Presentation Abstract

Session: P001-P110-Adult Reconstruction Hip Posters
Date/Time: Tuesday, Mar 19, 2013, 8:00 AM - 5:30 PM
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Location McCormick Place, Academy Hall B
Presentation Number: Poster P040
Posterboard Number: P040
Title: Magnetic Resonance Imaging is Predictive of Adverse Tissue Reaction in Failed Metal-on-metal Hip Arthroplasty
Classification: +Complications (Hip)
Keywords: Complications; Bearing Surfaces; Radiographic Analysis; Total Hip Arthroplasty; Outcomes
Author(s): Alissa J. Burge, MD, New York, New York
Danyal Nawabi, MD, FRCS (Orth), New York, New York
Stephanie L. Gold, BA, New York, New York
Stephen Lyman, PhD, New York, New York
Douglas E. Padgett, MD, New York, New York
Matthew Koff, PhD, New York, New York
Hollis Potter, MD, New York, New York
Abstract: SUMMARY: In patients with failed metal-on-metal (MOM) hip arthroplasty, magnetic resonance imaging (MRI) can be used to identify an adverse tissue reaction and predict the presence of soft tissue damage, helping guide the need for revision.
INTRODUCTION: Early reports on modes of failure of MOM hip arthroplasties focused on mechanical causes related to high implant wear and surgical factors. In recent years, there have been increasing reports of MOM failures secondary to adverse local tissue reactions (ALTR). Identifying these failures early is critical to preventing tissue damage and poor outcomes after revision. Serum metal ions have been used as a screening test to diagnose ALTR but have low sensitivity and specificity. The goal of this study was to develop an MRI classification system to predict ALTR and the presence of intraoperative tissue damage in patients with MOM hip arthroplasty.
METHODS: Seventy patients with failed MOM hip arthroplasties who underwent preoperative MRI evaluation and subsequent revision procedures were included. Images were analyzed for the burden of osteolysis, synovitis and maximal synovial thickness. The presence of edema, synovial decompression, low signal intensity deposits, pseudocapsule dehiscence, abductor disruption and neurovascular compression was recorded. These MRI characteristics were correlated with histology, intraoperative tissue damage and wear analyses. The aseptic lymphocytic vasculitis-associated lesion (ALVAL) score was used to grade the tissue samples, facilitating identification of a subset of patients with ALTR. Intraoperative tissue damage was graded using a four-point scale. Random forest decision trees were calculated to categorize the observations by majority vote and provide a mechanism for ranking predictor importance for the outcomes of presence of ALVAL (ALVAL score ≥ 5) and intraoperative tissue damage.
RESULTS: The presence and volume of synovitis, as well as maximal synovial thickness were found to correlate with ALVAL score and intraoperative tissue damage (p<0.0001; figure 1). Patients with pseudocapsular dehiscence had a higher median ALVAL score (p=0.0008), as did those with low signal intensity metallic deposits (p<0.0001) and soft tissue edema (p<0.0001). An association between abductor status and both intraoperative tissue damage and ALVAL score was found. A predictive MRI model was subsequently created, demonstrating sensitivity and specificity of 90% and 86% respectively for predicting the presence of ALVAL and 94% and 87% respectively for predicting intraoperative tissue damage.
CONCLUSION: MRI is highly sensitive and specific in identifying patients with failing MOM hip arthroplasties secondary to ALVAL and predicting intraoperative tissue damage. MRI remains the most comprehensive, non-invasive method of assessing patients with painful MOM hip arthroplasties. Our proposed MRI classification provides an objective tool to identify at-risk patients and ultimately aid the surgeon in proceeding towards timely revision surgery.
ACKNOWLEDGEMENT: We would like to acknowledge Giorgio Perino MD, Parina Shah MS and Kara Fields MS

Figure 1: Axial fast spin echo image of the hip in a 52 year-old man with MOM THA demonstrates marked synovial expansion with severe synovial thickening (white arrows) preoperatively, consistent with ALTR; postoperatively, histologic ALVAL score of 8 was confirmed.

Disclosures: Presenting Author
Author 1
Author 2
4 - Johnson & Johnson Medtronic Merck Pfizer Procter & Gamble
Author 3
Author 4
1 2 4 - MAKO; 3B - MAKO Stryker
Author 5

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