Results of mobile bearing knee implant at 5 years may be comparable to fixed bearing design

ORLANDO, Fla. — In a prospective study, cemented rotating-platform total knee arthroplasty prostheses demonstrated many of the same wear qualities as fixed bearing designs.

Chitranjan S. Ranawat, MD, presented the results of his investigation and publications concerning the PFC-Sigma rotating platform knee prosthesis (DePuy), an implant he has used since 2000, at the 26th Annual Current Concepts in Joint Replacement Winter Meeting.

In the study, Ranawat and his colleagues implanted an equal number of cemented rotating platform and fixed bearing designs in 150 patients (162 knees) between 2000 and 2003. The patients had an average age of 68 years and most had osteoarthritis.

5-year results

Chitranjan S. Ranawat, MD
Chitranjan S. Ranawat

“The clinical results were quite good [after 5 years follow-up],” Ranawat said. He noted that the study included all comers in order to test the safety and efficacy of the design.

Patients in the mobile bearing group attained Knee Society Scores greater than 90 points. None of the patients in the group had a bearing spin-out, Ranawat said.

“Short-term results at 5 years are as good as with fixed bearing knees,” he said.

Ranawat said that he was equally pleased with the performance of the PFC-Sigma mobile bearing design after implanting the prosthesis in 80 patients who had a fixed bearing tri-compartment total knee arthroplasty (TKA) in their contralateral knees.

He predicted that rotating platform knee implants would play an increased role in TKA in the future

“[It] is the knee of choice for the young active patient,” Ranawat said.

Reference:
Ranawat CS. Tri-compartment rotating bearing: A perfect pirouette. Paper #76. Presented at the 26th Annual Current Concepts in Joint Replacement Winter Meeting. Dec. 9-12, 2009. Orlando, Fla.
Ranawat receives royalties and grant/research support from DePuy, a Johnson & Johnson Company, and Stryker.