for Evidence-Based Medicine and into the category singlebundle, double-bundle or single-bundle versus double-bundle reconstruction. Studies were included if they fell into one of the following categories: randomized controlled trial, prospective comparative study and retrospective comparative study. If a study belonged to several categories, it was placed in the category of which the majority of study was related. Only studies comparing anatomic single-bundle versus double-bundle ACL reconstruction were included in this meta-analysis regardless of graft type or fixation method. The operative technique used to achieve anatomic ACL reconstruction had to be clearly described by the authors. The authors needed to state that grafts were placed in the native ACL footprints on both the tibial and femoral side in both single-bundle and double-bundle groups for the technique to be regarded as anatomic and the article to be eligible for inclusion. The study was analyzed in full text if the abstract did not provide enough data to make a decision. The researchers were not blinded to author, year and journal of publication. Disagreement between the reviewers was resolved by consensus or by discussion with the senior author when consensus was not reached.
was performed by the first, second and senior author and validated twice by the first author. Data items The data extracted from the included studies were as follows: author, year, title, journal, volume, issue, pages, ISSN, DOI, abstract, author-address, database provider, category, study type, level of evidence and country. Where stated, we extracted sample size and follow-up time. Surgical details regarding technique used in each case was also obtained and included drilling technique, placement of tibial and femoral tunnels and tension patterns of the grafts used. Data regarding kinematic tests were extracted and included pivot-shift test, Lachman test, anterior drawer test, KT-1000 measurements, A–P laxity measures using navigation and total internal– external (IRER) laxity measured using navigation. No predefined concept of what constitutes a graft failure was created. The number of graft failures were extracted from the included studies if the authors explicitly stated the terms graft failure or graft rupture. In the case of pivot-shift test and Lachman test, outcomes were dichotomized, yielding only ‘‘positive/normal’’ or ‘‘negative/abnormal’’ results. Several authors reported rotational laxity and A–P laxity measured at multiple flexion angles, and we chose to include those measured at 30° flexion for statistical analysis. Data regarding rotational laxities measured with pilot navigation were extracted; values of rotational laxity obtained using EMS or camera motion analysis were not extracted and were excluded from statistical analysis. Trials comparing double-bundle ACL reconstruction to two separate single-bundle groups (e.g. AM and PL) were included, but only data from the AM group were extracted and analyzed [43]. One study compared a double-bundle group to two single-bundle groups, one using metallic screws to anchor the graft and the other group using bioabsorbable screws; there was no statistical difference between the two single-bundle groups, and therefore, we chose to only include data from the bioabsorbable screw group in the analysis [40]. One study reporting internal and external rotation separately did not specify where the authors set the starting position and how they consistently used the same starting position, and thus, values were combined to yield a total rotation measurement [8]. In those cases where relevant unpublished results were desired, the authors were contacted [8, 13, 16, 34], and replies with the requested data from three of the authors were received [8, 16, 34]. To allow for statistical analysis, sample sizes were adjusted for each group taking into account patients lost to follow-up [8, 34].
Data collection process Synthesis of results Data from each study was extracted using a computerized database created in Microsoft Access (Version 2010, Microsoft Corporation, Redmond, WA, USA). Extraction
Statistical meta-analysis of the data was performed using the metan command version sbe24_3 for Stata (Version
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12.1, StataCorp LP, Texas, USA). In some studies, zero events were reported. Following the Cochrane recommendation, 0.5 was added to cases and non-cases in both study groups (http://handbook.cochrane.org). In the cases that standard error was not obtainable from the studies or after requesting these from the authors, standard errors were instead calculated based on the values reported in the studies within the same group with regard to that particular variable. Results were expressed as odds ratios (OR) with 95 % confidence intervals (CI) for dichotomous outcomes and for continuous outcomes as standardized mean differences (SMD) with 95 % CI. Random effect meta-analysis was used to account for heterogeneity. The I2 is provided in the graphs for each analysis to show the level of heterogeneity. The I2 index can be interpreted as the percentage of the total variability in a set of effect sizes that is attributable to genuine heterogeneity between the groups [10]. Assessment of risk of bias Until recently, the use of checklists and scores has been the modus operandi when evaluating the risk of bias in a study or trial. However, the Cochrane Collaboration has recommended against using such tools [9]. The reasons for this are numerous but include the fact that scores and checklists are suboptimal tools for evaluating internal validity as opposed to external validity. With scores and checklists, emphasis is often on the extent of reporting rather than on the conduct in that particular study. Another example is that to arrive at a score, the criteria therein must be weighted somehow and it is often difficult and unclear to justify how and why those weights are assigned. We chose to utilize the Cochrane Collaboration’s tool for assessing risk of bias developed by the Cochrane Bias Methods Group [9]. The assessment tool covers six domains of bias: sequence generation, allocation concealment, blinding, incomplete outcome data, selective outcome reporting and other sources of bias. Within each domain, an independent judgment by the two first authors of high, low or unclear risk of bias is made. Any discrepancies were resolved by consensus or by discussion with the senior author when consensus was not reached. Although primarily a tool intended for implementation on randomized controlled trials, we chose to use it on the prospective comparative studies in addition to the randomized controlled trials included in this metaanalysis. In those cases that insufficient information was reported by the authors of a study with regard to the parameters in the bias assessment tool, we awarded them an ‘‘unclear risk’’ grade. If sufficient information was reported by the author to determine the risk of bias, then
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they were awarded ‘‘high risk’’ or ‘‘low risk’’ for that particular bias parameter.
Results An electronic search yielded 5,608 studies in PubMed (MEDLINE), 5,421 studies in EMBASE and 700 studies in the Cochrane Library. Fifteen duplicates were removed from PubMed, 4,048 from EMBASE and 512 from Cochrane Library. There were 7,154 studies left in which 3,757 were excluded based on the abstracts and 1,887 based on full-text assessment. A total of 1,510 studies were included in the database and categorized into single-bundle, double-bundle and single-bundle versus double-bundle ACL reconstruction. Fifty-one studies were categorized as studies comparing single- and double-bundle ACL reconstruction. Two studies reported from the same pool of data in different publications with different outcomes, population sizes and follow-up times [14, 40], only the most recently published of these two studies was included for analysis [40]. Further screening of these 51 studies using the aforementioned inclusion criteria yielded eleven Level I or II studies that were regarded as having performed anatomic single-bundle and double-bundle ACL reconstruction. An updated search was performed in July 2012 only from the PubMed database yielding 596 studies. Of these, a total of 4 studies met the aforementioned selection process and were included in our analysis. This finally amounted to 15 studies in total, 8 RCTs and 7 prospective cohort studies that were included in our analysis [1, 3, 4, 6, 8, 11–13, 16, 23, 26, 34, 38, 40, 43] (Fig. 1). Characteristics of the studies Of the 15 studies included (n = 970 patients), 8 were randomized controlled trials (n = 513 patients) and 7 were prospective comparative studies (n = 457 patients). The included studies were published between 2007 and 2012. Follow-up times varied with mean follow-up times ranging from 5 months to 5 years. Three studies reported data obtained intra-operatively (using computer navigation) [13, 16, 34]. Where stated, information on drilling technique, tunnel placement and knee flexion angle at graft tensioning was noted (Table 1). Kinematic results Ten of the 15 included studies reported values of pivotshift test [3, 4, 6, 11, 12, 23, 26, 38, 40, 43]. Ten studies reported values of side-to-side difference in A–P laxity measured with KT-1000 [1, 3, 4, 11, 12, 23, 26, 38, 40, 43]
Knee Surg Sports Traumatol Arthrosc Fig. 1 Flow diagram of created ACL reconstruction database and the selection of studies for the meta-analysis
and one using Rolimeter [6]. Three studies reported A–P laxity measured by navigation [13, 16, 34]. Rotational laxity was reported in 5 studies using perioperative navigation [8, 13, 16, 23, 34] (Table 2; Figs. 2, 3, 4, 5, 6, 7, 8). Risk of bias in included studies Of the 15 studies included, the majority exhibited a high risk of selection bias illustrating poor methods of randomization or inadequate reporting of methods of randomization and allocation concealment, and these included both prospective comparative studies as well as certain randomized controlled trials [4, 6, 8, 11, 13, 16, 26, 34, 43]. One study clearly reported their method for allocation concealment, however, failed to describe how the randomization was performed and was graded accordingly [40]. One study states clearly how both randomization and allocation concealment was performed and therefore was determined to exhibit low risk of selection bias [12]. One study was graded ‘‘high risk’’ of other bias due to a baseline imbalance [13] (Table 3).
Reported significant findings from included studies Knee laxity Three studies reported a significant difference between single-bundle and double-bundle groups in laxity measurements with KT-1000, with results favouring doublebundle ACL reconstruction [1, 12, 38]. Two studies showed significant differences in manual pivot-shift test between single-bundle and double-bundle groups in favour of double-bundle ACL reconstruction, [12, 38]. Only two studies reported significantly less rotatory laxity in the double-bundle ACL reconstruction group compared to single-bundle reconstruction [23, 34] (see Table 4). Graft failure Graft failures were reported in six studies [1, 4, 6, 11, 38, 40]. Only one study performed statistical analysis of graft failures and reported statistically significant better results in the double-bundle group [40] (Table 5).
