title: A rare case of extensive diffuse nonpigmented villonodular synovitis as a cause of total knee arthroplasty failure.
abstract: BACKGROUND
  Nonpigmented villonodular synovitis (non-PVNS) is a benign proliferative disease involving the synovium. It is a rare condition that is little recognized. Non-PVNS has been reported as a cause of total knee replacement failure.
  
  
  METHODS
  We report a case of extensive diffuse non-PVNS in a patient with tibial component loosening after total knee replacement and review the related literature.
  
  
  CONCLUSIONS
  It is reported that pigmented villonodular synovitis (PVNS) occurs less frequently than non-PVNS after knee replacement. However, there are many more case reports of PVNS than non-PVNS after knee arthroplasty in the English-language literature.
  
  
  CONCLUSIONS
  Previously, there were no reported cases of extensive diffuse non-PVNS after total knee arthroplasty (TKA). This case study highlights an unusual case of non-PVNS as a cause of TKA failure. We propose that non-PVNS should be considered as a differential diagnosis in patients after TKA who present with recurrent pain and effusion/hemarthrosis of the knee, and that it is one of the causes of implant loosening after TKA.
authors.affiliation: Department of Orthopaedics and Traumatology, Faculty of Medicine, Adiyaman University, Adiyaman, Turkey. Electronic address: bayramtosun@hotmail.com.
authors.forename: Hacı Bayram
authors.initials: HB
authors.lastname: Tosun
authors.affiliation: Department of Orthopaedics and Traumatology, Faculty of Medicine, Adiyaman University, Adiyaman, Turkey.
authors.forename: Abuzer
authors.initials: A
authors.lastname: Uludağ
authors.affiliation: Department of Orthopaedic Surgery, Kırklareli State Hospital, Kırklareli, Turkey.
authors.forename: Sancar
authors.initials: S
authors.lastname: Serbest
authors.affiliation: Department of Orthopaedics and Traumatology, Faculty of Medicine, Adiyaman University, Adiyaman, Turkey.
authors.forename: Seyitali
authors.initials: S
authors.lastname: Gümüştaş
authors.affiliation: Department of Pathology, Faculty of Medicine, Adiyaman University, Adiyaman, Turkey.
authors.forename: Ibrahim Halil
authors.initials: IH
authors.lastname: Erdoğdu
keywords: Component loosening; Nonpigmented villonodular synovitis; Revision knee arthroplasty; Total synovectomy