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Primary Arthroscopic Repair of the Anterior Cruciate Ligament: A Systematic Review of Clinical Outcomes
Systematic Review
Primary Arthroscopic Repair of the Anterior Cruciate Ligament: A Systematic Review of Clinical Outcomes Darby A. Houck, B.A., Matthew J. Kraeutler, M.D., John W. Belk, B.A., Joshua A. Goode, M.A., Mary K. Mulcahey, M.D., and Jonathan T. Bravman, M.D.
Purpose: To describe the clinical outcomes after primary arthroscopic anterior cruciate ligament (ACL) repair. Methods: A systematic review of the PubMed, Embase, and Cochrane Library databases was performed according to the PRISMA guidelines. All English-language literature published from 2000 to 2018 that reported the clinical outcomes after primary arthroscopic repair (AR) of complete tear of the ACL (without augmentation) with a minimum 2-year follow-up was reviewed by 2 independent reviewers. Outcomes included repair failure, reoperation, postoperative knee stability, and patient-reported outcomes. Descriptive statistics are presented. Study quality was evaluated with the Modified Coleman Methodology Score (MCMS) and the Methodological Index for Nonrandomized Studies (MINORS) score. Results: Six studies (2 level III, 4 level IV) were included. The mean MCMS was 62.2. The mean MINORS score for noncomparative studies was 11.8, and for comparative studies, 18. Six studies reported outcomes of 89 patients who underwent AR of the ACL from 2007 to 2016 (age, 8 to 67 years; follow-up, 24 to 110 months). All 6 studies included exclusively proximal avulsion tears. Overall, 0% to 25.0% of patients experienced repair failure (I2 ¼ 23.7%; 95% confidence interval, 0% to 67.6%), and 0% to 20.0% of patients had a subsequent reoperation (I2 ¼ 12.1%; 95% confidence interval, 0% to 77.7%). Similar inconsistent results were shown for postoperative knee stability measures and patient-reported outcomes. Conclusions: The literature on clinical outcomes of primary arthroscopic ACL repair is limited. The reported rates of repair failure and reoperation are highly inconsistent. Most studies report relatively high failure rates. Level of Evidence: IV, systematic review of level III and IV studies.
See commentary on page 3328 ith an increasing incidence of anterior cruciate ligament (ACL) injuries in the literature,1,2 surgical treatment of ACL tears has continued to evolve. Initial results of primary open ACL repair were promising but were shown to fail at longer follow-up periods.3-7 Thus, the orthopaedic community shifted to ACL augmentation, and eventually to the current gold standard treatment, ACL reconstruction.8 The primary goal of surgical treatment in the setting of an ACL tear is to restore knee stability and the biomechanical and
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anatomic properties of the native ACL.9,10 Furthermore, nonanatomic tunnel placement (i.e., vertical tunnels) is one of the most common factors contributing to graft failure after ACL reconstruction.11 For these reasons, the potential for repairing the native ACL is particularly appealing.8 Recently, the concept of primarily repairing a torn ACL, rather than reconstructing it using a graft, has regained popularity for certain tear patterns.8,10,12-18 There have been profound improvements in
From the Department of Orthopedics, University of Colorado School of Medicine (D.A.H., J.W.B., J.T.B.), Aurora, Colorado, U.S.A.; the St. Joseph’s University Medical Center (M.J.K.), Paterson, New Jersey, U.S.A.; the Department of Sociology, Institute of Behavioral Science, University of Colorado Boulder (J.A.G.), Boulder, Colorado, U.S.A.; and the Department of Orthopedics, Tulane University School of Medicine (M.K.M.), New Orleans, Louisiana, U.S.A. The authors report the following potential conflicts of interest or sources of funding: M.K.M. reports board or committee member for AAOS, American Orthopaedic Society for Sports Medicine, Arthroscopy Association of North America, Ruth Jackson Orthopaedic Society. J.T.B. reports paid consultant from DJ Orthopaedics; other from Mitek; other and paid consultant from
Smith & Nephew; other and research support from Stryker; IP royalties and unpaid consultant from Shukla Medical; board or committee member for Western Orthopedic Association. Full ICMJE author disclosure forms are available for this article online, as supplementary material. Received February 26, 2019; accepted June 21, 2019. Address correspondence to Darby A. Houck, 2150 Stadium Dr, Room 222, Boulder, CO 80309, U.S.A. E-mail: [email protected] Ó 2019 by the Arthroscopy Association of North America 0749-8063/19250/$36.00 https://doi.org/10.1016/j.arthro.2019.06.034
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Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 35, No 12 (December), 2019: pp 3318-3327
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Fig 1. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram.
diagnostic and therapeutic capabilities, such as advanced arthroscopic techniques and instrumentation, since primary open ACL repair was initially abandoned.13 Additionally, current preoperative magnetic resonance imaging (MRI) techniques can accurately identify tear location and tissue quality, which can help guide the surgeon on which patients may be candidates for arthroscopic primary ACL repair.19 The purpose of this systematic review was to describe the clinical outcomes following primary arthroscopic ACL repair. The authors hypothesized that primary arthroscopic ACL repair would have a relatively high failure rate.
Methods This systematic search was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines using a PRISMA checklist. Two independent reviewers (D.A.H., J.W.B.) searched PubMed, Embase, and the Cochrane Library up to May 10, 2019. The following search phrase was used:
“anterior cruciate ligament” primary repair. Other sources were searched by reviewing reference lists and citing manuscripts to reduce the risk of omission of relevant articles. A total of 448 studies were reviewed by title and/or abstract to determine study eligibility based on inclusion criteria. In cases of disagreement, a third reviewer (M.J.K.) made the final decision. Inclusion and exclusion criteria followed the participants, interventions, comparators, outcomes, study design (PICOS) strategy. Studies selected for inclusion met the following criteria: studies reporting clinical outcomes of patients who underwent primary arthroscopic repair (AR) of the ACL without augmentation; patients with a complete ACL tear; studies with a minimum 2-year follow-up; studies that were published in English; retrospective and prospective studies of level I to IV evidence; studies that were published after January 1, 2000; and procedures that were performed after January 1, 2000. Exclusion criteria included cadaveric or animal studies, nonclinical studies, patients with a partial ACL
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Study Noncomparative studies Bigoni et al., 201715 DiFelice and van der List, 201816 Hoffman et al., 201717 Mukhopadhyay et al., 201832 Comparative studies Achtnich et al., 201612 Jonkergouw et al., 201931 NOTE. Follow-up data are reported as n/N (%), and patient age, time from injury to surgery, and follow-up duration are reported as mean (range). LOE, level of evidence; MCMS, Modified Coleman Methodology Score; NR, not reported; PDR, procedure date range.
Study Achtnich et al., 201612 Bigoni et al., 201715 DiFelice and van der List, 201816 Hoffman et al., 201717 Jonkergouw et al., 201931 Mukhopadhyay et al., 201832
Table 1. Studies Included
PDR 2010-2013 2007-2010 2008-2012 2009-2012 2008-2016 2014-2015
Country Germany Italy United States Germany United States India
LOE III IV IV IV III IV
MCMS 71 60 62 58 60 62
Follow-Up 20/21 (95.2) 5/5 (100) 10/11 (90.9) 12/13 (92.8) 29/29 (100) 13/13 (100)
Percentage of Males NR 80 90.9 30.8 62.1 100
Age (yr) 30 9.2 (8 to 10) 37 (17 to 57) 43.3 (19 to 67) 37 31.3 (21 to 40)
Time From Injury to Surgery (d) NR 81 (15 to 123) 39 (10 to 93) 5.8 (1 to 20) NR (9 to 4,018) 7.6 (3 to 12)
Follow-Up Duration (mo) 28 (24 to 31) 43.4 (25 to 56) 72 (58 to 110) 79 (60 to 98) 48 31.3 (26 to 38)
Table 2. Methodological Items for Nonrandomized Studies (MINORS) Scores MINORS Score 12 12 12 11
(75%) (75%) (75%) (68.8%)
21 (88%) 15 (62.5%)
NOTE. The global ideal score is 16 for noncomparative studies and 24 for comparative studies.
tear, healing response performed alone without repair of the ACL, primary ACL repair using augmentation, primary open ACL repair, and case reports. Primary ACL repair using augmentation was defined as any of the following procedures: internal bracing surgical techniques, such as dynamic intraligamentary stabilization and internal brace ligament augmentation, ligament advanced reinforcement system techniques, graft augmentation with an allograft or autograft, and bridgeenhanced ACL repair device. When presented with a duplicate study population in 2 studies,13,16 we chose the study with a longer duration of follow-up.16 Six studies were determined to meet inclusion and exclusion criteria (Fig 1). Data extraction from each study was performed independently (D.A.H.). When presented with comparative studies, only data from the population that met the above inclusion and exclusion criteria were extracted. There was no need for funding or a third party to obtain any of the collected data. Reporting Outcomes Outcome data recorded included repair failure, reoperation, physical examination findings (Lachman and pivot-shift tests), anteroposterior (AP) knee laxity, patient-reported outcomes (PROs), and the Objective International Knee Documentation Committee (IKDC) score. PROs included the Subjective IKDC score, the Lysholm score, and the Tegner activity score. Assessment of Study Quality The quality of study methodology was evaluated using the Modified Coleman Methodology Score (MCMS) based on a scaled potential score ranging from 0 to 100.20 Scores ranging from 85 to 100 are excellent, 70 to 84 are good, 55 to 69 are fair, and <55 are poor. Risk of bias was assessed according to the Methodological Index for Nonrandomized Studies (MINORS) score,21 which incorporates 8 items to assess overall bias in noncomparative studies and an additional 4 items in comparative studies. The MINORS score has a scaled potential score ranging from 0 to 16 for noncomparative studies and 0 to 24 for comparative
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Mukhopadhyay et al., 201832
Jonkergouw et al., 201931
Hoffman et al., 201717
DiFelice and van der List, 201816
Bigoni et al., 201715
ACL, anterior cruciate ligament; ACLR, anterior cruciate ligament reconstruction; AR, arthroscopic repair.
