2015 ISAKOS Biennial Congress ePoster #1308
Differences in Graft Signal Intensity on Magnetic Resonance Imaging Between Anteromedial and Posterolateral Bundles of Reconstructed Double Bundle Anterior Cruciate Ligament
Takeo Mammoto, MD, Mito, Ibaraki JAPAN
Atsushi Hirano, MD, PhD, Mito, Ibaraki JAPAN
Tsukuba University Mito Medical Center, Mitokyodo General Hospital, Mito, Ibaraki, JAPAN
FDA Status Not Applicable
Summary: Differences in graft signal intensity on MRI between anteromedial (AM) and posterilateral (PL) bundles of reconstructed anterior cruciate ligament were investigated. Signal intensity of PL tended to be higher than that of AM. Signal intensity was correlated to time from surgery. Remodeling process might be similar, but graft maturity of PL might be later than that of AM.
After anterior cruciate ligament (ACL) reconstruction, it is little known that the differences in graft signal intensity on magnetic resonance imaging (MRI) between the anteromedial (AM) and posterolateral (PL) bundles. The purpose of this study was to determine the graft signal intensity on MRI at femoral tunnel aperture in AM and PL bundles of reconstructed ACL and to determine time dependent signal intensity change of graft.
Materials And Methods
This study included 21 patients who underwent double bundle ACL reconstruction with autologous hamstring graft (12 male, 9 female; age 26 ± 14, range 14 - 57 years). At 3 and 12 months after surgery, all patients underwent MRI with a 1.5-Tesla using a standard knee evaluation protocol. Axial T2-weighted turbo spin echo images (TR 3800, TE 71) with 3mm slice thickness were used for analysis. Femoral bone tunnel aperture were used to distinguish the AM and PL bundle. Best one slice that demonstrated the AM or PL bundle was selected for analysis. The graft signal intensity was measured as well as the background approximately 1 cm lateral to the patella using a region-of-interest (ROI) function on a Picture Archiving and Communications System (PACS) monitor. To quantify the normalized signal intensity of the ACL graft, the signal/noise quotient (SNQ) of each graft was calculated using the following equation: SNQ = (signal of ACL graft/ signal of background). Paired t test was used to compare the SNQ between the AM and PL bundles. Pearson correlation coefficients were used to determine relationship between the SNQ with time from surgery. Statistical significance was set at p<0.05.
Result: At 3 months after surgery, the SNQ of PL graft was higher than that of AM (4.80 ± 1.61 and 4.27 ± 1.38, respectively), but showing no significant differences (p=0.16). The SNQ of PL was higher than that of AM at 12 months (2.82 ± 0.85 and 2.52 ± 0.59, respectively), but showing no significant differences (p=0.20). The SNQ of graft at 3 months was higher compared to that at 12 months in both the AM and PL grafts (p<0.05 for 3 and 12 months). There were strong correlations between the SNQ of AM or PL graft and time from surgery (r=0.85. p<0.05 for AM and r=0.70. p<0.05 for PL).
The result of this study shows that graft signal intensity of PL was higher than that of AM at femoral tunnel aperture, but there were no significant differences at 3 and 12 months after reconstruction. Also, there is a correlation between graft signal intensity and time from surgery, indicating decreased graft signal intensity with time from surgery. Previous study revealed that increased signal intensity is due to graft revascularization and synovialization, predicting structural properties of graft. This study suggests that there is a little difference in remodeling process between the AM and PL grafts, and graft maturity of PL might be later than that of AM.