The 2010 study presented at the Annual Meeting of the American Academy of Orthopedic Surgeons titled, “The High Failure Rate of a High-Flex Total Knee Arthroplasty Design,” indicated a high failure rate in patients who received a cementless high-flex femoral unit implanted as part of a total knee replacement. The study was conducted by Dr. Richard Berger and Dr. Craig J. Della Valle, both orthopedic surgeons at Chicago’s Rush University Medical Center. During the study 108 patients received the cementless device and were evaluated for evidence of bone integration. Of those evaluated, 39 (36%) were radiographically loose, 9 (8.3%) required Zimmer Knee revision surgery due to loosening and pain, and 1 (1%) was awaiting a revision surgery.
Dr. Richard A. Berger was a paid consultant for Zimmer Inc., a producer of joint replacement devices for more than a decade. The Zimmer NexGen CR-Flex device, a cementless total knee replacement implant, had been ineffective as a result of an alleged flaw in the design. The device was designed and expected to last 15 years. Berger, however, noticed within the first year of implantation a pattern of Zimmer Knee failure and alerted Zimmer officials to the potential issue. The knee replacement device was expected to fuse to the bone naturally instead of requiring an adhesive. After complaints from patients about pain it was revealed that the knee devices were coming loose and not fusing to the bone as intended.
Dr. Berger said he had initially hoped to avoid a public showdown with the company, by following a more traditional route and performing a study with another Rush University surgeon, Dr. Della Valle, who also had issues with the Zimmer knee. Soon after the study was made public, however, Zimmer cut Berger from its consultant payroll. Zimmer claims that the termination was part of a normal rotation of consultants. However, critics including Berger have questioned Zimmer’s motives in light of the circumstances surrounding his exit.
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