Failed total hip arthroplasty (THA) caused by mechanically assisted crevice corrosion (MACC) has serious consequences—notably, adverse local tissue reactions. Metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) has been used to evaluate failed THA for other reasons but has not been assessed for the analysis of cases of MACC in the setting of metal-on-polyethylene arthroplasties.
We examined the correlation between preoperative MARS MRI and surgical findings in a cohort of 20 consecutive patients undergoing revision THA for symptomatic MACC without other associated orthopedic diagnoses. Surgical findings included soft tissue and bone evaluation, presence and location of fluid, abductor disruption, composite tissue damage grade, and prosthesis trunnion damage at the time of revision.
MARS MRI complex synovitis, thickened pseudocapsule, and extra-articular fluid extension each strongly correlated with both the soft-tissue damage grade and trunnion damage noted at surgery. Bone marrow edema was also found to strongly correlate with bone necrosis intraoperatively.
MARS MRI is an excellent diagnostic tool for evaluation of patients with elevated serum Co after metal-on-polyethylene THA. Patients with complex synovitis, a thick pseudocapsule, bone marrow edema, and extra-articular fluid should strongly consider revision surgery.