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Knee Surg Sports Traumatol Arthrosc Table 1 Study characteristics Author
Year
Study type
LoE
Sample size (n)
Fujita et al. [4]
2011
PCS
2
36
Gobbi et al. [6]
2011
PCS
2
60
Surgery
Follow-up (months)
Drilling
Tension pattern (flexion angle at tensioning)
SB (n = 18)
Mean 31.9 (SB) and 33.7 (DB)
TT
60 AM/15 PL
TT (AM)/TP (PL)
60 AM/15 PL
Mean 46.2 minimum 36
TP
Not spec
TP
20 AM/0 PL
DB (n = 18) SB (n = 30) DB (n = 30) Hemmerich et al. [8]
2011
PCS
2
29
SB (n = 17)
5.2
DB (n = 12) Ishibashi et al. [13]
2008
PCS
2
125
SB (n = 45)
0
DB (n = 80) Misonoo et al. [26].
2011
PCS
2
44
Plaweski et al. [34]
2011
PCS
2
62
SB (n = 22)
9–20, minimum 12
DB (n = 22) SB (n = 32)
2010
RCT
1
70
SB (n = 35)
45 45 AM/15 PL
TT
0
AM not spec/TT (PL)
15 AM/15 PL
TT
20
TT (AM)/TP or TT (PL)
20
Not spec
Not spec
TP
Not spec
TP
20
TP
40 AM/20 PL
Mean 12 (SB), 13.5 (DB)
TP
15
0
DB (n = 30) Aglietti et al. [1]
TP TP
Minimum 24
DB (n = 35) Araki et al. [3]
2011
RCT
1
20
SB (n = 10)
TT (AM)/TP (PL)
60 AM/15 PL
Kanaya et al. [16]
2009
RCT
1
26
SB (n = 13) DB (n = 13)
0
TT or TP TT or TP (AM ? PL)
30 30 AM/15 PL
Siebold et al. [38]
2008
RCT
1
70
SB (n = 35)
Mean 19 months (range 13–24)
Not spec
60
Yagi et al. [43]
2007
RCT
1
40
SB (n = 20)
DB (n = 10)
DB (n = 35) 12
DB (n = 20) Hussein et al. [11]
2012
PCS
2
101
SB (n = 32)
Hussein et al. [12]
2012
RCT
1
209
DB (n = 69) SB (n = 78)
Lee et al. [23]
2012
RCT
1
37
Mean 30 (range 26–34) Mean 51.15 (range 39–63)
DB (n = 131) SB (n = 18)
24
DB (n = 19) Suomalainen et al. [40]
2012
RCT
1
41
SB (n = 21)
60
DB (n = 20)
TT (AM)/TP (PL)
60 AM/20 PL
TT
60
TT (AM)/TP (PL)
60 AM/15 PL
TP
0
TP TP
0 AM/60 PL 0
TP
0 AM/60 PL
Not spec
Not spec
TT or TP
10 AM/0 PL
TP
Not spec
TP
Not spec
PCS prospective comparative study, RCT randomized controlled trial, LoE level of evidence, SB single-bundle, DB double-bundle, TT transtibial, TP trans-portal, AM antero-medial, PL postero-lateral, Not spec not specified
Results of meta-analysis Anterior laxity measured using KT-1000 arthrometer readings showed statistically significant results favouring double-bundle reconstruction (p \ 0.001) with a SMD of 0.36 (95 % CI 0.214–0.513). A significant difference was observed in favour of double-bundle reconstruction when measuring A–P laxity using navigation (p = 0.042) with SMD of 0.29 (95 % CI 0.01–0.565). No significant
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differences were seen regarding pivot-shift, Lachman test, anterior drawer, IRER or graft failure (Table 6).
Discussion The most important findings of this meta-analysis were that anterior laxity as measured with the KT-1000 arthrometer and A–P laxity measured by navigation showed results
44
62
70
20
26
70
40
Misonoo et al. [26]
Plaweski et al. [34]
Aglietti et al. [1]
Araki et al. [3]
Kanaya et al. [16]
Siebold et al. [38]
Yagi et al. [43]
41
Suomalainen et al. [40]
13/5
DB (n = 30)
10/11 7/13
SB (n = 21) DB (n = 20)
12/6 13/6
SB (n = 18) DB (n = 19)
52/26 122/9
59/10
DB (n = 69) SB (n = 78) DB (n = 131)
27/5
SB (n = 32)
15/5 17/3
SB (n = 20)
34/1
DB (n = 35) DB (n = 20)
25/10
SB (n = 35) 15/5
14/5
10/8
17/3
16/3
1.6 ± 3.0
2.2 ± 2.8
2.62 ± 1.72
2.74 ± 1.65
1.6 ± 0.8 1.2 ± 0.9
1.5 ± 0.9
1.6 ± 0.9
1.3 ± 1.2
1.9 ± 1.6
1.0 ± 1.0
1.6 ± 1.3
11.5 ± 4.1
12.8 ± 3.7 12.5 ± 4.8
24.0 ± 7.0
26.6 ± 4.8
12
0.7 ± 1.8 8
10/0
22.5 ± 4.2
DB (n = 13)
9/1
11.5 ± 3.5 9.1 ± 3.6
17.5 ± 4.1b 30 ± 3.0
17.7 ± 4.2b
SB (n = 13)
DB (n = 10)
1.8 ± 1.7
1.3 ± 1.3 7/3
DB (n = 35) SB (n = 10)
2.3 ± 1.4
SB (n = 35)
13.7 ± 3.9
17.5 ± 4.0 13.2 ± 4.9
22/0
DB (n = 22) SB (n = 32)
1.3 ± 0.5
22/0
37.0 ± 5.8
SB (n = 22)
38.1 ± 5.7
21.2
23.4
IRER (°±SD)
DB (n = 80)
10.4 ± 5.2
10 ± 3.5
ER (°±SD)
SB (n = 45) 1.4 ± 0.4
IR (°±SD)
13.4 ± 6.0
1.4 ± 0.2a
1.4 ± 0.3a
0.3 ± 2.6
1.6 ± 2.3
KT-1000 (mm ± SD)
10.8 ± 6.4
10/0
Anterior drawer (neg/pos)
SB (n = 17)
26/4
DB (n = 30)
Lachman (neg/pos)
DB (n = 12)
25/5
SB (n = 30)
15/3 16/2
SB (n = 18)
Pivot shift (neg/pos)
DB (n = 18)
Surgery
2
3
3.4 ± 3.7
4.5 ± 2.6
4.6 ± 1.1
4.8 ± 1.5
A–P laxity (Pilot Nav) (mm ± SD)
b
a
Measured with motion Camera-system
Measured with Rolimeter
SB single-bundle, DB double-bundle, neg negative, pos positive, SD standard deviation, IR internal rotation, ER external rotation, IRER total internal–external rotation, A–P antero–posterior
37
Lee et al. [23]
209
125
Ishibashi et al. [13]
Hussein et al. [12]
29
Hemmerich et al. [8]
101
60
Gobbi et al. [6]
Hussein et al. [11]
36
Sample size (n)
Fujita et al. [4]
Author
Table 2 Kinematic results
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Fig. 2 Forest plot showing standard mean difference in KT-1000 arthrometer measurements between anatomic double- and single-bundle ACL reconstructions
Fig. 3 Forest plot showing standard mean difference in navigation measured antero–posterior laxity after anatomic double- versus single-bundle ACL reconstructions
favouring anatomic double-bundle ACL reconstruction. These results may to some extent give more information about the conditions reached in the reconstructed knee under dynamic conditions and what degenerative
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implications this may have on the joint with time [15]. Recently published meta-analyses on the subject revealed similar findings [25, 41, 42, 47]. Gadikota et al. [5] found no statistically significant differences in A–P laxity
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Fig. 4 Forest plot showing odds ratio of a normal pivot-shift test after anatomic double- versus single-bundle ACL reconstructions
between groups in an in vivo group. It appears the most recent meta-analysis and more importantly, the only metaanalysis that like ours compares exclusively anatomic reconstruction supports these findings [42]. The present meta-analysis, however, is unique in comparison with the above-mentioned studies as it focuses solely on anatomically performed single- and double-bundle ACL reconstruction and in addition includes a far more comprehensive database search resulting in inclusion of double the number of studies on anatomically performed single- and double-bundle ACL reconstructions compared with that of van Eck et al. [42]. Results from this meta-analysis of anatomic single-bundle and double-bundle ACL reconstruction revealed no statistically significant differences between the single- and double-bundle groups in terms of restoration of rotational laxity as measured by pivot-shift test or navigation. However, the results do point to a trend in support of that anatomic double-bundle ACL reconstruction is superior to singlebundle reconstruction in these regards. Kinematics and in particular rotatory laxity are important postoperative outcome measures in the short term [17, 18, 39]. We conclude that these measures, as opposed to subjective outcome scores, provide a more precise means to objectively evaluate differences in outcome between anatomic single-bundle and anatomic double-bundle ACL reconstruction. Restoration of rotatory laxity in particular is paramount to re-establish as closely as possible the pre-injury
