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No evidence of reduced autograft ACL rupture rates with synthetic reinforcement: A systematic review

Open AccessPublished:April 24, 2022DOI:https://doi.org/10.1016/j.jisako.2022.04.005

      Abstract

      Importance

      Synthetic reinforcement of autografts in anterior cruciate ligament reconstruction offers theoretical benefits in terms of improved graft strength, potentially reducing graft elongation and failure. Over the past three decades, a number of synthetic/autograft combinations have been used in clinical practice.

      Aim

      We aimed to assess the impact of synthetic reinforcement on graft rupture rates and functional outcomes following autograft ACL reconstruction.

      Evidence review

      A systematic review of Pubmed, Embase and Cochrane libraries was undertaken according to the PRISMA guidelines. Published clinical studies reporting outcomes after autograft ACL reconstruction with synthetic reinforcement, with a minimum of 20 patients and two-year follow-up were included. The MINORS tool was used for methodological assessment.

      Findings

      Twenty articles reporting 1888 patients managed with synthetically reinforced grafts were included in the analysis. The mean MINORS score was 13 (Range, 2–22). The synthetic reinforcement used was the Kennedy ligament augmentation device in eight studies, LARS in four, Fibretape in two, Leeds-Keio in two, and Trevira ligament, Dacron, PDS and Artelon in one study each. No study reported a significant reduction in graft failure with reinforcement. Two studies reported superior KT-1000 clinical stability in reinforced grafts. One study reported superior pain, KOOS and IKDC scores and earlier return to activity in reinforced grafts.

      Conclusions and relevance

      In this systematic review, synthetic reinforcement of ACL autografts did not result in a reduced rate of graft rupture. A small number of studies have reported superior stability and patient-reported outcome measures with modern synthetic reinforcement techniques.

      Level of evidence

      4

      Keywords

      What is already known?

      • Graft rupture remains a challenge in ACL reconstruction

      What are the new findings?

      • Synthetic reinforcement of ACL autografts has not been shown to reduce graft rupture rates
      • A small number of studies have reported superior stability and patient-reported outcome measures with modern synthetic reinforcement techniques

      Introduction

      Anterior cruciate ligament (ACL) rupture occurs annually in 77 per 100,000 population and incurs substantial health and economic burden [
      • Zbrojkiewicz D.
      • Vertullo C.
      • Grayson J.E.
      Increasing rates of anterior cruciate ligament reconstruction in young Australians, 2000-2015.
      ,
      • Mather 3rd, R.C.
      • Koenig L.
      • Kocher M.S.
      • Dall T.M.
      • Gallo P.
      • Scott D.J.
      • et al.
      Societal and economic impact of anterior cruciate ligament tears.
      ,
      • Oiestad B.E.
      • Engebretsen L.
      • Storheim K.
      • Risberg M.A.
      Knee osteoarthritis after anterior cruciate ligament injury: a systematic review.
      ]. ACL reconstruction aims to restore knee stability to allow the return to function and protect against subsequent injury. Graft rupture occurs in 3% of patients following ACL hamstrings autograft reconstruction [
      • Kvist J.
      • Kartus J.
      • Karlsson J.
      • Forssblad M.
      Results from the Swedish national anterior cruciate ligament register.
      ]; however, at-risk cohorts may experience rupture rates as high as 28% [
      • Webster K.E.
      • Feller J.A.
      Exploring the high reinjury rate in younger patients undergoing anterior cruciate ligament reconstruction.
      ].
      Reinforcement of autograft ACL reconstructions could theoretically reduce the incidence of graft rupture and improve knee stability. Those patients who are young, have small graft diameters, or who plan to return to pivoting and contact sports are at an elevated risk of graft rupture and may stand to benefit from graft reinforcement [
      • Takazawa Y.
      • Ikeda H.
      • Saita Y.
      • Kawasaki T.
      • Ishijima M.
      • Nagayama M.
      • et al.
      Return to play of rugby players after anterior cruciate ligament reconstruction using hamstring autograft: return to sports and graft failure according to age.
      ,
      • Conte E.J.
      • Hyatt A.E.
      • Gatt Jr., C.J.
      • Dhawan A.
      Hamstring autograft size can be predicted and is a potential risk factor for anterior cruciate ligament reconstruction failure.
      ,
      • Myklebust G.
      • Holm I.
      • Maehlum S.
      • Engebretsen L.
      • Bahr R.
      Clinical, functional, and radiologic outcome in team handball players 6 to 11 years after anterior cruciate ligament injury: a follow-up study.
      ].
      Autograft reinforcement options include allograft and synthetic augmentation. A recent systematic review assessing allograft reinforcement of hamstrings autograft found no improvement in failure rates compared to hamstrings autograft alone [
      • Wang H.D.
      • Gao S.J.
      • Zhang Y.Z.
      Hamstring autograft versus Hybrid graft for anterior cruciate ligament reconstruction: a systematic review.
      ]. Reinforcement with synthetic material offers an appealing alternative. The reported success of an ultra-high molecular weight polyethylene tape with a braided polyester jacket (Fibertape, Arthrex) for ankle reconstruction [
      • Yoo J.S.
      • Yang E.A.
      Clinical results of an arthroscopic modified Brostrom operation with and without an internal brace.
      ] has generated interest in its broader applications, including reinforcing ACL grafts [
      • Bachmaier S.
      • Smith P.A.
      • Bley J.
      • Wijdicks C.A.
      Independent suture tape reinforcement of small and standard diameter grafts for anterior cruciate ligament reconstruction: a biomechanical full construct model.
      ,
      • Smith P.A.
      Editorial commentary: anterior cruciate ligament graft reinforcement: a new era supported by science.
      ,
      • Aboalata M.
      • Elazab A.
      • Halawa A.
      • Imhoff A.B.
      • Bassiouny Y.
      Internal suture augmentation technique to protect the anterior cruciate ligament reconstruction graft.
      ,
      • Smith P.A.
      • Bley J.A.
      Allograft anterior cruciate ligament reconstruction utilizing internal brace augmentation.
      ,
      • Smith P.A.
      • Bradley J.P.
      • Konicek J.
      • Bley J.A.
      • Wijdicks C.A.
      Independent suture tape internal brace reinforcement of bone-patellar tendon-bone allografts: biomechanical assessment in a full-ACL reconstruction laboratory model.
      ,
      • Smith P.A.
      • Bradley J.P.
      • Konicek J.
      • Bley J.A.
      • Wijdicks C.A.
      Augmentation of anterior cruciate ligament reconstruction with bone marrow concentrate and a suture tape.
      ,
      • Lavender C.
      • Bishop C.
      The fertilized anterior cruciate ligament: an all-inside anterior cruciate ligament reconstruction augmented with amnion, bone marrow concentrate, and a suture tape.
      ,
      • Saper M.G.
      Quadriceps tendon autograft anterior cruciate ligament reconstruction with independent suture tape reinforcement.
      ,
      • Cook J.L.
      • Smith P.
      • Stannard J.P.
      • Pfeiffer F.
      • Kuroki K.
      • Bozynski C.C.
      • et al.
      A canine arthroscopic anterior cruciate ligament reconstruction model for study of synthetic augmentation of tendon allografts.
      ,
      • Daggett M.
      • Redler A.
      • Witte K.
      Anterior cruciate ligament reconstruction with suture tape augmentation.
      ].
      The use of synthetic materials in ACL reconstruction dates to 1914, when silver wire was used to reconstruct the ACL [
      • Corner E.M.
      Notes of a case illustrative of an artificial anterior crucial ligament, demonstrating the action of that ligament.
      ]. Since that time, polytetrafluoroethylene (Proplast, Gore Tex), polyester (Leeds Keio, Dacron), polypropylene (Kennedy LAD), polyurethane urea (Artelon), polyethylene terephthalate (LARS, Trevira-Hochfest), polydioxanone (PDS) and ultra-high molecular weight polyethylene tape with a braided polyester jacket (Fibertape) have been used as stand-alone prostheses or as reinforcements to other graft tissue. Initial enthusiasm for their immediate tensile strength, availability and lack of donor site morbidity was tempered by reports of mechanical fatigue [
      • Guidoin M.F.
      • Marois Y.
      • Bejui J.
      • Poddevin N.
      • King M.W.
      • Guidoin R.
      Analysis of retrieved polymer fiber based replacements for the ACL.
      ], wear particle deposition [
      • Indelicato P.A.
      • Pascale M.S.
      • Huegel M.O.
      Early experience with the GORE-TEX polytetrafluoroethylene anterior cruciate ligament prosthesis.
      ], tunnel widening [
      • Fukubayashi T.
      • Ikeda K.
      Follow-up study of Gore-Tex artificial ligament--special emphasis on tunnel osteolysis.
      ,
      • Muren O.
      • Dahlstedt L.
      • Brosjo E.
      • Dahlborn M.
      • Dalen N.
      Gross osteolytic tibia tunnel widening with the use of Gore-Tex anterior cruciate ligament prosthesis: a radiological, arthrometric and clinical evaluation of 17 patients 13-15 years after surgery.
      ], synovitis [
      • Klein W.
      • Jensen K.U.
      Synovitis and artificial ligaments.
      ], arthritic degeneration [
      • Klein W.
      • Jensen K.U.
      Synovitis and artificial ligaments.
      ,
      • Maletius W.
      • Gillquist J.
      Long-term results of anterior cruciate ligament reconstruction with a Dacron prosthesis. The frequency of osteoarthritis after seven to eleven years.
      ,
      • Murray A.W.
      • Macnicol M.F.
      10-16 year results of Leeds-Keio anterior cruciate ligament reconstruction.
      ,
      • Ventura A.
      • Terzaghi C.
      • Legnani C.
      • Borgo E.
      • Albisetti W.
      Synthetic grafts for anterior cruciate ligament rupture: 19-year outcome study.
      ], and high failure rates [
      • Klein W.
      • Jensen K.U.
      Synovitis and artificial ligaments.
      ,
      • Murray A.W.
      • Macnicol M.F.
      10-16 year results of Leeds-Keio anterior cruciate ligament reconstruction.
      ,
      • Ventura A.
      • Terzaghi C.
      • Legnani C.
      • Borgo E.
      • Albisetti W.
      Synthetic grafts for anterior cruciate ligament rupture: 19-year outcome study.
      ,
      • Arnauw G.
      • Verdonk R.
      • Harth A.
      • Moerman J.
      • Vorlat P.
      • Bataillie F.
      • et al.
      Prosthetic versus tendon allograft replacement of ACL-deficient knees.
      ,
      • Wilk R.M.
      • Richmond J.C.
      Dacron ligament reconstruction for chronic anterior cruciate ligament insufficiency.
      ,
      • Gillquist J.
      • Odensten M.
      Reconstruction of old anterior cruciate ligament tears with a Dacron prosthesis. A prospective study.
      ,
      • Rading J.
      • Peterson L.
      Clinical experience with the Leeds-Keio artificial ligament in anterior cruciate ligament reconstruction. A prospective two-year follow-up study.
      ,
      • Lai C.C.H.
      • Feller J.A.
      • Webster K.E.
      Fifteen-year audit of anterior cruciate ligament reconstructions in the Australian football league from 1999 to 2013: return to play and subsequent ACL injury.
      ]. Many of these synthetic devices have subsequently been withdrawn from use.
      Existing reviews of synthetic grafts have primarily assessed their use as stand-alone prostheses [
      • Batty L.M.
      • Norsworthy C.J.
      • Lash N.J.
      • Wasiak J.
      • Richmond A.K.
      • Feller J.A.
      Synthetic devices for reconstructive surgery of the cruciate ligaments: a systematic review.
      ]. The aim of this study was to assess the impact of synthetic reinforcement on graft rupture rates and functional outcomes in autograft ACL reconstruction. Our hypothesis was that synthetic reinforcement would not improve the outcomes of ACL reconstruction.

