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assessing lateral compartment gap, there were significant decreases (p 20º groupcompared to that of the other two groups throughout the knee flexion angle in spite of similarpatterns showing slight increases in the varus angle to 90º of knee flexion and constant balanceafter that. In the varus alignment > 20º group, more than 5 degrees of varus imbalance was leftafter 45 degrees of flexion. These result indicate that appropriate medial-lateral balancing isdifficult in the knee of pre-operative severe varus deformity especially with varus alignment >20º.To explore deeper insight in ligament balance kinematics in our patient population, wecalculated each medial and lateral compartment gap using the parameters obtained. Regardingmedial compartment gap, three groups showed similar pattern with no significant differencewith constant values after significant increases during initial 10 degree of knee flexion andsignificant decreases after 90 degrees of knee flexion in each group. In the assessment of lateralcompartment gap, however, the varus alignment > 20º group showed significant larger jointgaps especially at 45 and 90 degrees of flexion compared to the other groups, with a similarpattern showing decreasing values after significant increases during 90 degree of flexion in eachgroup. These results suggest that the kinematics of medial-lateral soft tissue balance may mainlydepend on, rather than the consistent length of medial structures, the larger length change oflateral structures. In the present study treating with only varus osteoarthritis patients, lateralstructures including lateral posterior capsule, popliteus tendon, and fibular ligament wereconsidered relative intact or elongated, whereas medial structures including posteromedialcapsule, MCL, semimenbranosus, and pes anserine tendons seemed to be contracted andshortened with their degeneration. In the severe deformed knee with more than 20 degrees ofpre-operative varus alignment, varus imbalance tends to remain to large extent in flexion due toelongated lateral structures, especially in PCL resected TKA.In the present study, the knees with the pre-operative varus alignment < 20º showed intraoperativelateral laxity of less than 5 degrees throughout the range of motion after soft tissuerelease on the medial side. Even in normal knees, lateral ligamentous laxity and medialligamentous laxity are not balanced. More lateral ligamentous laxity than medial ligamentouslaxity has been observed [27-29]. To restore joint line, we and the others allow some degrees oflateral side laxity as long as proper alignment is maintained [25, 26, 30]. Based on theseevidences, we believe that some degrees of lateral laxity less than 5 degrees of lateral laxity atextension observed in the varus alignment < 20º groups were considered acceptable. On theother hand, the knee with the varus alignment > 20º group resulted in the remaining amount oflateral laxity more than 5 degrees. Depend on the deformity and intra-operative soft tissuebalance with a spacer block, we performed step by step soft tissue release of medial structuresincluding posteromedial capsule, MCL, semimenbranosus, and pes anserine tendons in additionto removal of the osteophytes that impede on the medial soft tissue sleeve. In such severelydeformed varus knees, some surgeons may recommend the complete release of medial-sidedfile:///E|/ISTA2010-Abstracts.htm[12/7/2011 3:15:47 PM]