ABSTRACT
PURPOSE: We analyzed the patterns and causative factors of early aseptic loosening after total knee arthroplasty (TKR) using a legacy posterior stabilized (LPS)-flex prosthesis. MATERIALS AND METHODS: We examined 483 cases that occurred in 311 patients who underwent TKR using LPS-flex by single surgeon between August 2001 and March 2007 and who were followed-up for at least 2 years. The loosened group included 25 cases that exhibited early aseptic loosening on radiograph, the remaining 458 cases were regarded as the control group, and analysis was performed. RESULTS: The mean loosening period was 34.7 months and femoral component loosening alone was found in 22 cases (88%). There were no statistically significant differences in age, body mass index, or pre-operative range of motion between the 2 groups, but varus deformity was more severe in the loosened group (mean 8.92degrees) than in the control group (mean 5.21degrees) (p=0.003). Protrusion of the femoral component proximally over posterior condyle of the distal femur were more prominent in the loosened group (mean 20.3%) than in the control group (mean 13.4%) (p=0.001). CONCLUSION: Early loosening after TKR using LPS-flex prosthesis developed mostly in the femoral component. Choosing a proper size for the femoral component and cutting level for the distal femur should be considered.