      Methods

      Search strategy

      A systematic review of the literature was conducted to identify all studies reporting autograft ACL reconstruction with synthetic augmentation. The preferred reporting items for systematic reviews and meta-analysis (PRISMA) guidelines were followed. A search of Pubmed (MEDLINE), EMBASE and Cochrane databases was undertaken to identify articles published from their earliest entry until March 2021. The search criteria used were: (anterior cruciate OR ACL) AND (augmentation OR reinforcement OR artificial OR synthetic OR Fibertape OR Internalbrace OR Kennedy ligament OR Leeds-Keio OR Dacron OR polytetrafluoroethylene OR Trevira Hochfest OR LARS OR polyethylene terephthalate). Article titles and abstracts were screened according to the inclusion and exclusion criteria, and potentially relevant studies were reviewed in full text. References of relevant articles were also screened to identify additional publications. The review was not registered. Ethics approval was not sought, given it was a systematic review of existing literature.

      Study selection

      We included clinical studies reporting outcomes of unilateral primary ACL reconstruction using hamstrings, patella tendon or quadriceps tendon autograft with synthetic material reinforcement in a minimum of twenty patients.
      We excluded studies that examined synthetic reinforcement of partial ACL injuries or ACL repair, reconstructions using fascia lata or modified Marshall-MacIntosh grafts, fixation in an over the top position, multiligamentous knee injuries and non-English language publications.

      Data extraction

      Two authors (AP, DE) independently reviewed the full-text articles and extracted data (Fig. 1). Any disagreements were resolved by consensus. The data extracted from each article included study design, number of patients, patient selection criteria, patient demographics, operative details, follow-up duration, and loss to follow-up. The reported outcome data were extracted from each study, including graft failure rate (% patients), Lachman’s test (% patients grade 0–1), Pivot shift test (% patients grade 0), KT-1000 test (% patients <3 mm side–side difference), Lysholm score, Tegner score, Numerical pain score, Knee injury and osteoarthritis outcome score (KOOS), International knee documentation committee (IKDC) subjective knee form, Return to play (%), Radiographic evidence of arthritis and the occurrence of effusions or arthrofibrosis. Arthrofibrosis was identified based on reoperation for stiffness (manipulation or arthrolysis) or inability to achieve terminal extension in their operative knee [
      • Shelbourne K.D.
      • Wilckens J.H.
      • Mollabashy A.
      • DeCarlo M.
      Arthrofibrosis in acute anterior cruciate ligament reconstruction. The effect of timing of reconstruction and rehabilitation.
      ].

      Methodologic quality assessment

      The level of evidence of each included study was determined based on the study design utilised [
      • Hohmann E.
      • Feldman M.
      • Hunt T.J.
      • Cote M.P.
      • Brand J.C.
      Research pearls: how do we establish the level of evidence?.
      ]. The Methodological Index for Non-Randomised studies (MINORS) tool was then used to assess the quality of each study [
      • 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.
      ]. Non-comparative studies were assessed against eight items and comparative studies against 12 items. The risk of bias was quantified for each criterion on a scale; 0 (not reported), 1 (reported but inadequate), 2 (reported and adequate). Summative scores were calculated from 0 (the worst), to 18 (the best obtainable score for non-comparative studies) and 24 (the best obtainable score for comparative studies).

      Methodologic quality assessment

      Continuous variables are reported as mean ± standard deviation and categorical variables as percentages. A meta-analysis was not undertaken due to the heterogeneity of surgical techniques and reporting of outcomes.

