Comparison of Restricted Kinematic Alignment Versus Unrestricted Kinematic Alignment in Primary Total Knee Arthroplasty:- Randomized Controlled Trial

Furthermore, the commonest technique is neutral mechanical alignment total knee arthroplasty. Latest studies have revealed that the mechanical alignment technique repeatedly causing substantial anatomical alterations with a widespread of complex collateral ligament imbalances, which are not repairable by collateral ligament release. Consequently, the total knee arthroplasty individuals walk with an abnormal gait, and they do not experience a normal knee joint. This may be one of the causes that up to 20% of total knee arthroplasty individuals are disappointed, and over 50% may have remaining symptoms.

Consequently, the conventional mechanical alignment technique has been recently challenged by a new alternative technique, namely unrestricted kinematic alignment proposed by Howell, as a possible solution to the high dissatisfaction following total knee arthroplasty, aiming at reproducing the constitutional tibiofemoral tridimensional alignment and knee laxity. It is almost a pure bone procedure with only exceptional collateral ligament release, which has been shown to reliably position knee components.

The restricted kinematic alignment protocol suggested by Vendittoli has been developed as an alternative to the unrestricted kinematic alignment for patients with an outlier or atypical knee anatomy. The restricted kinematic alignment is founded on five principles: hip-knee-ankle angle should be maintained within ± 3° postoperatively; a limitation to a maximum of 5° for lateral distal femoral angle and medial proximal tibial angle may be considered; restoration of collateral ligament balance should be achieved without the gap balancing technique; native femoral anatomy preservation is suggested over tibial one to maintain knee biomechanics; resurface resection must be accomplished on the unworn side with a thickness equivalent to the width of the implant;cut fine-tuning may be sought at the worn side.