Evaluation of the development of osteopenia in the trabecular bone adjacent to the hemarthrosis, but not in the control knee, of F8^−/−mice. (A) Micro-CT analysis of trabecular bone showed significant bone loss next to the hemarthrosis, but not next to the control joint, of F8^−/− mice. The bone erosion was reduced by treatment with etanercept or in TNF-α–knockout or iRhom2-knockout mice. The micro-CT images shown are representative for the average sample of each treatment group. Quantification of the bone volume to total volume fraction (BV/TV) (B) and trabecular number (C) is shown as the percentage reduction compared with the unpunctured control knee (75% ± 4% and 39% ± 4%, respectively, for untreated F8^−/− mice [n = 8]; 51% ± 6% and 11% ± 4%, respectively, for etanercept-treated F8^−/− mice [n = 5]; 48% ± 6% and 15% ± 4% for F8^−/−/TNF-α^−/−mice [n = 7]; 49% ± 5.7% and 18% ± 3% for F8^−/−/iRhom2^−/− mice [n = 10]). *P ≤ .005, **P ≤ .001 vs untreated F8^−/− mice.