No
Yes
No
No
No
studies. Each item is scored 0 (not reported), 1 (reported but inadequate), or 2 (reported and adequate).
Study Summary Case-control study comparing primary AR of the ACL with suture anchors and microfracturing with anatomic single-bundle ACLR in patients with acute proximal avulsion ACL tears Retrospective review of skeletally immature patients with proximal ACL tears who underwent primary AR of the ACL with a bioabsorbable anchor Retrospective follow-up study of the previously reported short-term outcomes13 of patients with proximal avulsion ACL tears who underwent arthroscopic primary AR with suture anchors Retrospective review of patients with proximal ACL tears who underwent primary AR of the ACL with suture anchors Retrospective study of the first 56 consecutive patients with proximal ACL tears who underwent primary AR of the ACL with suture anchor (first 29 patients) or primary AR of the ACL with internal bracing (latter 27 patients) Prospective study of consecutive patients with proximal ACL tears who underwent primary AR of the ACL with suture pull-out technique Study Achtnich et al., 201612
Table 3. Summary of Studies Included
Presence of Control or Comparison Group Yes
PRIMARY ARTHROSCOPIC ACL REPAIR REVIEW
Statistical Analysis Individual study heterogeneity regarding patient populations and treatment prevented meta-analysis calculations. Therefore, descriptive statistics are presented for numerical demographic data (age and follow-up), AP laxity measurements, and PROs. Categorical variables (repair failure, reoperation, Lachman, and pivot-shift tests) were reported as percentages. Because of heterogeneity and quality of the included studies in this review, the outcomes were not pooled. Rather, a subjective synthesis was performed, where ranges were reported and individual study data were presented in a forest plot (only when data from 3 studies assessed an outcome). Using a random-effects model (due to anticipated heterogeneity) by the DerSimonian-Laird22 and Clopper-Pearson interval23 methods, single raw proportions and 95% confidence intervals (CIs) were calculated for individual study results and were presented in forest plots. As the studies are too diverse, and the methodologies are poor such that the risk of bias is high or known confounding variables are not accounted for, pooling of study results and reporting weighted mean calculations was avoided.24 According to Cote et al.,25 a systematic review with exploration of heterogeneity has been shown to result in valuable information regarding strengths and weaknesses of the currently available literature to help guide future research efforts.25-28 Therefore, the I2 statistic was calculated to quantify the degree of heterogeneity and was presented in forest plots. An I2 statistic 40% represents an acceptable degree of heterogeneity.29 Generation of forest plots and tests for heterogeneity were performed using the metaprop function of the Metafor Package (A Meta-Analysis Package for R).30
Results Included Studies Six studies (2 level III, and 4 level IV),12,15-17,31,32 published between 2016 and 2019, met inclusion and exclusion criteria (Fig 1). All 6 studies12,15-17,31,32 included patients who underwent primary arthroscopic ACL repair. Assessment of Study Quality Table 1 shows the MCMS scores from the 6 included studies (mean MCMS score, 62.2), 112 of which achieved a good score and 515-17,31,32 of which achieved fair scores. This indicates that the overall quality of the study was fair. The results of the methodologic quality and risk of bias assessment of included studies using the MINORS score are presented in Table 2. The mean
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Fig 2. Rate of repair failure and reoperation after primary anterior cruciate ligament repair. Forest plot showing the proportion of patients with repair failure (A) and subsequent reoperation (B). Two studies16,17 reported more patients when assessing graft failure than when reporting PROs and follow-up physical examination findings, explaining why the sample size in this table is larger than mentioned above. The repair failure and reoperation rates are represented by squares proportional in size to the sample size of the individual study and confidence intervals (CIs; horizontal lines) of repair failure and reoperation rates by individual study and by repair technique. I2 ¼ percentage of variation due to heterogeneity rather than chance.
MINORS score for noncomparative studies was 11.8,15-17,32 and the score for the comparative studies was 18.12,31 Patient Demographics A total of 89 patients who underwent AR between 200715 and 201631 were included in this systematic review. Patient age at the time of surgery ranged from 815 to 6717 years (Table 1). One study included patients who were skeletally immature at the time of surgery.15 The percentage of patients available for follow-up ranged from 90.9%16 to 100%.15,31,32 Further details on patient demographics and study design information are presented in Tables 1 and 3. ACL Tear Location All 6 studies12,15-17,31,32 that performed primary AR included only patients with proximal avulsion tears. Associated Injuries Five studies12,16,17,31,32 that performed AR included patients with concomitant injuries, including medial
and lateral meniscal tears, cartilage injuries (including chondromalacia), or medial/lateral collateral ligament injuries. Bigoni et al.15 did not include patients with any concomitant injuries. Postoperative Rehabilitation All 6 studies12,15-17,31,32 clearly reported postoperative protocols. Clinical Outcomes Failures and Reoperations Two studies15,32 did not clearly define repair failure. Two studies16,17 defined clinical failure as a 2þ Lachman or 2þ pivot-shift test, subjective knee instability, or radiological evidence of discontinuity of the repaired ligament. One study12 defined failure as recurrent instability, and 1 study31 defined failure as symptomatic instability or rerupture. Overall, 0% to 25.0% of patients experienced repair failure (Fig 2). Statistical assessment of heterogeneity found for repair failure was I2 ¼ 23.7% (95% CI, 0% to
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Fig 3. Pivot-shift results. Forest plot showing the proportion of patients with a 1þ (glide) (A) and 2þ (clunk) (B) pivot-shift findings after primary arthroscopic anterior cruciate ligament repair. Pivot-shift grades are represented by squares proportional in size to the sample size of the individual study and confidence intervals (CIs; horizontal lines) of pivot-shift grades by individual study and by repair technique. I2 ¼ percentage of variation due to heterogeneity rather than chance.
67.6%). Although a total of 11 of these patients were considered failures, it should be noted that 2 were reportedly noncompliant with postoperative physical therapy, brace use, and return to sport.12,16 Additionally, of the 2 studies12,15 that reported postoperative MRI results on all patients, 85.7%12 to 100%15 of patients who underwent AR had an intact ACL at final follow-up. Overall, 0% to 20.0% of patients had a subsequent reoperation (Fig 2), of which 0% to 9.1% were revision surgeries to address instability and 0% to 15% were for other injuries in the knee joint. As shown in Fig 2, statistical assessment of heterogeneity found for reoperation was I2 ¼ 12.1% (95% CI, 0% to 77.7%). Knee Stability Four studies12,15,16,32 that performed AR reported postoperative pivot-shift (Fig 3) and Lachman test (Fig 4) results. Overall, 0% to 100% of patients had 1þ pivot-shift findings, whereas 0% of patients had 2þ pivot-shift findings. Statistical assessment for heterogeneity for 1þ pivot-shift was I2 ¼ 95.5% (95% CI, 91.3% to 97.7%) (Fig 3); statistical assessment for heterogeneity for 2þ pivot-shift was I2 ¼ 0% (95% CI, 0% to 0%) (Fig 3). Overall, 10% to 20% of patients had a 1þ Lachman, and 0% of patients had a 2þ Lachman. Statistical assessment for heterogeneity for 1þ Lachman was I2 ¼ 0% for AR (95% CI, 0% to 0%) (Fig 4). Statistical
assessment for heterogeneity for 2þ Lachman was I2 ¼ 0% for AR (95% CI, 0% to 0%). Mean postoperative AP laxity was reported by 4 studies (Table 4).12,15,17,32 Objective IKDC Scores Three studies12,16,17 that performed AR reported Objective IKDC scores (Fig 5). Of these, only 1 study12 reported preoperative Objective IKDC scores (0 A, 4 B, 15 C, 1 D). Bigoni et al.15 noted that all patients had a normal or nearly normal IKDC scores. Jonkergouw et al.31 did not distinguish Objective IKDC scores of the 29 patients (51.8%) who underwent primary arthroscopic ACL repair and are included in this systematic review from the 27 patients (48.2%) who underwent primary ACL repair with internal bracing (not included here). The reported Objective IKDC scores of all 52 examined patients were A in 38 patients (73%), B in 8 (15%), and C/D in 6 (12%), and the authors noted that these scores did not differ between the groups. In the 3 studies12,16,17 that reported Objective IKDC scores, 82% to 100% of patients had A/B Objective IKDC scores, and 0% to 18% of patients had C/D Objective IKDC scores. Statistical assessment for heterogeneity for A/B Objective IKDC scores was I2 ¼ 36.5% for AR (95% CI, 0% to 79.8%) (Fig 5). Statistical assessment for heterogeneity for C/D Objective IKDC scores was I2 ¼ 36.5% for AR (95% CI, 0% to 79.8%).
