Abstract
Historically correction of deformity in primary TKA has involved release of collateral ligaments to correct deformity. This has been common to both measured resection and gap balancing techniques but particularly the former. Essentially the collateral ligaments have been released to balance the bone cuts. Another philosophy is to consider that the collateral ligaments do not contract and should never be released. After sacrificing both cruciates I use a tibia first technique. The AP femoral cuts are done by using collateral ligament tension to set femoral rotation and create a rectangular flexion gap which is then measured
A five degree conservative or precut is then made on the distal femur. Critically all osteophytes have now been removed. The extension gap is assessed using a spacer block. In a varus knee the definitive cut is frequently made in more varus to create a balanced extension gap to equal the flexion gap. It is rare to have to release the posteromedial capsule.
In contrast in severe fixed valgus the posterolateral capsule frequently has be cut before the definitive distal femora cut is made. The latter is often in more valgus. I never resurface the patella but ensure good patellar tracking after inserting a cementless mobile bearing knee which is used irrespective of deformity. I am more concerned about gap balance than the mechanical axis.
Essentially the concept proposed is to cut the bone to balance the soft tissues as opposed to the reverse. The aim is to restore pre-morbid alignment and not necessarily a neutral mechanical axis.