      Results

      The search identified 3218 articles; 1411 from Pubmed, 1668 from EMBASE and 139 from the Cochrane Database (Fig. 1). Twenty-two studies reporting autograft ACL reconstruction with synthetic reinforcement met inclusion criteria (Table 1). Three studies reported the same cohort of patients at different time points, and therefore, only the publication with the longest follow-up was included for analysis [
      • Elveos M.M.
      • Drogset J.O.
      • Engebretsen L.
      • Bronn R.
      Anterior cruciate ligament reconstruction using a bone-patellar tendon-bone graft with and without a ligament augmentation device: a 25-year follow-up of a prospective randomized controlled trial.
      ,
      • Grontvedt T.
      • Engebretsen L.
      • Bredland T.
      Arthroscopic reconstruction of the anterior cruciate ligament using bone-patellar tendon-bone grafts with and without augmentation. A prospective randomised study.
      ,
      • Drogset J.O.
      • Grontvedt T.
      Anterior cruciate ligament reconstruction with and without a ligament augmentation device : results at 8-Year follow-up.
      ]. Twenty studies were therefore included. The level of evidence of the included studies was; level 1 (n = 0), level 2 (n = 3), level 3 (n = 6) and level 4 (n = 11). Nine studies compared reinforced grafts to non-reinforced grafts (Table 2), while the remaining studies were case series. The mean MINORS score was 13 (Range, 2–22).
      Table 1Characteristics of included studies.
      StudyDesignLevel of evidencePatients with reinforced grafts (n)Control groupSex (F %)Age mean (yrs)GraftReinforcementGraft fixation FemurGraft fixation tibiaFollow-up duration mean (months)MINORS score
      Elveos et al. 2018RCT249PT auto55%27 ± NRPT autoKennedyStaplesStaples300 ± NR21
      Peterson et al. 2014RCT296PT auto33%27 ± 7PT autoArtelonScrewScrew48 ± NR22
      Barrett et al. 1993Comparative- Prospective225PT auto32%25 ± NRPT autoKennedyScrewScrew24 ± NR19
      Bodendorfer et al. 2019Comparative - Retrospective330HS auto or allo57%29 ± 7.6HS Auto, allo or hybridFibertapeButtonButton29 ± 4.820
      Parkes et al. 2021Comparative - Retrospective336HS auto31%25 ± 8.6HS autoFibertapeButtonButton26 ± 2.519
      Hamido et al. 2015Comparative - Retrospective327HS auto0%24 ± NRHS autoLARSCross pinScrew59 ± NR16
      Santi et al. 1994Comparative - Retrospective330HS auto25%27 ± 7.0HS autoKennedyScrew postStaple31 ± NR15
      Marumo et al. 2000Comparative - Retrospective360PT auto90%29 ± 9.9HS autoKennedyStapleNR109 ± NR8
      Sgaglione et al. 1992Comparative - Retrospective316HS auto40%27 ± 8.2HS autoKennedyVarietyStaples31 ± 6.716
      Ebert et al. 2019Case series46536%26 ± 9.3HS autoLARSButtonScrew24 ± NR11
      Nakayama et al. 1999Case series43855%22 ± NRPT autoLeeds KeioStapleScrew14 ± NR8
      Puddu et al. 1993Case series4587NRHS autoPDSStapleStapleNR2
      Kdolsky et al. 1997Case series415228 ± NRPT autoKennedyBurri plateBurri plate89 ± NR8
      Struewer et al. 2013Case series412640%32 ± NRPT autoTreviraPlateStaple29 ± NR9
      Hamido et al. 2011Case series411226 ± NRHS autoLARSVarietyVariety45 ± NR11
      Falconer et al. 2015Case series411134%34 ± NRHS autoLARSButtonScrew29 ± NR11
      Viola et al. 1993Case series46218%21 ± NRPT autoDacronScrew postScrew post44 ± NR8
      Asahina et al. 1995Case series45056%24 ± NRQuads auto or HS autoKennedyStapleNR18 ± NR6
      Nakayama et al. 1996Case series46659%24 ± NRPT autoLeeds KeioStapleScrew72 ± NR8
      Muneta et al. 2000Case series41265%23 ± 9HS autoKennedyNRNR89 ± 1213
      Auto = Autograft.
      Allo = Allograft.
      Hybrid = Hybrid graft.
      HS = Hamstrings.
      PT = Patella tendon.
      NR = Not reported.
      Table 2Outcomes of studies comparing non-reinforced to reinforced grafts.
      Graft rupture
      Non-reinforcedReinforcedp
      Elveos et al. 201825%16%0.40
      Peterson et al. 20144%6%NR
      Barrett et al. 19930%8%NR
      Bodendorfer et al. 20197%7%NR
      Parkes et al. 20216%3%0.66
      Hamido et al. 20150%0%NR
      Marumo et al. 20005%0%NR
      Sgaglione et al. 19924%7%NR
      Objective stability assessment

      Lachman’s (Grade 0–1)
      Non-reinforcedReinforcedp
      Elveos et al. 2018100%95%>0.99
      Peterson et al. 201485%86%0.65
      Barrett et al. 1993100%92%NR
      Parkes et al. 202199%98%0.70
      Santi et al. 199492%88%>0.05
      Sgaglione et al. 199282%73%NR
      Pivot shift (grade 0)
      Non-reinforcedReinforcedp
      Elveos et al. 2018NRNR0.49
      Peterson et al. 201481%82%1.0
      Barrett et al. 1993100%92%NR
      Parkes et al. 202197%100%0.55
      Santi et al. 199479%67%>0.05
      Marumo et al. 200045%36%NR
      Sgaglione et al. 199282%80%NR
      KT-1000 <3 mm side–side difference
      Non-reinforcedReinforcedp
      Elveos et al. 201873%86%0.46
      Peterson et al. 201472%72%1.0
      Barrett et al. 1993NRNR>0.05
      Hamido et al. 201571%89%0.01
      Santi et al. 1994NRNR>0.05
      Marumo et al. 2000NRNRNR
      Sgaglione et al. 199261%64%>0.05
      Patient-reported outcomes
      Lysholm score
      Non-reinforcedReinforcedp
      Elveos et al. 201885 ± 583 ± 40.40
      Barrett et al. 199393 ± NR88 ± NR>0.05
      Parkes et al. 202194 ± 1.896 ± 2.10.17
      Hamido et al. 201590 ± 6.995 ± 7.30.24
      Santi et al. 199492 ± 6.990 ± 10>0.05
      Sgaglione et al. 199287 ± 1692 ± 13NR
      Tegner score
      Non-reinforcedReinforcedp
      Elveos et al. 20183 ± NR3 ± NR0.82
      Peterson et al. 20145 ± NR6 ± NRNR
      Barrett et al. 19934.5 ± NR4.3 ± NR>0.05
      Parkes et al. 20216.4 ± 0.47.1 ± 0.60.03
      Hamido et al. 20156.7 ± 1.57.4 1.80.37
      Santi et al. 1994NRNR>0.05
      Sgaglione et al. 19925.3 ± 1.95.9 ± 2.2NR
      Numerical pain score
      Non-reinforcedReinforcedp
      Bodendorfer et al. 20191.7 ± 1.90.6 ± 1.30.02
      Barrett et al. 19931.3 ± NR2.7 ± NR0.01
      KOOS – pain
      Non-reinforcedReinforcedp
      Elveos et al. 201891 ± NR88 ± NR0.18
      Bodendorfer et al. 201990 ± 8.395 ± 9.50.05
      Hamido et al. 201581 ± NR85 ± NR>0.05
      KOOS – symptoms
      Non-reinforcedReinforcedp
      Elveos et al. 201885 ± NR86 ± NR0.72
      Bodendorfer et al. 201983 ± 1389 ± 120.10
      Hamido et al. 201578 ± NR86 ± NR>0.05
      KOOS – ADL
      Non-reinforcedReinforcedp
      Elveos et al. 201893 ± NR95 ± NR0.60
      Bodendorfer et al. 201995 ± 8.198 ± 4.80.07
      Hamido et al. 201592 ± NR94 ± NR>0.05
      KOOS – sport/recreation
      Non-reinforcedReinforcedp
      Elveos et al. 201878 ± NR73 ± NR0.29
      Bodendorfer et al. 201975 ± 2288 ± 180.04
      KOOS – QOL
      Non-reinforcedReinforcedp
      Elveos et al. 201877 ± NR73 ± NR0.47
      Bodendorfer et al. 201960 ± 2677 ± 190.01
      IKDC (Normal or nearly normal)
      Non-reinforcedReinforcedp
      Peterson et al. 201477%65%0.16
      Bodendorfer et al. 2019NRNR0.01
      Parkes et al. 2021NRNR0.44
      Hamido et al. 201571%96%0.05
      Complications
      Effusions
      Non-reinforcedReinforcedp
      Peterson et al. 20145%13%NR
      Barrett et al. 19930%8%NR
      Parkes et al. 20210%0%>0.99
      Santi et al. 19940%17%NR
      Marumo et al. 200010%10%NR
      Sgaglione et al. 19920%0%NR
      Arthrofibrosis
      Non-reinforcedReinforcedp
      Elveos et al. 20187%25%0.25
      Bodendorfer et al. 20193%7%NR
      Parkes et al. 20214%6%NR
      Hamido et al., 20152%0%NR
      Santi et al. 19944%7%NR
      Marumo et al. 200003%NR
      Sgaglione et al. 199211%13%NR
      NR = Not reported.
      Mean patient age ranged from 21 to 34 years. The proportion of female patients ranged between 0 and 90%. Reconstruction was undertaken using patella tendon grafts in eight studies, hamstrings tendon grafts in 10 studies and a variety of grafts in two studies. The synthetic reinforcement used was the Kennedy ligament augmentation device in eight studies, ligament augmentation and reconstruction system (LARS) in four, Fibertape in two, Leeds-Keio in two, and Trevira ligament, Dacron, polydioxanone (PDS) and Artelon in one study each. Mean follow-up ranged from 1.2 to 25 years postoperatively.

