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Pre-operative anteroposterior (a) and lateral (b) radiographs of the knee show loosening and osteolysis under the tibial component in the medial compartment.
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Blood tests, including for inflammatory and rheumatological markers, were normal, while plain radiography was consistent with suspected loosening that was found as a radiolucent lesion below the tibial component (Fig. 1).
Perfusion, blood pool, static phase, and anteroposterior whole-body images (three-phase bone imaging using technetium 99 m methylene diphosphonate). Periprosthetic hyperperfusion, hyperemia, and increased periprosthetic activity are seen around the tibial component of a right total knee replacement.
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Increased focal uptake around the tibial component was shown in the late static phase (Fig. 2).
Before (a) and after (b) synovectomy. Intra-operative photographs of the knee show diffuse papillae and nodules in the proliferating synovium, with yellow-brown areas (typical appearance of villonodular synovitis).
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During revision surgery, the orthopedic surgeon unexpectedly found excessive diffuse proliferation of the synovial hypertrophy, including papillae and nodules, with yellow and brown areas surrounding the prosthesis (Fig. 3).
Post-operative anteroposterior (a) and lateral (b) radiographs of the knee show acceptable alignment and a well-fixed tibial component after revision total knee replacement.
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After complete resection of all the pathological tissues, revision TKA was performed (Fig. 4).
(a) Photomicrograph of the specimen shows the synovial cell layer which is formed from different sized and shaped cellular areas surrounding the papillary villous structures (hematoxylin and eosin (H&E) staining, original magnification 40x). (b) Photomicrograph showing synovial proliferation with multinucleated giant cells, histiocytes, and a small number of lymphocytes under synovial cell structures surrounding the papillary villous (H&E, original magnification 40x). (c) Immunohistochemically there is diffuse infiltration of CD68-positive histiocytes (original magnification 20x).
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On histopathological examination, the specimen showed papillary villous structures surrounded by the synovial cell layer, which consisted of different sized and shaped cells (Fig. 5a). There was inflammatory cell infiltration by multinucleated giant cells, histiocytes, and a small number of lymphocytes under the synovial cell structures on the surrounding papillary villous structure (Fig. 5b). Histological analysis demonstrated the typical appearance of non-PVNS (Fig. 5c).