CHANGES OF THICKNESS OF TIBIAL POLYETHYLENE INSERT IN REVISIONAL TKA

Abstract

To investigate the amount and the factors of changes of the thickness of tibial polyethylene insert in revisional TKA compared to original thickness of primary TKA. We analyzed one hundred and twenty cases of wear, loosening and instability were included in this study. Infection cases were excluded. The period between the primary TKA and revision TKA was 88.5 months in average (range 1 to 17 year 3 months). The amount of increase of the tibial polyethylene thickness according to the main cause of failure and the wear site was analyzed.

The results of this study were: 1: The increased thickness was 6.7 mm in average. 2: The amount of increase in case of wear of anterior portion only was 2.3 mm, which was below the average. 3: The loosening cases showed 8.2 mm increase in average which was significantly greater than the average. 4: The cases of greater wear of medial side than lateral side showed 8.5 mm increase of the thickness which was significantly greater than the average. 5: The cases of only medial side wear showed 5.5 mm increase of the thickness, which was below the average. 6: The cases of the other causes such as patellar component wear, generalized wear, wear of posterior portion only, early wear less than 5 years after primary TKA because of flat polyethylene surface showed comparable amount of wear to the average.

The thickness of tibial polyethylene insert in revisional TKA compare to original thickness of primary TKA showed that it increased 6.7mm in average and was variable according to the cause of failure.