ADVANCE MEDIAL PIVOT
The Pivot Medial system has been designed to direct technological issues already tested, incorporating a cutting-edge design in kinematics.
The goals were established through the development process described below:
To restore normal stability and kinematics of the knee, lowering the wearing indexes of the polyethylene by increasing the tibiofemoral contact area, and to optimize mobility range with a predictable movement.
A normal knee pivots around the medial articular surface during the flexion; this is replicated by the ADVANCE prosthesis. Studies have shown that after a RTR this pivoting is replaced by a combined movement of slide AP and rotation, and this significantly increases the wearing and reduces the ROM. On the lateral side, a translation is allowed in a semi congruent arch directed from the medial joint.
In a ball in socket system, the femoral condyle behaves as a sphere contained within a sac formed on the medial side of the tibia, allowing to describe a constant radio during flexion-extension, maintaining ultra congruence between the components and, at the same time, producing the translation of the lateral condyle over the arch previously described, thus allowing the lateral anatomical rotation of the normal knee between 12 and 15°.
In the femoral component, the trochlear sulcus has a 3.6° angle to minimize the tension in the tissues of the lateral retinaculum, thus decreasing the need of release.
The lateral anterior flange is lifted by 3-4 mm above the ground of the trochlear sulcus and it provides resistance to lateral subluxation. The importance of an elevated lateral flange has been previously quoted as a design feature needed to achieve anatomical kinematics in the patello-femoral joint.
The deepened and extended sulcus of the ADVANCE® femoral component restores the anatomical tracking and it minimizes the contact for big flexion angles, thus reducing the stress of contact.
Anatomical femoral component with 5° of valgus, with distal and posterior augmentation blocks.
The tibial component has off-set in order to centralize the stem inside the tibial canal without the metallic base loosing contact with the external cortical.
The distal and posterior femoral augmentation blocks (5 and 10 mm) can be placed individually to substitute for the loss of femoral bone stock.
Augmentation blocks (5, 10 and 15 mm) and wedges (15°) can be placed independently at the tibial base to deal with different angular and bone deficiencies.
Tibial and femoral stems (2mm increase) with spines and floutes provide an immediate and rigid fixation and resistance to torsion movements.
A flexible tuning fork provides a dynamic structure to deal with long-term internal bone changes.