MRI IN LATE SEQUELAE OF PERTHES-DISEASE - IMAGING FINDINGS AND SYMPTOMATOLOGY IN 10 HIPS

Five painful (group A) and five symptomless (group B) hips in nine pat ients with late sequelae of Perthes' disease were studied with plain r adiography and magnetic resonance imaging (MRI) in order to correlate MRI findings with symptomatology. The unaffected hips were also studie d, In group A hips, poor congruence of the articular cartilage surface s was present in three of five cases, whereas good congruence was foun d in all group B hips. In one spherical but painful hip (group A), MRI revealed a protuberance in the anterolateral cartilage of the femoral head. The joint cartilage in group A and B hips was, on average, 0.5 and 1.5 mm thicker, respectively, than the cartilage in the unaffected hips. The lateral joint capsule was, on average, 3.0 mm thicker in gr oup A hips than in the unaffected hips (P < 0.05), which possibly refl ects reactive changes due to chronic irritation in the painful hips, T he mean joint capsule thickness differed by only 0.5 mm between the un affected and group B hips. Mean anterior acetabular coverage by MRI wa s 97% in group A and 98% in group B, while in the unaffected hips mean anterior coverage was 102%. In an aspherical painful hip, MRI reveale d a juxta-articular cyst not visible by radiography. A symptomless int ra-articular fragment, due to osteochondritis dissecans, was well visu alized with MRI, MRI is recommended for evaluation of pain in hips wit h late sequelae of Perthes' disease. It may show abnormalities in bony structures, as well as in joint capsule and cartilage.