Which parameters are related with a forgotten knee after TKA? The operated knee was said forgotten when it was similar to the normal controlateral knee in all situations. When a restriction existed, the knee was considered as not forgotten. 470 patients operated with a stabilised mobile bearing knee were examined with a minimal follow up of 5 years and answered to this question. 4 groups of parameters: patient, prosthesis, surgery and post operative care were compared to the binary answer to the forgotten knee question. 48% of the patients had a forgotten knee one year after the TKA; The following factors had a significant negative correlation with the forgotten knee:
low SF12 psychological profile; Patellofemoral dysplasic arthritis (p = 0,01); femoral oversizing (p=0,001); tight extension gap, femoral lengthening, tourniquet time; overcorrection superior to 2°(p = 0,02). We found no correlation between the following factors and the forgotten knees:
gender, BMI, approach, cemented or not, patellar resurfacing; preoperative Oxford and Knee Society knee scores; The forgotten knee is a simple objective clinical item because the answer to the question is binary and does not accept any unprecision. It is highly correlated with surgical scores and patients expectation scores (p = 0,0001). The forgotten knee is a painless and asymptomatic knee identical to a normal knee. Surgical factors have the highest infiuence on this parameter compared to patient or prosthetic related factors.
