| INTRODUCTIONAnterior Cruciate Ligament injuries are one of the most common and most serious Ligament injuries in the knee.Although after ACL reconstruction can make patients was recovered to close to the previous life state and athleticism,but quite a number of long-term clinical studies showed that knee ligament reconstruction surgery,about 50% of patients in an average of 10 to 15 years' time,have on the knee joint imaging in the diagnosis of post-trauma osteoarthritis(PTOA)pathological changes.With the progress of society and the improvement of people's living standards,the requirements on the quality of life have also undergone significant changes.More and more people are actively participating in all kinds of sports,but the rate of knee joint injuries is also significantly increased.The number of people with ACL injuries has been increasing,especially among teenagers.In the next decade,we are expected to face a growing number of young adults who are incapacitated by traumatic arthritis caused by ACL injuries.There is still a great debate in the academic world about what causes the development of joint degeneration after acute ACL injury.Although studies in recent years have yielded good results,the core question remains: do some soft tissue injuries caused by ACL injuries result in irreversible changes in the intra-articular environment after injuries? Will the kinematics of knee joint reconstructed by ACL be a fuse for the process of cartilage degeneration of knee joint?With faces many problems in the study,we conducted regularly in patients with acute ACL injury of Imaging examination,from quantitative MRI images(quantitative Magnetic Resonance Imaging,q MRI)T1?,T2 change in quantitative observation,to reveal in preoperative patients with acute ACL injury,postoperative 6 months,1 year of follow-upafter operation,observe the change of articular cartilage.In this study,we used advanced q MRI sequence Imaging examination,combined with the results of the semi-quantitative Whole Organ Magnetic Resonance Imaging Score(WORMS),to conduct a longitudinal cohort study of knee cartilage and subchondral bone edema in patients with acute anterior cruciate ligament injury.Different groups were compared in order to find the location or rule of early degeneration after acute knee injury,and to some extent to reveal the slight changes of knee physiologic and pathology after acute ACL injury and reconstruction,thus providing new clues for further scientific research.PURPOSEThe purpose of this study was to evaluate the trend of quantitative imaging and semi-quantitative morphology of knee cartilage in patients with acute ACL injury during the six months and one year after ligament reconstruction,so as to further reveal the potential association between ACL injury and traumatic osteoarthritis.METHODSWe studied 42 patients with unilateral acute ACL injuries and 30 healthy volunteers with asymptomatic bilateral knees at the University of California San Francisco(UCSF)sports medicine center from January 2012 to December 2013.The patients were divided into three groups,which were 42 knees of ACL patients group,42 knees of ACL patients group and 60 knees of healthy control group.For ACL and ACL lateral group,q MRI T1?identification scan,T2 scan and MRI morphology evaluation were performed before ACL reconstruction,6 months after surgery and 1 year after surgery.For the healthy control group,we only need the volunteers to visit our center for a q MRI T1? scan and T2 scan.In the imaging evaluation,the knee cartilage area was mainly divided into six rigions of interest(ROI),namely medial femoralcondyle(MFC)and lateral femoralcondyle(LFC).Medial tibial plateau(MT)and lateral platform(lateral tibial plateau(LT).And patella cartilage(PAT)and trochlea(TRO).Furthermore,LFC and MFC were divided into four sub-divisions,respectively c LFa,c LFc,c LFp,p LF and c MFa,c MFc,c MFp and p MF,with the boundary of the anterior and posterior corners of the meniscus as anatomical marker.C refers to centraland a to anterior and p to posterior region;MT and LT are divided into three sub-compartments,namely MTa,MTc,MTp and LTa,LTc and LTp,respectively.There are14 subcompartments.The measured results of T1? and T2 Relaxation Time(RT)of each ROI and its subcompartments in the study were expressed by means of average plus or minus standard deviation,and the transverse and longitudinal comparisons of the corresponding ROI and the mean values of T1? and T2 RT in each group or group were conducted.MRI WORMS at the same time in the study used the semi-quantitative method to determine the ACL side group in preoperative and postoperative 6 months,1 year after three time points in different regions of the bone marrow edema-like lesions(BMELs)change.In the specific data analysis,we compared the mean values of T1? and T2 RT in the healthy control group.The mean RT values of T1? and T2 were compared between the ACL treated group,the ACL healthy group and the healthy control group.The longitudinal control trend of T1? and T2 mean RT values of the three groups of subjects at the two follow-up time points of 6 months and 1 year after ACL reconstruction was observed.Finally,correlation analysis was performed on q MRI T1? and T2 mean RT values at different time points in ACL lateral group and other related multiple factors,such as age,gender,BMI,BMELs,etc.The results of T1? and T2 mean RT were expressed as mean plus or minus standard deviation in each ROI and subcompartment.The quantitative results of q MRI T1? and T2 were recorded at three different time points.In the specific data analysis,we compared the mean values of T1? and T2 RT in the healthy control group with the paired t-test method.A paired t test was used to compare the affected side knee and the healthy side knee of the same patient.The mean RT values of T1? and T2 were compared between the ACL treated group,the ACL healthy group and the healthy control group.Non-paired t test was used to compare the three groups of subjects at the time points of 6 months and 1 year of follow-up after ACL reconstruction,and the change trend was also described.For the incidence and