The continuing development of vibration arthrometry as a screening method in developmental dysplasia of the hip

As part of the continuing development of a non-invasive, objective screening method to achieve efficient early detection of developmental dysplasia of the hip (DDH), we determined the diagnostic sensitivity of an experienced nurse examiner and vibration arthrometry in the range of pathological anatomy of the disease. A cohort of 25 children were studied prior to commencement of their treatment. The hips were classified into four categories by an experienced paediatric orthopaedic surgeon with all diagnostic modalities available (“normal”, “stable but dysplastic”, “unstable and reducible” or “irreducible”). Of the 28 hips identified as abnormal, two hips were classified as stabledysplastic, 11 were unstable/reducible and 15 were irreducible hips. The experienced nurse examiner identified eight out of 11 unstable-reducible hips and reported clinical signs of abnormality in another 18 cases. Vibration arthrometry identified nine out of 11 unstable-reducible dislocations and detected abnormal signals from three irreducible hips. Vibration arthrometry may be of value in detecting abnormality in unstable-reducible and clicking hips. The low detection rate in the irreducible and dysplastic hips by vibration arthrometry was due to the absence of detectable vibration from mechanical events as the hips were manoeuvred. Examination by an experienced clinical examiner continues to be necessary if all degrees of mechanical abnormality in DDH are to be detected. Further development is required to achieve an objective non-invasive system of detecting all stages in the pathology of DDH.