Enhanced osteoclast formation in PJI patients was evident in TRAP staining at both explantation (Oc.N/BS: 0.107 vs 0.334 cells/mm, p = 0.001; Oc.S/BS: 0.585% vs 1.92%, p < 0.001) and reimplantation (Oc.N/BS: 0.107 vs 0.238 cells/mm, p = 0.001; Oc.S/BS: 0.585% vs 1.72%, p < 0.001; Fig. 2A, B). This evidence concerns the gene ACP5 and juvenile polyposis syndrome.