Is Your TKA Too Loose? What Infrared Gait Analysis Reveals About PCL Management

A surgeon's data-driven guide to gap balancing, PCL titration, and optimizing patient-reported outcome measures in modern knee replacement.

Up to 20% of patients remain unsatisfied after primary total knee arthroplasty (TKA), often reporting continued pain, stiffness, or an “unnatural” feel to the joint. One strategy to improve patient satisfaction and reduce the revision rate of TKAs due to symptomatic instability has been the development of ultracongruent bearings.

Ultracongruent designs aim to replicate native knee kinematics by allowing for posterior translation and external rotation during deep knee flexion. Similar to a posterior-stabilized design, the ultracongruent articular geometry of the tibial insert drives posterior femoral rollback but with the benefits of no cam-post mechanism and limiting bone sacrifice. Furthermore, while the role of the posterior cruciate ligament (PCL) remains debated in primary TKA, ultracongruent bearings allow surgeons the option to fully retain, partially resect, or fully release the PCL.