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Fig 4. Lachman test results. Forest plot showing the proportion of patients with a 1þ (anterior tibial translation 3 to 5 mm) (A) and 2þ (>5 mm) (B) Lachman test results after primary arthroscopic anterior cruciate ligament repair. The Lachman grades are represented by squares proportional in size to the sample size of the individual study and confidence intervals (CIs; horizontal lines) of Lachman grades by individual study and by repair technique. I2 ¼ percentage of variation due to heterogeneity rather than chance.
Patient-Reported Outcomes Four studies15-17,31 that performed AR reported mean Subjective IKDC scores (Table 5). Four studies15-17,31 reported Tegner scores (Table 5). Bigoni et al.15 noted that 4 patients (80%) returned to preinjury Tegner activity levels, whereas 1 patient decreased from a preinjury Tegner score of 6 to a score of 4 postoperatively. Five studies reported Lysholm scores (Table 5).15-17,31,32
Discussion The results of this systematic review suggest that, at a minimum follow-up of 24 months (range 24 to 110 months), patients undergoing primary arthroscopic ACL repair have variable clinical outcomes and show highly inconsistent failure rates (range, 0% to 25%). Table 4. Anteroposterior Laxity at Follow-Up Anteroposterior Laxity (mm) Study Achtnich et al., 201612 Bigoni et al., 201715 Hoffman et al., 201717 Mukhopadhyay et al., 201832
Mean 2.0 3.0 2.1 1.7
NR, not reported; SD, standard deviation.
SD 1.7 0.7 NR 0.8
Range NR 2.0 to 4.0 1.0 to 5.0 1.0 to 3.0
The literature quality and finding that moderate to high heterogeneity may be present is limited, as these statistics are greatly underpowered and preclude any definitive conclusions. Future study should be prospective and should use explicit eligibility criteria regarding the proper indications for performing primary arthroscopic ACL repair. A previous systematic review by Taylor et al.7 concluded that the long-term outcomes after primary open ACL repair are unacceptable, although a subset of patients with proximal tears and excellent tissue quality achieved acceptable long-term results. However, the previous systematic review only included 1 case series33 that performed AR of proximal avulsion tears through transepiphyseal femoral tunnels as opposed to standard arthroscopic portals. Since the previous systematic review was published in 2015, several studies examining clinical outcomes of patients with proximal avulsion tears6 after primary arthroscopic ACL repair have been published.12,15-17,31,32 This updated systematic review shows the variability in outcomes, failure definitions, concomitant injuries, and patient demographics among previous studies in the currently available literature. Therefore, the present systematic review focuses on clinical outcomes of primary AR of proximal avulsion ACL tears.
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Fig 5. Objective International Knee Documentation Committee (IKDC) scores. Forest plot showing the proportion of patients with A/B (A) and C/D (B) Objective IKDC scores after primary arthroscopic anterior cruciate ligament repair. The Objective IKDC scores are represented by squares proportional in size to the sample size of the individual study and confidence intervals (CIs; horizontal lines) of Objective IKDC scores by individual study and by repair technique. I2 ¼ percentage of variation due to heterogeneity rather than chance.
In 1991, Sherman et al.6 determined that only a certain subgroup of patients do well with primary ACL repair. This retrospective cohort study performed a subgroup analysis by tissue quality and tear location and determined that patients who had a proximal avulsion tear with excellent tissue quality and were most commonly injured during skiing had a trend toward improved outcomes compared with those with midsubstance tears. Higgins and Steadman34 reported that ACL repair in elite skiers with proximal avulsion tears can be successful, although 18.5% of patients reinjured their ACL. Additionally, although excluded from this study, Steadman et al.35 microfractured the cortical bone of the femoral ACL footprint (without repair) to stimulate a healing response in skeletally immature patients with proximal avulsion tears, which resulted in good clinical outcomes in some patients, yet 23% of patients sustained a reinjury requiring
subsequent ACL reconstruction. All 6 studies included in the current systematic review used a technique to induce a healing response along with repair of proximal ACL avulsion tears.12,15-17,31,32 Of the 6 studies, only 215,32 did not report any failures. Because arthroscopic ACL repair is less invasive than open repair, it may provide a solution for skeletally immature patients with proximal tears and good tissue quality, especially when there is a limited delay between ACL injury and repair.15,36,37 A meta-analysis by Frosch et al.38 showed that physeal-sparing techniques are associated with a greater risk of postoperative leglength differences than surgical approaches violating the growth plate. Additionally, in younger patients who have significant growth potential, graft tissues may not be able to stretch enough to follow significant knee growth.15,39 Because it has been shown that ACL suturing does not result in any growth disturbance,38
Table 5. Patient-Reported Outcomes Subjective IKDC Score
Lysholm Score
Postoperative Study Bigoni et al., 201715 DiFelice and van der List, 201816 Hoffman et al., 201717 Jonkergouw et al., 201931 Mukhopadhyay et al., 201832
Mean 93.3 92.3 87.3 90.6 NR
SD NR 11.3 16.6 12.1 NR
Range 67.8 to 95.0 64.0 to 100 51.7 to 100 NR NR
Tegner Score
Postoperative Mean 93.6 96.0 85.3 95.2 95
SD NR 4.5 19.9 7.4 NR
Range 68.0 to 100 88.0 to 100 45.0 to 100 NR 94 to 96
Preinjury Mean NR 7.2 6.3 6.4 NR
IKDC, International Knee Documentation Committee; NR, not reported; SD, standard deviation.
SD NR 1.2 1.5 1.4 NR
Range NR 5 to 9 4 to 8 NR NR
Postoperative Mean NR 6.6 5.2 6.0 NR
SD NR 1.8 1.8 1.3 NR
Range NR 3 to 9 1 to 7 NR NR
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the use of primary AR with suture anchors may provide a less invasive ACL treatment technique in this subset of patients compared with physeal-sparing ACL reconstruction techniques. Furthermore, Hoffman et al.17 stated that using a single anchor fixation technique may provide a potential advantage due to the reduced foreign material in the femur. Other potential benefits of arthroscopic ACL repair being less invasive may include an easier recovery, easier and earlier rehabilitation, earlier return to full range of motion,40 and thus quicker return to play. However, the studies included in this systematic review reported only Tegner activity scale. Additionally, revision surgery after primary arthroscopic ACL repair is similar to primary reconstruction, whereas revision of primary ACL reconstruction sometimes requires a 2-stage revision.11,31,41 As suggested by Feagin and Curl,42 repair after the isolated tear of the ACL should not go unrecognized and it does not have to be abandoned. They suggested that perhaps this type of tear may require augmentation or substitution.42 One of the studies included in this systematic review (Jonkergouw et al.31) reported the results of arthroscopic ACL repair for the first 29 patients (included in this systematic review) and arthroscopic ACL repair with internal bracing for the latter 27 patients (not included here). The authors failed to show a clinical benefit of internal bracing to primary arthroscopic ACL repair, although the comparison was underpowered. Therefore, it is possible that failure rates may differ in a larger cohort of patients.31 Recently, Hoogeslag et al.18 reported 2-year results of a randomized controlled trial comparing dynamic augmented ACL suture repair to single-bundle ACL reconstruction. The authors found that dynamic augmented ACL suture repair was not inferior to singlebundle ACL reconstruction in terms of subjective IKDC scores 2 years postoperatively. However, for reasons other than revision ACL surgery for rerupture, a nonsignificantly higher number of related adverse events leading to repeat surgery were seen in the dynamic augmented ACL suture repair group within 2 years postoperatively. Similar results were seen in a randomized controlled trial by Schliemann et al.,43 which compared contemporary (dynamic augmented) ACL suture repair with ACL reconstruction. Limitations The limitations of this study should be noted. Moderate to high heterogeneity may be present, although these statistics are greatly underpowered and preclude any definitive conclusions. The quality of the included noncomparative studies is low based on the MINORS criteria. It is necessary to recognize sources of bias present in the included studies. As the majority of studies were retrospective, selection bias is a principal
limitation. Additionally, there was appreciable variance among the included studies with regard to reported outcomes, failure definitions, concomitant injuries, and patient demographics. Moreover, it is possible that overall outcomes may have been influenced by the variance in patient age among the included studies. Most of these studies did not report preoperative PROs, and only 2 studies12,15 reported postoperative MRI results at final follow-up. The lack of similar outcomes decreased the sample size for each outcome analyzed and increased the presence of detection bias, whereas the different follow-up durations contributed to transfer bias. Performance and time-period bias may also be present. Some studies included patients who required surgical intervention for associated intra-articular injuries, which could have an influence on postoperative outcomes.
