MRI scanning for soft tissue pathology after total hip arthroplasty. A feasibility study study of a selected cohort

With the more recent availability of Metal-Artifact Reducing Sequence software
for Magnetic Resonance Imaging (MRI), several peer-reviewed publications have
addressed the issue of Adverse tissue reactions to metal debris (ARMD) after
Metal-on-Metal (MoM) hip arthroplasty (pseudotumors/cysts). These studies
report a significantly higher prevalence of MoM disease compared to studies
using standard follow-up (i.e. radiographs and clinical outcomes). Knowledge on
MoM disease is expanding but there is still little expertise on the grading of
MoM disease and on how to treat different grades of MoM disease. This carries
the risk of overreacting, possibly with unnecessary surgery as a consequence.
For radiologists it is especially difficult to grade small to medium MRI
abnormalities with MoM arthroplasty. Currently it is not possible to classify
such small deviations as being either normal or abnormal since there is no
baseline information on such MRI abnormalities. We simply do not know if these
minor deviations are normal reactions to hip surgery and can occur regardless
of the type of implant used. To established such a baseline, a cohort of hip
arthroplasty patients with another type of implant than MoM should be scanned
with MARS-MRI. We therefore selected 50 patients in our clinic, part is from an
existing study cohort of 200 patients from our clinic, to scan with MARS-MRI.

1) To diagnose occurrence and details (form, size, location) of cyst formation
or other MRI abnormalities in patients with Ceramic-on-Polyethylene bearings;
2) To correlate these findings to the clinical status of the patient;
.

The study is designed as a cross sectional study in a cohort of 50 Ceramic on
Polyethylene hip arthroplasty patients. One group of patients consists of 20
patients with a high wear rate (> 0.2mm per year) and 8-12 years follow-up. A
second group of 20 patients with a high wear rate (> 0.2mm per year) and 5-8
years of follow up and a third group of 10 patients with a
Ceramic-on-Polyethylene bearing at a follow-up of 2 to 5 years who have a
documented history of persistent complaints, for instance pain which is not
explained, by using the following diagnostic tools: clinical evaluation, plain
radiographs, wound infection parameters or bone scans.

The patients will have to undergo MARS-MRI (scanning time: 35 minutes) once.
Also, standardized clinical outcome scores will be completed (i.e. Harris Hip
Score, Oxford hip score) which will take approximately 10 minutes per patient.
The benefit for the involved patients is they will have one free MARS-MRI,
providing detailed information on any cyst development. All participating
patients will receive a 15 euro giftcard.