Article

Evaluation with contrast-enhanced magnetic resonance imaging of the anterior cruciate ligament graft during its healing process: a two-year prospective study.

Department of Radiology, University Hospital of Ioannina, Stavros Niarchos Avenue, Ioannina, 45500, Greece, .
Skeletal Radiology (Impact Factor: 1.74). 12/2012; 42(4). DOI: 10.1007/s00256-012-1534-y
Source: PubMed

ABSTRACT OBJECTIVE: The aim of this study was to evaluate, with contrast-enhanced-magnetic resonance imaging (MRI), the changing imaging appearance of an anterior cruciate ligament (ACL) graft during the revascularization phase by quantitatively assessing the morphological and signal intensity changes taking place at its cross-sectional surface over time. MATERIALS AND METHODS: Fifty patients underwent contrast-enhanced-MRI on the third postoperative day and at a mean of 6, 12, and 24 months time interval after surgery. Proton-density images were obtained to evaluate morphological and signal intensity characteristics. Oblique-axial T1-weighted images obtained before and after intravenous gadolinium administration were used for quantitative analysis. Enhancement index (EI: signal-to-noise quotient(after gadolinium)÷signal-to-noise quotient(before gadolinium)) and cross-sectional area (CSA) were calculated for two regions of interest: the transplanted graft and its surrounding hypervascular tissue, and at three distinct graft sites (intra-articular, intraosseous tibial tunnel, and intraosseous juxta screw sites). Comparisons of EI and CSA at every site and time interval were performed using analysis of variance. RESULTS: A variable MRI appearance of the graft during the different time intervals was attributed to the varying amount of the hypervascular tissue gradually surrounding the graft. Graft EI and peripheral tissue CSA progress in a parallel, time- and site-related pattern along the graft course. The initial heterogeneity with intermediate signal intensity at the intra-articular graft site reflected intense revascularization. A slower revascularization progress was noticed at the other two intraosseously enclosed sites. CONCLUSION: During the healing process the amount of revascularization tissue influences the MR imaging characteristics of the graft according to the examined site and the time interval after surgery. By 2 years postoperatively, revascularization completion coincides with the homogeneously low signal intensity of the graft, closely resembling native ACL.

