MRI of early symptomatic metal-on-metal total hip arthroplasty: a retrospective review of radiological findings in 20 hips

Toms, A.P.; Marshall, T.J.; Cahir, J.; Darrah, C.; Nolan, J.; Donell, S.T.; Barker, T.; Tucker, J.K.

doi:10.1016/j.crad.2007.07.012

« Previous Next »Clinical Radiology
Volume 63, Issue 1 , Pages 49-58, January 2008

MRI of early symptomatic metal-on-metal total hip arthroplasty: a retrospective review of radiological findings in 20 hips

A.P. Toms
- Department of Radiology, Norfolk and Norwich University Hospital, Norwich, Norfolk, UK
- Guarantor and correspondent: A.P. Toms, Department of Radiology, Norfolk & Norwich University Hospital, Colney Lane, Norwich NR4 7UY, UK. Tel.: +44 1603 286104; fax: +44 1603 286077.
T.J. Marshall
- Department of Radiology, Norfolk and Norwich University Hospital, Norwich, Norfolk, UK
J. Cahir
- Department of Radiology, Norfolk and Norwich University Hospital, Norwich, Norfolk, UK
C. Darrah
- Department of Orthopaedics, Norfolk and Norwich University Hospital, Norwich, Norfolk, UK
J. Nolan
- Department of Orthopaedics, Norfolk and Norwich University Hospital, Norwich, Norfolk, UK
S.T. Donell
- Institute of Health, University of East Anglia, Norwich, Norfolk, UK
T. Barker
- Department of Pathology, Norfolk and Norwich University Hospital, Norwich, Norfolk, UK
J.K. Tucker
- Department of Orthopaedics, Norfolk and Norwich University Hospital, Norwich, Norfolk, UK

Received 11 December 2006; received in revised form 17 May 2007; accepted 22 July 2007.

Aim

To perform a retrospective review of all the conventional radiographic and magnetic resonance imaging (MRI) studies performed in patients with early postoperative pain following cobalt–chrome metal-on-metal total hip arthroplasty.

Methods

A retrospective review of the radiology, surgical findings and histology in nineteen patients who had undergone a total of 20 hip arthroplasties using a cobalt-chromium on cobalt-chromium alloy prosthesis was undertaken.

Results

Measures of implant placement on the immediate postoperative radiographs were all within the normal ranges (n=20). Where more than one postoperative radiograph was available statistical analysis revealed no evidence of progressive change before the MRI examination (14). The median postoperative time to MRI was 35 months (range 11–63 months). Abnormalities were demonstrated using MRI in all symptomatic hips (n=20). These comprised: periprosthetic fluid collections (20), which were isointense to muscle on T1-weighted images in 19 cases and hyperintense on T2-weighted images in 18 cases, periprosthetic bone marrow oedema (n=6), muscle oedema (n=4), avulsion of the gluteus minimus and medius tendons (n=5), atrophy of piriformis (n=15) and obturator internus (n=17), and fracture of the medial calcar (n=1). Operative findings in patients who had undergone revision surgery (n=15) included: fluid-filled cavities (n=11), soft tissue necrosis (n=8), gluteal tendon avulsion (n=5), proximal femoral diaphyseal necrosis (n=4), and pitting and corrosion of the femoral stems (n=8), which were, in all cases, firmly fixed to the cement mantle. Histology revealed viable tissue in six hips with necrosis (n=12) and fibrin deposition (n=15) being the predominate findings. Other findings included a perivascular lymphocytic infiltrate (n=5), features of active inflammation (n=4), and metallosis (n=1).

Conclusion

A significant number of patients with metal-on-metal hip replacements presented with early postoperative pain because of an abnormal soft-tissue reaction. MRI can demonstrate characteristic soft-tissue disease in these patients where conventional radiographs are frequently normal.