Abstract

Introduction: Kyphoplasty is a popular therapy for osteoporotic vertebral fractures (OVF), based on an easy-to-learn technique and few perioperative complications. Good reimbursement and intense advertisement by the industry also play a role. The technique is not exclusively being performed by surgeons with experience in the treatment of traumatic spinal fractures. The PMMA-bone cement that is employed for the procedure is much stiffer than osteoporotic cancellous bone, it does not biologically integrate into bone and there is no secondary stabilization around the tamp. Methods: Analysis of 9 cases referred to our departments from 2006 through 2008. All patients had received kyphoplasty of the thoracolumbar junction or the thoracic spine at other institutions and were subsequently referred to our departments. After initial improvement, all patients experienced renewed pain and immobilization within weeks, several patients suffered neurological deficits. Presented is an analysis of the radiographic features of these fractures, their biomechanics, how these relate to the AO fracture classification and what the implications for the primary stability of these fractures are. Results: In all 9 cases, gross instability was found around the cement tamp, in several cases with advanced destruction of neighboring vertebrae and in several cases with subtotal spinal canal occlusion. 1 case had an infected bone tamp in addition. Analysis of the preoperative imaging studies gave evidence to unstable burst fractures, pedicle root discontinuity or disc-with endplate avulsion. The low contrast of severely osteoporotic vertebrae in CT combined with thick slices and incomplete multiplanar reconstructions may have been contributing to misjudging these fractures. 8 patients required multi segment posterior instrumentation, some with vertebral body replacement for anterior support. 1 patient died from complications of immobilization prior to the scheduled stabilization. Discussion and Conclusion: Performing kyphoplasty in unstable OVF may cause complications that far exceed the original problem. Correct fracture analysis is of paramount importance and a high-resolution, thin-slice CT scan with multiplanar reconstructions is required. Fractures of the thoracolumbar junction are demanding to treat and stand-alone kyphoplasty in this region carries significant risks. If, based on thorough fracture analysis, kyphoplasty cannot with certainty achieve adequate primary stability, additional pedicle screw stabilization should be used. Because of the osteoporosis, pedicle screw augmentation with PMMA may be needed in order to avoid screw cut-out. Alternatively, conservative treatment with a custom cast brace may be considered.