Balancing the posterior cruciate ligament during cruciate-retaining fixed and mobile-bearing total knee arthroplasty: description of the pull-out lift-off and slide-back tests.

Total knee arthroplasty (TKA) with posterior cruciate ligament (PCL) preservation is a technically demanding procedure but one that has been associated with excellent long-term results. It is crucial during this procedure that the PCL be placed under appropriate tension such that the kinetic benefits of its retention can be gained and so that the adverse affects of its being excessively tight or lax can be avoided. We describe 2 simple intraoperative tests that assess PCL tension in fixed-and mobile-bearing TKA. Performance of the "pull-out lift-off" (POLO) test in fixed bearing knees and the "slide-back test" in rotating platform knees will assure appropriate PCL tension after TKA by determining that it is neither too loose nor too tight. The authors have previously described the POLO test; however, this publication is no longer in print and, therefore, is not accessible as a reference (Chmell MJ, Scott RD. Balancing the posterior cruciate ligament during cruciate-retaining total knee arthroplasty: description of the POLO test. J Orthop Techniques 1996;4:12.). We therefore deemed it appropriate to once again describe it along with the analogous test for rotating platform TKAs.