      Results of comparative studies

      Graft rupture

      Eight studies reported graft rupture rates in reinforced and non-reinforced grafts. No study reported a significant difference in graft rupture rates between reinforced and non-reinforced grafts [
      • Elveos M.M.
      • Drogset J.O.
      • Engebretsen L.
      • Bronn R.
      Anterior cruciate ligament reconstruction using a bone-patellar tendon-bone graft with and without a ligament augmentation device: a 25-year follow-up of a prospective randomized controlled trial.
      ,
      • Hamido F.
      • Al Harran H.
      • Al Misfer A.R.
      • El Khadrawe T.
      • Morsy M.G.
      • Talaat A.
      • et al.
      Augmented short undersized hamstring tendon graft with LARS(R) artificial ligament versus four-strand hamstring tendon in anterior cruciate ligament reconstruction: preliminary results.
      ,
      • Peterson L.
      • Eklund U.
      • Engstrom B.
      • Forssblad M.
      • Saartok T.
      • Valentin A.
      Long-term results of a randomized study on anterior cruciate ligament reconstruction with or without a synthetic degradable augmentation device to support the autograft.
      ,
      • Barrett G.R.
      • Field L.D.
      Comparison of patella tendon versus patella tendon/Kennedy ligament augmentation device for anterior cruciate ligament reconstruction: study of results, morbidity, and complications.
      ,
      • Bodendorfer B.M.
      • Michaelson E.M.
      • Shu H.T.
      • Apseloff N.A.
      • Spratt J.D.
      • Nolton E.C.
      • et al.
      Suture augmented versus standard anterior cruciate ligament reconstruction: a matched comparative analysis.
      ,
      • Marumo K.
      • Kumagae Y.
      • Tanaka T.
      • Fujii K.
      Long-term results of anterior cruciate ligament reconstruction using semitendinosus and gracilis tendons with Kennedy ligament augmentation device compared with patellar tendon autografts.
      ,
      • Sgaglione N.A.
      • Del Pizzo W.
      • Fox J.M.
      • Friedman M.J.
      • Snyder S.J.
      • Ferkel R.D.
      Arthroscopic-assisted anterior cruciate ligament reconstruction with the semitendinosus tendon: comparison of results with and without braided polypropylene augmentation.
      ,
      • Parkes C.W.
      • Leland D.P.
      • Levy B.A.
      • Stuart M.J.
      • Camp C.L.
      • Saris D.B.F.
      • et al.
      Hamstring autograft anterior cruciate ligament reconstruction using an all-inside technique with and without independent suture tape reinforcement.
      ].

      Objective stability assessment

      Lachman’s test was reported in six studies. No study demonstrated a significant difference between reinforced and non-reinforced grafts [
      • Elveos M.M.
      • Drogset J.O.
      • Engebretsen L.
      • Bronn R.
      Anterior cruciate ligament reconstruction using a bone-patellar tendon-bone graft with and without a ligament augmentation device: a 25-year follow-up of a prospective randomized controlled trial.
      ,
      • Peterson L.
      • Eklund U.
      • Engstrom B.
      • Forssblad M.
      • Saartok T.
      • Valentin A.
      Long-term results of a randomized study on anterior cruciate ligament reconstruction with or without a synthetic degradable augmentation device to support the autograft.
      ,
      • Barrett G.R.
      • Field L.D.
      Comparison of patella tendon versus patella tendon/Kennedy ligament augmentation device for anterior cruciate ligament reconstruction: study of results, morbidity, and complications.
      ,
      • Sgaglione N.A.
      • Del Pizzo W.
      • Fox J.M.
      • Friedman M.J.
      • Snyder S.J.
      • Ferkel R.D.
      Arthroscopic-assisted anterior cruciate ligament reconstruction with the semitendinosus tendon: comparison of results with and without braided polypropylene augmentation.
      ,
      • Parkes C.W.
      • Leland D.P.
      • Levy B.A.
      • Stuart M.J.
      • Camp C.L.
      • Saris D.B.F.
      • et al.
      Hamstring autograft anterior cruciate ligament reconstruction using an all-inside technique with and without independent suture tape reinforcement.
      ,
      • Santi M.D.
      • Richardson A.B.
      The ligament augmentation device in hamstring grafts for reconstruction of the anterior cruciate ligament.
      ].
      Pivot shift testing was reported in seven studies. No study demonstrated a significant difference between reinforced and non-reinforced grafts [
      • Elveos M.M.
      • Drogset J.O.
      • Engebretsen L.
      • Bronn R.
      Anterior cruciate ligament reconstruction using a bone-patellar tendon-bone graft with and without a ligament augmentation device: a 25-year follow-up of a prospective randomized controlled trial.
      ,
      • Peterson L.
      • Eklund U.
      • Engstrom B.
      • Forssblad M.
      • Saartok T.
      • Valentin A.
      Long-term results of a randomized study on anterior cruciate ligament reconstruction with or without a synthetic degradable augmentation device to support the autograft.
      ,
      • Barrett G.R.
      • Field L.D.
      Comparison of patella tendon versus patella tendon/Kennedy ligament augmentation device for anterior cruciate ligament reconstruction: study of results, morbidity, and complications.
      ,
      • Marumo K.
      • Kumagae Y.
      • Tanaka T.
      • Fujii K.
      Long-term results of anterior cruciate ligament reconstruction using semitendinosus and gracilis tendons with Kennedy ligament augmentation device compared with patellar tendon autografts.
      ,
      • Sgaglione N.A.
      • Del Pizzo W.
      • Fox J.M.
      • Friedman M.J.
      • Snyder S.J.
      • Ferkel R.D.
      Arthroscopic-assisted anterior cruciate ligament reconstruction with the semitendinosus tendon: comparison of results with and without braided polypropylene augmentation.
      ,
      • Parkes C.W.
      • Leland D.P.
      • Levy B.A.
      • Stuart M.J.
      • Camp C.L.
      • Saris D.B.F.
      • et al.
      Hamstring autograft anterior cruciate ligament reconstruction using an all-inside technique with and without independent suture tape reinforcement.
      ,
      • Santi M.D.
      • Richardson A.B.
      The ligament augmentation device in hamstring grafts for reconstruction of the anterior cruciate ligament.
      ].
      KT-1000 was reported in seven studies. Three studies reported no significant difference in KT-1000 stability with or without reinforcement [
      • Peterson L.
      • Eklund U.
      • Engstrom B.
      • Forssblad M.
      • Saartok T.
      • Valentin A.
      Long-term results of a randomized study on anterior cruciate ligament reconstruction with or without a synthetic degradable augmentation device to support the autograft.
      ,
      • Barrett G.R.
      • Field L.D.
      Comparison of patella tendon versus patella tendon/Kennedy ligament augmentation device for anterior cruciate ligament reconstruction: study of results, morbidity, and complications.
      ,
      • Santi M.D.
      • Richardson A.B.
      The ligament augmentation device in hamstring grafts for reconstruction of the anterior cruciate ligament.
      ]. Two studies reported superior stability in reinforced grafts: Hamido et al. found better stability in undersized hamstrings grafts reinforced with LARS compared to regular-sized hamstrings autografts alone (p = 0.013) [
      • Hamido F.
      • Al Harran H.
      • Al Misfer A.R.
      • El Khadrawe T.
      • Morsy M.G.
      • Talaat A.
      • et al.
      Augmented short undersized hamstring tendon graft with LARS(R) artificial ligament versus four-strand hamstring tendon in anterior cruciate ligament reconstruction: preliminary results.
      ]. Elveos et al. reported superior mean KT-1000 stability in patella tendon grafts reinforced with a polypropylene augment at 25-year follow-up, compared to patella tendon alone (KT-1000 Mean 2 mm ± NR vs 0 mm ± NR p = 0.02) [
      • Elveos M.M.
      • Drogset J.O.
      • Engebretsen L.
      • Bronn R.
      Anterior cruciate ligament reconstruction using a bone-patellar tendon-bone graft with and without a ligament augmentation device: a 25-year follow-up of a prospective randomized controlled trial.
      ].

