Background:Acute inflammatory arthritis (AIA) in a native knee joint is a common pathology with a well-defined differential diagnosis which includes crystal-induced arthritis. Presenting symptoms in a knee joint arthroplasty (KJA) can mimic a periprosthetic hematogenous infection (PHI). There are few studies in current literature that describe possible causes of non-infectious arthritis in KJA. PHI requires, in most cases, an urgent combined surgical and antibiotic (AB) treatment. Describing and studying other possible diagnoses that may resemble PHI in a KJA is mandatory in order to minimize diagnostic errors and avoid unnecessary treatments.Objectives:To analyze the characteristics of AIA in KJA with negative cultures in patients with an initial diagnosis suspicion of PHI.Methods:A retrospective case series was conducted at a tertiary-level hospital including all patients diagnosed with an AIA in KJA with negative cultures from January 2012 to December 2019. Demographic data, clinical presentation, management and outcomes were recorded and analyzed.Results:A total of 11 cases in 9 patients were included (6 females and 3 males) with a median age of 69 years at the time of diagnosis. All patients had risk factors for AIA (6 had chondrocalcinosis (CC), 2 hyperuricemia and 1 psoriasis). However, crystal deposits in synovial fluid (SF) for none of the patients had been previously found.The median time from the index surgery to clinical presentation was 6 months, and from initial clinical presentation signs to referral was 24 hours. All cases presented with pain and swelling and 5 presented with erythema. Median body temperature on admission was 37.2°C. All patients presented with no acute distress.Initial blood tests showed a median white blood cell count and CRP of 11.160/mm3 and 90mg/L, respectively. Blood and SF cultures were taken for all cases. The median white blood cell count in SF was 75.883/mm3.Three cases had received AB treatment during a median of 6 days prior to microbiological sampling. After initial sampling, 6 cases received AB prior to surgery, 1 received AB after surgery, 1 received only AB and 3 were treated only with NSAIDs. In all cases, surgical treatment consisted in radical surgical debridement and polyethylene insert exchange.Further blood and SF tests were performed 4 days after admission. The mean decrease for systemic white blood cell count, CRP and synovial leukocyte count was 46%, 58% and 56%, respectively. All cultures were negative and crystal deposits were not identified for any of the samples.The median duration of symptoms was 127 days with a good outcome. 6 patients received AB for a median of 69 days.Conclusion:Non-infectious AIA in KJA is a rare entity that should be accounted for the differential diagnosis of periprosthetic joint infection. The initial diagnosis of infection could not be confirmed, although three patients had taken AB before sampling. It is important for physicians to have a suspicion for non-infectious arthritis, especially in patients with clinical and blood test result dissociation, radiological CC, medical history of hyperuricemia or psoriasis, in order to avoid unnecessary AB and surgical treatment.References:[1]Merit P. George, Floranne C. Ernste, Aaron Tande, Douglas Osmon, Tad Mabry, Elie F. Berbari. Clinical Presentation, Management, and Prognosis of Pseudogout in Joint Arthroplasty: A Retrospective Cohort Study. J. Bone Joint Infect. 2019, Vol. 4 (1): 20-26.Disclosure of Interests:None declared
Leptospirosis meningitis transmission from a pet mouse: a case report