conditions in the knee. Suboptimal restoration of rotational laxity, resulting in, for example, residual positive pivot shift after ACL reconstruction, has deleterious effects on meniscal and chondral structures in the knee and can at least theoretically be regarded as a predictor of future osteoarthritis (OA) [15, 24]. In addition to this, previous studies have also shown that excess persistent rotational laxity negatively affects patient reported outcomes and patient satisfaction [17, 18]. It should be noted, however, that the pivot-shift test is subjective and entails inter-observer variability that may prove it to be a rather crude test of rotational laxity [21, 32]. An important finding of this meta-analysis is the clear relationship observed between negative pivot-shift test and double-bundle reconstruction, where we observed significant differences with regard to number of negative pivotshift test in favour of the double-bundle group. van Eck et al. [42] also compared anatomic single-bundle to anatomic double-bundle ACL reconstructions. They included 12 studies, 7 of which they classify as anatomic singlebundle versus double-bundle reconstruction. Sub-group analysis comparing these anatomic groups revealed significant differences in favour of double-bundle reconstruction for restoration of rotational laxity using the pivot-shift test. There was, however, a discrepancy with regard to four studies classified as anatomic by van Eck et al. that we chose to classify as non-anatomic [20, 28, 29, 45]. All studies included in the present meta-analysis
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Fig. 5 Forest plot showing odds ratio of a normal Lachman test after anatomic double- versus single-bundle ACL reconstructions
Fig. 6 Forest plot showing odds ratio of a normal anterior drawer test after anatomic double- versus single-bundle ACL reconstructions
were selected on the premise that both single-bundle and double-bundle procedures were performed anatomically, and in accordance to that, the authors needed to clearly state that grafts were placed in the native ACL footprints on both the tibial and femoral side in both single-bundle and double-bundle groups. Two recently published metaanalysis one of which is a Cochrane meta-analysis comparing single- and double-bundle ACL reconstruction report findings of significantly higher number of negative pivot-shift test in the double-bundle group [41, 47]. In addition to these, one meta-analysis reports no significant difference between single- and double-bundle groups with regard to negative pivot-shift test [25], and one metaanalysis presents data on the subject from 7 in vitro and 3 in vivo biomechanical studies but performs no statistical analysis [5]. A shortcoming common to all these
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meta-analyses is that no distinction is made between anatomic and non-anatomic techniques. When analyzing graft failure, six studies reported data, one of which reported significantly less graft failures in the double-bundle group [40]. In the current meta-analysis, we also found results pointing to a trend favouring anatomic double-bundle reconstruction when it comes to graft failure rate without being able to show statistically significant fewer graft failures in the anatomic double-bundle group. Results reported by Tiamklamg et al. [41] in their Cochrane metaanalysis support our beliefs in that statistically significant differences were seen in favour of double-bundle reconstruction for newly occurring traumatic ACL rupture. Striving for anatomically placed single-bundled reconstruction with the goal of placing the graft both in the centres of the tibial and femoral footprints demands high technical
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Fig. 7 Forest plot showing standard mean difference of total internal–external rotation after anatomic double- versus single-bundle ACL reconstructions
Fig. 8 Forest plot showing odds ratio of negative graft failures after anatomic double- versus single-bundle ACL reconstructions
ability of the orthopaedic surgeon. This placement is difficult to achieve and is of essence to create a graft that does not elongate over time and potentially rupture. It is of the authors’ belief that if anatomic single-bundle reconstruction is performed with graft placement off-centre with regard to ACL footprints, this may result in excessive force to the graft which poses a future risk of future graft elongation and rupture. Overcoming this is achieved through reconstruction
of each individual graft and anatomic placement of each graft in the native bundle footprints. The present meta-analysis is unique in that, to our knowledge, it is the only meta-analysis to date addressing the aspect of kinematics in strictly anatomically performed single-bundle and double-bundle ACL reconstruction. An additional strength of this meta-analysis lies in its extensive and comprehensive database search, and adherence to strict
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Knee Surg Sports Traumatol Arthrosc Table 3 Bias evaluation Author
Random sequence generation (selection bias)
Allocation concealment (selection bias)
Blinding of participants and researchers (performance bias)
Blinding of outcome assessment (detection bias)
Incomplete outcome data (attrition bias)
Selective reporting (reporting bias)
Other bias
Fujita et al. [4]
-
-
-
-
?
?
?
Gobbi et al. [6]
-
-
?
?
?
?
?
Hemmerich et al. [8]
-
-
?
-
?
?
?
Ishibashi et al. [13]
-
-
-
-
?
?
-
Misonoo et al. [26]
-
-
-
-
?
?
?
Plaweski et al. [34]
-
-
-
-
?
?
?
Aglietti et al. [1]
?
?
?
?
-
?
?
Araki et al. [3]
-
?
-
-
?
?
?
Kanaya et al. [16]
-
-
-
-
?
?
?
Siebold et al. [38]
?
?
-
?
?
?
?
Yagi et al. [43]
-
-
-
-
?
?
?
Hussein et al. [11]
-
-
-
?
?
?
?
Hussein et al. [12]
?
?
-
?
?
?
?
Lee et al. [23]
?
?
?
?
?
?
?
Key ?, low risk of bias; -, high risk of bias; ?, unclear risk of bias
inclusion criteria further increases its quality. In those cases where relevant unpublished results were desired, the authors were contacted [8, 13, 16, 34], and we received replies with the requested data from three of the authors [8, 16, 34] increasing its comprehensiveness. By dichotomizing variables with otherwise graded values, e.g., pivot-shift test and Lachman test, we compared ‘‘normal’’/‘‘negative’’ results to all other results thereby allowing us to determine whether anatomic double-bundle reconstruction resulted in more ‘‘normal’’ results which was the hypothesis under study. Limitations of this meta-analysis include the fact that date restrictions were set to the electronic search and restricted the search to published studies and studies published in English which may contribute to an element of publication bias. The extensiveness of the search yielded a large number of studies to categorize, and there is a chance that some relevant articles were overlooked. Studies of Levels I and II were included, which inevitably lowers the overall Level of Evidence of the meta-analysis somewhat and, however, creates a more complete coverage of the trials on the topic. Bias assessment of the included studies using the Cochrane Collaboration’s tool for assessing risk revealed a limitation of this meta-analysis in that numerous studies showed systematic methodological errors (or simply lacking documentation) in, for example, randomization methods and allocation concealment deeming them to have an unclear or in cases high risk of bias. The tool is primarily designed for use in evaluating bias in randomized controlled trials; however,
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we applied it to prospective comparative studies to which to a certain extent accounts for the high number of ‘‘unclear’’ and/or ‘‘high risk’’ grades. The very nature of some prospective comparative studies entail an inevitable selection bias, which is why all of them in this metaanalysis received a ‘‘high risk’’ grade with regard to selection bias. In the clinical setting, optimal restoration of knee function and improvements in patient reported outcomes still remain a challenge. This has been observed and extensively studied regarding single-bundle ACL reconstruction primarily which to date has been the surgical method of choice. Recent evidence has emerged that both anatomic single- and double-bundle are proving to be promising surgical options. The results of this meta-analysis may illustrate the importance of the anatomic restoration of both the AM and PL bundles.
