title: Implant based differences in adverse local tissue reaction in failed total hip arthroplasties: a morphological and immunohistochemical study.
abstract: BACKGROUND
  Adverse local tissue reaction (ALTR) is characterized by periprosthetic soft tissue inflammation composed of a mixed inflammatory cell infiltrate, extensive soft tissue necrosis, and vascular changes. Multiple hip implant classes have been reported to result in ALTR, and clinical differences may represent variation in the soft tissue response at the cellular and tissue levels. The purpose of this study was to describe similarities and differences in periprosthetic tissue structure, organization, and cellular composition by conventional histology and immunohistochemistry in ALTR resulting from two common total hip arthroplasty (THA) implant classes.
  
  
  METHODS
  Consecutive patients presenting with ALTR from two major hip implant classes (N = 54 patients with Dual-Modular Neck implant; N = 14 patients with Metal-on-Metal implant) were identified from our prospective Osteolysis Tissue Database and Repository. Clinical characteristics including age, sex, BMI, length of implantation, and serum metal ion levels were recorded. Retrieved synovial tissue morphology was graded using light microscopy and cellular composition was assessed using immunohistochemistry.
  
  
  RESULTS
  Length of implantation was shorter in the DMN group versus MoM THA group (21.3 [8.4] months versus 43.6 [13.8] months respectively; p < 0.005) suggesting differences in implant performance. Morphologic examination revealed a common spectrum of neo-synovial proliferation and necrosis in both groups. Macrophages were more commonly present in diffuse sheets (Grade 3) in the MoM relative to DMN group (p = 0.016). Perivascular lymphocytes with germinal centers (Grade 4) were more common in the DMN group, which trended towards significance (p = 0.066). Qualitative differences in corrosion product morphology were seen between the two groups. Immunohistochemistry showed features of a CD4 and GATA-3 rich lymphocyte reaction in both implants, with increased ratios of perivascular T-cell relative to B-cell markers in the DMN relative to the MoM group (p = 0.032).
  
  
  CONCLUSIONS
  Our results demonstrate that both implant classes display common features of neo-synovial proliferation and necrosis with a CD4 and GATA-3 rich inflammatory infiltrate. Qualitative differences in corrosion product appearance, macrophage morphology, and lymphocyte distributions were seen between the two implant types. Our data suggests that ALTR represents a histological spectrum with implant-based features.
authors.affiliation: Department of Pathology, Hospital for Special Surgery, 535 East 70th Street, New York NY 10021, USA.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Perino
authors.affiliation: Department of Orthopedic Surgery, Hospital for Special Surgery, New York, NY, USA.
authors.forename: Benjamin F
authors.initials: BF
authors.lastname: Ricciardi
authors.affiliation: Department of Orthopedic Surgery, Hospital for Special Surgery, New York, NY, USA.
authors.forename: Seth A
authors.initials: SA
authors.lastname: Jerabek
authors.affiliation: Department of Pathology and Diagnostics, University of Verona, Verona and Pederzoli Hospital, Peschiera, Italy.
authors.forename: Guido
authors.initials: G
authors.lastname: Martignoni
authors.affiliation: Division of Research, Hospital for Special Surgery, New York, NY, USA.
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Wilner
authors.affiliation: Division of Research, Hospital for Special Surgery, New York, NY, USA.
authors.forename: Dan
authors.initials: D
authors.lastname: Maass
authors.affiliation: Division of Research, Hospital for Special Surgery, New York, NY, USA.
authors.forename: Steven R
authors.initials: SR
authors.lastname: Goldring
authors.affiliation: Division of Research, Hospital for Special Surgery, New York, NY, USA.
authors.forename: P Edward
authors.initials: PE
authors.lastname: Purdue
keywords: Adverse local tissue reaction; Corrosion products; Revision arthroplasty; Synovial inflammation