The patella clunk syndrome is not an uncommon complication, particularly after posterior-stabilized (PS) total knee arthroplasty. The present study was a consecutive unselected series comparing the incidence of the patella clunk syndrome amongst two comparable groups of elderly patients with knee arthritis implanted with the Insall-Burstein (IB II) total knee system and the newer NexGen Legacy total knee prosthesis. While 7.5% of patients in the PS IB II group developed patella clunk syndrome, none occurred in the NexGen group (P=0.05). We believe the difference is due mainly to a change in the design of the prosthesis, especially the more posterior intercondylar box and femoral cam of the NexGen femoral component.Résumé Le ressaut patellaire audible (clunk syndrome) n'est pas une complication rare en particulier après arthroplastie total du genou postéro -stabilisée (PS). La présente étude est celle d'une série consécutive de patients non sélectionnés comparant la fréquence de ce syndrome parmi deux groupes comparables de malades âgés avec arthrose du genou traités par prothèse de Insall-Bustein (IB II) ou par prothèse NexGen Legacy. Pendant que 7.5% de malades avaient un «clunk syndrome» dans le groupe IB II, aucun ne s'est produit dans le groupe NexGen (P=0.05). Nous croyons que la différence est principalement due à un changement dans le dessin de la prothèse, notamment un boitier intercondylien et une came fémorale plus postérieurs pour la prothèse Nexgen.
The overall early results from using the new implant were good, probably because of changes in design of the intercondylar box and its associated cam-and-post mechanism, and a more anatomic trochlea surface, so that the trochlea accommodates the natural patella.
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