Abstract
Multiple contemporary TKA designs that sacrifice the anterior cruciate ligament and then either retain or substitute for the posterior cruciate ligament have demonstrated-records of good durability and good function across joint registries worldwide. In recent years there has been an emphasis on improving function in TKA and to that end various strategies including changes in surgical alignment targets (kinematic alignment), the addition of advanced technologies such as computer navigation and sensors in trial components, the expansion of indications for unicompartmental knee arthroplasty and the re-introduction of total knee implants that preserve both the ACL and PCL have been championed. Early ACL/PCL retaining total knee implants had mixed results with some designs failing while others championed by Cloutier and by Pritchett have had some success in regard to reasonable durability. Unfortunately those early designs, despite decent durability, did not conclusively demonstrate better function.
More recently a new bi-cruciate retaining TKA was introduced with some substantial fanfare. Unfortunately, the widely touted theoretical or potential benefits of bi-cruciate preservation (in regard to better function) have failed to materialise or have been offset by a higher than expected re-operation rate. Even some of the initial proponents of the bi-cruciate implants have noted that the short-term findings are not very encouraging. The largest report to date shows 5% vs. 1.6% all-cause revision at 1 year (BCR vs. CR, respectively) and no improvement in standardised patient reported outcome measures. Some have placed their hopes for BCR TKA on the introduction of robotic technologies or advanced sensor devices but whether those prove to be meaningful enabling technologies remains to be determined. In 2017 it appears that while bi-cruciate retaining TKA is intellectually intriguing it does require the practicing surgeon to cross “a bridge too far.”
