| BackgroundDevelopmental dislocation of the hip(DDH),meaning the abnormal contact of acetabular and femoral head,is one of the common pediatric osteoarthritis.If the infant with DDH can not be timely diagnosed and treated,its hip dislocation will result in a series of secondary pathological changes,which including labrum varus,intra-articular fat hyperplasia,joint capsule thickening and adhesion,femoral head ossification center dysplasia.Thus the effect of reset was greatly affected.Preoperative diagnosis and evaluation of a series of secondary pathological changes in DDH is a critical step in clinical treatment,which can provide important and valuable information for the clinical selection of appropriate surgical procedures.In the past,the optimal methods of diagnosing DDH and evaluating of its secondary pathological changes were traditional imaging methods,including X-ray,CT,MRI.However,X-ray,CT only reflect the hip development of the bone structure,without comprehensive display of articular cartilage and peri-joint soft tissue.What’s worse,owing to the irradiation,it is not suitable for infants to take X-ray or CT examination.MRI has a high resolution on soft tissue,and it clearly displays the hip anatomical structure.Thus it can be used to diagnose DDH and display the secondary pathological changes.Yet,due to the its disadvantages of expensive,non-dynamic imaging,time-consuming and requiring calm sleep,it is not easy to promote the application.High-frequency ultrasound has a good tissue resolution,which can clearly show the acetabular morphology,acetabular labia andthe peri-joint soft tissue.In recent years,with the merit of simple,noninvasive,dynamical imaging,ultrasound was widely used to diagnose of DDH.However,there is rare report about using high-frequency ultrasound to evaluate the secondary pathological changes of DDH domestically.This study aims to use high-frequency ultrasound to observe the secondary pathological changes of DDH,including the labrum,intra-articular fat,joint capsule and femoral head ossification center,which provides valuable information for clinical diagnosis and treatment.ObjectiveThis study aims to explore the value of high-frequency ultrasound in observing the secondary pathological changes of DDH.Materials and methods1 Clinical dataThis study was carried out between February 2014 and August 2015.34 infants with DDH were included into Pediatric orthopedics department in the 3rd Affiliated Hospital of Southern Medical University.There were 7 male and 27 female,and the average age was 15±7 months old(ranging from 2 months old to 33 months old).There were 32 unilateral DDH(20 on the left side and 12 on the right side)and 2 bilateral DDH in all.That was 36 dislocated hips in total.Inclusion criteria:infants diagnosed by clinical examination,including unequal length of bilateral lower limbs,limited of activity of hip abduction,gait abnormalities,and so on.Exclusion criteria:infants with secondary hip dislocation resulting from trauma,cerebral palsy,multi-joint contracture.2 Equipment and ultrasonography2.1 Equipment:Philips iU22 ultrasonic diagnostic apparatus.L12-5 Linear array probe,frequency 5-12MHz.2.2 2D ultrasonographyFirstly,the shape and position changes of the labrum and cartilage acetabular top were observed on coronal section with lateral position by ultrasound and the labrum varus or valgus was diagnosed.The thickness of the joint capsule on bilateral the femoral head wasmeasured both on coronal section and cross section.And the development of the ipsilateral and contralateral femoral head ossification centers were compared.Then,the proliferation of intra-acetabular fossa adipose tissue of the dislocated hip was observed in inguinal level with supine position by ultrasound.All of the infants accepted bilateral hip MRI examination as the gold standard.And the result of the labrum varus or valgus and the proliferation of intra-acetabular fossa adipose tissue of the dislocated hip were compared between the two methods.2.3 Color Doppler UltrasoundThe peak systolic velocity(PSV)and RI(resistance index)of both ipsilateral and contralateral medial circumflex femoral artery of the 32 unilateral DDH infants were measured by Color Doppler ultrasound with supine position.3 Statistical analysisAll statistical analysis was performed using SPSS for windows version 17.0(SPSS Inc.,Chicago,IL,USA).Chi-Square was adopted for measuring the sensitivity and specificity of ultrasonography in diagnosing labrum varus.Data of the thickness of the joint capsule and the PSV and RI of medial circumflex femoral artery were expressed as means±standard deviations and the data between ipsilateral and contralateral hips were compared with T test.A P value of<0.05 was considered significant.Results1.Among the 36 dislocated hips,33 were diagnosed as labrum varus and 3 were diagnosed as labrum valgus by MRI,while 27 were diagnosed as labrum varus and 9 were diagnosed as labrum valgus by ultrasound.Compared to MRI,the sensitivity and specificity were 82%and 100%respectively in diagnosing labrum varus by ultrasound.And the coincident rate of diagnosing labrum varus or valgus by ultrasound was 83%.2.Among the 36 dislocated hips,MRI displayed the proliferation of intra-acetabular fossa adipose tissue in all the cases,while ultrasonography detected 31 cases with proliferation of intra-acetabular fossa adipose tissue.Those undetected by ultrasonography displayed only a small amount of adipose tissue.3.The ultrasound display of the bilateral femoral head ossification centers in the 34cases infants were as follows.① The ipsilateral side was smaller than the contralateral side(64.7%).② The ipsilateral side was not showed while the contralateral side was showed(20.6%).③ Bilateral sides were not showed(11.8%).④Bilateral sides were dysplasia(2.9%).4.The average thickness of the ipsilateral hip capsule was(2.8±0.6)mm,and that of the contralateral hip capsule was(1.7±0.4)mm.The thickness of the ipsilateral hip capsule was significantly thicker than that of the contralateral hip(P<0.001).5.The average PSV of the ipsilateral medial circumflex femoral artery was(11.8±3.5)cm/s,and that of the contralateral medial circumflex femoral artery was(16.1 ±7.2)cm/s.That of the ipsilateral side was significantly lower than that of the contralateral side(P<0.001).The average RI of the ipsilateral medial circumflex femoral artery was 0.78±0.09,and that of the contralateral medial circumflex femoral artery was 0.80±0.11.There were no significant differences between the two groups(P>0.05).Conclusions1.The abnormal changes of acetabulum can be showed clearly by high frequency ultrasound.The cartilage acetabular top was pushed downwards by the dislocated femeral head,and the labrum was stuck between the femeral head and the cartilage acetabular top,which resulted in the labrum varus and the labrum hypertrophy.2.The high frequency ultrasound can be used to detect the thickness of the hip capsule and the proliferation of intra-acetabular fossa adipose tissue,which provide important reference information for the clinical selection of appropriate treatment.3.The color Doppler ultrasonography can be used to detect the medial circumflex femoral artery,which was the main blood supply of the femeral head.This can provide important basis and information for the clinical analysis of the reasons for dysplasia of DDH femoral head ossification center. |
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