Histopathological differential diagnosis of arthrofibrosis [Histopathologische Differenzialdiagnostik der Arthrofibrose]

Background: Arthrofibosis is clinically defined as fibrotic disease of synovial/neosynovial membranes as a posttraumatic, postinfectious, postinterventional complication or after endoprosthetic joint interventions, leading to painful joint stiffness. Methods: For histopathology biopsy samples should be of sufficient number and size for a certain diagnosis, at least 5-10 mm in diameter and from five different localizations, including biopsy samples near and distant to the endoprosthesis. Histopathology shows varying degrees of fibrosis without detectable ossification, without wear particle reaction and without signs of a bacterial infection. A 3-stage schematic grading has been introduced for the diagnosis of arthrofibrosis which is based on the cellular density of fibrous tissue (fibroblast cellularity). A threshold of 20 β-catenin positive cells/high power field (HPF) was determined and using this threshold a sensitivity of 0.720 and a specificity of 0.867 can be achieved. The most relevant differential diagnosis in non-endoprosthesis- associated arthrofibrosis are specific and non-specific bacterial infections. In the revised classification of the periprosthetic membrane (synovial-like interface membrane SLIM) the diagnostic criteria of endoprosthesis-associated arthrofibrosis and the differential diagnosis from immunological/allergic alterations and bacterial infections are defined. Conclusion: Interdisciplinary teamwork between arthroscopists, pathologists, radiologists, microbiologists and orthopedic surgeons is mandatory for the diagnosis of arthrofibrosis. © 2013 Springer-Verlag Berlin Heidelberg.