Pathological findings of septic loosening

Bone loss secondary to an infectious process in total joint replacement progresses in different stages. The first stage is primary osteolysis which is the direct action of the infecting bacteria and by the host's immune response to these bacteria. Implant removal causes additional damage to the bone if not performed carefully. If a two-stage revision is planned a temporary antibiotic loaded spacer that is not stable can also cause further bone loss. The soft tissues are involved with a progressive thickening of the joint capsule, and with an iperplasia of the synovial membrane (Fig. 1). In the active phase of the infectous process, synovial membrane exudate can be found in the joint space. In the chronic phase this exudate evolves into a scar tissue.