The investigative body, which is administered by the Council of Better Business Bureaus Inc. and known as NAD, found that the analyses used by the Virtua Joint Replacement Institute to back up its advertisements were not adequately tailored to prove the claims it was making.
Virtua, which employs 8,500 and has 1,800 physicians on staff, said it disagreed with the decision but would change its marketing.
"We do believe that the minimally invasive quad-sparing technique practiced by our highly trained surgeons at our Virtua Joint Replacement Institute allows patients to reach a positive outcome sooner than traditional techniques," John Matsinger, Virtua's chief clinical officer, said in an interview.
Matsinger said Virtua would participate in research to demonstrate that claim.
The Rothman Institute said in a statement that it agreed with the NAD decision.
To support its challenge, Rothman had submitted five randomized studies from peer-reviewed journals comparing the results of the procedure touted by Virtua with other approaches to knee replacement.
Four of the studies found downsides to the quad-sparing procedure and no benefit in terms of recovery time or complications, according the NAD decision.
The fifth study, which included just 20 patients, found some signs of benefit, but no evidence that length of stay in the hospital was reduced by the "quad-sparing" procedure, which has been used for 13 years.
NAD also said it had "significant concerns with the reliability of the study" because, among other factors, its statistical analysis had been called into question.
Virtua said it would continue to use patient testimony about the "quad-sparing" procedure, but, in compliance with the NAD decision, without the faster-recovery claims.