To determine if reactivation of the endochondral pathway of ossification, which leads to sacroiliac joint fusion and ankylosis in the transgenic TNF mouse model after inhibition of the wnt pathway inhibitor DKK-1 [6], is involved in the remodeling process, we analyzed in situ the expression of established markers of chondrocyte hypertrophy. This evidence concerns the gene DKK1 and ankylosis.