Conclusion Anatomic double-bundle ACL reconstruction is superior to anatomic single-bundle reconstruction in terms of restoration of knee kinematics, primarily A–P laxity. Whether these improvements of laxity result in long-term improvement of clinical meaningful outcomes remains uncertain. Interestingly, the only significant differences we observed favouring anatomic double-bundle ACL reconstruction in this metaanalysis were those of instrumented laxity measurements (using KT-1000 and navigation). This illustrates the
Knee Surg Sports Traumatol Arthrosc Table 4 Reported significant findings from included studies Study
Lachman test sign/nonsign
Anterior drawer test Sign/nonsign
KT-1000
A–P laxity
Sign/non-sign
Sign/ non-sign
Method
nsa
Fujita et al. [4]
Pivot-shift test
Rotatory laxity
Sign/ non-sign
Sign/ non-sign
Method (navigation system)
ns
8 camera MAS
ns
Ortho-pilot
ns
ns
9 camera MAS
ns
DB sig (p \ 0.001)
Praxim
ns
Ortho-pilot
DB sig (p \ 0.05)
Ortho-pilot
nsa
Gobbi et al. [6]
ns
Rolimeter
ns
Hemmerich et al. [8] Ishibashi et al. [13] Misonoo et al. [26]
ns ns
Orthopilot
ns
Plaweski et al. [34]
ns
Praxim
Aglietti et al. [1]
ns
DB sig (p \ 0.03)
ns
Araki et al. [3]
ns
ns
nsb
Kanaya et al. [16]
ns
Siebold et al. [38] Yagi et al. [43]
ns
Hussein et al. [11] Hussein et al. [12] Lee et al. [23]
ns
ns
Suomalainen et al. [40]
Orthopilot
DB sig (p = 0.054)
DB sig (p = 0.01)
ns
nsb
ns DB sig (p = 0.002)
ns DB sig (p \ 0.001)
ns
ns
Orthopilot
ns
ns ns
DB double-bundle, MAS motion analysis system, sig significant, ns not significant a
Double-bundle group better than PL group but not better than AM group
b
Not significant with manual pivot-shift test but significant with quantitative measurement with electromagnetic sensor
Table 5 Graft failures
SB single-bundle, DB doublebundle, AM antero-medial, PL postero-lateral, ACL anterior cruciate ligament
Study
Graft failure
Comment
SB
DB
Fujita et al. [4]
2
0
Gobbi et al. [6]
0
0
Aglietti et al. [1]
3
1
One traumatic graft rupture in single-bundle group, the rest nontraumatic graft failures of instability
Siebold et al. [38]
0
1
One traumatic graft rupture
Hussein et al. [11]
1
1
One from each group succumbed to graft failure defined as graft ruptures due to new injury
Suomalainen et al. [40]
7
1
All graft failures in both SB and DB group were defined as traumatic graft ruptures
Two single-bundle groups, AM and PL. Both graft failures were in PL group and were reported as graft re-ruptures
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Knee Surg Sports Traumatol Arthrosc Table 6 Significant results after meta-analysis Variable
Pooled OR/SMD
95 % CI
Sig/n.s.
I2 (%)
Pivot shift [3, 4, 6, 11, 12, 23, 26, 38, 40, 43]
1.96
0.99 to 3.87
n.s. (p = 0.053)
48.9
Lachman [3, 23, 43]
1.99
0.72 to 5.45
n.s. (p = 0.182)
0
Anterior drawer [23]
2.05
0.41 to 10.24
n.s. (p = 0.381)
–
KT-1000 [1, 3, 4, 6, 11, 12, 23, 26, 38, 40, 43]
0.36
0.21 to 0.51
sig (p \ 0.001)
0
Total internal–external rotation [8, 13, 16, 23, 26, 34]
0.27
-0.51 to 1.05
n.s. (p = 0.501)
89.9
Antero–posterior laxity [13, 16, 34]
0.29
0.01 to 0.57
sig (p = 0.042)
0
Graft failure [1, 4, 6, 11, 38, 40]
2.96
0.96 to 9.18
n.s. (p = 0.060)
0
SMD standardized mean difference, CI confidence interval, sig significant, n.s. not significant
underlying importance of developing and implementing standardized and quantified clinical examination tests in the future.
10. 11.
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34. Plaweski S, Grimaldi M, Courvoisier A, Wimsey S (2011) Intraoperative comparisons of knee kinematics of double-bundle versus single-bundle anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 19(8):1277–1286 35. Rahr-Wagner L, Thillemann TM, Pedersen AB, Lind MC (2013) Increased risk of revision after anteromedial compared with transtibial drilling of the femoral tunnel during primary anterior cruciate ligament reconstruction: results from the Danish Knee Ligament Reconstruction Register. Arthroscopy 29(1):98–105 36. Samuelsson K, Desai N, McNair E, van Eck CF, Petzold M, Fu FH, Bhandari M, Karlsson J (2012) Level of evidence in anterior cruciate ligament reconstruction research: a systematic review. Am J Sports Med 41(4):924–934 37. Schindler OS (2012) Surgery for anterior cruciate ligament deficiency: a historical perspective. Knee Surg Sports Traumatol Arthrosc 20(1):5–47 38. Siebold R, Dehler C, Ellert T (2008) Prospective randomized comparison of double-bundle versus single-bundle anterior cruciate ligament reconstruction. Arthroscopy 24(2):137–145 39. Snyder-Mackler L, Fitzgerald GK, Bartolozzi AR 3rd, Ciccotti MG (1997) The relationship between passive joint laxity and functional outcome after anterior cruciate ligament injury. Am J Sports Med 25(2):191–195 40. Suomalainen P, Jarvela T, Paakkala A, Kannus P, Jarvinen M (2012) Double-bundle versus single-bundle anterior cruciate ligament reconstruction: a prospective randomized study with 5-year results. Am J Sports Med 40(7):1511–1518 41. Tiamklang T, Sumanont S, Foocharoen T, Laopaiboon M (2012) Double-bundle versus single-bundle reconstruction for anterior cruciate ligament rupture in adults. Cochrane Database Syst Rev 11: CD008413 42. van Eck CF, Kopf S, Irrgang JJ, Blankevoort L, Bhandari M, Fu FH, Poolman RW (2012) Single-bundle versus double-bundle reconstruction for anterior cruciate ligament rupture: a metaanalysis-does anatomy matter? Arthroscopy 28(3):405–424 43. Yagi M, Kuroda R, Nagamune K, Yoshiya S, Kurosaka M (2007) Double-bundle ACL reconstruction can improve rotational stability. Clin Orthop Rel Res 454:100–107 44. Yagi M, Wong EK, Kanamori A, Debski RE, Fu FH, Woo SL (2002) Biomechanical analysis of an anatomic anterior cruciate ligament reconstruction. Am J Sports Med 30(5):660–666 45. Yasuda K, Kondo E, Ichiyama H, Tanabe Y, Tohyama H (2006) Clinical evaluation of anatomic double-bundle anterior cruciate ligament reconstruction procedure using hamstring tendon grafts: comparisons among 3 different procedures. Arthroscopy 22(3): 240–251 46. Zavras TD, Race A, Bull AM, Amis AA (2001) A comparative study of ‘isometric’ points for anterior cruciate ligament graft attachment. Knee Surg Sports Traumatol Arthrosc 9(1):28–33 47. Zhu Y, Tang RK, Zhao P, Zhu SS, Li YG, Li JB (2012) Doublebundle reconstruction results in superior clinical outcome than single-bundle reconstruction. Knee Surg Sports Traumatol Arthrosc 21(5):1085–1096
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KNEE
Anatomic single- versus double-bundle ACL reconstruction: a meta-analysis Neel Desai • Haukur Bjo¨rnsson • Volker Musahl • Mohit Bhandari • Max Petzold • Freddie H. Fu • Kristian Samuelsson
Received: 19 October 2013 / Accepted: 30 November 2013 Ó Springer-Verlag Berlin Heidelberg 2013
Abstract Purpose To determine whether anatomic double-bundle anterior cruciate ligament (ACL) reconstruction compared to anatomic single-bundle ACL reconstruction more effectively restored antero–posterior (A–P) laxity, rotatory laxity and reduced frequency of graft rupture. Our hypothesis was that anatomic double-bundle ACL reconstruction results in superior rotational knee laxity and fewer graft ruptures due to its double-bundle tension pattern, compared with anatomic single-bundle ACL reconstruction. Methods An electronic search was performed using the PubMed, EMBASE and Cochrane Library databases. All therapeutic trials written in English reporting knee kinematic outcomes and graft rupture rates of primary anatomic double- versus single-bundle ACL reconstruction were included. Only clinical studies of levels I–II evidence were included. Data regarding kinematic tests were extracted and included pivot-shift test, Lachman test, anterior drawer test, KT-1000 measurements, A–P laxity measures using
N. Desai H. Bjo¨rnsson K. Samuelsson (&) Department of Orthopaedics, Sahlgrenska University Hospital, 431 80 Mo¨lndal, Sweden e-mail: [email protected] V. Musahl F. H. Fu Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA M. Bhandari Division of Orthopaedic Surgery, Department of Surgery, McMaster University, Hamilton, ON, Canada M. Petzold Centre for Applied Biostatistics, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
navigation and total internal–external (IRER) laxity measured using navigation, as well as graft failure frequency. Results A total of 7,154 studies were identified of which 15 papers (8 randomized controlled trials and 7 prospective cohort studies, n = 970 patients) met the eligibility criteria. Anatomic ACL double-bundle reconstruction demonstrated less anterior laxity using KT-1000 arthrometer with a standard mean difference (SMD) = 0.36 (95 % CI 0.214–0.513, p \ 0.001) and less A–P laxity measured with navigation (SMD = 0.29 95 % CI 0.01–0.565, p = 0.042). Anatomic double-bundle ACL reconstruction did not lead to significant improvements in pivot-shift test, Lachman test, anterior drawer test, total IRER or graft failure rates compared to anatomic single-bundle ACL reconstruction. Conclusion Anatomic double-bundle ACL reconstruction is superior to anatomic single-bundle reconstruction in terms of restoration of knee kinematics, primarily A–P laxity. Whether these improvements of laxity result in long-term improvement of clinical meaningful outcomes remains uncertain. Level of evidence II. Keywords Anterior cruciate ligament ACL Reconstruction Single-bundle Double-bundle Anatomic Meta-analysis
Introduction Anterior cruciate ligament (ACL) injuries can lead to longterm functional deficits of knee function, often significantly limiting the patients’ partaking in sporting activities, particularly those involving rapid changes of direction and pivoting. One of the goals of ACL reconstruction is the
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Knee Surg Sports Traumatol Arthrosc
