No Discernible Difference in Revision Rate or Survivorship Between Posterior Cruciate-Retaining and Posterior Cruciate-Substituting TKA

Background: Many authors and the data of multiple registries have suggested that the use of posterior cruciate-substituting (posterior stabilized [PS]) total knee arthroplasty (TKA) leads to a higher risk of revision compared with the use of posterior cruciate-retaining (CR) TKA. The aim of the present prospective, randomized, long-term study was to compare PS and CR TKA with regard to the clinical, radiographic, and computed tomography (CT) results; the prevalence of osteolysis; revision rate; and survivorship. Methods: This study included a consecutive series of 300 patients (mean age [and standard deviation], 63.6 ± 6 years) who underwent simultaneous, bilateral TKA in the same anesthetic session. Each patient received a NexGen CR-Flex prosthesis on 1 side and a NexGen LPS-Flex prosthesis on the contralateral side. The mean follow-up period was 18 years (range, 17.5 to 19.5 years). Results: There were no significant differences between the NexGen CR and LPS-Flex TKA groups at the latest follow-up with regard to the mean Knee Society knee score (93 versus 92 points, respectively); the Western Ontario and McMaster Universities Osteoarthritis Index score (19.1 points for both); the University of California Los Angeles activity score (6.1 points for both); range of motion (125° ± 6.1° versus 126° ± 6.5°); radiographic and CT results; and revision rate (6.0% versus 6.3%). No knee had osteolysis. The estimated survival rate at 19.5 years was 94% (95% confidence interval [CI], 91% to 100%) for the NexGen CR-Flex prosthesis and 93.7% (95% CI, 91% to 100%) for the LPS-Flex prosthesis, with revision or aseptic loosening as the end point. Conclusions: The findings of the present, long-term (minimum follow-up of 17.5 years) clinical study showed that NexGen CR-Flex and NexGen LPS-Flex implants produced excellent clinical and radiographic results. There was no notable clinical advantage of a NexGen CR-Flex implant over a NexGen LPS-Flex implant. Level of Evidence: Therapeutic Level II . See Instructions for Authors for a complete description of levels of evidence.