| Objective: The T2* mapping and T2 mapping sequences of MRI were used to quantitatively evaluate the healing status of the grafts after ACLR,exploring the correlation between quantitative values and knee stability,clinical function scores.Observing the changes of thigh muscle cross-sectional area(CSA)and fat infiltration after ACLR,so as to further guide the decision-making of clinical rehabilitation treatment.Materials and methods:The data of 26 patients received autologous hamstring tendon ACLR(ACLR group,male: 10,female: 16)from February to August 2021 in the department of sports medicine,the first affiliated hospital of Kunming medical university were prospectively collected.26 healthy control group(male: 12,female: 14)were collected and all subjects were scanned by MRI three-dimensional fast imaging employing steady state acquisition(3D-FIESTA),T2* mapping and T2 mapping.The scanning time of ACLR group was 1,3,6 and 12 months after surgery,and the control group performed a single scan with the same sequence.In the ACLR group,clinical function evaluation(IKDC score and Lysholm score)were performed in 6 and 12 months after surgery,and MRI T1 WI,IDEAL-IQ sequence scanning of thigh muscle and Ligs measurement(measurement of knee stability)were performed in the 12 months after surgery.Image post-processing was performed at GE AW4.6 postprocessing workstation and Neusoft Pacs workstation,and the T2* values,T2 values of ACL or grafts at each time point,area parameters,fat fraction of bilateral thigh muscles,and anatomical parameters of knee related(medial/lateral tibial posterior slope,depth of the medial tibial plateau,the width of intercondylar notch,the cross-sectional area of the intercondylar notch,the notch width index,coronal/ sagittal obliquity of the graft)were obtained.According to Ligs measurement results,the patients were divided into stable group and unstable group with the SSD value of the anteriorly translation difference of the tibia between the operative side and the healthy side under 89N(SSD=ATT on the operative side-ATT on the healthy side,SSD > 3mm as unstable group,SSD < 3mm as stable group).Anova analysis was used to compare T2* values and T2 values between ACLR group at different times after surgery and control group,and LSD-t method is used for further comparison between the two.Person correlation analysis was conducted to analyze the correlation between T2* values,T2 values of grafts and clinical scores in 6,12 months after ACLR.Independent sample t test was used to observe the differences of thigh muscle area parameters and fat fraction between the affected side and healthy side,stable group and unstable group after ACLR.This method is also used to compare T2* values,T2 values,clinical scores and anatomical parameters between the stable group and unstable group.Results: The T2* values of the grafts in 1 and 3 months after ACLR was lower than that of the control group,the T2* values of grafts in 6 and 12 months was higher than that of 1 and 3 months after surgery,the differences were statistically significant(all P< 0.01).The T2 values of the grafts in 1 and 3 months after ACLR was lower than that of the control group,the T2 values of grafts in 6 months was higher than that of the control group,the T2 values of the grafts in 6 and 12 months after ACLR was higher than that of 1 and 3 months after surgery,the T2 values of the grafts in 12 months was lower than that of 6 months after surgery,the differences were statistically significant(all P < 0.05).There was no statistically significant difference of the T2* and T2 values of grafts or ACL between other different time points after surgery or control group(all P>0.05).IKDC scores and Lysholm scores in 12 months were significantly higher than 6 months after surgery,and the differences were statistically significant(P < 0.001).The T2* values of grafts and IKDC scores,Lysholm scores in 6 months after surgery,the T2* values of grafts and Lysholm score in 12 months after surgery,the T2 values of grafts and IKDC scores in 12 months after surgery were moderately negatively correlated(r=-0.525,P<0.01;r=-0.517,P<0.01;r=-0.440,P<0.05;r=-0.522,P<0.05).There was no correlation between other quantitative values of MRI and clinical scores in 6,12 months after surgery(r<0.4,all P>0.05).The LTPS,the graft T2*values in 6 months and 12 months after surgery,and the graft T2 values in 12 months after surgery in the unstable group were higher than those in the stable group,while the IKDC score and Lysholm score in 12 months after surgery were lower than those in the stable group,with statistical significance(all P < 0.01).There were no significant differences in the quantitative MRI values of the grafts at other time point and the clinical function scores in 6 months after surgery between the stable group and the unstable group(all P >0.05).12 months after surgery,the total muscle,the muscles of the anterolateral group,the vastus lateralis,the vastus medialis and the rectus femoris CSA of the affected side were significantly smaller than that of the healthy side,with statistical significance(all P < 0.01).There was no significant difference in other bilateral thigh muscle CSA(all P >0.05).There were no significant differences in the average FF of all muscle groups and each muscle in bilateral thigh(all P>0.05).There were no significant differences in all area parameters and FF between the stable group and the unstable group(all P>0.05).Conclusions:1.Quantitative MRI T2* mapping and T2 mapping sequences can be used for dynamic monitoring ligamentalization of graft and non-invasive quantitative evaluation of graft repair and healing status after ACLR.The increase of T2* value of graft in the early stage after ACLR may predict postoperative knee instability.2.T2* and T2 values of grafts after ACLR are related to the functional status of patients’ knee joints to a certain extent,which provides a new reference for the comprehensive evaluation methods and parameters of ACLR posterior knee joints.3.The quadriceps femoris of the affected limb significantly atrophied,and other thigh muscle CSA and muscle FF of thigh did not change significantly compared with the healthy side,so attention should be paid to the recovery of morphological indexes of the quadriceps femoris in rehabilitation treatment. |
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