The ossific nucleus in Developmental Dysplasia of the Hip. A study of relative ossific nuceus size in hips treated in the Pavlik harness and its predictive value in treatment outcome.

Purpose

To assess the value of measuring relative ossific nucleus (ON) size difference in Developmental Dysplasia of the hip (DDH) as a potential predictor of outcome of hips treated in the Pavlik Harness.

Study Design

Prospective study of all unilateral cases (n=68) of DDH identified in Southampton by dynamic ultrasound and treated in a Pavlik harness studying changes in relative ON size and acetabular indices over a mean follow up period of 3.6 years.

Results

All cases responding to the Pavlik harness showed a progressive correction of ON size difference. Initial ON size difference was not associated with any difference in acetabular index at the date of last follow-up. Ultrasound grading of dysplasia did not affect the rate of normalisation of ON size difference.

Conclusion and clinical relevance

In patients responding to treatment of DDH in a Pavlik harness, ON size difference was not found to be a useful prognostic indicator of outcome.

Impedance plethysmography has great potential in the non-invasive detection of dangerous iliofemoral thrombosis. It was used to examine 198 patients undergoing total hip replacement for evidence of proximal venous segment thrombosis. There were 13 abnormal results, and subsequent venography in 12 of these revealed a false-positive rate of 4.0%; there was one false-negative result giving a sensitivity of 85.7%. A venographic study of 46 other patients clinically suspected of having a proximal deep-vein thrombosis confirmed this sensitivity. The iliofemoral thrombosis rate was 3.9% after total hip replacement and this rate increased significantly in the group of patients over 70 kg in weight. Impedance plethysmography was found to be a useful non-invasive screening procedure for potentially fatal proximal venous thrombosis.