      Patient reported outcomes

      Lysholm score was reported in six studies. No study reported significantly different Lysholm scores at postoperative follow-up between reinforced and non-reinforced grafts [
      • Elveos M.M.
      • Drogset J.O.
      • Engebretsen L.
      • Bronn R.
      Anterior cruciate ligament reconstruction using a bone-patellar tendon-bone graft with and without a ligament augmentation device: a 25-year follow-up of a prospective randomized controlled trial.
      ,
      • Hamido F.
      • Al Harran H.
      • Al Misfer A.R.
      • El Khadrawe T.
      • Morsy M.G.
      • Talaat A.
      • et al.
      Augmented short undersized hamstring tendon graft with LARS(R) artificial ligament versus four-strand hamstring tendon in anterior cruciate ligament reconstruction: preliminary results.
      ,
      • Barrett G.R.
      • Field L.D.
      Comparison of patella tendon versus patella tendon/Kennedy ligament augmentation device for anterior cruciate ligament reconstruction: study of results, morbidity, and complications.
      ,
      • Sgaglione N.A.
      • Del Pizzo W.
      • Fox J.M.
      • Friedman M.J.
      • Snyder S.J.
      • Ferkel R.D.
      Arthroscopic-assisted anterior cruciate ligament reconstruction with the semitendinosus tendon: comparison of results with and without braided polypropylene augmentation.
      ,
      • Parkes C.W.
      • Leland D.P.
      • Levy B.A.
      • Stuart M.J.
      • Camp C.L.
      • Saris D.B.F.
      • et al.
      Hamstring autograft anterior cruciate ligament reconstruction using an all-inside technique with and without independent suture tape reinforcement.
      ,
      • Santi M.D.
      • Richardson A.B.
      The ligament augmentation device in hamstring grafts for reconstruction of the anterior cruciate ligament.
      ].
      Tegner score was reported in seven studies. No study reported a significantly different Tegner score between reinforced and non-reinforced grafts [
      • Elveos M.M.
      • Drogset J.O.
      • Engebretsen L.
      • Bronn R.
      Anterior cruciate ligament reconstruction using a bone-patellar tendon-bone graft with and without a ligament augmentation device: a 25-year follow-up of a prospective randomized controlled trial.
      ,
      • Hamido F.
      • Al Harran H.
      • Al Misfer A.R.
      • El Khadrawe T.
      • Morsy M.G.
      • Talaat A.
      • et al.
      Augmented short undersized hamstring tendon graft with LARS(R) artificial ligament versus four-strand hamstring tendon in anterior cruciate ligament reconstruction: preliminary results.
      ,
      • Peterson L.
      • Eklund U.
      • Engstrom B.
      • Forssblad M.
      • Saartok T.
      • Valentin A.
      Long-term results of a randomized study on anterior cruciate ligament reconstruction with or without a synthetic degradable augmentation device to support the autograft.
      ,
      • Barrett G.R.
      • Field L.D.
      Comparison of patella tendon versus patella tendon/Kennedy ligament augmentation device for anterior cruciate ligament reconstruction: study of results, morbidity, and complications.
      ,
      • Sgaglione N.A.
      • Del Pizzo W.
      • Fox J.M.
      • Friedman M.J.
      • Snyder S.J.
      • Ferkel R.D.
      Arthroscopic-assisted anterior cruciate ligament reconstruction with the semitendinosus tendon: comparison of results with and without braided polypropylene augmentation.
      ,
      • Parkes C.W.
      • Leland D.P.
      • Levy B.A.
      • Stuart M.J.
      • Camp C.L.
      • Saris D.B.F.
      • et al.
      Hamstring autograft anterior cruciate ligament reconstruction using an all-inside technique with and without independent suture tape reinforcement.
      ,
      • Santi M.D.
      • Richardson A.B.
      The ligament augmentation device in hamstring grafts for reconstruction of the anterior cruciate ligament.
      ].
      Numerical pain scores were reported in two studies. Bodendorfer et al. found superior mean and maximum numeric pain scores at mean 29-month follow-up in 30 patients with Fibertape-reinforced hamstrings grafts compared to 30 matched patients managed with hamstrings grafts alone (Mean: 1.7 ± 1.9 vs 0.6 ± 1.7), p = 0.02) (Maximum: 3.4 ± 2.3 vs 1.6 ± 1.8, p = 0.004) [
      • Bodendorfer B.M.
      • Michaelson E.M.
      • Shu H.T.
      • Apseloff N.A.
      • Spratt J.D.
      • Nolton E.C.
      • et al.
      Suture augmented versus standard anterior cruciate ligament reconstruction: a matched comparative analysis.
      ]. The degree of improvement in maximum daily pain score was greater in patients managed with reinforced grafts (−3.5 ± 2.5 vs −5.6 ± 2.4, p = 0.003). In contrast, Barrett et al. found higher mean pain scores in Kennedy LAD reinforced grafts at 2-year follow-up (1.3 ± NR vs 2.7 ± NR, p = 0.01) [
      • Barrett G.R.
      • Field L.D.
      Comparison of patella tendon versus patella tendon/Kennedy ligament augmentation device for anterior cruciate ligament reconstruction: study of results, morbidity, and complications.
      ].
      KOOS was reported in three studies. Two studies found no significant difference in KOOS with reinforcement using Kennedy LAD and LARS fibres [
      • Elveos M.M.
      • Drogset J.O.
      • Engebretsen L.
      • Bronn R.
      Anterior cruciate ligament reconstruction using a bone-patellar tendon-bone graft with and without a ligament augmentation device: a 25-year follow-up of a prospective randomized controlled trial.
      ,
      • Hamido F.
      • Al Harran H.
      • Al Misfer A.R.
      • El Khadrawe T.
      • Morsy M.G.
      • Talaat A.
      • et al.
      Augmented short undersized hamstring tendon graft with LARS(R) artificial ligament versus four-strand hamstring tendon in anterior cruciate ligament reconstruction: preliminary results.
      ]. Bodendorfer et al. reported superior outcomes in reinforced grafts in the KOOS sport and recreation and quality of life subsections [
      • Bodendorfer B.M.
      • Michaelson E.M.
      • Shu H.T.
      • Apseloff N.A.
      • Spratt J.D.
      • Nolton E.C.
      • et al.
      Suture augmented versus standard anterior cruciate ligament reconstruction: a matched comparative analysis.
      ].
      The IKDC was reported in four studies. Three studies found no significant difference in the proportion of patients with grade A or B knees between reinforced and non-reinforced grafts [
      • Hamido F.
      • Al Harran H.
      • Al Misfer A.R.
      • El Khadrawe T.
      • Morsy M.G.
      • Talaat A.
      • et al.
      Augmented short undersized hamstring tendon graft with LARS(R) artificial ligament versus four-strand hamstring tendon in anterior cruciate ligament reconstruction: preliminary results.
      ,
      • Peterson L.
      • Eklund U.
      • Engstrom B.
      • Forssblad M.
      • Saartok T.
      • Valentin A.
      Long-term results of a randomized study on anterior cruciate ligament reconstruction with or without a synthetic degradable augmentation device to support the autograft.
      ,
      • Parkes C.W.
      • Leland D.P.
      • Levy B.A.
      • Stuart M.J.
      • Camp C.L.
      • Saris D.B.F.
      • et al.
      Hamstring autograft anterior cruciate ligament reconstruction using an all-inside technique with and without independent suture tape reinforcement.
      ]. Bodendorfer et al. reported superior mean IKDC in Fibertape reinforced grafts (73 ± 20 vs 88 ± 14, p = 0.006) [
      • Bodendorfer B.M.
      • Michaelson E.M.
      • Shu H.T.
      • Apseloff N.A.
      • Spratt J.D.
      • Nolton E.C.
      • et al.
      Suture augmented versus standard anterior cruciate ligament reconstruction: a matched comparative analysis.
      ].
      Five studies reported a return to play. Four studies reported no significant difference in return to preinjury activity between reinforced and non-reinforced grafts [
      • Elveos M.M.
      • Drogset J.O.
      • Engebretsen L.
      • Bronn R.
      Anterior cruciate ligament reconstruction using a bone-patellar tendon-bone graft with and without a ligament augmentation device: a 25-year follow-up of a prospective randomized controlled trial.
      ,
      • Barrett G.R.
      • Field L.D.
      Comparison of patella tendon versus patella tendon/Kennedy ligament augmentation device for anterior cruciate ligament reconstruction: study of results, morbidity, and complications.
      ,
      • Sgaglione N.A.
      • Del Pizzo W.
      • Fox J.M.
      • Friedman M.J.
      • Snyder S.J.
      • Ferkel R.D.
      Arthroscopic-assisted anterior cruciate ligament reconstruction with the semitendinosus tendon: comparison of results with and without braided polypropylene augmentation.
      ,
      • Santi M.D.
      • Richardson A.B.
      The ligament augmentation device in hamstring grafts for reconstruction of the anterior cruciate ligament.
      ]. Bodendorfer et al. reported a significantly earlier return to preinjury activity levels with graft reinforcement (12.8 ± 3.9 vs 9.2 ± 2.1 months, p = 0.002) [
      • Bodendorfer B.M.
      • Michaelson E.M.
      • Shu H.T.
      • Apseloff N.A.
      • Spratt J.D.
      • Nolton E.C.
      • et al.
      Suture augmented versus standard anterior cruciate ligament reconstruction: a matched comparative analysis.
      ].

