Postoperative aseptic osteonecrosis in a case of kyphoplasty.

Aseptic osteonecrosis appears to be an infrequent adverse event after kyphoplasty which has not previously been reported. In the following, we present the case of a 73-year-old female who sustained a compression fracture of the first lumbar vertebra (L1) in a motor vehicle accident. The fracture was treated by kyphoplasty using PMMA cement. Three weeks after hospital discharge the patient was presented with increasing back pain. In imaging, dislocation of the PMMA cement could be shown combined with a total collapse of the L1 vertebra. The resulting significant kyphosis was first reduced by dorsal transpedicular (Th12-L2) internal fixation and stabilized by an anterior cage after total removal of the cement plomb and some remaining bone of the L1 vertebra. Bacterial as well as histological examination of the cement and bone led to the diagnosis of aseptic osteonecrosis. Different underlying events could be discussed. We think it most likely that the osteoporotic bone was unable to interface sufficiently with the PMMA cement and, therefore, disintegrated under loading. Furthermore, the volume of injected cement could have significantly compromised the blood supply within the bone.