Morphologic Study Of Hip OA Cartilage Based On MRI

Background and purpose:Osteoarthritis(OA)is a common chronic,progressive and highly disabled joint disease featured by joint pain and progressive loss of joint function.More severely,OA can cause disability,which increases health burden to human life.With the global population aging and increasing rates of obesity and sports injuries,the incidence of OA is increasing year by year.It is estimated that 250 million people worldwide are affected by OA,which has become the main cause of disability and the main source of social cost consumption for the elderly.Osteoarthritis often occurs in joints with high load-bearing and mobility.The most common site is the knee joint,followed by the wrist and the hip joint.It is reported that about a quarter of the world's population may develop symptomatic hip arthritis in their lifetime.As a complex chronic total joint disease,OA involves structural changes of hyaline articular cartilage,subchondral bone,ligament,articular capsule,synovium and peri-articular muscle.It is an active dynamic process caused by metabolic imbalance in the process of destruction and repair of articular cartilage and non-cartilage tissue,ultimately leading to the destruction of articular structure.In the process of osteoarthritis,the elements of articular cartilage changes and the integrity of cartilage is disrupted.The main pathological features of osteoarthritis are articular cartilage degeneration and progressive cartilage loss.Other features include subchondral bone abnormalities,osteophyte formation at the articular margin,synovitis,ligament and muscle abnormalities and labrum tear and so on.The pathogenesis of osteoarthritis is complex,According to the cause of the disease,it can be divided into primary OA and secondary OA.Primary OA is often associated with age,heredity,nutrition,obesity,etc;secondary OA is often secondary to trauma,inflammation,congenital dysplasia such as femoral acetabular impingement syndrome,acetabular labrum structure damage and so on.It is considered that acetabular labrum injury can lead to changes in hip biomechanics,which is closely related to the occurrence of hip osteoarthritis.McCarthy et al.found that 73% of patients with acetabular labral tear have acetabular and femoral cartilage injuries.It is believed that acetabular labrum cartilage tear may precede the occurrence of arthritis,which is one of the pathological factors leading to arthritis.However,at present,the clinical symptoms of both acetabulum tear and the lesion of femoral and acetabular cartilage in osteoarthritis are not obvious in early stage,and the cartilage has no obvious morphological changes,which can not be easily detected by conventional X-ray.When obvious clinical symptoms appear,the disease has progressed to the middle and late stages.Conservative treatment can only relieve the symptoms or arthroplasty is required,which greatly reduces the life-quality of patients.Therefore,clinical and imaging doctors are making unremitting efforts to diagnose OA risk factors and OA diseases early and accurately,make early intervention treatments,slow down the process of the disease,reduce the disability rate,and improve the life quality of patients to most.With the development of MRI technology,MRI-based morphological semi-quantitative and quantitative evaluation methods of acetabular labrum cartilage,acetabular cartilage and femoral cartilage have been widely used in the evaluation the occurrence and long-term effect of hip OA.However,the sensitivity and accuracy of conventional MRI techniques in the diagnosis of acetabular labral injury are still low,which easily cause missed diagnosis,misdiagnosis and delay in the disease,and ultimately lead to an increase in the incidence of hip OA.Although MRI-based quantitative assessment of articular cartilage has become the main indicator of the long-term efficacy of OA,the studies in this area most focus on patients with knee OA.There are some challenges and difficulties in the research of hip joint due to its special anatomical structure,deep spherical fossa joint and narrow joint space.The purpose of this study is: 1)To compare the diagnostic performance of 1.5T radial magnetic resonance imaging(MRI)and conventional MRI for acetabular labrum tear,and to explore the value of the radial magnetic resonance in the diagnosis of labrum tear and early arthritis,2)To apply MRI-3D-DESS(3D Dual Echo Steady State,3D-DESS)combined with Knee-Cap automatic segmentation software for the detection of progress of femoral and acetabular cartilage of hip joint.The volume of femoral and acetabular cartilage was quantitatively assessed by automatic segmentation,and the difference of cartilage volume between different grades of hip OA was compared.The quantitative value of automatic cartilage segmentation in evaluating the clinical value of OA disease was discussed.Materials and Methods:1.We retrospectively analyzed the clinical data of 22 mild to moderate OA patients with acetabular labrum tear confirmed by hip arthroscopy in our hospital from April to November,2018.All the patients underwent conventional MRI and radial MRI of the hips before the operations.And the imaging data were read by two senior radiologists independently.The MR findings were compared with the findings by hip arthroscopy to assess the performance of 1.5T radial MRI and conventional MRI for the diagnosis of acetabular labrum tear.2.In this study,117 patients with suspected OA were scanned by 3D-DESS-MRI.The injuries of femur and acetabular cartilage of hip joint were evaluated on MRI images.The patients were divided into normal group(n=37),mild OA group(n=35)and severe OA group(n=45).The 3D-DESS images of all patients were loaded into Knee-Cap automatic segmentation software for automatic segmentation of hip femur and acetabular cartilage,generating three-dimensional views and volume values of each subarea.According to the results of automatic cartilage segmentation,the percentages of the femur and acetabulum cartilage subregions were calculated.The homogeneity of the baseline was tested by homogeneity of variance.One-Way ANOVA was used to analyze the difference of relative cartilage volume and volume percentage between the normal group,mild OA group and severe OA group.Result:1.With arthroscopy as the gold standard,the sensitivity,specificity,accuracy,positive predictive value,negative predictive value and likelihood ratio of conventional MRI and radial MRI to diagnosis of acetabular labrum tear were 37.2%/93.0%,86.9%/87.0%,54.5%/90.9%,84.2%/93.0%,42.5%/86.9%,2.85/7.15,respectively.And P value < 0.05.The radial MRI has higher diagnostic value in the injury of labrum laceration,can reduce the rate of misdiagnosis and missed diagnosis,and has important clinical value.2.The automatic segmentation of the hip technology can achieve cartilage segmentation of the femur and acetabulum cartilage in patients of hip OA,as well as for volume measurement of each subregion respectively.Our results showed that there were significant differences between normal control group and severe OA group in total femoral volume(P = 0.002),anterior and superior acetabulum(P = 0.017)and total acetabular cartilage volume(P = 0.002),and the volume reduction in patients with severe OA;mild OA group and severe OA group: total femoral volume(P = 0),anterior and superior femur(P = 0.003),and medial and anterior femur(P = 0.05),posterior and superior femur(P = 0.001),anterior and superior acetabulum(P = 0.003)and total acetabulum volume(P = 0.008)had statistical differences,the patients with severe OA have the smallest volume;there was no significant difference in cartilage volume between normal control group and mild OA group,but the average volume of femur and acetabulum in mild OA group was(6.10±1.19/ 3.02±0.53),slightly higher than that in normal group(5.97±0.10/ 2.93±0.57).This may be due to swelling of articular cartilage in the early stage of OA.Conclusions:1.In summary,the use of the acetabular labrum radial MRI scanning technology can achieve an early and accurate assessment of the hip acetabular labrum cartilage damage,Increasing the detection rate of acetabular labrum cartilage injury.2.Automated cartilage segmentation based on computer software can achieve quantitative assessment of cartilage volume.Our study found that the volume of patients with severe OA is lower than that of normal and mild OA patients,indicating a reduction in cartilage volume during the course of OA disease.Dynamic assessment of the condition can be achieved by longitudinally assessing changes in the patient's cartilage volume.By using the clinical combination method of the semi-quantitative assessment and the quantitative assessment,a comprehensive evaluation of OA can be achieved,and the best intervention treatment plan can be selected to greatly improve the life quality of patients.