Magnetic resonance imaging pelvimetry before and after a periacetabular osteotomy.

BACKGROUND: The majority of patients who undergo a reconstructive pelvic osteotomy because of symptomatic hip dysplasia are young women of childbearing potential. The purpose of this paper was to evaluate the effect of periacetabular osteotomy on the dimensions of the pelvic inlet and outlet in these patients.

METHODS: The dimensions of the osseous pelvis of seven women with symptomatic hip dysplasia were measured with use of magnetic resonance imaging pelvimetry before and after periacetabular osteotomy. Four measurements were made: the bispinous diameter, the anterior-posterior inlet measurement, the anterior-posterior midpelvis measurement, and the transverse inlet measurement. Radiographic correction obtained with the osteotomy was documented with preoperative and postoperative anteroposterior pelvic and false-profile radiographs.

RESULTS: Periacetabular osteotomy improved the T nnis angle and the Lequesne angle of the hip joint to an average of 8 degrees and 30 degrees, respectively. The hip center of rotation was medialized an average of 8 mm. None of the four measurements made with the magnetic resonance imaging pelvimetry decreased substantially after the periacetabular osteotomy.

CONCLUSION: Periacetabular osteotomy does not markedly alter the pertinent pelvic dimensions in young female patients.