[A biomechanical study on polyethylene liner cementing into a fixed acetabular shell in revision total hip...

To evaluate the strength of polyethylene linercement interface when cementing a new liner into a fixed acetabular cup in revision.

Twenty-five pairs of metal acetabular cups with polyethylene liners were randomly divided into 5 groups: 1 group with standard locking device as control group (group A), other liners were cemented into acetabular cups as 4 experimental groups. According to different intersection angles of metal acetabular cups with polyethylene liners and the polyethylene liners with or without metal ball, the 4 experimental groups were no ball 0 degrees group (group B), 0 degrees group (group C), 10 degrees group (group D), and 20 degrees group (group E), metal acetabular cups intersected with polyethylene liners without metal ball in group B, with metal ball in groups C, D, and E, respectively. The lever-out biomechanical test reproduced in vivo failure mechanism was then performed to evaluate the lever-out failure strength of liner-cement-metal cup interface.

The values of liver-out failure force were (626.68 +/- 206.12), (915.04 +/- 197.49), (449.02 +/- 119.78), (814.68 +/- 53.89), and (1 033.05 +/- 226.44) N in groups A, B, C, D, and E, respectively, showing significant differences for comparison among groups (F = 8.989, P = 0.000). The values of liver-out failure force in groups B and E were significantly higher than that in group A (P < 0.05), but no significant difference was found between groups C, D and group A (P > 0.05).

Cementation of polyethylene liner into a malposition shell meeting within 20 degrees can provide enough fixed strength.