title: Shorter, rough trunnion surfaces are associated with higher taper wear rates than longer, smooth trunnion surfaces in a contemporary large head metal-on-metal total hip arthroplasty system.
abstract: Taper wear at the head-neck junction is a possible cause of early failure in large head metal-on-metal (LH-MoM) hip replacements. We hypothesized that: (i) taper wear may be more pronounced in certain product designs; and (ii) an increased abductor moment arm may be protective. The tapers of 104 explanted LH-MoM hip replacements revised for adverse reaction to metal debris (ARMD) from a single manufacturer were analyzed for linear and volumetric wear using a co-ordinate measuring machine. The mated stem was a shorter 12/14, threaded trunnion (n=72) or a longer, smooth 11/13 trunnion (n=32). The abductor moment arm was calculated from pre-revision radiographs. Independent predictors of linear and volumetric wear included taper angle, stem type, and the horizontal moment arm. Tapers mated with the threaded 12/14 trunnion had significantly higher rates of volumetric wear (0.402 mm3/yr vs. 0.123 mm3/yr [t=-2.145, p=0.035]). There was a trend to larger abductor moment arms being protective (p=0.055). Design variation appears to play an important role in taper-trunnion junction failure. We recommend that surgeons bear these findings in mind when considering the use of a short, threaded trunnion with a cobalt-chromium head.
authors.affiliation: Newcastle University, Newcastle, United Kingdom.
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Brock
authors.affiliation: Newcastle University, Newcastle, United Kingdom.
authors.forename: Raghavendra
authors.initials: R
authors.lastname: Sidaginamale
authors.affiliation: Newcastle University, Newcastle, United Kingdom.
authors.forename: Steven
authors.initials: S
authors.lastname: Rushton
authors.affiliation: Department of Orthopaedics, University Hospital of North Tees, North Tees, United Kingdom.
authors.forename: Antoni V F
authors.initials: AV
authors.lastname: Nargol
authors.affiliation: FDA, Silver Spring, Maryland.
authors.forename: John G
authors.initials: JG
authors.lastname: Bowsher
authors.affiliation: FDA, Silver Spring, Maryland.
authors.forename: Christina
authors.initials: C
authors.lastname: Savisaar
authors.affiliation: Newcastle University, Newcastle, United Kingdom.
authors.forename: Tom J
authors.initials: TJ
authors.lastname: Joyce
authors.affiliation: Newcastle University, Newcastle, United Kingdom.
authors.forename: David J
authors.initials: DJ
authors.lastname: Deehan
authors.affiliation: Biomedical and General Engineering, California Polytechnic State University, San Luis Obispo, California.
authors.forename: James K
authors.initials: JK
authors.lastname: Lord
authors.affiliation: North Tees Explant Centre (NTEC), University Hospital of North Tees, North Tees, United Kingdom.
authors.forename: David J
authors.initials: DJ
authors.lastname: Langton
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000295:instrumentation*; D002857:Chromium / Q000737:chemistry; D003035:Cobalt / Q000737:chemistry; D003343:Corrosion; D005260:Female; D006621:Hip Joint / Q000601:surgery; D006622:Hip Prosthesis / Q000009:adverse effects; D006801:Humans; D008297:Male; D008422:Materials Testing; D008670:Metals / Q000737:chemistry; D008875:Middle Aged; D015999:Multivariate Analysis; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure; D013499:Surface Properties
chemical_list: D008670:Metals; D002857:Chromium; D003035:Cobalt
keywords: arthroplasty; explant analysis; metal-on-metal; taper-junction