Conclusions The literature on clinical outcomes of primary arthroscopic ACL repair is limited. The reported rates of repair failure and reoperation are highly inconsistent. Most studies report relatively high failure rates.
References 1. Kaeding CC, Leger-St-Jean B, Magnussen RA. Epidemiology and diagnosis of anterior cruciate ligament injuries. Clin Sports Med 2017;36:1-8. 2. Mall NA, Chalmers PN, Moric M, et al. Incidence and trends of anterior cruciate ligament reconstruction in the United States. Am J Sports Med 2014;42:2363-2370. 3. Odensten M, Lysholm J, Gillquist J. Suture of fresh ruptures of the anterior cruciate ligament. A 5-year followup. Acta Orthop Scand 1984;55:270-272. 4. Engebretsen L, Svenningsen S, Benum P. Poor results of anterior cruciate ligament repair in adolescence. Acta Orthop Scand 1988;59:684-686. 5. Engebretsen L, Benum P, Fasting O, Molster A, Strand T. A prospective, randomized study of three surgical techniques for treatment of acute ruptures of the anterior cruciate ligament. Am J Sports Med 1990;18:585-590. 6. Sherman MF, Lieber L, Bonamo JR, Podesta L, Reiter I. The long-term followup of primary anterior cruciate ligament repair. Defining a rationale for augmentation. Am J Sports Med 1991;19:243-255. 7. Taylor SA, Khair MM, Roberts TR, DiFelice GS. Primary repair of the anterior cruciate ligament: A systematic review. Arthroscopy 2015;31:2233-2247. 8. Lubowitz JH. Editorial commentary: Anterior cruciate ligament primary repair, revisited. Arthroscopy 2015;31: 2172. 9. Kraeutler MJ, Wolsky RM, Vidal AF, Bravman JT. Anatomy and biomechanics of the native and reconstructed anterior cruciate ligament: Surgical implications. J Bone Joint Surg Am 2017;99:438-445. 10. Hohmann E. Editorial commentary: Renaissance of primary anterior cruciate ligament repair: Is history repeating itself? Arthroscopy 2016;32:2570-2571.
PRIMARY ARTHROSCOPIC ACL REPAIR REVIEW 11. Kraeutler MJ, Welton KL, McCarty EC, Bravman JT. Revision anterior cruciate ligament reconstruction. J Bone Joint Surg Am 2017;99:1689-1696. 12. Achtnich A, Herbst E, Forkel P, et al. Acute proximal anterior cruciate ligament tears: Outcomes after arthroscopic suture anchor repair versus anatomic single-bundle reconstruction. Arthroscopy 2016;32:2562-2569. 13. DiFelice GS, Villegas C, Taylor S. Anterior cruciate ligament preservation: Early results of a novel arthroscopic technique for suture anchor primary anterior cruciate ligament repair. Arthroscopy 2015;31:2162-2171. 14. Lubowitz JH. Editorial commentary: Anterior cruciate ligament primary repair is a holy grail. Arthroscopy 2015;31:2248. 15. Bigoni M, Gaddi D, Gorla M, et al. Arthroscopic anterior cruciate ligament repair for proximal anterior cruciate ligament tears in skeletally immature patients: Surgical technique and preliminary results. Knee 2017;24:40-48. 16. DiFelice GS, van der List JP. Clinical outcomes of arthroscopic primary repair of proximal anterior cruciate ligament tears are maintained at mid-term follow-up. Arthroscopy 2018;34:1085-1093. 17. Hoffmann C, Friederichs J, von Ruden C, Schaller C, Buhren V, Moessmer C. Primary single suture anchor refixation of anterior cruciate ligament proximal avulsion tears leads to good functional mid-term results: A preliminary study in 12 patients. J Orthop Surg Res 2017;12:171. 18. Hoogeslag RAG, Brouwer RW, Boer BC, de Vries AJ. Huis In ‘t Veld R. Acute anterior cruciate ligament rupture: repair or reconstruction? Two-year results of a randomized controlled clinical trial. Am J Sports Med 2019;47: 567-577. 19. van der List JP, DiFelice GS. Preoperative magnetic resonance imaging predicts eligibility for arthroscopic primary anterior cruciate ligament repair. Knee Surg Sports Traumatol Arthrosc 2018;26:660-671. 20. Coleman BD, Khan KM, Maffulli N, Cook JL, Wark JD. Studies of surgical outcome after patellar tendinopathy: Clinical significance of methodological deficiencies and guidelines for future studies. Victorian Institute of Sport Tendon Study Group. Scand J Med Sci Sports 2000;10:2-11. 21. Slim K, Nini E, Forestier D, Kwiatkowski F, Panis Y, Chipponi J. Methodological index for non-randomized studies (minors): Development and validation of a new instrument. ANZ J Surg 2003;73:712-716. 22. DerSimonian R, Laird N. Meta-analysis in clinical trials. Control Clin Trials 1986;7:177-188. 23. Clopper CJ, Pearson ES. The use of confidence or fiducial limits illustrated in the case of the binomial. Biometrika 1934;26:404-413. 24. Harris JD, Brand JC, Cote MP, Dhawan A. Research pearls: The significance of statistics and perils of pooling. Part 3: Pearls and pitfalls of meta-analyses and systematic reviews. Arthroscopy 2017;33:1594-1602. 25. Cote MP, Lubowitz JH, Rossi MJ, Brand JC. Reviews pooling heterogeneous, low-evidence, high-bias data result in incorrect conclusions: But heterogeneity is an opportunity to explore. Arthroscopy 2018;34:3126-3128. 26. Lubowitz JH, Brand JC, Rossi MJ. Where do arthroscopy editors stand on systematic reviews of the literature? Arthroscopy 2017;33:1753-1754.
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27. Dhawan A, Brand JC, Provencher MT, Rossi MJ, Lubowitz JH. Research pearls: The significance of statistics and perils of pooling. Arthroscopy 2017;33:1099-1101. 28. Lubowitz JH, Brand JC, Provencher MT, Rossi MJ. Systematic reviews keep arthroscopy up to date. Arthroscopy 2016;32:237. 29. Higgins JP, Thompson SG, Deeks JJ, Altman DG. Measuring inconsistency in meta-analyses. BMJ 2003;327: 557-560. 30. Viechtbauer W. Conducting meta-analyses in R with the metafor package. J Stat Software 2010;36:1-48. 31. Jonkergouw A, van der List JP, DiFelice GS. Arthroscopic primary repair of proximal anterior cruciate ligament tears: Outcomes of the first 56 consecutive patients and the role of additional internal bracing. Knee Surg Sports Traumatol Arthrosc 2019;27:21-28. 32. Mukhopadhyay R, Shah N, Vakta R, Bhatt J. ACL femoral avulsion repair using suture pull-out technique: A case series of thirteen patients. Chin J Traumatol 2018;21: 352-355. 33. Gaulrapp HM, Haus J. Intraarticular stabilization after anterior cruciate ligament tear in children and adolescents: Results 6 years after surgery. Knee Surg Sports Traumatol Arthrosc 2006;14:417-424. 34. Higgins RW, Steadman JR. Anterior cruciate ligament repairs in world class skiers. Am J Sports Med 1987;15:439-447. 35. Steadman JR, Cameron-Donaldson ML, Briggs KK, Rodkey WG. A minimally invasive technique (“healing response”) to treat proximal ACL injuries in skeletally immature athletes. J Knee Surg 2006;19:8-13. 36. van der List JP, DiFelice GS. Primary repair of the anterior cruciate ligament: A paradigm shift. Surgeon 2017;15: 161-168. 37. Magarian EM, Fleming BC, Harrison SL, Mastrangelo AN, Badger GJ, Murray MM. Delay of 2 or 6 weeks adversely affects the functional outcome of augmented primary repair of the porcine anterior cruciate ligament. Am J Sports Med 2010;38:2528-2534. 38. Frosch KH, Stengel D, Brodhun T, et al. Outcomes and risks of operative treatment of rupture of the anterior cruciate ligament in children and adolescents. Arthroscopy 2010;26:1539-1550. 39. Anderson AF. Transepiphyseal replacement of the anterior cruciate ligament using quadruple hamstring grafts in skeletally immature patients. J Bone Joint Surg Am 2004;86:201-209 (suppl 1 pt 2). 40. van der List JP, DiFelice GS. Range of motion and complications following primary repair versus reconstruction of the anterior cruciate ligament. Knee 2017;24:798-807. 41. Lefevre N, Klouche S, Mirouse G, Herman S, Gerometta A, Bohu Y. Return to sport after primary and revision anterior cruciate ligament reconstruction: A prospective comparative study of 552 patients from the FAST cohort. Am J Sports Med 2017;45:34-41. 42. Feagin JA Jr, Curl WW. Isolated tear of the anterior cruciate ligament: 5-year follow-up study. Am J Sports Med 1976;4:95-100. 43. Schliemann B, Glasbrenner J, Rosenbaum D, et al. Changes in gait pattern and early functional results after ACL repair are comparable to those of ACL reconstruction. Knee Surg Sports Traumatol Arthrosc 2018;26:374-380.