restoration of native anatomy and kinematics. Up to recently, transtibial single-bundle ACL reconstruction has been the standard surgical option to treat ACL-deficient knees [7]. It was developed during an era where isometric graft placement was the norm [37]. The concept of isometric placement denotes that the distance between ACL graft origin and insertion remains constant during flexion and extension. The reasons for the adherence to the isometric concept were that biomechanical studies had shown irreversible elongation of the graft if stretched repetitively more than four per cent, and surgeons believed that this elongation was prevented when placing the graft isometrically [35, 46]. In addition to this, to achieve effective isometry, optimal graft placement was high in the intercondylar notch of the femur close to the proximal limit of Blumensaat’s line, and this graft position was outside the native femoral ACL footprint. Recent biomechanical and clinical studies have shown suboptimal restoration of knee kinematics and sustained pivot-shift with isometrically placed grafts in comparison with those placed in the native ACL footprints [22, 30, 33]. Today, it is known that native ACL is in not isometric, owing largely to its complex, non-uniform multiple-bundle anatomy, with each bundle exhibiting different tensile properties [2]. The antero-medial (AM) bundle is taut predominantly during knee flexion with a maximum at 45°–60°, whereas the postero-lateral (PL) bundle is maximally taut with the knee in full extension. Efforts have been made to develop techniques to reconstruct AM and PL bundles separately, as well as focusing increased emphasis on the positioning of the individual grafts to as closely as possible resemble that of the native ACL bundles, the so-called anatomic double-bundle reconstruction. Recent biomechanical and clinical trials have shown superior results in support of this technique [19, 31, 44]. The theoretical advantage is that the two bundles can be tensioned separately, therefore mimicking more of the native tension patterns of the ACL bundles. As a result, in addition to restoring A–P laxity by reconstructing the AMbundle, it is believed that double-bundle ACL reconstruction more effectively re-establishes rotational laxity of which primarily the PL bundle contributes. Striving for anatomically placed single-bundled reconstruction with the goal of placing the graft both in the centres of the tibial and femoral footprints demands high technical ability of the orthopaedic surgeon. Results from previous biomechanical studies on elongation still stand true; thus, if single-bundle reconstruction is performed with graft placement off-centre with regard to ACL footprints, this poses a risk of elongation and graft rupture [46]. A number of systematic reviews and meta-analyses have recently emerged focusing on single-bundle and double-bundle ACL reconstruction. A
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shortcoming common to all these are that there are no strict distinctions between anatomic and non-anatomic techniques. In the clinical setting, this analysis is of great importance as there is a growing interest in both techniques as promising surgical intervention options. Current comparative studies on anatomic single-bundle and double-bundle ACL reconstruction with focus on knee kinematics and graft ruptures were investigated. To obtain true homogeneity, only studies comparing anatomically placed single- and double-bundle ACL reconstruction were included. Kinematic variables was the main focus of analysis, as we believe they are the most significant contributors to subjective and objective outcomes in the long term and that subjective short-term outcome measures are too coarse a tool to detect differences between the two techniques. It was hypothesized that anatomic single-bundle ACL reconstruction was less effective than anatomic doublebundle reconstruction in terms of restoration of knee kinematics and leads to higher graft failure frequency.
Materials and methods This systematic review was conducted in accordance with the PRISMA guidelines (preferred reporting items of systematic reviews and meta-analyses) [27]. PRISMA is comprised of a checklist including 27 items relating to the content of systematic reviews and meta-analyses and a four-phase flow diagram depicting the processing of this content. Eligibility criteria Inclusion criteria were clinical studies comparing anatomic single- and double-bundle primary ACL reconstruction. Only studies on human adults with isolated total ACL rupture were eligible for inclusion. Studies on patients with open physes and cadavers were not included. Only therapeutic studies were included, whereas prognostic and diagnostic studies were excluded unless the authors reported a clear relation between the outcome measures and the surgical technique. No Economical and Decision analysis studies were included. Concomitant meniscus and minor cartilage injuries were not grounds for exclusion [36]. Information sources and search Electronic search A systematic electronic search was performed from PubMed (MEDLINE), EMBASE and Cochrane Library
Knee Surg Sports Traumatol Arthrosc
databases. Publication dates set for inclusion were from January 1995 to August 2011. An additional updated search was performed in July 2012 only from the PubMed (MEDLINE) database and relevant publications between August 2011 and July 2012 were included. Two experts in electronic search methods at the **MASKED** Library performed and validated the search. The following search strings were used in the fields Title, Abstract and Keywords: (‘‘Anterior Cruciate Ligament’’ [Mesh] OR ‘‘anterior cruciate ligament’’ [tiab] OR ACL [tiab]) AND (‘‘Surgical Procedures, Operative’’ [Mesh] OR surgical [tiab] OR surgery [tiab] OR reconstruction [tiab] OR reconstructive [tiab] OR reconstructed [tiab]) AND (English [lang] AND (‘‘1995’’ [PDAT]: ‘‘3000’’ [PDAT])). Only papers written in English were included [36]. Data collection and analysis Study selection All the studies yielded from the electronic search were sorted based on abstracts by three reviewers, each reviewer sorting one database each that in turn was validated twice by the other reviewers. The included studies were then categorized into study types proposed by the Oxford Centre for Evidence-Based Medicine and into the category singlebundle, double-bundle or single-bundle versus double-bundle reconstruction. Studies were included if they fell into one of the following categories: randomized controlled trial, prospective comparative study and retrospective comparative study. If a study belonged to several categories, it was placed in the category of which the majority of study was related. Only studies comparing anatomic single-bundle versus double-bundle ACL reconstruction were included in this meta-analysis regardless of graft type or fixation method. The operative technique used to achieve anatomic ACL reconstruction had to be clearly described by the authors. The authors needed to state that grafts were placed in the native ACL footprints on both the tibial and femoral side in both single-bundle and double-bundle groups for the technique to be regarded as anatomic and the article to be eligible for inclusion. The study was analyzed in full text if the abstract did not provide enough data to make a decision. The researchers were not blinded to author, year and journal of publication. Disagreement between the reviewers was resolved by consensus or by discussion with the senior author when consensus was not reached.
was performed by the first, second and senior author and validated twice by the first author. Data items The data extracted from the included studies were as follows: author, year, title, journal, volume, issue, pages, ISSN, DOI, abstract, author-address, database provider, category, study type, level of evidence and country. Where stated, we extracted sample size and follow-up time. Surgical details regarding technique used in each case was also obtained and included drilling technique, placement of tibial and femoral tunnels and tension patterns of the grafts used. Data regarding kinematic tests were extracted and included pivot-shift test, Lachman test, anterior drawer test, KT-1000 measurements, A–P laxity measures using navigation and total internal– external (IRER) laxity measured using navigation. No predefined concept of what constitutes a graft failure was created. The number of graft failures were extracted from the included studies if the authors explicitly stated the terms graft failure or graft rupture. In the case of pivot-shift test and Lachman test, outcomes were dichotomized, yielding only ‘‘positive/normal’’ or ‘‘negative/abnormal’’ results. Several authors reported rotational laxity and A–P laxity measured at multiple flexion angles, and we chose to include those measured at 30° flexion for statistical analysis. Data regarding rotational laxities measured with pilot navigation were extracted; values of rotational laxity obtained using EMS or camera motion analysis were not extracted and were excluded from statistical analysis. Trials comparing double-bundle ACL reconstruction to two separate single-bundle groups (e.g. AM and PL) were included, but only data from the AM group were extracted and analyzed [43]. One study compared a double-bundle group to two single-bundle groups, one using metallic screws to anchor the graft and the other group using bioabsorbable screws; there was no statistical difference between the two single-bundle groups, and therefore, we chose to only include data from the bioabsorbable screw group in the analysis [40]. One study reporting internal and external rotation separately did not specify where the authors set the starting position and how they consistently used the same starting position, and thus, values were combined to yield a total rotation measurement [8]. In those cases where relevant unpublished results were desired, the authors were contacted [8, 13, 16, 34], and replies with the requested data from three of the authors were received [8, 16, 34]. To allow for statistical analysis, sample sizes were adjusted for each group taking into account patients lost to follow-up [8, 34].
