Signal intensity on magnetic resonance imaging after allograft double-bundle anterior cruciate ligament reconstruction.
OBJECTIVE
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.


METHODS
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.


RESULTS
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).


CONCLUSIONS
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.


METHODS
Retrospective case series, Level IV.
Department of Orthopedic Surgery, University of Pittsburgh, 3471 Fifth Avenue, Pittsburgh, PA, 15213, USA.
Motoko
M
Miyawaki
Daniel
D
Hensler
Kenneth D
KD
Illingworth
James J
JJ
Irrgang
Freddie H
FH
Fu
D000293:Adolescent; D000328:Adult; D064591:Allografts; D016118:Anterior Cruciate Ligament / Q000473:pathology* / Q000601:surgery*; D000070598:Anterior Cruciate Ligament Injuries; D059549:Anterior Cruciate Ligament Reconstruction; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000175:diagnosis / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D014945:Wound Healing; D055815:Young Adult