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We investigated the changes seen on serial metal artefact reduction magnetic resonance imaging scans (MARS-MRI) of metal-on-metal total hip arthroplasties (MoM THAs). In total 155 THAs, in 35 male and 100 female patients (mean age 70.4 years, 42 to 91), underwent at least two MRI scans at a mean interval of 14.6 months (2.6 to 57.1), at a mean of 48.2 months (3.5 to 93.3) after primary hip surgery. Scans were graded using a modification of the Oxford classification. Progression of disease was defined as an increase in grade or a minimum 10% increase in fluid lesion volume at second scan. A total of 16 hips (30%) initially classified as 'normal' developed an abnormality on the second scan. Of those with 'isolated trochanteric fluid' 9 (47%) underwent disease progression, as did 7 (58%) of 'effusions'. A total of 54 (77%) of hips initially classified as showing adverse reactions to metal debris (ARMD) progressed, with higher rates of progression in higher grades. Disease progression was associated with high blood cobalt levels or an irregular pseudocapsule lining at the initial scan. There was no association with changes in functional scores. Adverse reactions to metal debris in MoM THAs may not be as benign as previous reports have suggested. Close radiological follow-up is recommended, particularly in high-risk groups.

Original publication

DOI

10.1302/0301-620x.97b10.34131

Type

Journal article

Journal

The bone & joint journal

Publication Date

10/2015

Volume

97-B

Pages

1328 - 1337

Addresses

Hampshire Hospitals NHS Foundation Trust, Aldermaston Rd, Basingstoke, UK.

Keywords

Humans, Disease Progression, Cobalt, Magnetic Resonance Imaging, Arthroplasty, Replacement, Hip, Artifacts, Longitudinal Studies, Hip Prosthesis, Adult, Aged, Aged, 80 and over, Middle Aged, Female, Male, Metal-on-Metal Joint Prostheses