Anterior cruciate ligament grafts display differential maturation patterns on magnetic resonance imaging following reconstruction: a systematic review
The appearance of anterior cruciate ligament (ACL) grafts on magnetic resonance imaging (MRI) is related to graft maturity and mechanical strength after ACL reconstruction (ACLR). Accordingly, the purpose of this review was to quantitatively analyze reports of serial MRI of the ACL graft during the first year following ACLR; the hypothesis tested was that normalized MRI signal intensity would differ significantly by ACL graft type, graft source, and postoperative time.
PubMed, Scopus, and CINAHL were searched for all studies published prior to June 2018 reporting MRI signal intensity of the ACL graft at multiple time points during the first postoperative year after ACLR. Signal intensity values at 6 and 12 months post-ACLR were normalized to initial measurements and analyzed using a least-squares regression model to study the independent variables of postoperative time, graft type, and graft source on the normalized MRI signal intensity.
An effect of graft type (P = 0.001) with interactions of graft type * time (P = 0.012) and graft source * time (P = 0.001) were observed. Post hoc analyses revealed greater predicted normalized MRI signal intensity of patellar tendon autografts than both hamstring (P = 0.008) and hamstring with remnant preservation (P = 0.001) autografts at postoperative month 12.
MRI signal varies with graft type, graft source, and time after ACLR. Enhanced graft maturity during the first postoperative year was associated with hamstring autografts, with and without remnant preservation. Serial MRI imaging during the first postoperative year may be clinically useful to identify biologically or mechanically deficient ACL grafts at risk for failure.
Level of evidence
KeywordsAnterior cruciate ligament Magnetic resonance imaging Signal–noise-quotient Ligamentization
Anterior cruciate ligament
Anterior cruciate ligament reconstruction
Magnetic resonance imaging
Bone–patellar tendon–bone graft
Hamstring graft with minimal debridement/remnant preservation surgical technique
Tibialis anterior graft
Quadriceps bone graft
Analysis of variance
TEH conceived the study, participated in the critical evaluation of the data and drafting of the manuscript. KEW participated in the critical evaluation of the data and drafting of the manuscript. JAP conducted the literature review, performed the critical evaluation of the data, and participated in the drafting and revision of the manuscript.
Compliance with Ethical Standards
Conflict of Interest
The authors declare that they have no conflict of interest.
Funding was provided by National Institute of Arthritis and Musculoskeletal and Skin Diseases (Grant Nos. R01AR55563, R01AR056259 and T32AR56950).
Ethical approval was not required as this is a review of the literature not involving humans or animals.
- 4.Ahn JH, Lee YS, Jeong HJ, Park JH, Cho Y, Kim KJ et al (2017) Comparison of transtibial and retrograde outside-in techniques of anterior cruciate ligament reconstruction in terms of graft nature and clinical outcomes: a case control study using 3T MRI. Arch Orthop Trauma Surg 137:357–365CrossRefGoogle Scholar
- 9.Biercevicz AM, Miranda DL, Machan JT, Murray MM, Fleming BC (2013) In Situ, noninvasive, T2*-weighted MRI-derived parameters predict ex vivo structural properties of an anterior cruciate ligament reconstruction or bioenhanced primary repair in a porcine model. Am J Sports Med 41:560–566CrossRefGoogle Scholar
- 17.Gohil S, Annear PO, Breidahl W (2007) Anterior cruciate ligament reconstruction using autologous double hamstrings: a comparison of standard versus minimal debridement techniques using MRI to assess revascularisation. A randomised prospective study with a one-year follow-up. J Bone Jt Surg Br 89:1165–1171CrossRefGoogle Scholar
- 18.Hakozaki A, Niki Y, Enomoto H, Toyama Y, Suda Y (2015) Clinical significance of T2*-weighted gradient-echo MRI to monitor graft maturation over one year after anatomic double-bundle anterior cruciate ligament reconstruction: a comparative study with proton density-weighted MRI. Knee 22:4–10CrossRefGoogle Scholar
- 21.Hsu CJ, Hsu HC, Jim YF (2003) A radiological study after anterior cruciate ligament reconstruction. J Chin Med Assoc 66:160–165Google Scholar
- 25.Lee S, Seong SC, Jo CH, Han HS, An JH, Lee MC (2007) Anterior cruciate ligament reconstruction with use of autologous quadriceps tendon graft. J Bone Jt Surg Am 89(Suppl 3):116–126Google Scholar
- 28.Li H, Tao H, Cho S, Chen S, Yao Z, Chen S (2012) Difference in graft maturity of the reconstructed anterior cruciate ligament 2 years postoperatively: a comparison between autografts and allografts in young men using clinical and 3.0-T magnetic resonance imaging evaluation. Am J Sports Med 40:1519–1526CrossRefGoogle Scholar
- 37.Scheffler SU, Schmidt T, Gangey I, Dustmann M, Unterhauser F, Weiler A (2008) Fresh-frozen free-tendon allografts versus autografts in anterior cruciate ligament reconstruction: delayed remodeling and inferior mechanical function during long-term healing in sheep. Arthroscopy 24:448–458CrossRefGoogle Scholar