Data collection process Synthesis of results Data from each study was extracted using a computerized database created in Microsoft Access (Version 2010, Microsoft Corporation, Redmond, WA, USA). Extraction
Statistical meta-analysis of the data was performed using the metan command version sbe24_3 for Stata (Version
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12.1, StataCorp LP, Texas, USA). In some studies, zero events were reported. Following the Cochrane recommendation, 0.5 was added to cases and non-cases in both study groups (http://handbook.cochrane.org). In the cases that standard error was not obtainable from the studies or after requesting these from the authors, standard errors were instead calculated based on the values reported in the studies within the same group with regard to that particular variable. Results were expressed as odds ratios (OR) with 95 % confidence intervals (CI) for dichotomous outcomes and for continuous outcomes as standardized mean differences (SMD) with 95 % CI. Random effect meta-analysis was used to account for heterogeneity. The I2 is provided in the graphs for each analysis to show the level of heterogeneity. The I2 index can be interpreted as the percentage of the total variability in a set of effect sizes that is attributable to genuine heterogeneity between the groups [10]. Assessment of risk of bias Until recently, the use of checklists and scores has been the modus operandi when evaluating the risk of bias in a study or trial. However, the Cochrane Collaboration has recommended against using such tools [9]. The reasons for this are numerous but include the fact that scores and checklists are suboptimal tools for evaluating internal validity as opposed to external validity. With scores and checklists, emphasis is often on the extent of reporting rather than on the conduct in that particular study. Another example is that to arrive at a score, the criteria therein must be weighted somehow and it is often difficult and unclear to justify how and why those weights are assigned. We chose to utilize the Cochrane Collaboration’s tool for assessing risk of bias developed by the Cochrane Bias Methods Group [9]. The assessment tool covers six domains of bias: sequence generation, allocation concealment, blinding, incomplete outcome data, selective outcome reporting and other sources of bias. Within each domain, an independent judgment by the two first authors of high, low or unclear risk of bias is made. Any discrepancies were resolved by consensus or by discussion with the senior author when consensus was not reached. Although primarily a tool intended for implementation on randomized controlled trials, we chose to use it on the prospective comparative studies in addition to the randomized controlled trials included in this metaanalysis. In those cases that insufficient information was reported by the authors of a study with regard to the parameters in the bias assessment tool, we awarded them an ‘‘unclear risk’’ grade. If sufficient information was reported by the author to determine the risk of bias, then
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they were awarded ‘‘high risk’’ or ‘‘low risk’’ for that particular bias parameter.
Results An electronic search yielded 5,608 studies in PubMed (MEDLINE), 5,421 studies in EMBASE and 700 studies in the Cochrane Library. Fifteen duplicates were removed from PubMed, 4,048 from EMBASE and 512 from Cochrane Library. There were 7,154 studies left in which 3,757 were excluded based on the abstracts and 1,887 based on full-text assessment. A total of 1,510 studies were included in the database and categorized into single-bundle, double-bundle and single-bundle versus double-bundle ACL reconstruction. Fifty-one studies were categorized as studies comparing single- and double-bundle ACL reconstruction. Two studies reported from the same pool of data in different publications with different outcomes, population sizes and follow-up times [14, 40], only the most recently published of these two studies was included for analysis [40]. Further screening of these 51 studies using the aforementioned inclusion criteria yielded eleven Level I or II studies that were regarded as having performed anatomic single-bundle and double-bundle ACL reconstruction. An updated search was performed in July 2012 only from the PubMed database yielding 596 studies. Of these, a total of 4 studies met the aforementioned selection process and were included in our analysis. This finally amounted to 15 studies in total, 8 RCTs and 7 prospective cohort studies that were included in our analysis [1, 3, 4, 6, 8, 11–13, 16, 23, 26, 34, 38, 40, 43] (Fig. 1). Characteristics of the studies Of the 15 studies included (n = 970 patients), 8 were randomized controlled trials (n = 513 patients) and 7 were prospective comparative studies (n = 457 patients). The included studies were published between 2007 and 2012. Follow-up times varied with mean follow-up times ranging from 5 months to 5 years. Three studies reported data obtained intra-operatively (using computer navigation) [13, 16, 34]. Where stated, information on drilling technique, tunnel placement and knee flexion angle at graft tensioning was noted (Table 1). Kinematic results Ten of the 15 included studies reported values of pivotshift test [3, 4, 6, 11, 12, 23, 26, 38, 40, 43]. Ten studies reported values of side-to-side difference in A–P laxity measured with KT-1000 [1, 3, 4, 11, 12, 23, 26, 38, 40, 43]
Knee Surg Sports Traumatol Arthrosc Fig. 1 Flow diagram of created ACL reconstruction database and the selection of studies for the meta-analysis
and one using Rolimeter [6]. Three studies reported A–P laxity measured by navigation [13, 16, 34]. Rotational laxity was reported in 5 studies using perioperative navigation [8, 13, 16, 23, 34] (Table 2; Figs. 2, 3, 4, 5, 6, 7, 8). Risk of bias in included studies Of the 15 studies included, the majority exhibited a high risk of selection bias illustrating poor methods of randomization or inadequate reporting of methods of randomization and allocation concealment, and these included both prospective comparative studies as well as certain randomized controlled trials [4, 6, 8, 11, 13, 16, 26, 34, 43]. One study clearly reported their method for allocation concealment, however, failed to describe how the randomization was performed and was graded accordingly [40]. One study states clearly how both randomization and allocation concealment was performed and therefore was determined to exhibit low risk of selection bias [12]. One study was graded ‘‘high risk’’ of other bias due to a baseline imbalance [13] (Table 3).
Reported significant findings from included studies Knee laxity Three studies reported a significant difference between single-bundle and double-bundle groups in laxity measurements with KT-1000, with results favouring doublebundle ACL reconstruction [1, 12, 38]. Two studies showed significant differences in manual pivot-shift test between single-bundle and double-bundle groups in favour of double-bundle ACL reconstruction, [12, 38]. Only two studies reported significantly less rotatory laxity in the double-bundle ACL reconstruction group compared to single-bundle reconstruction [23, 34] (see Table 4). Graft failure Graft failures were reported in six studies [1, 4, 6, 11, 38, 40]. Only one study performed statistical analysis of graft failures and reported statistically significant better results in the double-bundle group [40] (Table 5).
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Knee Surg Sports Traumatol Arthrosc Table 1 Study characteristics Author
Year
Study type
LoE
Sample size (n)
Fujita et al. [4]
2011
PCS
2
36
Gobbi et al. [6]
2011
PCS
2
60
Surgery
Follow-up (months)
Drilling
Tension pattern (flexion angle at tensioning)
SB (n = 18)
Mean 31.9 (SB) and 33.7 (DB)
TT
60 AM/15 PL
TT (AM)/TP (PL)
60 AM/15 PL
Mean 46.2 minimum 36
TP
Not spec
TP
20 AM/0 PL
DB (n = 18) SB (n = 30) DB (n = 30) Hemmerich et al. [8]
2011
PCS
2
29
SB (n = 17)
5.2
DB (n = 12) Ishibashi et al. [13]
2008
PCS
2
125
SB (n = 45)
0
DB (n = 80) Misonoo et al. [26].
2011
PCS
2
44
Plaweski et al. [34]
2011
PCS
2
62
SB (n = 22)
9–20, minimum 12
DB (n = 22) SB (n = 32)
2010
RCT
1
70
SB (n = 35)
45 45 AM/15 PL
TT
0
AM not spec/TT (PL)
15 AM/15 PL
TT
20
TT (AM)/TP or TT (PL)
20
Not spec
Not spec
TP
Not spec
TP
20
TP
40 AM/20 PL
Mean 12 (SB), 13.5 (DB)
TP
15
0
DB (n = 30) Aglietti et al. [1]
TP TP
Minimum 24
DB (n = 35) Araki et al. [3]
2011
RCT
1
20
SB (n = 10)
TT (AM)/TP (PL)
60 AM/15 PL
Kanaya et al. [16]
2009
RCT
1
26
SB (n = 13) DB (n = 13)
0
TT or TP TT or TP (AM ? PL)
30 30 AM/15 PL
Siebold et al. [38]
2008
RCT
1
70
SB (n = 35)
Mean 19 months (range 13–24)
Not spec
60
Yagi et al. [43]
2007
RCT
1
40
SB (n = 20)
DB (n = 10)
DB (n = 35) 12
DB (n = 20) Hussein et al. [11]
2012
PCS
2
101
SB (n = 32)
Hussein et al. [12]
2012
RCT
1
209
DB (n = 69) SB (n = 78)
Lee et al. [23]
2012
RCT
1
37
Mean 30 (range 26–34) Mean 51.15 (range 39–63)
DB (n = 131) SB (n = 18)
24
DB (n = 19) Suomalainen et al. [40]
2012
RCT
1
41
SB (n = 21)
60
DB (n = 20)
TT (AM)/TP (PL)
60 AM/20 PL
TT
60
TT (AM)/TP (PL)
60 AM/15 PL
TP
0
TP TP
0 AM/60 PL 0
TP
0 AM/60 PL
Not spec
Not spec
TT or TP
10 AM/0 PL
TP
Not spec
TP
Not spec
PCS prospective comparative study, RCT randomized controlled trial, LoE level of evidence, SB single-bundle, DB double-bundle, TT transtibial, TP trans-portal, AM antero-medial, PL postero-lateral, Not spec not specified
Results of meta-analysis Anterior laxity measured using KT-1000 arthrometer readings showed statistically significant results favouring double-bundle reconstruction (p \ 0.001) with a SMD of 0.36 (95 % CI 0.214–0.513). A significant difference was observed in favour of double-bundle reconstruction when measuring A–P laxity using navigation (p = 0.042) with SMD of 0.29 (95 % CI 0.01–0.565). No significant
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differences were seen regarding pivot-shift, Lachman test, anterior drawer, IRER or graft failure (Table 6).
