Arthroplasty Joint Histology and Surgical Outcomes in Patients on Immune Checkpoint Inhibitors: A Single-Center Case Series

<h3>Plain Language Summary</h3> This is a case series of 16 patients with cancer who were treated with immune checkpoint inhibitor (ICI) therapy and who underwent 23 joint replacements. Some of these patients were known to have inflammatory arthritis (joint inflammation) as a side effect of the ICI therapy, whereas others were thought to have worsening of established osteoarthritis (OA). We wanted to know whether the patients with OA had ICI-related joint inflammation that was simply not recognized before surgery. We also wanted to know whether patients who undergo joint replacements on ICI have more surgery complications than other people. What we found was that the people who were diagnosed with OA prior to surgery had OA on joint histology. Only the patients with known inflammatory arthritis from ICI had significant inflammation on joint histology. One patient required a revision of her hip joint replacement 3.7 years after surgery (while still on ICI) due to an inflammatory reaction to her joint replacement. We could not determine whether ICI played a role in that complication.