Authors: Kamal Bali Richard W McCalden Douglas D R Naudie Steven J MacDonald Matthew G Teeter
Publish Date: 2015/07/23
Volume: 474, Issue: 2, Pages: 374-382
Abstract
The purpose of this study was to answer the following questions 1 With conventional polyethylene CPE did the acetabular design make a difference in backside wear 2 Is there a difference in backside damage between CPE and crosslinked polyethylene XLPE liners 3 With XLPE is the difference in backside wear between designs still present 4 Is there any difference in backside damage in various zones on backside of individual linersThis singleinstitution retrieval analysis involved visual damage scoring on the backside of 233 polyethylene liners implanted between 2002 and 2011 The liners were retrieved from either polished/dovetail cups PD or roughened/wire cups RW made by two different manufacturers The inserts were divided into four groups PDCPE n = 105 PDXLPE n = 16 RWCPE n = 99 and RWXLPE n = 13 Aseptic loosening and polyethylene wear were the predominant reasons for revision of CPE liners whereas instability and infection were the common reasons for revision of XLPE liners The time in situ TIS was shorter for the XLPE liners as compared with the CPE liners PDCPE 85 years SD 44 RDCPE 95 SD 48 PDCPE 38 SD 37 RDXLPE 40 SD 43 The backside of each liner was divided into five zones and graded initially from a scale of 0 to 3 for seven different damage modes by one observer There was substantial interobserver kappa 0769 and intraobserver 0736 reliability on repeat scoring To compare the effects of crosslinking a subset of the conventional polyethylene liners was matched to the crosslinked liners based on TIS resulting in 16 per group for the two PD types and 13 per group for the two RW typesTotal damage scores in the RWCPE 19 ± 7 group were greater p 0001 than the PDCPE group 8 ± 4 Damage was reduced with XLPE p = 002 only for the RWXLPE 9 ± 9 versus RWCPEtype sockets 4 ± 4 There was no difference p = 016 between the RWXLPE group and the PDXLPE group Damage scores in the peripheral zone of the locking mechanisms were higher for RWCPE 4 ± 3 compared with PDCPE 14 ± 10 p 0001 and RWXLPE 13 ± 13 p = 002 Damage was greater p 0001 within the superior zones 7 ± 4 compared with the inferior zones 30 ± 28 of all linersAlthough the polished/dovetail cups seem to cause less backside damage in the CPE liners than roughened/wire cups the use of XLPE liners has been shown to protect the liner from backside damage in either cup design If an acetabular shell has a functional locking mechanism surgeons should not worry about cup design when undertaking isolated liner revision using XLPE liners
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