Revision total knee arthroplasty: how much constraint is enough?

Revision total knee arthroplasty is a complex situation that requires meticulous technique to restore a functional outcome. The surgical objective is the same as primary total knee arthroplasty: restore the original anatomy, restore function, and provide a stable joint. To this point of stability, it is preferable to implant the prosthesis with the least degree of constraint. Therefore, in the majority of patients undergoing revision surgery, a posterior-stabilized articulation is used. However, if there is functional loss of the medial collateral ligament or lateral collateral ligament, inability to balance the flexion and extension spaces, or a severe valgus deformity, then a constrained condylar prosthesis is necessary.