Revision total knee replacement ligament balancing for deformity.

Ligament balancing in revision settings requires attention to flexion-extension gap balancing and adjusting the asymmetry of the gaps. The tension-stress examination must be understood and done. The shortcomings of ligament tightening procedures have been experienced. Standard concave-side releases may be done, with attention given to the maintenance of adequate vascularity to the subjacent bone. However, frequently exact and sufficient balance may not be achievable, and resorting to varus-valgus constraint will be necessary. Particular emphasis has been given to the issue of controlling the flexion space and the possibility of losing that control. In the situation of loss of collateral integrity possibly exaggerated by the loss of posterior capsular integrity, one sees a gross enlargement of the flexion space. Addressing this with placement of a thicker tibial component simply leads to great flexion contracture. The larger flexion space may provide the opportunity for subluxation of the intercondylar peg of a varus-valgus constrained prosthesis. Although quadriceps tension may hold the tibia up and control the flexion space, this mechanism of stabilization will fail if the patient's knee regains substantial range of motion.