The effect of entrapped bone particles on the surface morphology and wear of polyethylene

Foreign Body Entrapment on the Bearing Surface in Total Hip Arthroplasty: A Report of Three Cases

Total hip arthroplasty (THA) is a highly effective surgical intervention for end-stage hip joint disorders. While common complications such as infection, dislocation, and prosthetic loosening are well-documented, rarer complications remain underreported. One such complication is foreign body interposition on the bearing surface, which can compromise joint mechanics and adversely affect outcomes. This study presents three cases of foreign body interposition involving soft tissue, bone fragments, and cement debris, observed postoperatively in patients undergoing THA. In the first case, a 79-year-old woman presented with soft tissue interposition, which resolved spontaneously through joint motion without surgical intervention. The second case involved a 71-year-old woman with a bone fragment interposed between the femoral head and liner, necessitating reoperation for removal. The third case, a 32-year-old man, required immediate reoperation to remove a 1 cm cement fragment causing a gap on the bearing surface. In all cases, postoperative outcomes were favorable, with patients resuming independent ambulation and reporting no persistent symptoms. These cases underscore the potential for foreign body interposition to occur during or after THA due to residual debris or displaced tissues. This rare complication has an estimated incidence of 0.2% based on 1,340 procedures at three affiliated hospitals over two years. Key preventive strategies include meticulous removal of debris before reduction, thorough irrigation, and intraoperative imaging to confirm proper alignment. For management, immediate mobilization may resolve soft tissue interpositions, but solid foreign bodies typically require reoperation to prevent long-term damage to the bearing surfaces and subsequent complications, such as osteolysis, implant loosening, or catastrophic ceramic fracture. This report emphasizes the importance of heightened awareness, careful intraoperative techniques, and prompt postoperative imaging to identify and address this preventable complication. By sharing these insights, we aim to enhance perioperative safety and improve long-term outcomes for patients undergoing THA.

Scratching vulnerability of conventional vs highly cross-linked polyethylene liners because of large embedded third-body particles

The hypothesis of this study was that acetabular liner vulnerability to scratching from femoral heads, roughened by third bodies embedded in the liner, is not significantly lower for highly cross-linked polyethylene (HXPE) than for conventional polyethylene (CPE). Six CPE and 6 HXPE acetabular liners were each reproducibly embedded with 5 cobalt-chromium-molybdenum (CoCrMo) beads then run for 10,000 cycles in a joint simulator. By visual rank ordering, there was low association between liner scratch severity and polyethylene type. The CPE and HXPE liner scratches were not significantly different in scratch peak-valley height or width or in liner roughness in the vicinity of the embedded beads. This model indicated that high cross-linking of polyethylene does not offer appreciable protection against severe scratching induced by large embedded third-body particles.