Abstract
Introduction
Incidence of adverse soft tissue reaction following metal on metal hip has a reported incidence of up to 48%. The current imaging modality of choice is metal artefact reduction sequence (MARS) MRI. Consensus is that large, symptomatic pseudotumours should be treated surgically, changing the bearing surfaces to other materials. There is debate as to how asymptomatic pseudotumours should be monitored and managed.
Patients/Materials & Methods
From our unit's database, 22 patients (7 female, 15 male) were identified with metal on metal hip replacements that had a ‘pseudotumour’ detected on MARS MRI but remained assymptomatic (mean 68 months post op). All underwent serial imaging and clinical follow up (mean interval 14.5 months).
Results
At initial imaging 16 pseudotumours were Norwich classification C1 (mild), 5 were C2 (moderate) and 1 was C3 (severe). At follow up no pseudotumours had increased in size or increased in severity with regards to Norwich classification. Four initially classified as C1 had changed to ‘A’. Oxford Hip score did not change significantly in this interval.
Discussion
Previously published studies have been either small or ‘snap shot’ and have not provided conclusive guidance as to how these patients should be managed. Our study shows that this patient group can be treated expectantly and avoid revision surgery.
Conclusion
Pseudotumour Norwich grade, size and characteristics remain unchanged on MARS MRI at a period of over one year in our cohort. Our study suggests serial imaging is not necessary unless patients develop symptoms.