Primary Arthroscopic Repair of the Anterior Cruciate Ligament: A Systematic Review of Clinical Outcomes Darby A. Houck, B.A., Matthew J. Kraeutler, M.D., John W. Belk, B.A., Joshua A. Goode, M.A., Mary K. Mulcahey, M.D., and Jonathan T. Bravman, M.D.
Purpose: To describe the clinical outcomes after primary arthroscopic anterior cruciate ligament (ACL) repair. Methods: A systematic review of the PubMed, Embase, and Cochrane Library databases was performed according to the PRISMA guidelines. All English-language literature published from 2000 to 2018 that reported the clinical outcomes after primary arthroscopic repair (AR) of complete tear of the ACL (without augmentation) with a minimum 2-year follow-up was reviewed by 2 independent reviewers. Outcomes included repair failure, reoperation, postoperative knee stability, and patient-reported outcomes. Descriptive statistics are presented. Study quality was evaluated with the Modified Coleman Methodology Score (MCMS) and the Methodological Index for Nonrandomized Studies (MINORS) score. Results: Six studies (2 level III, 4 level IV) were included. The mean MCMS was 62.2. The mean MINORS score for noncomparative studies was 11.8, and for comparative studies, 18. Six studies reported outcomes of 89 patients who underwent AR of the ACL from 2007 to 2016 (age, 8 to 67 years; follow-up, 24 to 110 months). All 6 studies included exclusively proximal avulsion tears. Overall, 0% to 25.0% of patients experienced repair failure (I2 ¼ 23.7%; 95% confidence interval, 0% to 67.6%), and 0% to 20.0% of patients had a subsequent reoperation (I2 ¼ 12.1%; 95% confidence interval, 0% to 77.7%). Similar inconsistent results were shown for postoperative knee stability measures and patient-reported outcomes. Conclusions: The literature on clinical outcomes of primary arthroscopic ACL repair is limited. The reported rates of repair failure and reoperation are highly inconsistent. Most studies report relatively high failure rates. Level of Evidence: IV, systematic review of level III and IV studies.
See commentary on page 3328 ith an increasing incidence of anterior cruciate ligament (ACL) injuries in the literature,1,2 surgical treatment of ACL tears has continued to evolve. Initial results of primary open ACL repair were promising but were shown to fail at longer follow-up periods.3-7 Thus, the orthopaedic community shifted to ACL augmentation, and eventually to the current gold standard treatment, ACL reconstruction.8 The primary goal of surgical treatment in the setting of an ACL tear is to restore knee stability and the biomechanical and
W
anatomic properties of the native ACL.9,10 Furthermore, nonanatomic tunnel placement (i.e., vertical tunnels) is one of the most common factors contributing to graft failure after ACL reconstruction.11 For these reasons, the potential for repairing the native ACL is particularly appealing.8 Recently, the concept of primarily repairing a torn ACL, rather than reconstructing it using a graft, has regained popularity for certain tear patterns.8,10,12-18 There have been profound improvements in
From the Department of Orthopedics, University of Colorado School of Medicine (D.A.H., J.W.B., J.T.B.), Aurora, Colorado, U.S.A.; the St. Joseph’s University Medical Center (M.J.K.), Paterson, New Jersey, U.S.A.; the Department of Sociology, Institute of Behavioral Science, University of Colorado Boulder (J.A.G.), Boulder, Colorado, U.S.A.; and the Department of Orthopedics, Tulane University School of Medicine (M.K.M.), New Orleans, Louisiana, U.S.A. The authors report the following potential conflicts of interest or sources of funding: M.K.M. reports board or committee member for AAOS, American Orthopaedic Society for Sports Medicine, Arthroscopy Association of North America, Ruth Jackson Orthopaedic Society. J.T.B. reports paid consultant from DJ Orthopaedics; other from Mitek; other and paid consultant from
Smith & Nephew; other and research support from Stryker; IP royalties and unpaid consultant from Shukla Medical; board or committee member for Western Orthopedic Association. Full ICMJE author disclosure forms are available for this article online, as supplementary material. Received February 26, 2019; accepted June 21, 2019. Address correspondence to Darby A. Houck, 2150 Stadium Dr, Room 222, Boulder, CO 80309, U.S.A. E-mail: [email protected] Ó 2019 by the Arthroscopy Association of North America 0749-8063/19250/$36.00 https://doi.org/10.1016/j.arthro.2019.06.034
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Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 35, No 12 (December), 2019: pp 3318-3327
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Fig 1. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram.
diagnostic and therapeutic capabilities, such as advanced arthroscopic techniques and instrumentation, since primary open ACL repair was initially abandoned.13 Additionally, current preoperative magnetic resonance imaging (MRI) techniques can accurately identify tear location and tissue quality, which can help guide the surgeon on which patients may be candidates for arthroscopic primary ACL repair.19 The purpose of this systematic review was to describe the clinical outcomes following primary arthroscopic ACL repair. The authors hypothesized that primary arthroscopic ACL repair would have a relatively high failure rate.
Methods This systematic search was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines using a PRISMA checklist. Two independent reviewers (D.A.H., J.W.B.) searched PubMed, Embase, and the Cochrane Library up to May 10, 2019. The following search phrase was used:
“anterior cruciate ligament” primary repair. Other sources were searched by reviewing reference lists and citing manuscripts to reduce the risk of omission of relevant articles. A total of 448 studies were reviewed by title and/or abstract to determine study eligibility based on inclusion criteria. In cases of disagreement, a third reviewer (M.J.K.) made the final decision. Inclusion and exclusion criteria followed the participants, interventions, comparators, outcomes, study design (PICOS) strategy. Studies selected for inclusion met the following criteria: studies reporting clinical outcomes of patients who underwent primary arthroscopic repair (AR) of the ACL without augmentation; patients with a complete ACL tear; studies with a minimum 2-year follow-up; studies that were published in English; retrospective and prospective studies of level I to IV evidence; studies that were published after January 1, 2000; and procedures that were performed after January 1, 2000. Exclusion criteria included cadaveric or animal studies, nonclinical studies, patients with a partial ACL
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Study Noncomparative studies Bigoni et al., 201715 DiFelice and van der List, 201816 Hoffman et al., 201717 Mukhopadhyay et al., 201832 Comparative studies Achtnich et al., 201612 Jonkergouw et al., 201931 NOTE. Follow-up data are reported as n/N (%), and patient age, time from injury to surgery, and follow-up duration are reported as mean (range). LOE, level of evidence; MCMS, Modified Coleman Methodology Score; NR, not reported; PDR, procedure date range.
Study Achtnich et al., 201612 Bigoni et al., 201715 DiFelice and van der List, 201816 Hoffman et al., 201717 Jonkergouw et al., 201931 Mukhopadhyay et al., 201832
Table 1. Studies Included
PDR 2010-2013 2007-2010 2008-2012 2009-2012 2008-2016 2014-2015
Country Germany Italy United States Germany United States India
LOE III IV IV IV III IV
MCMS 71 60 62 58 60 62
Follow-Up 20/21 (95.2) 5/5 (100) 10/11 (90.9) 12/13 (92.8) 29/29 (100) 13/13 (100)
Percentage of Males NR 80 90.9 30.8 62.1 100
Age (yr) 30 9.2 (8 to 10) 37 (17 to 57) 43.3 (19 to 67) 37 31.3 (21 to 40)
Time From Injury to Surgery (d) NR 81 (15 to 123) 39 (10 to 93) 5.8 (1 to 20) NR (9 to 4,018) 7.6 (3 to 12)
Follow-Up Duration (mo) 28 (24 to 31) 43.4 (25 to 56) 72 (58 to 110) 79 (60 to 98) 48 31.3 (26 to 38)
Table 2. Methodological Items for Nonrandomized Studies (MINORS) Scores MINORS Score 12 12 12 11
(75%) (75%) (75%) (68.8%)
21 (88%) 15 (62.5%)
NOTE. The global ideal score is 16 for noncomparative studies and 24 for comparative studies.
tear, healing response performed alone without repair of the ACL, primary ACL repair using augmentation, primary open ACL repair, and case reports. Primary ACL repair using augmentation was defined as any of the following procedures: internal bracing surgical techniques, such as dynamic intraligamentary stabilization and internal brace ligament augmentation, ligament advanced reinforcement system techniques, graft augmentation with an allograft or autograft, and bridgeenhanced ACL repair device. When presented with a duplicate study population in 2 studies,13,16 we chose the study with a longer duration of follow-up.16 Six studies were determined to meet inclusion and exclusion criteria (Fig 1). Data extraction from each study was performed independently (D.A.H.). When presented with comparative studies, only data from the population that met the above inclusion and exclusion criteria were extracted. There was no need for funding or a third party to obtain any of the collected data. Reporting Outcomes Outcome data recorded included repair failure, reoperation, physical examination findings (Lachman and pivot-shift tests), anteroposterior (AP) knee laxity, patient-reported outcomes (PROs), and the Objective International Knee Documentation Committee (IKDC) score. PROs included the Subjective IKDC score, the Lysholm score, and the Tegner activity score. Assessment of Study Quality The quality of study methodology was evaluated using the Modified Coleman Methodology Score (MCMS) based on a scaled potential score ranging from 0 to 100.20 Scores ranging from 85 to 100 are excellent, 70 to 84 are good, 55 to 69 are fair, and <55 are poor. Risk of bias was assessed according to the Methodological Index for Nonrandomized Studies (MINORS) score,21 which incorporates 8 items to assess overall bias in noncomparative studies and an additional 4 items in comparative studies. The MINORS score has a scaled potential score ranging from 0 to 16 for noncomparative studies and 0 to 24 for comparative
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Mukhopadhyay et al., 201832
Jonkergouw et al., 201931
Hoffman et al., 201717
DiFelice and van der List, 201816
Bigoni et al., 201715
ACL, anterior cruciate ligament; ACLR, anterior cruciate ligament reconstruction; AR, arthroscopic repair.
