[Validity of diagnostic methods in detection of congenital hip luxation in primary care].

Objective: To find the validity of the clinical and radiological methods used within Primary Care in the early diagnosis of Congenital Hip Luxation (CHL).
Design: A prospective observation study.
Setting: Zaidín-Sur Basic Health Area (HA), Granada. An urban Health Centre.
Patients: All new-born and nursing babies born in our HA between October 1991 and March 1993 (N = 352), followed and studied over an average period of 22.4 months (SD = 5.6) (Range, 12 to 30 months).
Results: The prevalence of clinically and/or radiologically-based suspected CHL was 19% (Cl 95%; 12.7-25.3%) and the prevalence of confirmed CHL was 4.2% (Cl 95%; 1.96-6.44%). Ortolani-Barlow sensitivity (O-B) was 46.7%, specificity 85.2%; positive predictive value 12.3%, negative predictive value 97.6%, false positives 14.8% and false negatives 53.3%. When positive O-B and/or other positive clinical signs were taken into consideration, sensitivity rose to 73.3% and false negatives went down to 26.7%. If we had not performed radiologies systematically on all the nursing children, we would have missed CHL diagnosis in 1.14% of our basic HA's population-group.
Conclusion: We question the clinical diagnosis of CHL due to its low sensitivity and an excessive number of false negatives. We recommended systematic testing by means of a diagnostic image method, which could be X-Rays at 3 to 5 months.