[Magnetic resonance tomography in diagnosis and therapy follow-up of patients with congenital hip dysplasia and hip dislocation].

AIM: In patients with congenital dislocation of the hip the assessment of the correct position of the hip joint after closed or open reduction is very difficult to make from the radiograph with the hips in plaster. As the delayed recognition of a recurrent hip dislocation has bad effects on the outcome of the affected hip a safe and reliable imaging method must be employed.
METHOD: From 1993 to 1996 6 patients with 8 congenital dislocations of the hip joint were examined by magnetic resonance imaging for evaluation of the position of the hip in plaster after reduction. Magnetic resonance imaging was performed immediately after closed or open reduction. 3 hips had to be treated by open surgery.
RESULTS: The investigation confirmed that magnetic resonance imaging allows perfect differentiation between the bony and cartilaginous parts of the hip joint in plaster as well. Interpositioning of soft tissues which prevent reduction could also be visualized clearly. The best sequence in order to differentiate bony from cartilaginous structures was a gradient echo sequence in flash-technique using a flip-angle of 60 degrees. In all cases the correct position of the hip joint after reduction could be demonstrated in plaster.
CONCLUSION: Therefore, magnetic resonance imaging is the imaging method of choice for confirmation and documentation of the reduced position of the hip joint in plaster. Radiographs are no longer needed.