No
Yes
No
No
No
studies. Each item is scored 0 (not reported), 1 (reported but inadequate), or 2 (reported and adequate).
Study Summary Case-control study comparing primary AR of the ACL with suture anchors and microfracturing with anatomic single-bundle ACLR in patients with acute proximal avulsion ACL tears Retrospective review of skeletally immature patients with proximal ACL tears who underwent primary AR of the ACL with a bioabsorbable anchor Retrospective follow-up study of the previously reported short-term outcomes13 of patients with proximal avulsion ACL tears who underwent arthroscopic primary AR with suture anchors Retrospective review of patients with proximal ACL tears who underwent primary AR of the ACL with suture anchors Retrospective study of the first 56 consecutive patients with proximal ACL tears who underwent primary AR of the ACL with suture anchor (first 29 patients) or primary AR of the ACL with internal bracing (latter 27 patients) Prospective study of consecutive patients with proximal ACL tears who underwent primary AR of the ACL with suture pull-out technique Study Achtnich et al., 201612
Table 3. Summary of Studies Included
Presence of Control or Comparison Group Yes
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Statistical Analysis Individual study heterogeneity regarding patient populations and treatment prevented meta-analysis calculations. Therefore, descriptive statistics are presented for numerical demographic data (age and follow-up), AP laxity measurements, and PROs. Categorical variables (repair failure, reoperation, Lachman, and pivot-shift tests) were reported as percentages. Because of heterogeneity and quality of the included studies in this review, the outcomes were not pooled. Rather, a subjective synthesis was performed, where ranges were reported and individual study data were presented in a forest plot (only when data from 3 studies assessed an outcome). Using a random-effects model (due to anticipated heterogeneity) by the DerSimonian-Laird22 and Clopper-Pearson interval23 methods, single raw proportions and 95% confidence intervals (CIs) were calculated for individual study results and were presented in forest plots. As the studies are too diverse, and the methodologies are poor such that the risk of bias is high or known confounding variables are not accounted for, pooling of study results and reporting weighted mean calculations was avoided.24 According to Cote et al.,25 a systematic review with exploration of heterogeneity has been shown to result in valuable information regarding strengths and weaknesses of the currently available literature to help guide future research efforts.25-28 Therefore, the I2 statistic was calculated to quantify the degree of heterogeneity and was presented in forest plots. An I2 statistic 40% represents an acceptable degree of heterogeneity.29 Generation of forest plots and tests for heterogeneity were performed using the metaprop function of the Metafor Package (A Meta-Analysis Package for R).30
Results Included Studies Six studies (2 level III, and 4 level IV),12,15-17,31,32 published between 2016 and 2019, met inclusion and exclusion criteria (Fig 1). All 6 studies12,15-17,31,32 included patients who underwent primary arthroscopic ACL repair. Assessment of Study Quality Table 1 shows the MCMS scores from the 6 included studies (mean MCMS score, 62.2), 112 of which achieved a good score and 515-17,31,32 of which achieved fair scores. This indicates that the overall quality of the study was fair. The results of the methodologic quality and risk of bias assessment of included studies using the MINORS score are presented in Table 2. The mean
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Fig 2. Rate of repair failure and reoperation after primary anterior cruciate ligament repair. Forest plot showing the proportion of patients with repair failure (A) and subsequent reoperation (B). Two studies16,17 reported more patients when assessing graft failure than when reporting PROs and follow-up physical examination findings, explaining why the sample size in this table is larger than mentioned above. The repair failure and reoperation rates are represented by squares proportional in size to the sample size of the individual study and confidence intervals (CIs; horizontal lines) of repair failure and reoperation rates by individual study and by repair technique. I2 ¼ percentage of variation due to heterogeneity rather than chance.
MINORS score for noncomparative studies was 11.8,15-17,32 and the score for the comparative studies was 18.12,31 Patient Demographics A total of 89 patients who underwent AR between 200715 and 201631 were included in this systematic review. Patient age at the time of surgery ranged from 815 to 6717 years (Table 1). One study included patients who were skeletally immature at the time of surgery.15 The percentage of patients available for follow-up ranged from 90.9%16 to 100%.15,31,32 Further details on patient demographics and study design information are presented in Tables 1 and 3. ACL Tear Location All 6 studies12,15-17,31,32 that performed primary AR included only patients with proximal avulsion tears. Associated Injuries Five studies12,16,17,31,32 that performed AR included patients with concomitant injuries, including medial
and lateral meniscal tears, cartilage injuries (including chondromalacia), or medial/lateral collateral ligament injuries. Bigoni et al.15 did not include patients with any concomitant injuries. Postoperative Rehabilitation All 6 studies12,15-17,31,32 clearly reported postoperative protocols. Clinical Outcomes Failures and Reoperations Two studies15,32 did not clearly define repair failure. Two studies16,17 defined clinical failure as a 2þ Lachman or 2þ pivot-shift test, subjective knee instability, or radiological evidence of discontinuity of the repaired ligament. One study12 defined failure as recurrent instability, and 1 study31 defined failure as symptomatic instability or rerupture. Overall, 0% to 25.0% of patients experienced repair failure (Fig 2). Statistical assessment of heterogeneity found for repair failure was I2 ¼ 23.7% (95% CI, 0% to
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Fig 3. Pivot-shift results. Forest plot showing the proportion of patients with a 1þ (glide) (A) and 2þ (clunk) (B) pivot-shift findings after primary arthroscopic anterior cruciate ligament repair. Pivot-shift grades are represented by squares proportional in size to the sample size of the individual study and confidence intervals (CIs; horizontal lines) of pivot-shift grades by individual study and by repair technique. I2 ¼ percentage of variation due to heterogeneity rather than chance.
67.6%). Although a total of 11 of these patients were considered failures, it should be noted that 2 were reportedly noncompliant with postoperative physical therapy, brace use, and return to sport.12,16 Additionally, of the 2 studies12,15 that reported postoperative MRI results on all patients, 85.7%12 to 100%15 of patients who underwent AR had an intact ACL at final follow-up. Overall, 0% to 20.0% of patients had a subsequent reoperation (Fig 2), of which 0% to 9.1% were revision surgeries to address instability and 0% to 15% were for other injuries in the knee joint. As shown in Fig 2, statistical assessment of heterogeneity found for reoperation was I2 ¼ 12.1% (95% CI, 0% to 77.7%). Knee Stability Four studies12,15,16,32 that performed AR reported postoperative pivot-shift (Fig 3) and Lachman test (Fig 4) results. Overall, 0% to 100% of patients had 1þ pivot-shift findings, whereas 0% of patients had 2þ pivot-shift findings. Statistical assessment for heterogeneity for 1þ pivot-shift was I2 ¼ 95.5% (95% CI, 91.3% to 97.7%) (Fig 3); statistical assessment for heterogeneity for 2þ pivot-shift was I2 ¼ 0% (95% CI, 0% to 0%) (Fig 3). Overall, 10% to 20% of patients had a 1þ Lachman, and 0% of patients had a 2þ Lachman. Statistical assessment for heterogeneity for 1þ Lachman was I2 ¼ 0% for AR (95% CI, 0% to 0%) (Fig 4). Statistical
assessment for heterogeneity for 2þ Lachman was I2 ¼ 0% for AR (95% CI, 0% to 0%). Mean postoperative AP laxity was reported by 4 studies (Table 4).12,15,17,32 Objective IKDC Scores Three studies12,16,17 that performed AR reported Objective IKDC scores (Fig 5). Of these, only 1 study12 reported preoperative Objective IKDC scores (0 A, 4 B, 15 C, 1 D). Bigoni et al.15 noted that all patients had a normal or nearly normal IKDC scores. Jonkergouw et al.31 did not distinguish Objective IKDC scores of the 29 patients (51.8%) who underwent primary arthroscopic ACL repair and are included in this systematic review from the 27 patients (48.2%) who underwent primary ACL repair with internal bracing (not included here). The reported Objective IKDC scores of all 52 examined patients were A in 38 patients (73%), B in 8 (15%), and C/D in 6 (12%), and the authors noted that these scores did not differ between the groups. In the 3 studies12,16,17 that reported Objective IKDC scores, 82% to 100% of patients had A/B Objective IKDC scores, and 0% to 18% of patients had C/D Objective IKDC scores. Statistical assessment for heterogeneity for A/B Objective IKDC scores was I2 ¼ 36.5% for AR (95% CI, 0% to 79.8%) (Fig 5). Statistical assessment for heterogeneity for C/D Objective IKDC scores was I2 ¼ 36.5% for AR (95% CI, 0% to 79.8%).
