Intraoperative loosening of Bagby and Kuslich cages during anterior lumbar interbody fusion

The Bagby and Kuslich (BAK) interbody fusion system has been shown to be a safe and effective method for obtaining solid fusion while maintaining lumbar lordosis. Although postoperative cage loosening has been reported, intraoperative cage loosening has not. The authors describe three cases in which BAK cages became loosened during operation. After the first BAK cage was inserted, it appeared to be well positioned and firmly seated; after placement of the second cage, however, the first cage was loose. Each of these cages was replaced without incident and appeared well placed on follow-up. It is crucial for the surgeon to verify that all cages are firmly seated before closure. This may reduce the incidence of postoperative cage migration.