Chondrogenesis in the synovial tissue is associated with the onset of pseudogout after total knee arthroplasty.

Postoperative pseudogout after total knee arthroplasty (TKA) is very rare, and its physical findings are very similar to infectious symptoms. In pseudogout, the mechanism underlying the deposition of calcium pyrophosphate dehydrate crystals remains unclear. Here, we report the histologic findings in a pseudogout attack in the late postoperative period after TKA. She had acute onset of arthritis of the knee 2 years after TKA. Histologic examination showed significant neutrophil infiltration. Interestingly, chondrogenesis was noted in the synovial tissue, and calcium pyrophosphate dehydrate crystals were synthesized mainly at the site of chondrogenesis, suggesting a potential mechanism underlying the occurrence of pseudogout after TKA.