title: Material loss at the taper junction of retrieved large head metal-on-metal total hip replacements.
abstract: It has been speculated that material loss, either as corrosion or wear, at the head-stem taper junction is implicated in the high revision rates reported for metal-on-metal total hip replacements. We measured the volume of material loss from the taper and bearing surfaces of retrieved devices, and investigated the associations with blood metal ion levels and the diagnosis of a cystic or solid pseudotumor. The median volumes of material lost from the female and male taper surfaces were 2.0 and 0.29 mm(3) , respectively, while the median volumes of wear from the cup and head bearing surfaces were 1.94 and 3.44 mm(3) , respectively. Material loss from the female taper was similar to that from the acetabular bearing surface (p = 0.55), but significantly less than that from the femoral bearing surface (p < 0.001). Material loss from the male taper was less than that from both bearing surfaces (p < 0.001). Multivariable analysis demonstrated no significant correlations between the volume of material lost from the taper surfaces and either blood cobalt or chromium ions, or the presence of pseudotumor. While a substantial volume of material is lost at the taper junction, the clinical significance of this debris remains unclear.
authors.affiliation: Institute of Orthopaedics and Musculoskeletal Science (University College London), Royal National Orthopaedic Hospital, Stanmore, United Kingdom.
authors.forename: Ashley K
authors.initials: AK
authors.lastname: Matthies
authors.forename: Radu
authors.initials: R
authors.lastname: Racasan
authors.forename: Paul
authors.initials: P
authors.lastname: Bills
authors.forename: Liam
authors.initials: L
authors.lastname: Blunt
authors.forename: Suzie
authors.initials: S
authors.lastname: Cro
authors.forename: Anna
authors.initials: A
authors.lastname: Panagiotidou
authors.forename: Gordon
authors.initials: G
authors.lastname: Blunn
authors.forename: John
authors.initials: J
authors.lastname: Skinner
authors.forename: Alister J
authors.initials: AJ
authors.lastname: Hart
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D003343:Corrosion; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008670:Metals; D008875:Middle Aged; D012189:Retrospective Studies
chemical_list: D008670:Metals
keywords: metal ions; metal-on-metal; retrievals; taper; wear