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Fig 4. Lachman test results. Forest plot showing the proportion of patients with a 1þ (anterior tibial translation 3 to 5 mm) (A) and 2þ (>5 mm) (B) Lachman test results after primary arthroscopic anterior cruciate ligament repair. The Lachman grades are represented by squares proportional in size to the sample size of the individual study and confidence intervals (CIs; horizontal lines) of Lachman grades by individual study and by repair technique. I2 ¼ percentage of variation due to heterogeneity rather than chance.
Patient-Reported Outcomes Four studies15-17,31 that performed AR reported mean Subjective IKDC scores (Table 5). Four studies15-17,31 reported Tegner scores (Table 5). Bigoni et al.15 noted that 4 patients (80%) returned to preinjury Tegner activity levels, whereas 1 patient decreased from a preinjury Tegner score of 6 to a score of 4 postoperatively. Five studies reported Lysholm scores (Table 5).15-17,31,32
Discussion The results of this systematic review suggest that, at a minimum follow-up of 24 months (range 24 to 110 months), patients undergoing primary arthroscopic ACL repair have variable clinical outcomes and show highly inconsistent failure rates (range, 0% to 25%). Table 4. Anteroposterior Laxity at Follow-Up Anteroposterior Laxity (mm) Study Achtnich et al., 201612 Bigoni et al., 201715 Hoffman et al., 201717 Mukhopadhyay et al., 201832
Mean 2.0 3.0 2.1 1.7
NR, not reported; SD, standard deviation.
SD 1.7 0.7 NR 0.8
Range NR 2.0 to 4.0 1.0 to 5.0 1.0 to 3.0
The literature quality and finding that moderate to high heterogeneity may be present is limited, as these statistics are greatly underpowered and preclude any definitive conclusions. Future study should be prospective and should use explicit eligibility criteria regarding the proper indications for performing primary arthroscopic ACL repair. A previous systematic review by Taylor et al.7 concluded that the long-term outcomes after primary open ACL repair are unacceptable, although a subset of patients with proximal tears and excellent tissue quality achieved acceptable long-term results. However, the previous systematic review only included 1 case series33 that performed AR of proximal avulsion tears through transepiphyseal femoral tunnels as opposed to standard arthroscopic portals. Since the previous systematic review was published in 2015, several studies examining clinical outcomes of patients with proximal avulsion tears6 after primary arthroscopic ACL repair have been published.12,15-17,31,32 This updated systematic review shows the variability in outcomes, failure definitions, concomitant injuries, and patient demographics among previous studies in the currently available literature. Therefore, the present systematic review focuses on clinical outcomes of primary AR of proximal avulsion ACL tears.
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Fig 5. Objective International Knee Documentation Committee (IKDC) scores. Forest plot showing the proportion of patients with A/B (A) and C/D (B) Objective IKDC scores after primary arthroscopic anterior cruciate ligament repair. The Objective IKDC scores are represented by squares proportional in size to the sample size of the individual study and confidence intervals (CIs; horizontal lines) of Objective IKDC scores by individual study and by repair technique. I2 ¼ percentage of variation due to heterogeneity rather than chance.
In 1991, Sherman et al.6 determined that only a certain subgroup of patients do well with primary ACL repair. This retrospective cohort study performed a subgroup analysis by tissue quality and tear location and determined that patients who had a proximal avulsion tear with excellent tissue quality and were most commonly injured during skiing had a trend toward improved outcomes compared with those with midsubstance tears. Higgins and Steadman34 reported that ACL repair in elite skiers with proximal avulsion tears can be successful, although 18.5% of patients reinjured their ACL. Additionally, although excluded from this study, Steadman et al.35 microfractured the cortical bone of the femoral ACL footprint (without repair) to stimulate a healing response in skeletally immature patients with proximal avulsion tears, which resulted in good clinical outcomes in some patients, yet 23% of patients sustained a reinjury requiring
subsequent ACL reconstruction. All 6 studies included in the current systematic review used a technique to induce a healing response along with repair of proximal ACL avulsion tears.12,15-17,31,32 Of the 6 studies, only 215,32 did not report any failures. Because arthroscopic ACL repair is less invasive than open repair, it may provide a solution for skeletally immature patients with proximal tears and good tissue quality, especially when there is a limited delay between ACL injury and repair.15,36,37 A meta-analysis by Frosch et al.38 showed that physeal-sparing techniques are associated with a greater risk of postoperative leglength differences than surgical approaches violating the growth plate. Additionally, in younger patients who have significant growth potential, graft tissues may not be able to stretch enough to follow significant knee growth.15,39 Because it has been shown that ACL suturing does not result in any growth disturbance,38
Table 5. Patient-Reported Outcomes Subjective IKDC Score
Lysholm Score
Postoperative Study Bigoni et al., 201715 DiFelice and van der List, 201816 Hoffman et al., 201717 Jonkergouw et al., 201931 Mukhopadhyay et al., 201832
Mean 93.3 92.3 87.3 90.6 NR
SD NR 11.3 16.6 12.1 NR
Range 67.8 to 95.0 64.0 to 100 51.7 to 100 NR NR
Tegner Score
Postoperative Mean 93.6 96.0 85.3 95.2 95
SD NR 4.5 19.9 7.4 NR
Range 68.0 to 100 88.0 to 100 45.0 to 100 NR 94 to 96
Preinjury Mean NR 7.2 6.3 6.4 NR
IKDC, International Knee Documentation Committee; NR, not reported; SD, standard deviation.
SD NR 1.2 1.5 1.4 NR
Range NR 5 to 9 4 to 8 NR NR
Postoperative Mean NR 6.6 5.2 6.0 NR
SD NR 1.8 1.8 1.3 NR
Range NR 3 to 9 1 to 7 NR NR
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the use of primary AR with suture anchors may provide a less invasive ACL treatment technique in this subset of patients compared with physeal-sparing ACL reconstruction techniques. Furthermore, Hoffman et al.17 stated that using a single anchor fixation technique may provide a potential advantage due to the reduced foreign material in the femur. Other potential benefits of arthroscopic ACL repair being less invasive may include an easier recovery, easier and earlier rehabilitation, earlier return to full range of motion,40 and thus quicker return to play. However, the studies included in this systematic review reported only Tegner activity scale. Additionally, revision surgery after primary arthroscopic ACL repair is similar to primary reconstruction, whereas revision of primary ACL reconstruction sometimes requires a 2-stage revision.11,31,41 As suggested by Feagin and Curl,42 repair after the isolated tear of the ACL should not go unrecognized and it does not have to be abandoned. They suggested that perhaps this type of tear may require augmentation or substitution.42 One of the studies included in this systematic review (Jonkergouw et al.31) reported the results of arthroscopic ACL repair for the first 29 patients (included in this systematic review) and arthroscopic ACL repair with internal bracing for the latter 27 patients (not included here). The authors failed to show a clinical benefit of internal bracing to primary arthroscopic ACL repair, although the comparison was underpowered. Therefore, it is possible that failure rates may differ in a larger cohort of patients.31 Recently, Hoogeslag et al.18 reported 2-year results of a randomized controlled trial comparing dynamic augmented ACL suture repair to single-bundle ACL reconstruction. The authors found that dynamic augmented ACL suture repair was not inferior to singlebundle ACL reconstruction in terms of subjective IKDC scores 2 years postoperatively. However, for reasons other than revision ACL surgery for rerupture, a nonsignificantly higher number of related adverse events leading to repeat surgery were seen in the dynamic augmented ACL suture repair group within 2 years postoperatively. Similar results were seen in a randomized controlled trial by Schliemann et al.,43 which compared contemporary (dynamic augmented) ACL suture repair with ACL reconstruction. Limitations The limitations of this study should be noted. Moderate to high heterogeneity may be present, although these statistics are greatly underpowered and preclude any definitive conclusions. The quality of the included noncomparative studies is low based on the MINORS criteria. It is necessary to recognize sources of bias present in the included studies. As the majority of studies were retrospective, selection bias is a principal
limitation. Additionally, there was appreciable variance among the included studies with regard to reported outcomes, failure definitions, concomitant injuries, and patient demographics. Moreover, it is possible that overall outcomes may have been influenced by the variance in patient age among the included studies. Most of these studies did not report preoperative PROs, and only 2 studies12,15 reported postoperative MRI results at final follow-up. The lack of similar outcomes decreased the sample size for each outcome analyzed and increased the presence of detection bias, whereas the different follow-up durations contributed to transfer bias. Performance and time-period bias may also be present. Some studies included patients who required surgical intervention for associated intra-articular injuries, which could have an influence on postoperative outcomes.
