A soluble factor (EMMPRIN) in exudate influences knee motion after total arthroplasty.

Few studies have been conducted to investigate biological factors that affect postoperative knee motion after total knee arthroplasty (TKA). The purpose of this study is to test the hypothesis that range of knee motion (ROM) at 4 weeks after TKA is correlated with the concentration of extracellular matrix metalloproteinase inducer (EMMPRIN) and transforming growth factor (TGF)-beta1 in the exudative fluid harvested from the joint after surgery. A prospective measurement study was conducted with 20 osteoarthritis patients who underwent TKA. At 48 h after surgery, the exudate was harvested from a closed drainage system. Enzyme-linked immunosorbent assay was performed to measure the concentration of TGF-beta1, EMMPRIN, MMP-1, 2, 9, tissue inhibitor of metalloproteinase-1, and Hyalunonan. Knee flexion angle was measured before and at 4 weeks after surgery. There was a significant correlation between the EMMPRIN levels and knee flexion angle (r = 0.557, p = 0.0148). Western blot analysis of the exudate showed a prominent band for EMMPRIN at 27 kDa. On the other hand, there was no correlation between the TGF-beta1 levels and the knee flexion angle. This study showed that EMMPRIN levels after TKA affect the postoperative ROM. As to clinical relevance, EMMPRIN in the exudate after TKA is a promising biological indicator to predict difficulty in restoring postoperative ROM.