2Marc J. Nieuwenhuijse,Carla S. P. van Rijswijk,Arian R. van Erkel,Sander P. D. Dijkstra.The Intravertebral Cleft in Painful Long-Standing Osteoporotic Vertebral Compression Fractures Treated With Percutaneous Vertebroplasty: Diagnostic Assessment and Clinical Significance[J]. Spine . 2012 (11)