IFNA1 and frozen shoulder: It resolved completely shortly after IFN discontinuation, and did not recur after switching treatment to GA.11 A 38-year-old woman with RRMS presented with left pre-patellar bursitis with no particular involvement three months after initiation of IFN-β1a.11 A 29-year-old woman with RRMS presented with severe acute-onset arthralgia, swelling of both knees, and inflammatory synovial fluid reaction three weeks after beginning treatment with IFN-β1b.