Smooth Pins Reinforcing Static Cement Spacers for Infected Total Knee Arthroplasty Are Not Safe

Prosthetic joint infection is one of the most dreaded complications following elective lower extremity primary total joint arthroplasty, resulting in substantial pain, disability, and health care costs. Both static and articulating antibiotic-impregnated spacers have been used in the management of 2-stage revision for infected total knee arthroplasty, which remains the gold standard for treatment of these infections. Articulating spacers may provide theoretical benefits with regard to improved range of motion after reimplantation secondary to less scar formations and soft tissue contractures. However, static spacers may be necessary to overcome instability associated with substantial bone defects, incompetent extensor mechanisms, and collateral ligament insufficiencies. In these scenarios, static spacers are often reinforced with intramedullary rods or Steinmann pins to provide additional knee stability, improve construct strength, maintain extension, and avoid flexion contractures. This case report describes an extremely rare case of migration of smooth pins through the posterior tibia into the calf following static spacer use in a 48-year-old man. Various mechanical and systemic complications have been reported in up to 50% of patients with the use of polymethyl methacrylate spacer devices, such as acute renal failure, allergic reactions from antibiotic use, stiffness, bone loss, fractures, and dislocations. However, to the best of the authors' knowledge, this complication of hardware migration has not been reported previously in the literature. The authors believe that orthopedic surgeons should consider the use of threaded pin dowels or intramedullary rods to avoid this potential untoward complication. [Orthopedics. 2016; 39(3):e553-e557.].