CHANGE IN THE SUBCHONDRAL TRABECULAE OF THE FEMORAL HEAD IN TRANSIENT OSTEOPOROSIS OF THE HIP

Introduction: The etiology of transient osteoporosis of the hip (TOH) remains unknown. Recently subchondral bone injury of the femoral head has been proposed as a possible etiology. Methods: A 28-year-old woman presented with bilateral hip pain that started sequentially during the peripartum period. Diagnosis of TOH was made based on typical findings of plain radiographs and magnetic resonance images. The subchondral trabeculae of the femoral head were evaluated on serially taken coronal multiplanar reformation CT images. Results: At 4 weeks after pain onset, a marked decrease in the sclerotic density with irregular discontinuation was observed in the primary compression trabeculae. At 12 weeks, a focal area of irregular thickening of trabeculae was observed. At 20 weeks, sclerotic density of trabeculae recovered markedly and the focal area of irregular trabecular thickening disappeared. At 1 year, subchondral trabeculae recovered almost completely. Conclusion: Evidence of subchondral trabecular injury was observed in the femoral heads of TOH.