A Radiological And Clinical Study On Cam Deformity Of Femoral Head And Neck Junction In Adult Hip Dysplasia

ObjectiveDevelopmental Dysplasia of the Hip(DDH)has been considered as one of the most important reasons of hip osteoarthritis in adults.With the rapid development of hip basic research,hip imaging technology and surgical technique have made great progress.Direct Magnetic Resonance Arthrography(dMRA)are gradually replacing X-ray and CT scan & reconstruction,and then playing a more and more important role in diagnosis and treatment of hip joint disorders.Many studies have shown that Periacetabular Osteotomy has become “gold standard” for treatment of adult hip dysplasia,the Cam deformity at the femoral head and neck junction might be a major reason for poor postoperative hip function.The aim of this study is to further clarify the value of dMRA,especially radial reconstruction imaging,in the diagnosis of hip joint disease,and todiscuss the morphology characteristics of femoral head and neck junction inpatients who suffered developmental dysplasia of the hip,as well as the incidence,related factors and clinical meaning of Cam deformity in DDH.MethodsThis study has been divided into four parts.Part ?,the Cam type FAI patients has been chosen as the research objects.The Cam deformity has been confirmed using three methods: pelvic X-ray anteroposterior position,Dunn view radiographs and Radial imaging of dMRA.With the Alpha angle being the main index,it will be considered as Cam when the index is greater than or equal to 55 degrees,and then analyze the value and significance of the 3 methods.Part ?,based on the radial reconstruction images acquired from direct MRA,we measure the Alphaangle,and summerize the morphology characteristics of femoral head and neck junction for Developmental Dysplasia of the Hip in adult,comparing FAI with Cam type patients who have no acetabulum dysplasia and asymptomatic volunteers.Finally,to draw a tomographyfor femoral head& neck junction of DDH patients.Part ?,we did some analysis to find the correlations between the Cam deformity and other indexes,which can provide a significant relation to investigate the formation m e c h a n i s m o f C a m d e f o r m i t y o n t h e f e m o r a l h e a d a n d n e c k j u n c t i o n.Part ?,the patients of developmental dysplasia of the hip who has Cam deformity will be included in the research,the cases were divided into two groups according to whether Cam deformity be rectified,summarize and analyze the discrepancy of clinicalfollow-up results,draw conclusions that can guide the clinical practice of D e v e l o p m e n t a l D y s p l a s i a o f t h e H i p w i t h c o n b i n e d C a m d e f o r m i t y.ResultsIn Part?,there were 14 Cam type patients enrollment,total 20 hip joints,13 male and 1 female,9 left and 11 right.Their age was 14 to 48 years,(average33.1years).Measuring the Alpha angle in pelvic X-ray anteroposterior position,Dunn view radiographs and radial imaging of dMRA.The result would be recorded as positive when the Alpha angle is larger thanor equal to 55 degrees,negative when the Alpha angle is smaller than 55 degrees.The positive relevance ratio of pelvic X-ray A-P view,Dunn view radiographs and Radial imaging of dMRA is 20%,70%,100% respectively.Then we process these three groups of data in totally material,McNemar Test was used in the comparison of the ratios.P=0.013,<0.05.According to ? =0.05,There was significant difference among the three groups.The result shown that the femoral Cam ratio of pelvic X-ray anteroposterior position,Dunn view radiographs and Radial reconstruction imaging of dMRA were different,and the difference has statistic significance.Part ?,there were three groups.The DDH group had 100 hip joints,including 17 males and 83 females,while the left was 39 and the right was 61.The FAI group had 20 hip joints,including 13 males and 1 female,while the left was 9 and the right was 11.The asymptomatic volunteers group,including10 males 10 hips and 25 females 25 hips,as control group.The morphology of femoral head and neck junction among the three groups had been made based on the application of radial reconstruction image on dMRA.It can be used to estimate the form of femoral head and neck junction.The form of femoral head and neck junction from the three groups of data are all oval,which have a prominent part in superanterior quarter.The morphology mapping show: an obvious "peak" shape,embodied from 11:00 to 3:00,where the highest peak are all in the scope from 1:00 to 1:30.The FAI group is the most prominent,the DDH group and the control group take second and third place.Using SNK method and choosing the most obvious points in the scope from 11:00 to 3:00 to do statistic analysis,P>0.05,so there is nostatistical significance regarding Alpha angleamongthe three groups.Part ?,60 patients were included in the research,including 11 males and 49 females,left 21 and right 39.The ages of patients were from 11 to 50,and average 26.2.The Alpha angle measured by radial reconstruction image through dMRA from 1:30,Put the data of Lateral CE angle,Acetabular index angle,anterior CE angle and so on into the blanks,the scatter diagram shown that Alpha angle has no clear relevance with other indexes.We then make hypothesis testing for the result of the Pearson correlation analysis among each group.All the result shows that P?0.05.It can be seen that there is no obvious correlation between Alpha angle and other indexes.Part ?,71 DDH cases selected from case database(2012.01-2013.12),totally 81 hips,20 hips in 18 cases of male,female 53 cases(61 hips,right 33,left 38),average 30 years old,BMI 22.3.Alpha angle minimum 55 degree(Cam standard)measured by MR radial image,Group A underwent only a PAO surgery,including 33 cases 41 hips;Group B underwent the surgery that PAO combined with femoral head and neck Cam repair surgery,including 38 patients 40 hips.Independent samples T test was used to analyze hip flexion angle and Harris scores during final follow-up.The Harris scores of the two groups showed significant difference,group B was slightly better than group A,no difference in hip flexion angle though.The results suggested that the better clinical outcome can be acquired using the combination surgery in DDH patients with Cam deformity.ConclusionRadial reconstruction images of dMRA is a reliable method to observe femoral Cam deformity.The sensitivity and specificity of radial images focusing on Cam were higher than that of other ordinary anteroposterior pelvic X-ray and Dunn radiographs.It was a fine and effective method for diagnosis and assessment of femoral head and neck junction.From the research data,the morphology characteristics of femoral head and neck junction among DDH adults were similar with asymptomatic volunteers.It is easy to identify a Cam phenomeno n in the scope from 12:00 to 3:00.The Cam of femoral head and neck junction has no obvious correlation with other hip joint morphology indexes.The results of clinical research show that the combination surgery,PAO and Cam debridement,is better for DDH patients with Cam deformity.In conclusion,the Cam deformity of femoral head and neck junction in Developmental Dysplasia of the Hip may be a ordinary morphology structure.It does not play a deciding role in the treatment process.The radiographic data,clinical manifestation and physical examination of the dysplasia hip should be adequately considered before making a final clinical decision.