Sanford Health paid the federal government $625,000 earlier this year to settle a whistle-blower lawsuit which claimed two Sioux Falls doctors engaged in a kickback scheme to encourage use of a spinal implant. The "Anterior Lumbar Interbody Fusion" was developed by Dr. Wilson Asfora. It was hailed by Sanford as a major development in the treatment of spinal conditions when it was approved for use by the FDA in 2009. The device also is known as the Asfora Bullet Cage. It's difficult to pinpoint just how many patients have been treated with the bullet cage, but Medicare data obtained and analyzed by Argus Leader Media shows that Asfora and Dr. Bryan Wellman are among the most aggressive in the state in performing spinal fusion surgeries.