      Radiographic evaluation

      Radiological evaluation was reported in five studies with follow-ups ranging from 24 to 300 months. No study reported a significant difference in radiographic changes of osteoarthritis between reinforced and non-reinforced grafts [
      • Elveos M.M.
      • Drogset J.O.
      • Engebretsen L.
      • Bronn R.
      Anterior cruciate ligament reconstruction using a bone-patellar tendon-bone graft with and without a ligament augmentation device: a 25-year follow-up of a prospective randomized controlled trial.
      ,
      • Hamido F.
      • Al Harran H.
      • Al Misfer A.R.
      • El Khadrawe T.
      • Morsy M.G.
      • Talaat A.
      • et al.
      Augmented short undersized hamstring tendon graft with LARS(R) artificial ligament versus four-strand hamstring tendon in anterior cruciate ligament reconstruction: preliminary results.
      ,
      • Barrett G.R.
      • Field L.D.
      Comparison of patella tendon versus patella tendon/Kennedy ligament augmentation device for anterior cruciate ligament reconstruction: study of results, morbidity, and complications.
      ,
      • Marumo K.
      • Kumagae Y.
      • Tanaka T.
      • Fujii K.
      Long-term results of anterior cruciate ligament reconstruction using semitendinosus and gracilis tendons with Kennedy ligament augmentation device compared with patellar tendon autografts.
      ,
      • Santi M.D.
      • Richardson A.B.
      The ligament augmentation device in hamstring grafts for reconstruction of the anterior cruciate ligament.
      ].

      Complications

      The most frequently reported complications were effusions and arthrofibrosis. Effusions were reported in six studies. Santi et al. reported a 0% incidence of effusions in knees with non-reinforced hamstrings grafts versus 17% in knees with polypropylene-reinforced hamstrings grafts (p = NR) [
      • Santi M.D.
      • Richardson A.B.
      The ligament augmentation device in hamstring grafts for reconstruction of the anterior cruciate ligament.
      ]. These patients subsequently underwent arthroscopic resection of the synthetic reinforcement with resultant improvement in their symptoms. Peterson et al. reported a 5% incidence of effusions in knees with non-reinforced grafts versus 13% in those with polyurethane urea reinforced grafts (p = NR) [
      • Peterson L.
      • Eklund U.
      • Engstrom B.
      • Forssblad M.
      • Saartok T.
      • Valentin A.
      Long-term results of a randomized study on anterior cruciate ligament reconstruction with or without a synthetic degradable augmentation device to support the autograft.
      ]. Two studies reported comparable rates of effusion with and without polypropylene reinforcement, and one study reported no effusions in knees with hamstrings grafts with and without Fibertape reinforcement [
      • Marumo K.
      • Kumagae Y.
      • Tanaka T.
      • Fujii K.
      Long-term results of anterior cruciate ligament reconstruction using semitendinosus and gracilis tendons with Kennedy ligament augmentation device compared with patellar tendon autografts.
      ,
      • Sgaglione N.A.
      • Del Pizzo W.
      • Fox J.M.
      • Friedman M.J.
      • Snyder S.J.
      • Ferkel R.D.
      Arthroscopic-assisted anterior cruciate ligament reconstruction with the semitendinosus tendon: comparison of results with and without braided polypropylene augmentation.
      ,
      • Parkes C.W.
      • Leland D.P.
      • Levy B.A.
      • Stuart M.J.
      • Camp C.L.
      • Saris D.B.F.
      • et al.
      Hamstring autograft anterior cruciate ligament reconstruction using an all-inside technique with and without independent suture tape reinforcement.
      ].
      Arthrofibrosis was reported in seven studies. No study reported a significant difference in arthrofibrosis rates between reinforced and non-reinforced grafts [
      • Elveos M.M.
      • Drogset J.O.
      • Engebretsen L.
      • Bronn R.
      Anterior cruciate ligament reconstruction using a bone-patellar tendon-bone graft with and without a ligament augmentation device: a 25-year follow-up of a prospective randomized controlled trial.
      ,
      • Bodendorfer B.M.
      • Michaelson E.M.
      • Shu H.T.
      • Apseloff N.A.
      • Spratt J.D.
      • Nolton E.C.
      • et al.
      Suture augmented versus standard anterior cruciate ligament reconstruction: a matched comparative analysis.
      ,
      • Marumo K.
      • Kumagae Y.
      • Tanaka T.
      • Fujii K.
      Long-term results of anterior cruciate ligament reconstruction using semitendinosus and gracilis tendons with Kennedy ligament augmentation device compared with patellar tendon autografts.
      ,
      • Sgaglione N.A.
      • Del Pizzo W.
      • Fox J.M.
      • Friedman M.J.
      • Snyder S.J.
      • Ferkel R.D.
      Arthroscopic-assisted anterior cruciate ligament reconstruction with the semitendinosus tendon: comparison of results with and without braided polypropylene augmentation.
      ,
      • Parkes C.W.
      • Leland D.P.
      • Levy B.A.
      • Stuart M.J.
      • Camp C.L.
      • Saris D.B.F.
      • et al.
      Hamstring autograft anterior cruciate ligament reconstruction using an all-inside technique with and without independent suture tape reinforcement.
      ,
      • Santi M.D.
      • Richardson A.B.
      The ligament augmentation device in hamstring grafts for reconstruction of the anterior cruciate ligament.
      ].

