Análise fluoroscópica da movimentação in vivo do insert na ATJ de plataforma rotatória

Abstract

Objective: To confirm by fluoroscopic analysis the rotational movement of the polyethylene insert in rotating platform total knee arthroplasty (TKA) after a minimum postoperative time of six months. Fifteen knees submitted to rotating platform TKA with the LEPINE NEW WAVE prosthesis were studied. Methods: A fluoroscopic appliance in an anterior-posterior view of the proximal tibia was used to evaluate the rotation of the polyethylene insert, with the knee at a 90º flexion. If the image of the polyethylene radiopaque marker remained unchanged, i.e. if it accompanied the femur, then it was considered that rotation was occurring between the insert and the tibial component. Results: Of the fifteen knees analyzed, fourteen displayed demonstrable movements of the polyethylene insert, totaling 93.3%. For the rotating platform TKA to maintain its potential, the rotating movements of the polyethylene insert must be maintained over time. Conclusion: The study of this sample demonstrated that the rotation is consistently maintained (93%). This confirmation suggests that rotating platform TKA effectively has the potential to present lower polyethylene wear due to the higher articulation congruence, compared with fixed support TKA, besides having the additional advantage of self-alignment of the extensor mechanism.