Discussion The most important findings of this meta-analysis were that anterior laxity as measured with the KT-1000 arthrometer and A–P laxity measured by navigation showed results
44
62
70
20
26
70
40
Misonoo et al. [26]
Plaweski et al. [34]
Aglietti et al. [1]
Araki et al. [3]
Kanaya et al. [16]
Siebold et al. [38]
Yagi et al. [43]
41
Suomalainen et al. [40]
13/5
DB (n = 30)
10/11 7/13
SB (n = 21) DB (n = 20)
12/6 13/6
SB (n = 18) DB (n = 19)
52/26 122/9
59/10
DB (n = 69) SB (n = 78) DB (n = 131)
27/5
SB (n = 32)
15/5 17/3
SB (n = 20)
34/1
DB (n = 35) DB (n = 20)
25/10
SB (n = 35) 15/5
14/5
10/8
17/3
16/3
1.6 ± 3.0
2.2 ± 2.8
2.62 ± 1.72
2.74 ± 1.65
1.6 ± 0.8 1.2 ± 0.9
1.5 ± 0.9
1.6 ± 0.9
1.3 ± 1.2
1.9 ± 1.6
1.0 ± 1.0
1.6 ± 1.3
11.5 ± 4.1
12.8 ± 3.7 12.5 ± 4.8
24.0 ± 7.0
26.6 ± 4.8
12
0.7 ± 1.8 8
10/0
22.5 ± 4.2
DB (n = 13)
9/1
11.5 ± 3.5 9.1 ± 3.6
17.5 ± 4.1b 30 ± 3.0
17.7 ± 4.2b
SB (n = 13)
DB (n = 10)
1.8 ± 1.7
1.3 ± 1.3 7/3
DB (n = 35) SB (n = 10)
2.3 ± 1.4
SB (n = 35)
13.7 ± 3.9
17.5 ± 4.0 13.2 ± 4.9
22/0
DB (n = 22) SB (n = 32)
1.3 ± 0.5
22/0
37.0 ± 5.8
SB (n = 22)
38.1 ± 5.7
21.2
23.4
IRER (°±SD)
DB (n = 80)
10.4 ± 5.2
10 ± 3.5
ER (°±SD)
SB (n = 45) 1.4 ± 0.4
IR (°±SD)
13.4 ± 6.0
1.4 ± 0.2a
1.4 ± 0.3a
0.3 ± 2.6
1.6 ± 2.3
KT-1000 (mm ± SD)
10.8 ± 6.4
10/0
Anterior drawer (neg/pos)
SB (n = 17)
26/4
DB (n = 30)
Lachman (neg/pos)
DB (n = 12)
25/5
SB (n = 30)
15/3 16/2
SB (n = 18)
Pivot shift (neg/pos)
DB (n = 18)
Surgery
2
3
3.4 ± 3.7
4.5 ± 2.6
4.6 ± 1.1
4.8 ± 1.5
A–P laxity (Pilot Nav) (mm ± SD)
b
a
Measured with motion Camera-system
Measured with Rolimeter
SB single-bundle, DB double-bundle, neg negative, pos positive, SD standard deviation, IR internal rotation, ER external rotation, IRER total internal–external rotation, A–P antero–posterior
37
Lee et al. [23]
209
125
Ishibashi et al. [13]
Hussein et al. [12]
29
Hemmerich et al. [8]
101
60
Gobbi et al. [6]
Hussein et al. [11]
36
Sample size (n)
Fujita et al. [4]
Author
Table 2 Kinematic results
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Fig. 2 Forest plot showing standard mean difference in KT-1000 arthrometer measurements between anatomic double- and single-bundle ACL reconstructions
Fig. 3 Forest plot showing standard mean difference in navigation measured antero–posterior laxity after anatomic double- versus single-bundle ACL reconstructions
favouring anatomic double-bundle ACL reconstruction. These results may to some extent give more information about the conditions reached in the reconstructed knee under dynamic conditions and what degenerative
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implications this may have on the joint with time [15]. Recently published meta-analyses on the subject revealed similar findings [25, 41, 42, 47]. Gadikota et al. [5] found no statistically significant differences in A–P laxity
Knee Surg Sports Traumatol Arthrosc
Fig. 4 Forest plot showing odds ratio of a normal pivot-shift test after anatomic double- versus single-bundle ACL reconstructions
between groups in an in vivo group. It appears the most recent meta-analysis and more importantly, the only metaanalysis that like ours compares exclusively anatomic reconstruction supports these findings [42]. The present meta-analysis, however, is unique in comparison with the above-mentioned studies as it focuses solely on anatomically performed single- and double-bundle ACL reconstruction and in addition includes a far more comprehensive database search resulting in inclusion of double the number of studies on anatomically performed single- and double-bundle ACL reconstructions compared with that of van Eck et al. [42]. Results from this meta-analysis of anatomic single-bundle and double-bundle ACL reconstruction revealed no statistically significant differences between the single- and double-bundle groups in terms of restoration of rotational laxity as measured by pivot-shift test or navigation. However, the results do point to a trend in support of that anatomic double-bundle ACL reconstruction is superior to singlebundle reconstruction in these regards. Kinematics and in particular rotatory laxity are important postoperative outcome measures in the short term [17, 18, 39]. We conclude that these measures, as opposed to subjective outcome scores, provide a more precise means to objectively evaluate differences in outcome between anatomic single-bundle and anatomic double-bundle ACL reconstruction. Restoration of rotatory laxity in particular is paramount to re-establish as closely as possible the pre-injury
conditions in the knee. Suboptimal restoration of rotational laxity, resulting in, for example, residual positive pivot shift after ACL reconstruction, has deleterious effects on meniscal and chondral structures in the knee and can at least theoretically be regarded as a predictor of future osteoarthritis (OA) [15, 24]. In addition to this, previous studies have also shown that excess persistent rotational laxity negatively affects patient reported outcomes and patient satisfaction [17, 18]. It should be noted, however, that the pivot-shift test is subjective and entails inter-observer variability that may prove it to be a rather crude test of rotational laxity [21, 32]. An important finding of this meta-analysis is the clear relationship observed between negative pivot-shift test and double-bundle reconstruction, where we observed significant differences with regard to number of negative pivotshift test in favour of the double-bundle group. van Eck et al. [42] also compared anatomic single-bundle to anatomic double-bundle ACL reconstructions. They included 12 studies, 7 of which they classify as anatomic singlebundle versus double-bundle reconstruction. Sub-group analysis comparing these anatomic groups revealed significant differences in favour of double-bundle reconstruction for restoration of rotational laxity using the pivot-shift test. There was, however, a discrepancy with regard to four studies classified as anatomic by van Eck et al. that we chose to classify as non-anatomic [20, 28, 29, 45]. All studies included in the present meta-analysis
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Knee Surg Sports Traumatol Arthrosc
Fig. 5 Forest plot showing odds ratio of a normal Lachman test after anatomic double- versus single-bundle ACL reconstructions
Fig. 6 Forest plot showing odds ratio of a normal anterior drawer test after anatomic double- versus single-bundle ACL reconstructions
were selected on the premise that both single-bundle and double-bundle procedures were performed anatomically, and in accordance to that, the authors needed to clearly state that grafts were placed in the native ACL footprints on both the tibial and femoral side in both single-bundle and double-bundle groups. Two recently published metaanalysis one of which is a Cochrane meta-analysis comparing single- and double-bundle ACL reconstruction report findings of significantly higher number of negative pivot-shift test in the double-bundle group [41, 47]. In addition to these, one meta-analysis reports no significant difference between single- and double-bundle groups with regard to negative pivot-shift test [25], and one metaanalysis presents data on the subject from 7 in vitro and 3 in vivo biomechanical studies but performs no statistical analysis [5]. A shortcoming common to all these
123
meta-analyses is that no distinction is made between anatomic and non-anatomic techniques. When analyzing graft failure, six studies reported data, one of which reported significantly less graft failures in the double-bundle group [40]. In the current meta-analysis, we also found results pointing to a trend favouring anatomic double-bundle reconstruction when it comes to graft failure rate without being able to show statistically significant fewer graft failures in the anatomic double-bundle group. Results reported by Tiamklamg et al. [41] in their Cochrane metaanalysis support our beliefs in that statistically significant differences were seen in favour of double-bundle reconstruction for newly occurring traumatic ACL rupture. Striving for anatomically placed single-bundled reconstruction with the goal of placing the graft both in the centres of the tibial and femoral footprints demands high technical
Knee Surg Sports Traumatol Arthrosc
Fig. 7 Forest plot showing standard mean difference of total internal–external rotation after anatomic double- versus single-bundle ACL reconstructions
Fig. 8 Forest plot showing odds ratio of negative graft failures after anatomic double- versus single-bundle ACL reconstructions
ability of the orthopaedic surgeon. This placement is difficult to achieve and is of essence to create a graft that does not elongate over time and potentially rupture. It is of the authors’ belief that if anatomic single-bundle reconstruction is performed with graft placement off-centre with regard to ACL footprints, this may result in excessive force to the graft which poses a future risk of future graft elongation and rupture. Overcoming this is achieved through reconstruction
of each individual graft and anatomic placement of each graft in the native bundle footprints. The present meta-analysis is unique in that, to our knowledge, it is the only meta-analysis to date addressing the aspect of kinematics in strictly anatomically performed single-bundle and double-bundle ACL reconstruction. An additional strength of this meta-analysis lies in its extensive and comprehensive database search, and adherence to strict
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Knee Surg Sports Traumatol Arthrosc Table 3 Bias evaluation Author
Random sequence generation (selection bias)
Allocation concealment (selection bias)
Blinding of participants and researchers (performance bias)
Blinding of outcome assessment (detection bias)
Incomplete outcome data (attrition bias)
Selective reporting (reporting bias)
Other bias
Fujita et al. [4]
-
-
-
-
?
