[Gray scale histographic analysis of the acetabular cartilage for quantifying hip ultrasound images].
Congenital dislocated hips are classified in ultrasound studies using the angle measuring system of Graf and evaluating the typical changes in acetabular form and structure. We attempted to quantify physiological and pathological changes in the acetabular cartilage using B-mode scan ultrasound studies. Gray-level histograms were performed on 894 infant hips; 833 were classified by the Graf scheme as Type IIa and 61 as Type IIIa/b. We compared the histological structure of the cartilage of both the acetabulum and the head of the femur using objective parameters. We could show that gray-level histograms of the acetabular cartilage are an ideal way to study objectively ultrasound evaluations of the same area. Type IIa hips with histographically identified ossification zones show significantly higher healing rates than those without such areas. Type IIIb hips with histographically demonstrated pathological changes showed a significantly longer healing rate and a higher incidence of persistent dislocations that did Type IIa hips with normal cartilage. Structural changes in the acetabular cartilage can be evaluated not only qualitatively but also quantitatively to provide prognostic information in infants with congenially dislocated hips. Gray-level histograms nicely supplement ultrasound examination.