Knee replacement; Knee surgery NOS; Right knee re-placement; Slight fever; This spontaneous case was reported by a consumer and describes the occurrence of KNEE ARTHROPLASTY (Knee replacement), KNEE ARTHROPLASTY (Right knee re-placement) and KNEE OPERATION (Knee surgery NOS) in a 59-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.    Co-suspect product included non-company product UPADACITINIB (RINVOQ) for Rheumatoid arthritis.    The patient's past medical history included Knee surgery NOS. Concurrent medical conditions included Rheumatoid arthritis.   In March 2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. In April 2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. In August 2021, received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. On an unknown date, the patient started UPADACITINIB (RINVOQ) (Oral) at an unspecified dose. In 2021, the patient experienced PYREXIA (Slight fever). On 07-Oct-2021, the patient experienced KNEE ARTHROPLASTY (Right knee re-placement) (seriousness criterion medically significant). On an unknown date, the patient experienced KNEE ARTHROPLASTY (Knee replacement) (seriousness criterion medically significant) and KNEE OPERATION (Knee surgery NOS) (seriousness criterion medically significant). In 2021, PYREXIA (Slight fever) had resolved. At the time of the report, KNEE ARTHROPLASTY (Knee replacement) had resolved, KNEE ARTHROPLASTY (Right knee re-placement) was resolving and KNEE OPERATION (Knee surgery NOS) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Blood test: Normal. On an unknown date, Glycosylated haemoglobin: Normal. On an unknown date, Weight: Lost 27 pounds from keto diet..         Treatment and concomitant medications were not reported. Patient had knee surgery many years ago but it started to bother again. Patients thinks physician needs to clean it and updated the hardware. The knee replacement was going through therapy not did bad, patient just graduated to use a cane. On 07-Oct-2021 patient had right knee re-placement and was doing really well. Causality as per reporter and Causality as per Mfr. of events knee replacement, right knee re-placement and fever for co-suspect RINVOQ was reported as no reasonable possibility. This case was identified as part of a retrospective clean-up activity where certain emails received in the Moderna mailbox were missed to be booked-in.  Company comment-This spontaneous case concerns a female patient aged 59 years with relevant medical history of Rheumatoid arthritis and knee surgery reported, who experienced the unexpected serious (medically significant) events of Knee arthroplasty (Knee replacement), Knee arthroplasty (Right knee re-placement) and Knee operation in the context of mRNA-1273 vaccination. Patient had received initial two doses of mRNA-1273 approximately at an interval of one month and third dose four months later. The event Knee arthroplasty (Knee replacement) occurred on an unknown date and resolved, Knee arthroplasty (Right knee re-placement) occurred approximately 2 months after third dose and is resolving, Knee operation occurred on an unknown date with outcome unknown. No further information on detailed clinical course, investigations, treatment of the events was available in the report.  Relevant medical history remains a confounder to the events. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report. Event seriousness assessed as per medical judgement; Sender's Comments: This spontaneous case concerns a female patient aged 59 years with relevant medical history of Rheumatoid arthritis and knee surgery reported, who experienced the unexpected serious (medically significant) events of Knee arthroplasty (Knee replacement), Knee arthroplasty (Right knee re-placement) and Knee operation in the context of mRNA-1273 vaccination. Patient had received initial two doses of mRNA-1273 approximately at an interval of one month and third dose four months later. The event Knee arthroplasty (Knee replacement) occurred on an unknown date and resolved, Knee arthroplasty (Right knee re-placement) occurred approximately 2 months after third dose and is resolving, Knee operation occurred on an unknown date with outcome unknown. No further information on detailed clinical course, investigations, treatment of the events was available in the report.  Relevant medical history remains a confounder to the events. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report. Event seriousness assessed as per medical judgement.