DIAGNOSTIC OF PATELLAR INSTABILITY AFTER TOTAL KNEE ARTHROPLASTY

Objectives - to identify main reasons of patella instability after primary total knee arthroplasty, and to determine further treatment strategy of this complication. Material and methods. Since 2011 till 2014 1098 total knee arthroplasties have been performed in Yaroslavl Regional Hospital for Veterans of Wars. We observed 14 (1.3%) patients with postoperative patella instability. The evaluation included clinical and radiographic methods. Rotational alignment of the femoral and tibial components was studied by computed tomography (CT) scanner. Conclusion. Position of the femoral components ranged from 2 degrees excessive external to 8 degrees excessive internal rotation. Position of the tibial components ranged from 0 degrees to 6 degrees excessive internal rotation. The summary endoprosthetic position ranged from 1 degrees to 10 degrees excessive internal rotation. We found direct correlation between summary implant internal rotation and the severity of postoperative complications in patellafemoral joint. Results. The main reason of the patella instability is implant summary internal malrotation. Extensive lateral release with patella resurfacing was sufficient for pain relief and tracking correction if the combined internal rotation did not exceed 6 degrees. Large value of internal malrotation was the indication for revision surgery with selective approach.