| Part Ⅰ:The Dynamic Changes In The Values Of T2 Signals Of Ligament And Its Relevant Factor After The Reconstruction Of Knee Patellar Ligament In RabbitObjective:To investigate the dynamic changes in the values of T2 signals of ligament and its pathological relevant factor after the reconstruction of knee patellar ligament in rabbit by MR T2-mapping.Methods:New Zealand female rabbits of 18-week-old were randomly divided into the control group（19）and the operation group（30）,and the operation group was randomly sub-divided into three groups（the 4-week group,the 8-week group and the12-week group）,with 10 in each group,left knees of which were selected for the experiment.1/3 segment under left knee patella to patella-patellar tendon junction were resected from rabbits in the operation group.The patella was drilled,and patellar ligaments were sutured and bound and then went through the hole of patella and tightened,to fit the section of patella with patellar ligament closely,so as to construct rabbit knee patellar ligament reconstruction models,which were well healed 4 weeks after operation with normal activity.T2-map sagittal scan was performed at the fourth,eighth and twelfth week after operation,to observed the changes in T2 images of reconstructed patellar tendon at different time points and to measure the values of T2signals at 3 regions of interest.Patellar tendon knitting place and patellar ligament were resected after scanning to prepare pathological sections for HE staining and Masson staining,as well as immunohistochemical staining of type Ⅰ,Ⅱ and Ⅲ collagens for semi quantitative analysis of the expression levels of type Ⅰ,Ⅱ and Ⅲ type collagens.The control group did not undergo operation and was performed with the sagittal T2-mapping scan at the fourth,eighth and twelfth week.The differences between groups and within a group in terms of the changes in the values of T2 signals at patella-patellar tendon junction（A region）,middle patellar ligament（B region）and posterior cruciate ligament（C region）in the operation group and the control group were statistically summarized,to analyze the relationship between the changes in the values of T2 signals with the expression levels of collagens.Results:（1）Values of T2 signals at the A region and the B region of reconstructed rabbit patellar ligaments at the 4th,8thh and 12thh week were higher in the operation group than in the control group（（49）=0.000,0.000,0.000 and（49）=0.000,0.000,0.002）.The mean values of T2 signals at the C region was higher in the operation group than in the control group at the 4thh week,the difference being statistically significant（（49）=0.017）;the mean values of T2 signals measured at the 8thh and the 12thh week were not statistically significant between the two groups（（49）=0.281 and 0.920）.（2）The differences in the mean values of T2 signals measured at the A region and the B region at the 4th,8thh and the 12thh week in the operation group were statistically significant（（49）=0.000,0.002,0.007）.（3）The differences in the mean values of T2 signals measured at the A region and the B region at the 4thh week and the 8thh week,at the 4thh week and the 12thh week,as well as at the 8thh week and the 12thh week in the operation group were statistically significant（（49）=0.000 and=0.000）,and the value of T2 signal decreased with the prolongation of the healing time（at the A region and the B region）.The differences in the mean values of T2 signals measured at the A region and the B region at the 4thh week and the 8thh week,at the 4thh week and the 12thh week,as well as at the 8thh week and the 12thh week in the control group were not statistically significant（（49）=0.125和（49）=0.128）.（4）Values of T2 signals at the A region and the B region in the operation group decreased with the increase of type Ⅲ collagen,and values of T2 signals at the A region were significantly negatively correlated with the scores of type Ⅲ collagen,r=-0.760,P<0.01,and values of T2 signals at the B region were negatively correlated with the scores of type Ⅱcollagen,r=-0.677,p<0.01.Conclusions:（1）T2-mapping technique can be used to measure and evaluate the dynamic changes in the values of T2 signals during the growth of ligaments after knee ligament reconstruction.（2）Values of T2 signals of the reconstructed ligament decreased with the prolongation of the healing time,and the main related factors may include the increase of type Ⅲ collagen and the decrease of water content..Part Ⅱ:The change of T2 value of ligament after ACL reconstruction and the relation with stability of knee jointObjective: MR T2-mapping was applied to investigate the dynamic changes of T2 values in reconstructed ACL and its relation with stability of knee joint after ACL reconstruction.Methods : 31,35 and 47 patients were enrolled after anterior cruciate ligament reconstruction for 7-12 months,13-18 months and after 18 months.There were 20 healthy volunteers,who were performed MR routine and T2 mapping scan.The location of bone tunnel opening was observed on MR images.The T2 values of femoral tunnel section,intercondylar fossa,tibial tunnel section and normal ACL T2 value were measured after ACL reconstruction.The patients were divided into stable knee group and unstable group in accordance with the examination results of clinical stability of knee joint after ACL reconstruction.MR was used to evaluate whether can normal walking by the bone tunnel for the consistency of and the changing degree in the diameter of the bone tunnel and the stability of the joint in the clinical examination.There were no differences in T2 values between 3 segments of each group during each period.The reconstruction ligament,normal ACL and T2 values of stability group and unstable group were compared between the two groups.The change of T2 value with time in the stable group and unstable group was analyzed.Result:（1）After reconstruction,there were significant differences in the number of cases of abnormal bone tunnel between the stability group and the unstable group for knee joint by MR diagnosis（x2=23.563,p=0.000）.（2）After reconstruction,there were no statistically significant differences in the percentage of femoral diameter changes between the the stable knees and the unstable groups（t =1.2638,P=0.1190）;there were no significant differences in the percentage of tibial internal diameter changes between the the stable knees and the unstable groups（t =1.2152,P=0.1261）.（3）The T2 mean values of the femoral tunnel section,the intercondylar fossa section and the tibial tunnel section of the stable group in each period were compared,while there was no statistical difference between them（P=0.095,P=0.615,P=0.660）.The T2 values of the femoral tunnel section,the intercondylar fossa section and the tibial tunnel section of the unstable group reconstruction ligaments in each period were compared.There was no statistical differences between the two groups（P=0.926,P=0.817,P=0.271）.（4）After reconstruction,patients in stable and unstable groups reconstructed ligaments and normal ACL were compared.T2 value mean difference was statistically significant in all 3 time periods: 7-12 months（H=36.227,p=0.000）,13-18months（H=41.384,p=0.000）and after 18 months（F=102.68,p=0.000）.（5）After reconstruction,the mean value of T2 measured for the stable ligament in 3time periods was statistically significant（H=70.845,p=0.000）.The T2 value decreased with the prolongation of healing time.There was no significant difference in the mean value of T2 between the 3 groups after the reconstruction of the unstable ligament（H=70.845,p=0.000）.Conclusion:（1）6 months after ACL reconstruction,whether the knee was stable or not,the T2 values of the femoral tunnel section,the intercondylar fossa section and the tibial tunnel section of the reconstructed ligament were consistent.There was no difference in the T2 values between the segments.（2）Regular dynamic tracking the changes in the T2 value of the reconstructed ligament in 2 years after ACL reconstruction,and comprehensive consideration of bone tunnel factors could help to assess the stability of ACL after reconstruction joint.（3）Combined with the two parts of this experiment,the T2-mapping technique has the potential to evaluate the postoperative joint stability and is expected to be a quantitative index to evaluate the curative effect of ligament reconstruction。... |
