RELIABILITY OF ULTRASOUND IN THE EARLY DIAGNOSIS OF DEVELOPMENTAL DYSPLASIA OF THE HIP

The purpose of this study was to determine inter- and intra-observer a greement in assessing hip morphology and stability by ultrasound. Thre e groups of infants, of 206, 74 and 78 newborns respectively, were exa mined. Morphology was classified into four categories (normal, immatur e, minor dysplastic and major dysplastic) according to subjective asse ssment, objective measurement (of the acetabular inclination angle a) or a combination of the two. Inter- and intra-observer agreement was d etermined for reading of recorded ultrasound scans, and for examinatio n (recording plus reading of the scans). Hip stability was subjectivel y classified as stable, unstable, dislocatable or dislocated, and inte r-observer agreement was determined. There was a high degree of agreem ent for morphological classification based on repeated readings of rec orded scans by the same observer (206 infants, kappa = 0.7 and 0.8 for the two observers, respectively) while the degree of agreement betwee n observers was moderate (kappa = 0.5). The agreement between observer s for repeated readings and recordings was moderate when based on a su bjective classification (kappa = 0.5). Adding the a angle did not impr ove agreement. There was a moderate inter-observer agreement in determ ining hip stability (70 infants, kappa = 0.4). The authors concluded t hat a high degree of inter- and intra-observer agreement in classifyin g hip morphology may be obtained for the reading of recorded ultrasoun d scans. Inter- and intra-observer agreement in producing the scans is poorer than for reading. To obtain a high degree of inter-observer ag reement in assessing hip morphology and stability in the newborn, subs tantial training, attention to details in the technique, and evaluatio n of results are necessary.