volvedsignificantly lessbloodloss(about 121 mL vs 464 mL), and required a significantly shorter hospital stay (3.5 days vs4.4days).Therateofcomplicationswas similarinbothgroups,with3%ofpatients contracting an infection, 1% developing a deep vein thrombosis, and 4% requiring reoperation. Bothgroupshadsignificantly lesspain comparedwithpresurgerylevels,asmeasuredbytheOswestryDisabilityIndexand visualanalogscaleassessments.However, overall success(basedonphysicalexamination and data from patient questionnaires)wassignificantlygreaterinpatients inthediskreplacementgroup(68%)comparedwiththoseinthespinalfusiongroup (55%). The disk replacement group also had significantly greater neurologic recovery/success (91%) than those who hadspinalfusion(81%).Inaddition,those receivingtheartificialdiskretainedsome range of lumbar spine motion. Preserving such flexibility results in less stress above and below the artificial disk than in comparable areas above and below a fusion site. According to Delamarter, the study is the first randomized clinical trial of an investigational artificial spinal disk to show statistical superiority compared with fusion, as well as the first such trial to include range of motion as an endpoint component of overall treatment success. “At this stage, artificial disk replacement appears as a safe and effective alternative to fusion for 1-level symptomatic lumbar disk disease in properly selected patients,” he said. Several studies evaluating the efficacy of other disk designs are currently under way, including the Maverick (developed by Medtronic Sofamor Danek, Minneapolis, Minn), the Flexicore (developed by SpineCore Inc/ Warburg Pincus Industries, New York City), and the Kineflex (developed by SpinalMotion Inc, Mountain View, Calif). These new research protocols are currently recruiting patients and undergoing design modifications, but outcome data are not yet available. Notallpatientswithdisk-relatedpain and spine instability are candidates for a disk implant. In its final report (http: //www.fda.gov/cdrh/pdf5/p050010a .pdf), the FDA stressed that there are several contraindications to implant use. Such contraindications include active systemic infection or infection at the implant site, osteopenia or osteoporosis, severe spinal stenosis, clinically compromised vertebrae at the affected level due to congenital defects or trauma, and most cases of spondylolisthesis.