Reactive synovitis of the knee joint after COVID‐19 vaccination: The first ultrastructural analysis of synovial fluid

Abstract

Background Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection and the resulting coronavirus 2019 disease (COVID‐19) have spread all around the world since 2019 and have affected millions of people. The development of COVID‐19 vaccines helped to decelerate the spread of the virus. However, as in the case of vaccines against other infectious diseases, adverse events can also present with COVID‐19 vaccines. Case Presentation We report here a rare case of a 53‐year‐old man with knee‐joint synovitis, after the first dose of messenger RNA vaccine, with no fever and a negative COVID‐19 reverse transcription polymerase chain reaction test. During a clinical examination the suspicion of pyogenic arthritis was excluded by blood tests and by a complex joint effusion examination, including a microbiological and cytological‐energy analysis of the synovial fluid. The treatment received by our patient consisted of 3 doses of dexamethasone administered intravenously over a period of 3 days. All the symptoms improved after this therapy, and in the 3‐week follow‐up period we recorded full recovery with no consequences. Conclusion Case reports on patients undergoing COVID‐19 vaccination should be examined in order to detect rare and long‐term side‐effects. This is the first report to present the outcomes of an ultrastructural analysis of post‐vaccination synovitis.

Response to commentary: Reactive synovitis of the knee joint and COVID‐19 vaccination

“…The results from cytological‐energy analysis are known within a few hours after the puncture so this method can promptly exclude pyogenic complications. 3 This exclusion of an ongoing inflammatory process in the synovial fluid equally clarifies this in other extravascular body fluids. 4 The cytological‐energy analysis of the synovial fluid may also be used in the diagnostic process and typing of the tumor and promote the start of treatment.…”

“…Ultrastructural analysis is an accessible, rapid and affordable method which can provide this decision. The results from cytological‐energy analysis are known within a few hours after the puncture so this method can promptly exclude pyogenic complications 3 . This exclusion of an ongoing inflammatory process in the synovial fluid equally clarifies this in other extravascular body fluids 4 .…”

Reactive arthritis after vaccination against SARS-CoV-2: A case series and a mini-review

“…7 In 11 patients, small joints were affected, whereas in 12 patients, the disease was located in large joints. Of 16 cases, only 4 of them had monoarthritis, 9 , 11 , 12 , 14 1 had oligoarthritis, 1 had sacroilitis, and the rest had polyarthritis. Thirteen patients reported normal condition during follow-up and in two the symptoms reoccurred after the second dose of the vaccine.…”

New-Onset Arthritis Following COVID-19 Vaccination: A Systematic Review of Case Reports

“…Five patients were diagnosed by doctors as ReA, presenting with clinical symptoms in the knee [ 11 , 27 ], shoulder/elbow [ 12 ], and facet joints of the hand (e.g., wrist and metacarpophalangeal and proximal interphalangeal joints) [ 25 ]. All symptoms appeared within five days after vaccination.…”