distribution of BMELs in knee joints of ACL patients and healthy patients,we used chi-square test for statistical comparison.BMELs were found in the ACL lateral group preoperatively,and the paired t-test method was used to compare with the mean values ofq MRI T1? and T2 RT in the knee corresponding region of the ACL healthy side group.The comparison was made at three time points.In this paper,a generalized equations(GEE)model is established.The mixed linear model analysis of multiple time points and multiple factors for ACL lateral group was completed.All statistical processing is performed using SPSS Statistics23.0(IBM,Armonk,NY)software.When doing chi-square test,t test and GEE analysis,we believe that when A and p<0.05,the results have statistical significance.RESULTS:In the healthy control group,there was no significant difference in T1? and T2 mean RT values in all regions and subregions of the articular cartilage of both knees(p>0.05).Before ACL reconstruction,the mean values of T1? RT in the ACL-injured group and the healthy control group were compared,and the values of T1? in PAT were significantly decreased(p<0.05).TRO was significantly increased(p<0.05).Although MFC and LFC were slightly decreased,there was no statistical difference(p>0.05).There was no significant difference in the elevation of MT and LT(p>0.05).In comparison with the mean values of T2 RT in the healthy control group,T2 RT values at MT,LT and TRO were significantly increased(p<0.05).A significant decrease was seen at PAT(p<0.05).No statistically significant differences were found in MFC and LFC(p>0.05).Before the ACL reconstruction,the mean values of T1? RT in the ACL-uninjured group and the healthy control group were compared,and T1? RT values at MT were significantly increased(p<0.05).PAT decreased significantly(p<0.05).No significant differences were observed between MFC,LFC,LT and TRO(p>0.05).In comparison with the mean values of T2 RT in the healthy control group,the T2 RT values at MT were significantly increased(p<0.05).No statistically significant differences were found in MFC,LFC,LT,PAT and TRO(p>0.05).At 6 months after the operation,the values of T1? RT in ACL-injured group and healthy control group were compared,and LFC was significantly increased(p<0.05).PAT decreased significantly(p<0.05).There was no significant increase in MFC,and a small decrease in MT,LT and TRO,but no statistically significant difference(p>0.05).In comparison with T2 RT values in the healthy control group,significant increases were observed in MFC,MT,LT,and TRO(p<0.05).PAT decreased significantly(p<0.05).There was no significant difference in LFC elevation(p>0.05).At 6 months after the operation,T1? RT values of ACL injured group and ACL healthy group were compared,and significant increases were observed in MFC and LFC partitions(p<0.05).PAT decreased significantly(p<0.05).No statistically significant differences were found in MT,LT and TRO(p>0.05).Compared with the T2 RT values of ACL healthy side group,the MFC and TRO partition increased significantly(p<0.05).No significant differences were found in LFC,MT,LT and PAT(p>0.05).At 1 year after the operation,T1? RT values of ACL treated group and healthy control group were compared,and MT partition was significantly increased(p<0.05).There were significant differences in PAT subarea reduction(p<0.05).No significant differences were observed in MFC,LFC,LT and TRO(p>0.05).In comparison with T2 RT values in the healthy control group,significant increases were observed in MFC,LFC,MT and LT partitions(p<0.05).PAT and TRO declined significantly(p<0.05).At 1 year after surgery,there was a significant difference in the decrease of PAT subarea between ACL treated group and ACL healthy group(p<0.05).There were no significant differences in MFC,LFC,MT,LT and TRO(p>0.05).In comparison with T2 RT values of the ACL healthy side group,the TRO partition value increased significantly(p<0.05).PAT value significantly decreased(p<0.05);No significant differences were found in MFC,LFC,MF and LT(p>0.05).Before operation,WORMS semi-quantitative evaluation results indicated that among 42 patients with ACL injury,37 knee joint BMELs were developed,among which 31 knees were distributed in the ACL injured side group(incidence of 73.8%)and 6 knees were distributed in the ACL healthy side group(incidence of 14.3%),showing significant differences(p<0.001).In the ACL lateral group,31 knees present a total of 81 BMELs,which are located at 32 lateral tibial plateau,20 lateral femoral condyle,5 medial femoral condyle,18 medial tibial plateau,5 patella,and 1 trocar.The regression analysis results ofGEE model suggested that among the multiple parameters such as time point of follow-up,cartilage area and subpartition,BMELs,age,gender,BMI,and meniscus tear,the BMELs occurrence before and after surgery at 6 months and 1 year was positively and linearly correlated with the increase of cartilage T1? and T2 value.During the period from ACL reconstruction to 1 year after surgery,the region or subpartition of BMELs was found in those preoperative WORMS examination.Compared with ACL healthy side group,the average injury variation trend of q MRI T1? and T2 RT was more significant in the ACL infested side group(p<0.05).CONSLUSION:The combination of q MRI T1? and T2 imaging with semi-quantitative MRI WORMS method can well evaluate the degeneration of knee cartilage after acute ACL injury.After acute ACL injury,the cartilage of the bilateral knee joint presents a change of continuous deterioration within 1 year after reconstruction even in a short time,among which the cartilage injury of the posterolateral side of the tibial plateau is the most serious and lasting.Among the multiple factors such as age,gender,BMI,and meniscus tear after injury in patients with acute ACL injury,BMELs are independent risk factors for predicting the degree of cartilage degeneration injury.QMRI T1? and T2 imaging combined with semi-quantitative MRI WORMS method have certain predictive and tracking value for the prediction of the development of PTOA after acute ACL injury. |
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