Download full-text

Full-text

Available from: Aikaterini Ntoulia, Mar 25, 2014
0 Followers
 · 
248 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Background: Augmentation consisting of a selective reconstruction of the ruptured bundle while preserving the remnant bundle has been proposed as a treatment option for partial anterior cruciate ligament (ACL) tears. Good clinical outcomes after selective anteromedial (AM) bundle augmentation have been reported, whereas little is known about selective reconstruction of the pos- terolateral (PL) bundle with preservation of the AM bundle remnant. Purpose: The purpose of this study was to evaluate the clinical outcomes and the magnetic resonance imaging (MRI) charac- teristics of selective PL bundle reconstruction with a median follow-up of 24 months. Study Design: Case series; Level of evidence, 4. Methods: In a consecutive series of 741 ACL reconstructions, 44 patients underwent a selective PL bundle reconstruction with preservation of the AM remnant. Four patients with contralateral knee ligament surgery and 1 patient who sustained a traumatic rupture of his graft were excluded, leaving 39 patients for final evaluation. Clinical evaluation of knee function and laxity were recorded preoperatively and at a mean 24.2-month follow-up. Magnetic resonance imaging was performed on 35 patients at a mean 25.9-month follow-up for evaluation of graft and remnant bundle continuity, tunnel enlargement, and graft remodeling status by measuring the signal intensity of the graft (contrast/noise quotient [CNQ]). Results: Tegner and Lysholm knee scores were significantly improved after surgery. The subjective International Knee Docu- mentation Committee (IKDC) score was 43.5 + 16.6 preoperatively and 89.9 + 6.6 at the final follow-up (P < .01). The objective IKDC score was ‘‘B’’ for 17 patients, ‘‘C’’ for 21 patients, and ‘‘D’’ for 1 patient preoperatively, while it was ‘‘A’’ for 34 patients and ‘‘B’’ for 5 patients postoperatively (P < .01). The mean side-to-side anteroposterior laxity was 5 mm (range, 4-10 mm) preopera- tively and 1.5 mm (range, 􏰀1 to 4 mm) at final follow-up (P < .01). On MRI, the graft was visible and continuous in all cases. No cyclops lesions were noted. The average CNQ for the PL graft and the AM remnant bundle was 3.2 + 1 and 2.9 + 1.2, respectively. Minimum bone tunnel enlargement was found. Conclusion: Selective PL bundle reconstruction restores knee stability and function. At final follow-up, MRI showed continuity of the PL graft without signs of dramatic tunnel enlargement or cyclops syndrome. Keywords: ACL partial tear; anterior cruciate ligament; posterolateral (PL) bundle
    08/2013; DOI:10.1177/2325967113501624
  • [Show abstract] [Hide abstract]
    ABSTRACT: To evaluate magnetic resonance imaging (MRI) graft signal intensity after allograft double-bundle (DB) anterior cruciate ligament (ACL) reconstruction and determine the relationship between signal intensity and time from surgery. Twenty-six patients with an intact graft on MRI after anatomic allograft DB ACL reconstruction up to 1 year post-operatively were included. All subjects underwent post-operative MRI using a 1.5-T magnet. Sagittal proton density-weighted images (PDWI) and sagittal T2-weighted images (T2WI) were analysed. Using the region-of-interest (ROI) function on imaging software, the anteromedial (AM) and posterolateral (PL) bundles of the graft and the posterior cruciate ligament (PCL) were outlined. Mean signal intensity of the three ROIs were recorded as absolute signal intensity. Signal intensity (SI ratio) was calculated based on the signal intensity of the PCL. Correlation coefficients were calculated to determine the relationship between signal intensity and time from surgery. SI ratio of the PL bundle was higher than that of the AM bundle for both the PDWI (1.7 ± 1.5 vs. 2.5 ± 1.7, p < 0.05) and T2WI (1.3 ± 0.4 vs 1.6 ± 0.6, p < 0.05). There were weak correlations between AM SI ratio and time from surgery (r = 0.38, p < 0.05 on PDWI), and moderate correlations between PL SI ratio and time from surgery (r = 0.43, p < 0.05 on PDWI) (r = 0.44, p < 0.05 on T2WI). The PL bundle displayed increased signal intensity compared to the AM bundle and based on previous studies may indicate a longer healing process. Plain MRI may be useful to assess graft healing after ACL reconstruction. Retrospective case series, Level IV.
    Knee Surgery Sports Traumatology Arthroscopy 01/2014; 22(5). DOI:10.1007/s00167-014-2856-1 · 2.84 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Aim: To determine the relationship between knee pain following anterior cruciate ligament (ACL) graft placement with morphological graft findings and dynamic contrast enhancement as assessed at MRI. Material and methods: Following institutional review board approval, 37 consecutive patients with double-bundle ACL reconstruction were enrolled. Thirteen patients had pain and 24 were asymptomatic. Imaging was performed using a 1.5 T MRI machine an average of 7.6 months after surgery. Graft-related (increase signal intensity, abnormal orientation, discontinuity, cystic degeneration, anterior translation of lateral tibia, arthrofibrosis), and non-graft related causes of knee pain (meniscal tear, cartilage injury, loose bodies, and synovitis) were evaluated. During dynamic contrast enhancement analysis, peak enhancement (ePeak) was calculated by placing a region of interest at the osteoligamentous interface of each bundle. Student's t-test was used for continuous variables analysis and chi-square or Fisher's exact test was used for categorical variables analysis. Results: There was no difference between symptomatic and asymptomatic patients regarding morphological graft-related or non-graft-related causes of knee pain. For dynamic contrast enhancement analysis, symptomatic patients had significantly lower ePeak values than asymptomatic patients in the anteromedial (p = 0.008) and posterolateral (p = 0.001) bundles or when using the higher ePeak value in either bundle (p = 0.003). Conclusion: Morphological ACL graft findings as assessed at MRI could not be used to distinguish between symptomatic and asymptomatic patients. However, lower ePeak values had a significant association with knee pain. This may indicate poor neovascularization of the graft, potentially leading to graft failure.
    Clinical Radiology 07/2014; DOI:10.1016/j.crad.2014.06.018 · 1.66 Impact Factor