| Background:Knee osteoarthritis is a common chronic degenerative disease in middle-aged and elderly people.The main pathological changes are cartilage degeneration on the surface of the knee,osteophyte formation and joint space narrowing.At the same time,knee osteoarthritis can be combined with meniscus degeneration or disappearance,synovial hyperplasia,fat pad inflammation and other intra-articular and peripheral soft tissue changes.Infrapatellar fat pad,as the intra-articular adipose tissue outside the synovium,plays a major role in restricting the excessive activity of the knee joint,secreting lubrication to reduce friction,cushion oscillation and protect the knee joint.In recent years,more and more attention has been paid to adipose-derived mesenchymal stem cells because of their potential biomechanics,endocrine function and easy to get the tissue.They can produce a variety of inflammatory cytokines,chemokines,inflammatory modulation and rich in nerve fiber structure.Magnetic resonance imaging of the knee has obvious advantages in displaying cartilage and soft tissue,such as meniscus,ligament and infrapatellar fat pad.It can identify cartilage injuries,osteophyte formation,synovitis and joint effusion of knee joint earlier,so as to evaluate the shape change of fat pad and osteoarthritis of knee joint early and effectively.At present,there are relatively few reports on the relationship between infrapatellar fat pad and abnormal structure of knee joint.The relationship between morphological characteristics of infrapatellar fat pad and knee osteoarthritis is mainly achieved by measuring the volume of infrapatellar fat pad or the maximum sagittal cross-sectional area by magnetic resonance image sequence.The results of different researchers are obviously different.To study the relationship between knee osteoarthritis and the morphology of infrapatellar fat pad is helpful for us to better understand the pathogenesis of knee osteoarthritis and the changes of knee tissue structure.Objective:To explore the morphological characteristics of infrapatellar fat pad(depth,sagittal maximum cross-sectional area,volume)and the correlation with the general situation of the research population and the knee joint bone structure,so as to explore the general rule of human infrapatellar fat pad morphology;to analyze the correlation between the changes of infrapatellar fat pad morphology and signal intensity and the severity of osteoarthritis in patients with knee osteoarthritis,and to explore the relationship between the changes of infrapatellar fat pad,then the relationship between the changes of shape and signal of fat pad and osteoarthritis can be deduced,and the role of infrapatellar fat pad in the pathogenesis and progress of knee osteoarthritis can be further supsected,which will provide new idea and methods for the prevention and treatment of osteoarthritis.Methods:From November 2016 to December 2018,276 patients with knee osteoarthritis and 33 patients with non-knee osteoarthritis and knee pain(asymptomatic or imaging changes of osteoarthritis)were enrolled in our hospital.According to the inclusion and exclusion criteria,188 patients and 20 patients in the control group were included in the final study.A retrospective analysis was made of the general condition of the patients and the imaging data of the knee joint(X-ray and magnetic resonance imaging of the knee).The severity of imaging changes in knee osteoarthritis was assessed by Kellgren-Lawrence grading criteria according to X-ray,cartilage injuries and osteophyte formation were assessed by using total knee MR imaging integral based on T1 images,high signal changes in fat pad were assessed by using T2-weighted three-dimensional fat suppression imaging,and the MR vector of knee joint was assessed by using medical image control system 19.0 software.infrapatellar fat pad depth,sagittal maximum cross-sectional area and tissue volume were measured on sagittal image sequence.Finally,the data were analyzed by using social science statistical software package 22.0.Results:1.The volume of infrapatellar fat pad(27.84±6.57)cm~3 was significantly correlated with height and weight,and the volume of infrapatellar fat pad was significantly different between males and females.The volume of infrapatellar fat pad was significantly correlated with the length of patellar tendon,but not with the length of patella.The sagittal maximum cross-sectional area of the infrapatellar fat pad(6.11±1.14)cm~2 in the study population was significantly correlated with body weight,but not with height.There was a significant gender difference in the sagittal maximum cross-sectional area of the infrapatellar fat pad between males and females.Subpatellar fat pad depth was significantly correlated with body weight(P<0.05).2.The volume of the infrapatellar fat pad was significantly correlated with the patellar cartilage injury score in the total knee MR image score,and with the patellar and femoral osteophyte hyperplasia score,P<0.05.3.There were significant differences in the volume of infrapatellar fat pad between different osteoarthritis groups(P<0.05).As the severity of osteoarthritis increased,the volume tended to be smaller and smaller.4.Univariate correlation analysis showed that high signal intensity in the subpatellar fat pad was significantly correlated with total knee cartilage injury score and osteophyte hyperplasia score(P<0.05).Conclusion:1.The shape and size of infrapatellar fat pad were significantly correlated with patient's sex,weight and height.There were significant differences in the shape and size of infrapatellar fat pad between men and women.The shape and size of infrapatellar fat pad in men were generally larger than that in women.2.The shape and size of the infrapatellar fat pad in patients with knee osteoarthritis are correlated with the condition of articular cartilage injuries and osteophyte formation,suggesting that the shape and size of the infrapatellar fat pad are correlated with the abnormal structure of the knee joint.3.With the aggravation of the severity of osteoarthritis,the volume of infrapatellar fat pad tends to be smaller and smaller,suggesting that with the progress of osteoarthritis,infrapatellar fat pad may be gradually consumed,thus speculating that infrapatellar fat pad may play a protective role in the pathogenesis of knee osteoarthritis.4.The positive correlation between the change of signal intensity of infrapatellar fat pad and knee cartilage injuries and osteophyte formation in patients with knee osteoarthritis suggests that the change of signal intensity of infrapatellar fat pad may be an important part of the pathological changes of osteoarthritis.The inflammation,vascular proliferation and interlobular septal thickening may have causal relationship with the development of osteoarthritis.The high signal of infrapatellar fat pad indicates the development of pathological changes of osteoarthritis.The high signal of infrapatellar fat pad can be used as one of the imaging signs for assistant diagnosis or disease prediction of knee osteoarthritis.5.Pay attention to the existence value of infrapatellar fat pad.Normal infrapatellar fat pad,especially dense vascular area,should be preserved during knee surgery. |
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