Single Stage Instead of Two - Stage Bilateral Total Knee Arthroplasty to Avoid Leg Length Discrepancy in Severe Varus Knee Deformity - Propose a Mathematical Model to Support the Hypothesis

Single total knee arthroplasty (TKA) may be beneficial for its one admission, one anesthesia, cost reduction and faster recovery including shorter rehabilitation. However, controversial opinion against the idea for its higher complication rate, such as deep vein thrombosis and more blood loss. Limited discussion upon the point of leg length discrepancy (LLD) as a result of one side TKA in severe varus knee deformity. In this entity, single stage TKA may gain its significant beneficial effect to avoid LLD. A mathematical model is proposed to calculate the LLD severity in a standardized condition and provide the formula to predict LLD before a two stage bilateral TKA is going to be performed.