High-turnover periprosthetic bone remodeling and immature bone formation around loose cemented total hip joints

Aseptic loosening and periprosthetic osteolysis are the major problems awai ting solution in total hip surgery. The clinical investigation focused on t he analysis of periprosthetic bone remodeling to clarify one important key event in the cascade of periprosthetic connective tissue weakening and oste olysis around loose artificial hip joints. Twelve acetabular bone samples a djacent to granulomatous synovial-like membrane of loose hip prosthesis wer e retrieved at revision surgery and processed for Villanueva bone staining for morphological observation and bone histomorphometric analysis. Eight we ll-fixed bony samples were used as control, Although osteoclastic surface a nd eroded surface by osteoclasts were evident in the periprosthetic bone fr om loose hip joints (p = 0.003 and p = 0.027), increased osteoid/low-minera lized bone matrix (p < 0.001) and osteoid width (p < 0.001) also were signi ficant findings in structural analysis. In addition, not only elevated mine ral apposition rate (MAR; p = 0.044) but also increased mineralizing surfac e (p = 0.044) and bone formation rate (BFR; p = 0.002) in loose periprosthe tic bones were shown in dynamic data analysis, These results were confirmed by precise morphological observation by confocal laser scanning microscopy , Active coupling of bone formation and resorption and increased osteocytes with abundant bone canalicular projections were found in combined with the presence of immature bone matrices (osteoid and low-mineralized bone areas ) in periprosthetic bones from loose hip joints, These results indicated th at active osteoclastic bone resorption and/or defective bone formation are coupled with monocyte/macrophage-mediated foreign body-type granuloma in th e synovial-like interface membrane of loose hip joints. Thus, this unique h igh-turnover periprosthetic bone remodeling with bad bone quality probably is caused by the result of cellular host response combined with inappropria te cyclic mechanical loading, The fragile periprosthetic bone may contribut e to hip prosthesis loosening.