Systemic Migration of Particles Derived from Implants There are numerous reports in the literature of migration of particles, released from implants, to lymph nodes and many organs. The spread particles of silicone elastomer and liquid droplets(namely, from breast implants) is well documented(see for review Travis, et al."). The translocation of these particles has been found to be due to a) migration through soft tissues, b) entry into the lymphatic system, and c) direct entry into the vascular system". Silicone particles have been found to migrate from breast implants through soft tissue to sites as distant as the groin. The finding of silicone lymphadenopathy in axillary lymph nodes is common in patients with breast implants. The hematogenous dissemination of silicone to viscera has also been reported as a result of soft tissue injection of the material22. In the orthopedic literature, silicone lymphadenopathy has become a common finding in patients receiving finger joint prostheses made of silicone elastomer 6, 7 Reports documenting dissemination of particles in the lymphatic system from total joint prostheses are mounting, suggesting that this phenomenon may be more common than previously thought Table 1). There are several animal studies documenting lymphatic spread of polyethylene particles to regional nodes3, 24. bos et al. recently provided evidence from human autopsies that polyethylene, polymethylmethacrylate, and metal particles released from stable total hip replacements spread to inguinal, parailiac, and paraaortic lymph nodes as early as 1.5 years following implantationof the prosthesis. Sinus histiocytosis in association with wear particles of polyethylene has been an incidental finding in lymph nodes biopsied at revision arthroplasty 4, and the staging of prostate,0 and breast cancer. Adenopathy related to an implant is not limited to total hip and knee replacement prostheses. O Connell recently reported a case of axillary histiocytic lymphadenopathy in association with polyethylene wear particles from a total shoulder Kinetics of Particle migration from joints and bone The kinetics of migration of particles from joints and osseous sites have been the subject of several investigations. Noble, et al., investigated the leakage of particles labeled with a albumin, carbonized microspheres, gold colloid, and ferric hydroxide, with sizes ranging from m radioisotope from intra-articular injection sites in the rabbit knee; particles included human ser hirty nanometers to tens of micrometers. Approximately l per cent of the injected dose of ferric hydroxide("inert")particles, less than one micrometer in diameter, migrated from the joint twenty four hours after injection. The kinetics of migration(leakage rate)of particles from the joint space was related to particle size; there was an order-of-magnitude difference in the leakage rates (2.2 to 0.1 per cent after twenty four hours) for particles ranging from less than 0. 1 to 15.0 In other studies a canine model was used to investigate the spread of cell-sized radioactive microspheres from the distal femur into the lymphatic system, venous drainage, and local tissue. In this model microspheres, fifteen micrometers in diameter, were injected into the medullary canal of the femur. Particles entered directly into the venous system( within fifteen seconds ofSystemic Migration of Particles Derived from Implants There are numerous reports in the literature of migration of particles, released from implants, to lymph nodes and many organs. The spread particles of silicone elastomer and liquid droplets (namely, from breast implants) is well documented (see for review Travis, et al.25). The translocation of these particles has been found to be due to a) migration through soft tissues, b) entry into the lymphatic system, and c) direct entry into the vascular system22. Silicone particles have been found to migrate from breast implants through soft tissue to sites as distant as the groin5. The finding of silicone lymphadenopathy in axillary lymph nodes is common in patients with breast implants23. The hematogenous dissemination of silicone to viscera has also been reported as a result of soft tissue injection of the material22. In the orthopedic literature, silicone lymphadenopathy has become a common finding in patients receiving finger joint prostheses made of silicone elastomer6,7. Reports documenting dissemination of particles in the lymphatic system from total joint prostheses are mounting, suggesting that this phenomenon may be more common than previously thought (Table 1). There are several animal studies documenting lymphatic spread of polyethylene particles to regional nodes13,24. Bos et al. recently provided evidence from human autopsies that polyethylene, polymethylmethacrylate, and metal particles released from stable total hip replacements spread to inguinal, parailiac, and paraaortic lymph nodes as early as 1.5 years following implantationof the prosthesis3. Sinus histiocytosis in association with wear particles of polyethylene has been an incidental finding in lymph nodes biopsied at revision arthroplasty14, and the staging of prostate2,6 and breast cancer15. Adenopathy related to an implant is not limited to total hip and knee replacement prostheses. O’Connell recently reported a case of axillary histiocytic lymphadenopathy in association with polyethylene wear particles from a total shoulder replacement15. Kinetics of Particle Migration from Joints and Bone The kinetics of migration of particles from joints and osseous sites have been the subject of several investigations. Noble, et al., 14 investigated the leakage of particles labeled with a radioisotope from intra-articular injection sites in the rabbit knee; particles included human serum albumin, carbonized microspheres, gold colloid, and ferric hydroxide, with sizes ranging from thirty nanometers to tens of micrometers. Approximately 1 per cent of the injected dose of ferric hydroxide ("inert") particles, less than one micrometer in diameter, migrated from the joint twenty four hours after injection. The kinetics of migration (leakage rate) of particles from the joint space was related to particle size; there was an order-of-magnitude difference in the leakage rates (2.2 to 0.1 per cent after twenty four hours) for particles ranging from less than 0.1 to 15.0 millimeters. In other studies a canine model was used to investigate the spread of cell-sized radioactive microspheres from the distal femur into the lymphatic system, venous drainage, and local tissue17. In this model microspheres, fifteen micrometers in diameter, were injected into the medullary canal of the femur. Particles entered directly into the venous system (within fifteen seconds of