      Discussion

      The most important finding of this systematic review was that synthetic reinforcement of autografts in ACL reconstruction has not been proven to reduce graft rupture rates [
      • Hamido F.
      • Al Harran H.
      • Al Misfer A.R.
      • El Khadrawe T.
      • Morsy M.G.
      • Talaat A.
      • et al.
      Augmented short undersized hamstring tendon graft with LARS(R) artificial ligament versus four-strand hamstring tendon in anterior cruciate ligament reconstruction: preliminary results.
      ,
      • Peterson L.
      • Eklund U.
      • Engstrom B.
      • Forssblad M.
      • Saartok T.
      • Valentin A.
      Long-term results of a randomized study on anterior cruciate ligament reconstruction with or without a synthetic degradable augmentation device to support the autograft.
      ,
      • Barrett G.R.
      • Field L.D.
      Comparison of patella tendon versus patella tendon/Kennedy ligament augmentation device for anterior cruciate ligament reconstruction: study of results, morbidity, and complications.
      ,
      • Bodendorfer B.M.
      • Michaelson E.M.
      • Shu H.T.
      • Apseloff N.A.
      • Spratt J.D.
      • Nolton E.C.
      • et al.
      Suture augmented versus standard anterior cruciate ligament reconstruction: a matched comparative analysis.
      ,
      • Marumo K.
      • Kumagae Y.
      • Tanaka T.
      • Fujii K.
      Long-term results of anterior cruciate ligament reconstruction using semitendinosus and gracilis tendons with Kennedy ligament augmentation device compared with patellar tendon autografts.
      ,
      • Sgaglione N.A.
      • Del Pizzo W.
      • Fox J.M.
      • Friedman M.J.
      • Snyder S.J.
      • Ferkel R.D.
      Arthroscopic-assisted anterior cruciate ligament reconstruction with the semitendinosus tendon: comparison of results with and without braided polypropylene augmentation.
      ,
      • Parkes C.W.
      • Leland D.P.
      • Levy B.A.
      • Stuart M.J.
      • Camp C.L.
      • Saris D.B.F.
      • et al.
      Hamstring autograft anterior cruciate ligament reconstruction using an all-inside technique with and without independent suture tape reinforcement.
      ,
      • Ebert J.R.
      • Annear P.T.
      ACL reconstruction using autologous hamstrings augmented with the ligament augmentation and reconstruction system provides good clinical scores, high levels of satisfaction and return to sport, and a low retear rate at 2 years.
      ]. Of the eight studies reporting graft rupture rates using synthetically reinforced patella tendon or hamstrings autografts, none found a significant reduction in rupture with the use of synthetic reinforcement. However, two studies demonstrated improved clinical stability [
      • Elveos M.M.
      • Drogset J.O.
      • Engebretsen L.
      • Bronn R.
      Anterior cruciate ligament reconstruction using a bone-patellar tendon-bone graft with and without a ligament augmentation device: a 25-year follow-up of a prospective randomized controlled trial.
      ,
      • Hamido F.
      • Al Harran H.
      • Al Misfer A.R.
      • El Khadrawe T.
      • Morsy M.G.
      • Talaat A.
      • et al.
      Augmented short undersized hamstring tendon graft with LARS(R) artificial ligament versus four-strand hamstring tendon in anterior cruciate ligament reconstruction: preliminary results.
      ] and one demonstrated improved patient-reported outcome measures with graft reinforcement [
      • Bodendorfer B.M.
      • Michaelson E.M.
      • Shu H.T.
      • Apseloff N.A.
      • Spratt J.D.
      • Nolton E.C.
      • et al.
      Suture augmented versus standard anterior cruciate ligament reconstruction: a matched comparative analysis.
      ].
      ACL graft rupture remains an unsolved challenge in orthopaedics. Despite contemporary techniques, graft failure occurs in up to 28% of grafts [
      • Webster K.E.
      • Feller J.A.
      Exploring the high reinjury rate in younger patients undergoing anterior cruciate ligament reconstruction.
      ]. Younger patients, those with smaller grafts, and those who return to pivoting sports are at increased risk [
      • Takazawa Y.
      • Ikeda H.
      • Saita Y.
      • Kawasaki T.
      • Ishijima M.
      • Nagayama M.
      • et al.
      Return to play of rugby players after anterior cruciate ligament reconstruction using hamstring autograft: return to sports and graft failure according to age.
      ,
      • Conte E.J.
      • Hyatt A.E.
      • Gatt Jr., C.J.
      • Dhawan A.
      Hamstring autograft size can be predicted and is a potential risk factor for anterior cruciate ligament reconstruction failure.
      ,
      • Myklebust G.
      • Holm I.
      • Maehlum S.
      • Engebretsen L.
      • Bahr R.
      Clinical, functional, and radiologic outcome in team handball players 6 to 11 years after anterior cruciate ligament injury: a follow-up study.
      ] and could potentially benefit from a stronger graft construct. Recently reported success using Fibertape (Arthrex, Naples, FL) in an extra-articular fashion for ankle reconstruction has generated enthusiasm for its potential application to reinforce ACL grafts. Bodendorfer et al. undertook a matched comparative analysis of patients undergoing auto or allograft ACL reconstruction reinforced by a Fibertape construct [
      • Bodendorfer B.M.
      • Michaelson E.M.
      • Shu H.T.
      • Apseloff N.A.
      • Spratt J.D.
      • Nolton E.C.
      • et al.
      Suture augmented versus standard anterior cruciate ligament reconstruction: a matched comparative analysis.
      ]. The authors found lower mean pain scores (1.7 ± 1.9 vs 0.6 ± 1.7, p = 0.02), higher IKDC (73 ± 20 vs 88 ± 14), p = 0.006), and superior KOOS sport and quality of life sub-scores in reinforced grafts, at mean 29-month follow-up. It is noteworthy that the reported mean IKDC of non-reinforced grafts in the study is lower than that reported with contemporary graft techniques in other studies and below the reported threshold of 75 to achieve a patient acceptable symptom state [
      • McCarthy M.
      • Mallett K.
      • Abola M.
      • Vassallo S.
      • Nguyen J.
      Hospital for special surgery ACL registry: 2-year outcomes suggest low revision and return to OR rates.
      ,
      • Magnitskaya N.
      • Mouton C.
      • Gokeler A.
      • Nuehrenboerger C.
      • Pape D.
      • Seil R.
      Younger age and hamstring tendon graft are associated with higher IKDC 2000 and KOOS scores during the first year after ACL reconstruction.
      ,
      • Muller B.
      • Yabroudi M.A.
      • Lynch A.
      • Lai C.L.
      • van Dijk C.N.
      • Fu F.H.
      • et al.
      Defining thresholds for the patient Acceptable symptom state for the IKDC subjective knee form and KOOS for patients who underwent ACL reconstruction.
      ].
      Synthetic materials have a chequered past in ACL reconstruction. As a stand-alone graft, they have been largely abandoned due to high reported rates of graft failure, tunnel widening, synovitis and premature osteoarthritis [
      • Ventura A.
      • Terzaghi C.
      • Legnani C.
      • Borgo E.
      • Albisetti W.
      Synthetic grafts for anterior cruciate ligament rupture: 19-year outcome study.
      ,
      • Batty L.M.
      • Norsworthy C.J.
      • Lash N.J.
      • Wasiak J.
      • Richmond A.K.
      • Feller J.A.
      Synthetic devices for reconstructive surgery of the cruciate ligaments: a systematic review.
      ]. Similarly, enthusiasm for synthetic materials as reinforcement in autograft ACL reconstructions has fluctuated with time. Potential advantages, such as greater graft strength, were outweighed by the perceived disadvantages of increased graft failure rates, inflammatory reactions to the synthetic materials and additional cost [
      • Elveos M.M.
      • Drogset J.O.
      • Engebretsen L.
      • Bronn R.
      Anterior cruciate ligament reconstruction using a bone-patellar tendon-bone graft with and without a ligament augmentation device: a 25-year follow-up of a prospective randomized controlled trial.
      ,
      • Peterson L.
      • Eklund U.
      • Engstrom B.
      • Forssblad M.
      • Saartok T.
      • Valentin A.
      Long-term results of a randomized study on anterior cruciate ligament reconstruction with or without a synthetic degradable augmentation device to support the autograft.
      ,
      • Barrett G.R.
      • Field L.D.
      Comparison of patella tendon versus patella tendon/Kennedy ligament augmentation device for anterior cruciate ligament reconstruction: study of results, morbidity, and complications.
      ,
      • Marumo K.
      • Kumagae Y.
      • Tanaka T.
      • Fujii K.
      Long-term results of anterior cruciate ligament reconstruction using semitendinosus and gracilis tendons with Kennedy ligament augmentation device compared with patellar tendon autografts.
      ,
      • Sgaglione N.A.
      • Del Pizzo W.
      • Fox J.M.
      • Friedman M.J.
      • Snyder S.J.
      • Ferkel R.D.
