Fig. 6

Phases of macrophagic pattern of ALTR in MoM LHTHA prosthesis. Circle 1: Nano-scale particles generated at the bearing surface by sliding tribocorrosion and nano and micron-scale at the metallic adapter sleeve-femoral neck surface by fretting/crevice corrosion where larger aggregates are formed. Conventional abrasion metallic wear can also be generated at the bearing surface by edge loading and/or neck junction at any time of implantation. Circle 2: Phagocytosis/pinocytosis of particulate material by neo-synovial superficial and deep layer macrophages with multinucleated giant cells containing large particulate aggregates. Circle 3: Massive apoptosis of neo-synovial particle-laden macrophages through oxidative stress with formation of degenerated foamy forms (right side) and release of necrotic cellular debris and secondary particles of corrosion products/abrasion metallic particles with disruption of cytoplasmic phagosomes. Circle 4: Accumulation of viable macrophages, necrotic cellular debris, red blood cells, and entrapped small and large aggregates of primary and secondary particles of corrosion products in the femoral head groove with substantial increase in thickness of the synovial fluid and subsequent modification of its lubrication properties. Circle 5: Bone marrow involvement by neo-synovial particle-laden macrophagic infiltrate through resorptive osteoblastic activity and direct invasion through cortical gaps with formation of osteolytic cavity (right side), diffuse seeding of the fatty marrow (middle area), and involvement of the hematopoietic marrow (left side)