title: Determining material loss from the femoral stem trunnion in hip arthroplasty using a coordinate measuring machine.
abstract: In contrast to the articulating and taper surfaces of failed total hip replacements, volumetric wear analysis of trunnions is not routinely performed. Metal wear particles from the trunnion may contribute not only to the failures of metal-on-metal total hip replacements but also to all hip replacements utilising metal trunnions. A validation study was performed with the material removed in stages from the trunnions of an Exeter V40 stem, a Corail stem and an Accolade stem to simulate different magnitudes of wear. The material loss from the trunnions was measured both volumetrically with a coordinate measuring machine and gravimetrically with a high-precision balance. A cohort of 28 ex vivo trunnions was also measured using the coordinate measuring machine. The maximum error between the two methods was found to be 0.13 mm(3). This result was comparable with the coordinate measuring machine method for the taper surface (0.2 mm(3)). The ex vivo trunnions had a median wear volume of 0.14mm(3) (range: 0.04-0.28 mm(3)). This is the first study to determine the accuracy of volumetric wear measurements of trunnions by comparing against gravimetric measurements. Volumetric wear analysis of trunnions may provide additional insights into failures of modular total hip prostheses and will be performed routinely at our centre.
authors: School of Mechanical and Systems Engineering, Newcastle University, Newcastle upon Tyne, UK Mbone05@hotmail.co.uk.
authors: Martin C
authors: MC
authors: Bone
authors: School of Mechanical and Systems Engineering, Newcastle University, Newcastle upon Tyne, UK.
authors: Raghavendra P
authors: RP
authors: Sidaginamale
authors: Biomedical & General Engineering, California Polytechnic State University, San Luis Obispo, CA, USA.
authors: James K
authors: JK
authors: Lord
authors: School of Mechanical and Systems Engineering, Newcastle University, Newcastle upon Tyne, UK.
authors: Susan C
authors: SC
authors: Scholes
authors: School of Mechanical and Systems Engineering, Newcastle University, Newcastle upon Tyne, UK.
authors: Thomas J
authors: TJ
authors: Joyce
authors: University Hospital of North Tees, Stockton-on-Tees, UK.
authors: Anthony V F
authors: AV
authors: Nargol
authors: North Tees Explant Centre (NTEC), University Hospital of North Tees, Stockton-on-Tees, UK.
authors: David J
authors: DJ
authors: Langton
mesh_terms: D019544:Equipment Failure Analysis / Q000295:instrumentation* / Q000379:methods*; D005272:Femur Neck / Q000502:physiology* / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D010316:Particle Size; D011474:Prosthesis Design; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: Explant analysis; coordinate measuring machine; trunnion; validation; volumetric wear