ABSTRACT
PURPOSE: We analyzed the causative factors of femoral component radiologic abnormality after total knee arthroplasty (TKA) using a Legacy Posterior Stabilized (LPS)-Flex prosthesis. MATERIALS AND METHODS: 140 cases of TKA using LPS-Flex and 140 cases of Vanguard from Jan 2008 to June 2010 were analyzed and radiographic abnormalities around the femoral stems were compared. Secondly, TKA using LPS-Flex was divided into two groups according to the posterior femoral cutting technique, which were single cutting method and additional cutting method. Accuracy of the femoral posterior resection was compared. RESULTS: Radiographically, anterior radiolucent line was found in eight cases with LPS-Flex but no case with Vanguard. Posterior overhang more than 30% was found in ten cases in both groups. Posterior bone defect more than 50% was found in 23 and seven cases respectively. Anterior radiolucent line and posterior bone defect were observed significantly more in LPS-Flex. In the second study, we found femoral posterior bone defect in 20 cases with additional cutting method which was caused by flexion of the femoral box-cutting guide. CONCLUSION: Posterior bone defect from LPS-Flex was caused by inappropriate resection due to flexion of the box cutting guide. Single cutting method should be adopted for more accurate posterior femoral cutting.
Subject(s)
Arthroplasty , Knee , Osteoarthritis , Prostheses and ImplantsABSTRACT
PURPOSE: This study compared the clinical and functional results of LPS-Flex with those of Scorpio-Flex TKA. MATERIALS AND METHODS: Fifty cases of High-Flex TKA (24 LPS-Flex and 26 Scorpio-Flex) were analyzed retrospectively. All the procedures were performed during the same period by the senior author and the patients were followed-up for more than 5 years. A functional evaluation was performed by a questionnaire on the high flexion-related activities, including cross-leg sitting, squatting, standing from the floor, standing from a chair and ascending and descending stairs. Each function was classified by the patients into five grades. The clinical evaluation included the range of motion, the Knee Society Knee Score and Function Score (KSKS & KSFS), the WOMAC score and the patient's satisfaction score. RESULTS: The functional evaluation showed a better result in the LPS-Flex group for the cross-leg sitting function (p=0.039) but there was no difference in the other functions. The clinical evaluation showed more flexion in the LPS-Flex group than that in the Scorpio-Flex group (p=0.044) but there were no difference in the KSKS, KSFS, WOMAC score and the patient's satisfaction score. CONCLUSION: LPS-Flex TKA showed better functional results for cross-leg sitting than did Scorpio-Flex TKA. This difference was attributed to the LPS-Flex group having more flexion than that of in the Scorpio-Flex group.