Conclusions The literature on clinical outcomes of primary arthroscopic ACL repair is limited. The reported rates of repair failure and reoperation are highly inconsistent. Most studies report relatively high failure rates.
References 1. Kaeding CC, Leger-St-Jean B, Magnussen RA. Epidemiology and diagnosis of anterior cruciate ligament injuries. Clin Sports Med 2017;36:1-8. 2. Mall NA, Chalmers PN, Moric M, et al. Incidence and trends of anterior cruciate ligament reconstruction in the United States. Am J Sports Med 2014;42:2363-2370. 3. Odensten M, Lysholm J, Gillquist J. Suture of fresh ruptures of the anterior cruciate ligament. A 5-year followup. Acta Orthop Scand 1984;55:270-272. 4. Engebretsen L, Svenningsen S, Benum P. Poor results of anterior cruciate ligament repair in adolescence. Acta Orthop Scand 1988;59:684-686. 5. Engebretsen L, Benum P, Fasting O, Molster A, Strand T. A prospective, randomized study of three surgical techniques for treatment of acute ruptures of the anterior cruciate ligament. Am J Sports Med 1990;18:585-590. 6. Sherman MF, Lieber L, Bonamo JR, Podesta L, Reiter I. The long-term followup of primary anterior cruciate ligament repair. Defining a rationale for augmentation. Am J Sports Med 1991;19:243-255. 7. Taylor SA, Khair MM, Roberts TR, DiFelice GS. Primary repair of the anterior cruciate ligament: A systematic review. Arthroscopy 2015;31:2233-2247. 8. Lubowitz JH. Editorial commentary: Anterior cruciate ligament primary repair, revisited. Arthroscopy 2015;31: 2172. 9. Kraeutler MJ, Wolsky RM, Vidal AF, Bravman JT. Anatomy and biomechanics of the native and reconstructed anterior cruciate ligament: Surgical implications. J Bone Joint Surg Am 2017;99:438-445. 10. Hohmann E. Editorial commentary: Renaissance of primary anterior cruciate ligament repair: Is history repeating itself? Arthroscopy 2016;32:2570-2571.
PRIMARY ARTHROSCOPIC ACL REPAIR REVIEW 11. Kraeutler MJ, Welton KL, McCarty EC, Bravman JT. Revision anterior cruciate ligament reconstruction. J Bone Joint Surg Am 2017;99:1689-1696. 12. Achtnich A, Herbst E, Forkel P, et al. Acute proximal anterior cruciate ligament tears: Outcomes after arthroscopic suture anchor repair versus anatomic single-bundle reconstruction. Arthroscopy 2016;32:2562-2569. 13. DiFelice GS, Villegas C, Taylor S. Anterior cruciate ligament preservation: Early results of a novel arthroscopic technique for suture anchor primary anterior cruciate ligament repair. Arthroscopy 2015;31:2162-2171. 14. Lubowitz JH. Editorial commentary: Anterior cruciate ligament primary repair is a holy grail. Arthroscopy 2015;31:2248. 15. Bigoni M, Gaddi D, Gorla M, et al. Arthroscopic anterior cruciate ligament repair for proximal anterior cruciate ligament tears in skeletally immature patients: Surgical technique and preliminary results. Knee 2017;24:40-48. 16. DiFelice GS, van der List JP. Clinical outcomes of arthroscopic primary repair of proximal anterior cruciate ligament tears are maintained at mid-term follow-up. Arthroscopy 2018;34:1085-1093. 17. Hoffmann C, Friederichs J, von Ruden C, Schaller C, Buhren V, Moessmer C. Primary single suture anchor refixation of anterior cruciate ligament proximal avulsion tears leads to good functional mid-term results: A preliminary study in 12 patients. J Orthop Surg Res 2017;12:171. 18. Hoogeslag RAG, Brouwer RW, Boer BC, de Vries AJ. Huis In ‘t Veld R. Acute anterior cruciate ligament rupture: repair or reconstruction? Two-year results of a randomized controlled clinical trial. Am J Sports Med 2019;47: 567-577. 19. van der List JP, DiFelice GS. Preoperative magnetic resonance imaging predicts eligibility for arthroscopic primary anterior cruciate ligament repair. Knee Surg Sports Traumatol Arthrosc 2018;26:660-671. 20. Coleman BD, Khan KM, Maffulli N, Cook JL, Wark JD. Studies of surgical outcome after patellar tendinopathy: Clinical significance of methodological deficiencies and guidelines for future studies. Victorian Institute of Sport Tendon Study Group. Scand J Med Sci Sports 2000;10:2-11. 21. Slim K, Nini E, Forestier D, Kwiatkowski F, Panis Y, Chipponi J. Methodological index for non-randomized studies (minors): Development and validation of a new instrument. ANZ J Surg 2003;73:712-716. 22. DerSimonian R, Laird N. Meta-analysis in clinical trials. Control Clin Trials 1986;7:177-188. 23. Clopper CJ, Pearson ES. The use of confidence or fiducial limits illustrated in the case of the binomial. Biometrika 1934;26:404-413. 24. Harris JD, Brand JC, Cote MP, Dhawan A. Research pearls: The significance of statistics and perils of pooling. Part 3: Pearls and pitfalls of meta-analyses and systematic reviews. Arthroscopy 2017;33:1594-1602. 25. Cote MP, Lubowitz JH, Rossi MJ, Brand JC. Reviews pooling heterogeneous, low-evidence, high-bias data result in incorrect conclusions: But heterogeneity is an opportunity to explore. Arthroscopy 2018;34:3126-3128. 26. Lubowitz JH, Brand JC, Rossi MJ. Where do arthroscopy editors stand on systematic reviews of the literature? Arthroscopy 2017;33:1753-1754.
3327
27. Dhawan A, Brand JC, Provencher MT, Rossi MJ, Lubowitz JH. Research pearls: The significance of statistics and perils of pooling. Arthroscopy 2017;33:1099-1101. 28. Lubowitz JH, Brand JC, Provencher MT, Rossi MJ. Systematic reviews keep arthroscopy up to date. Arthroscopy 2016;32:237. 29. Higgins JP, Thompson SG, Deeks JJ, Altman DG. Measuring inconsistency in meta-analyses. BMJ 2003;327: 557-560. 30. Viechtbauer W. Conducting meta-analyses in R with the metafor package. J Stat Software 2010;36:1-48. 31. Jonkergouw A, van der List JP, DiFelice GS. Arthroscopic primary repair of proximal anterior cruciate ligament tears: Outcomes of the first 56 consecutive patients and the role of additional internal bracing. Knee Surg Sports Traumatol Arthrosc 2019;27:21-28. 32. Mukhopadhyay R, Shah N, Vakta R, Bhatt J. ACL femoral avulsion repair using suture pull-out technique: A case series of thirteen patients. Chin J Traumatol 2018;21: 352-355. 33. Gaulrapp HM, Haus J. Intraarticular stabilization after anterior cruciate ligament tear in children and adolescents: Results 6 years after surgery. Knee Surg Sports Traumatol Arthrosc 2006;14:417-424. 34. Higgins RW, Steadman JR. Anterior cruciate ligament repairs in world class skiers. Am J Sports Med 1987;15:439-447. 35. Steadman JR, Cameron-Donaldson ML, Briggs KK, Rodkey WG. A minimally invasive technique (“healing response”) to treat proximal ACL injuries in skeletally immature athletes. J Knee Surg 2006;19:8-13. 36. van der List JP, DiFelice GS. Primary repair of the anterior cruciate ligament: A paradigm shift. Surgeon 2017;15: 161-168. 37. Magarian EM, Fleming BC, Harrison SL, Mastrangelo AN, Badger GJ, Murray MM. Delay of 2 or 6 weeks adversely affects the functional outcome of augmented primary repair of the porcine anterior cruciate ligament. Am J Sports Med 2010;38:2528-2534. 38. Frosch KH, Stengel D, Brodhun T, et al. Outcomes and risks of operative treatment of rupture of the anterior cruciate ligament in children and adolescents. Arthroscopy 2010;26:1539-1550. 39. Anderson AF. Transepiphyseal replacement of the anterior cruciate ligament using quadruple hamstring grafts in skeletally immature patients. J Bone Joint Surg Am 2004;86:201-209 (suppl 1 pt 2). 40. van der List JP, DiFelice GS. Range of motion and complications following primary repair versus reconstruction of the anterior cruciate ligament. Knee 2017;24:798-807. 41. Lefevre N, Klouche S, Mirouse G, Herman S, Gerometta A, Bohu Y. Return to sport after primary and revision anterior cruciate ligament reconstruction: A prospective comparative study of 552 patients from the FAST cohort. Am J Sports Med 2017;45:34-41. 42. Feagin JA Jr, Curl WW. Isolated tear of the anterior cruciate ligament: 5-year follow-up study. Am J Sports Med 1976;4:95-100. 43. Schliemann B, Glasbrenner J, Rosenbaum D, et al. Changes in gait pattern and early functional results after ACL repair are comparable to those of ACL reconstruction. Knee Surg Sports Traumatol Arthrosc 2018;26:374-380.