Background: The association between advanced imaging, serum metal ion levels, and histologic adverse local tissue reaction (ALTR) severity has not been previously reported for Rejuvenate modular neck femoral stems.
Methods: A cohort of 90 patients with 98 Rejuvenate modular neck femoral stems was revised by a single surgeon from July 2011 to December 2014. Before revision, patients underwent multiacquisition variable resonance image combination sequence magnetic resonance imaging (MRI), and serum cobalt and chromium ion levels were measured. Histologic samples from the revision surgery were scored for synovial lining, inflammatory infiltrate, and tissue organization as proposed by Campbell. Regression based on the generalized estimating equations approach was used to assess the univariate association between each MRI, demographic, and metal ion measure and ALTR severity while accounting for the correlation between bilateral hips. Random forest analysis was then used to determine the relative importance of MRI characteristics, demographics, and metal ion levels in predicting ALTR severity.
Results: Synovial thickness as measured on MRI was found to be the strongest predictor of ALTR histologic severity in a recalled modular neck femoral stem.
Conclusion: MRI can accurately describe ALTR in modular femoral neck total hip arthroplasty. MRI characteristics, particularly maximal synovial thickness and synovitis volume, predicted histologic severity. Serum metal ion levels do not correlate with histologic severity in Rejuvenate modular neck total hip arthroplasty.
Keywords: ALTR; MRI; histology; modular; revision; synovial.
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