[Influence and role of expression of extracellular matrix metalloproteinase inducer and matrix metalloproteinase 9 in aseptic loosening of prosthesis].

OBJECTIVE: To observe the expressions of extracellular matrix metalloproteinase inducer (EMMPRIN) and matrix metalloproteinase 9 (MMP-9) around the prosthesis, and to study the relationship between the expressions of EMMPRIN and MMP-9 and osteolysis around prosthesis.

METHODS: Interface tissues were obtained at three Delee-Charnley acetabular sections and seven Gruen femur sections from 8 cases (8 hips) undergoing revision after total hip arthroplasty between February 2010 and January 2012, and were divided into osteolysis group and non-osteolysis group based on preoperative X-ray film and intraoperative observation; the tissues from another 8 patients with osteoarthritis undergoing total hip arthroplasty as the control group. The immunohistochemical staining and RT-PCR assays were used to determine the expressions of EMMPRIN and MMP-9. The correlation between the positive cells and the severity of osteolysis were analyzed and compared.

RESULTS: Histological examination showed that many macrophages, multinucleated giant cells assembled in the membrane of osteolysis zone, but many fibroblasts and synovial cells in non-osteolysis zones. EMMPRIN and MMP-9 positive cells and gene expressions were observed in every group. The percentage of positive cells and gene expression of EMMPRIN and MMP-9 in osteolysis group were significantly higher than those in non-osteolysis and control groups (P < 0.05), but no significant difference was found between non-osteolysis group and control group (P > 0.05). The percentage of positive cells of EMMPRIN in zone III of acetabular was higher than that in zone I and zone II of revision hip (P < 0.05), but no significant difference between zone I and zone II (P > 0.05). The percentage of positive cells of MMP-9 in zone I and zone III was significantly higher than that in zone II of revision hip (P < 0.05), but no significant difference between zone I and zone III (P > 0.05). The expression of EMMPRIN from high to low in order was zones 1, 7, 4, 2, 3, 5, and 6 at femur; the values of zones 1, 7, and 4 were significantly higher than those of zones 2, 3, 5, and 6 (P < 0.05), but no significant difference among zones 1, 7, and 4, and among zones 2, 3, 5, and 6 (P > 0.05). The expression of MMP-9 from high to low in order was zones 1, 7, 4, 2, 3, 6, and 5 at femur; the values of zones 1 and 7 were significantly higher than those of zones 4, 2, 3, 6, and 5 (P < 0.05), and the values of zones 4 and 2 were significantly higher than those of zones 3, 6, and 5 (P < 0.05), but no significant difference between zone 1 and zone 7, between zone 4 and zone 2, and among zones 3, 5, and 6 (P > 0.05).

CONCLUSION: The expressions of EMMPRIN and MMP-9 have certain coherence. The over-expressions of EMMPRIN and MMP-9 may be one of the key points of inhibiting bone reconstruction and bone resorption at bone-implant interface under the stimulation of wear debris.