?
?
Gobbi et al. [6]
-
-
?
?
?
?
?
Hemmerich et al. [8]
-
-
?
-
?
?
?
Ishibashi et al. [13]
-
-
-
-
?
?
-
Misonoo et al. [26]
-
-
-
-
?
?
?
Plaweski et al. [34]
-
-
-
-
?
?
?
Aglietti et al. [1]
?
?
?
?
-
?
?
Araki et al. [3]
-
?
-
-
?
?
?
Kanaya et al. [16]
-
-
-
-
?
?
?
Siebold et al. [38]
?
?
-
?
?
?
?
Yagi et al. [43]
-
-
-
-
?
?
?
Hussein et al. [11]
-
-
-
?
?
?
?
Hussein et al. [12]
?
?
-
?
?
?
?
Lee et al. [23]
?
?
?
?
?
?
?
Key ?, low risk of bias; -, high risk of bias; ?, unclear risk of bias
inclusion criteria further increases its quality. In those cases where relevant unpublished results were desired, the authors were contacted [8, 13, 16, 34], and we received replies with the requested data from three of the authors [8, 16, 34] increasing its comprehensiveness. By dichotomizing variables with otherwise graded values, e.g., pivot-shift test and Lachman test, we compared ‘‘normal’’/‘‘negative’’ results to all other results thereby allowing us to determine whether anatomic double-bundle reconstruction resulted in more ‘‘normal’’ results which was the hypothesis under study. Limitations of this meta-analysis include the fact that date restrictions were set to the electronic search and restricted the search to published studies and studies published in English which may contribute to an element of publication bias. The extensiveness of the search yielded a large number of studies to categorize, and there is a chance that some relevant articles were overlooked. Studies of Levels I and II were included, which inevitably lowers the overall Level of Evidence of the meta-analysis somewhat and, however, creates a more complete coverage of the trials on the topic. Bias assessment of the included studies using the Cochrane Collaboration’s tool for assessing risk revealed a limitation of this meta-analysis in that numerous studies showed systematic methodological errors (or simply lacking documentation) in, for example, randomization methods and allocation concealment deeming them to have an unclear or in cases high risk of bias. The tool is primarily designed for use in evaluating bias in randomized controlled trials; however,
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we applied it to prospective comparative studies to which to a certain extent accounts for the high number of ‘‘unclear’’ and/or ‘‘high risk’’ grades. The very nature of some prospective comparative studies entail an inevitable selection bias, which is why all of them in this metaanalysis received a ‘‘high risk’’ grade with regard to selection bias. In the clinical setting, optimal restoration of knee function and improvements in patient reported outcomes still remain a challenge. This has been observed and extensively studied regarding single-bundle ACL reconstruction primarily which to date has been the surgical method of choice. Recent evidence has emerged that both anatomic single- and double-bundle are proving to be promising surgical options. The results of this meta-analysis may illustrate the importance of the anatomic restoration of both the AM and PL bundles.
Conclusion Anatomic double-bundle ACL reconstruction is superior to anatomic single-bundle reconstruction in terms of restoration of knee kinematics, primarily A–P laxity. Whether these improvements of laxity result in long-term improvement of clinical meaningful outcomes remains uncertain. Interestingly, the only significant differences we observed favouring anatomic double-bundle ACL reconstruction in this metaanalysis were those of instrumented laxity measurements (using KT-1000 and navigation). This illustrates the
Knee Surg Sports Traumatol Arthrosc Table 4 Reported significant findings from included studies Study
Lachman test sign/nonsign
Anterior drawer test Sign/nonsign
KT-1000
A–P laxity
Sign/non-sign
Sign/ non-sign
Method
nsa
Fujita et al. [4]
Pivot-shift test
Rotatory laxity
Sign/ non-sign
Sign/ non-sign
Method (navigation system)
ns
8 camera MAS
ns
Ortho-pilot
ns
ns
9 camera MAS
ns
DB sig (p \ 0.001)
Praxim
ns
Ortho-pilot
DB sig (p \ 0.05)
Ortho-pilot
nsa
Gobbi et al. [6]
ns
Rolimeter
ns
Hemmerich et al. [8] Ishibashi et al. [13] Misonoo et al. [26]
ns ns
Orthopilot
ns
Plaweski et al. [34]
ns
Praxim
Aglietti et al. [1]
ns
DB sig (p \ 0.03)
ns
Araki et al. [3]
ns
ns
nsb
Kanaya et al. [16]
ns
Siebold et al. [38] Yagi et al. [43]
ns
Hussein et al. [11] Hussein et al. [12] Lee et al. [23]
ns
ns
Suomalainen et al. [40]
Orthopilot
DB sig (p = 0.054)
DB sig (p = 0.01)
ns
nsb
ns DB sig (p = 0.002)
ns DB sig (p \ 0.001)
ns
ns
Orthopilot
ns
ns ns
DB double-bundle, MAS motion analysis system, sig significant, ns not significant a
Double-bundle group better than PL group but not better than AM group
b
Not significant with manual pivot-shift test but significant with quantitative measurement with electromagnetic sensor
Table 5 Graft failures
SB single-bundle, DB doublebundle, AM antero-medial, PL postero-lateral, ACL anterior cruciate ligament
Study
Graft failure
Comment
SB
DB
Fujita et al. [4]
2
0
Gobbi et al. [6]
0
0
Aglietti et al. [1]
3
1
One traumatic graft rupture in single-bundle group, the rest nontraumatic graft failures of instability
Siebold et al. [38]
0
1
One traumatic graft rupture
Hussein et al. [11]
1
1
One from each group succumbed to graft failure defined as graft ruptures due to new injury
Suomalainen et al. [40]
7
1
All graft failures in both SB and DB group were defined as traumatic graft ruptures
Two single-bundle groups, AM and PL. Both graft failures were in PL group and were reported as graft re-ruptures
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Knee Surg Sports Traumatol Arthrosc Table 6 Significant results after meta-analysis Variable
Pooled OR/SMD
95 % CI
Sig/n.s.
I2 (%)
Pivot shift [3, 4, 6, 11, 12, 23, 26, 38, 40, 43]
1.96
0.99 to 3.87
n.s. (p = 0.053)
48.9
Lachman [3, 23, 43]
1.99
0.72 to 5.45
n.s. (p = 0.182)
0
Anterior drawer [23]
2.05
0.41 to 10.24
n.s. (p = 0.381)
–
KT-1000 [1, 3, 4, 6, 11, 12, 23, 26, 38, 40, 43]
0.36
0.21 to 0.51
sig (p \ 0.001)
0
Total internal–external rotation [8, 13, 16, 23, 26, 34]
0.27
-0.51 to 1.05
n.s. (p = 0.501)
89.9
Antero–posterior laxity [13, 16, 34]
0.29
0.01 to 0.57
sig (p = 0.042)
0
Graft failure [1, 4, 6, 11, 38, 40]
2.96
0.96 to 9.18
n.s. (p = 0.060)
0
SMD standardized mean difference, CI confidence interval, sig significant, n.s. not significant
underlying importance of developing and implementing standardized and quantified clinical examination tests in the future.
10. 11.
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