      Arthroscopic-assisted anterior cruciate ligament reconstruction with the semitendinosus tendon: comparison of results with and without braided polypropylene augmentation.
      ,
      • Santi M.D.
      • Richardson A.B.
      The ligament augmentation device in hamstring grafts for reconstruction of the anterior cruciate ligament.
      ].
      One proposed mechanism by which reinforced grafts failed was stress shielding [
      • Johnson D.L.
      • Swenson T.M.
      • Irrgang J.J.
      • Fu F.H.
      • Harner C.D.
      Revision anterior cruciate ligament surgery: experience from Pittsburgh.
      ,
      • Mascarenhas R.
      • MacDonald P.B.
      Anterior cruciate ligament reconstruction: a look at prosthetics--past, present and possible future.
      ]. In this process, the autograft tissue failed to ligamentize because inadequate forces were taken up by the tissue to allow collagen remodelling. Historical reinforcements were frequently sutured along the entirety of the graft’s length. Modern “seat belt” reinforcement techniques, with independent tensioning of graft and reinforcement, may allow graft loading to assist maturation but prevent excessive elongation under higher loads [
      • Bachmaier S.
      • Smith P.A.
      • Bley J.
      • Wijdicks C.A.
      Independent suture tape reinforcement of small and standard diameter grafts for anterior cruciate ligament reconstruction: a biomechanical full construct model.
      ,
      • Smith P.A.
      Editorial commentary: anterior cruciate ligament graft reinforcement: a new era supported by science.
      ]. Bachmaier et al. assessed the use of suture tape to reinforce ACL grafts in an animal model. The reinforcement was tensioned to have 1 mm of laxity compared to the graft. Biomechanical testing displayed reduced graft elongation and increased ultimate load to failure, without evidence of stress shielding [
      • Bachmaier S.
      • Smith P.A.
      • Bley J.
      • Wijdicks C.A.
      Independent suture tape reinforcement of small and standard diameter grafts for anterior cruciate ligament reconstruction: a biomechanical full construct model.
      ]. Similarly, Lai et al. tested Fibertape reinforcement of partially transected ACL grafts in a porcine model, in order to replicate a weakened remodelling graft state. The authors found synthetic reinforcement significantly improved yield strength in weakened grafts but had a minimal biomechanical impact on intact grafts [
      • Lai V.J.
      • Reynolds A.W.
      • Kindya M.
      • Konicek J.
      • Akhavan S.
      The use of suture augmentation for graft protection in ACL reconstruction: a biomechanical study in porcine knees.
      ].
      Reactions to synthetic materials are well recognised. This is particularly a problem after the failure of synthetic grafts, where rupture of the synthetic material leads to the release of fibres into the joint, which may contribute to synovitis, effusions and possibly premature degenerative changes [
      • Olson E.J.
      • Kang J.D.
      • Fu F.H.
      • Georgescu H.I.
      • Mason G.C.
      • Evans C.H.
      The biochemical and histological effects of artificial ligament wear particles: in vitro and in vivo studies.
      ]. Synovitis has been described with many previous synthetic fibers, including polytetrafluoroethylene (Proplast, Gore-Tex) [
      • Olson E.J.
      • Kang J.D.
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      ], polyester (Leeds Keio, Dacron) [
      • Olson E.J.
      • Kang J.D.
      • Fu F.H.
      • Georgescu H.I.
      • Mason G.C.
      • Evans C.H.
      The biochemical and histological effects of artificial ligament wear particles: in vitro and in vivo studies.
      ,
      • Barrett G.R.
      • Line Jr., L.L.
      • Shelton W.R.
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      ,
      • Seitz H.
      • Marlovits S.
      • Schwendenwein I.
      • Muller E.
      • Vecsei V.
      Biocompatibility of polyethylene terephthalate (Trevira hochfest) augmentation device in repair of the anterior cruciate ligament.
      ,
      • Claes L.
      • Durselen L.
      • Kiefer H.
      • Mohr W.
      The combined anterior cruciate and medial collateral ligament replacement by various materials: a comparative animal study.
      ], polypropylene (Kennedy LAD) [
      • Olson E.J.
      • Kang J.D.
      • Fu F.H.
      • Georgescu H.I.
      • Mason G.C.
      • Evans C.H.
      The biochemical and histological effects of artificial ligament wear particles: in vitro and in vivo studies.
      ,
      • Kdolsky R.K.
      • Gibbons D.F.
      • Kwasny O.
      • Schabus R.
      • Plenk Jr., H.
      Braided polypropylene augmentation device in reconstructive surgery of the anterior cruciate ligament: long-term clinical performance of 594 patients and short-term arthroscopic results, failure analysis by scanning electron microscopy, and synovial histomorphology.
      ], polyurethane urea (Artelon) [
      • Peterson L.
      • Eklund U.
      • Engstrom B.
      • Forssblad M.
      • Saartok T.
      • Valentin A.
      Long-term results of a randomized study on anterior cruciate ligament reconstruction with or without a synthetic degradable augmentation device to support the autograft.
      ] and polyethylene terephthalate (LARS, Trevira-Hochfest) [
      • Tulloch S.J.
      • Devitt B.M.
      • Norsworthy C.J.
      • Mow C.
      Synovitis following anterior cruciate ligament reconstruction using the LARS device.
      ,
      • Sinagra Z.P.
      • Kop A.
      • Pabbruwe M.
      • Parry J.
      • Clark G.
      Foreign body reaction associated with artificial LARS ligaments: a retrieval study.
      ,
      • Glezos C.M.
      • Waller A.
      • Bourke H.E.
      • Salmon L.J.
      • Pinczewski L.A.
      Disabling synovitis associated with LARS artificial ligament use in anterior cruciate ligament reconstruction: a case report.
      ]. The present review found a trend towards higher rates of effusion in reinforced grafts, but no study reported a significant difference [
      • Peterson L.
      • Eklund U.
      • Engstrom B.
      • Forssblad M.
      • Saartok T.
      • Valentin A.
      Long-term results of a randomized study on anterior cruciate ligament reconstruction with or without a synthetic degradable augmentation device to support the autograft.
      ,
      • Barrett G.R.
      • Field L.D.
      Comparison of patella tendon versus patella tendon/Kennedy ligament augmentation device for anterior cruciate ligament reconstruction: study of results, morbidity, and complications.
      ,
      • Santi M.D.
      • Richardson A.B.
      The ligament augmentation device in hamstring grafts for reconstruction of the anterior cruciate ligament.
      ]. Newer synthetics proposed for autograft augmentation have been tested in animal models and have not shown the reactivity of older synthetics [
      • Smith P.A.
      • Bozynski C.C.
      • Kuroki K.
      • Henrich S.M.
      • Wijdicks C.A.
      • Cook J.L.
      Intra-articular biocompatibility of multistranded, long-chain polyethylene suture tape in a canine ACL model.
      ]. However, at present, there is a lack of clinical data to confirm that this will not be an issue with these materials.
      The present study has a number of limitations. First, most available studies were retrospective and thus prone to selection and intervention bias. Second, many studies experienced substantial loss to follow-up. Third, due to the relative infrequency of graft rupture, studies were often underpowered to detect significant differences in rupture rates. Parkes et al. undertook a sample size calculation and found that for a power of 0.8, a sample size of 1,290 patients would be required [
      • Parkes C.W.
      • Leland D.P.
      • Levy B.A.
      • Stuart M.J.
      • Camp C.L.
      • Saris D.B.F.
      • et al.
      Hamstring autograft anterior cruciate ligament reconstruction using an all-inside technique with and without independent suture tape reinforcement.
      ]. Such large patient cohorts are rarely practically feasible and highlight the limitations of graft rupture as an endpoint. Finally, heterogeneity between studies and outcome reporting prevented a meta-analysis from being undertaken.

      Conclusion

      In this systematic review, synthetic reinforcement of ACL autografts did not result in a reduced rate of graft rupture. A small number of studies have reported superior stability and patient-reported outcome measures with modern synthetic reinforcement techniques. Further clinical studies are required to establish the benefit of synthetic reinforcement of ACL autograft reconstruction.

      Declaration of competing interest

      None declared.

      Financial support

      This research received no sources of funding.

      Ethics approval statement

      Ethics approval was not required for this study as it was a review of existing literature.

      Acknowledgements

      None to declare.

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