[Covering extensive soft tissue defects in infected knee endoprostheses by gastrocnemius flap]

Total knee arthroplasty has become a routine procedure in surgery. Deep infections have an incidence of 2-5%. Major risk factors are large prostheses, rheumatoid arthritis, diabetes mellitus and postoperative wound-healing complications. In large soft-tissue defects with skin necrosis, local wound care shows poor results, especially if loosening of the prosthesis and necrosis of the patellar ligament are evident. In these cases, no standard surgical therapy has been developed yet. Thus, we consider meticulous débridement with synovialectomy to be mandatory. Exchange of the prosthesis may be necessary. Soft-tissue coverage ought to be performed with a gastrocnemius muscle flap covered with a split-thickness skin graft. In the last three years, 11 patients with large soft-tissue defects and necrosis of the ligament were treated according to this concept. In all cases the muscle flap healed primarily and soft tissue coverage was excellent. Two patients who underwent single-stage removal and reimplantation of the prosthesis showed reinfections of the prosthesis. Reconstruction of the ligament was performed with the flap tendon. The patients with two-stage removal and reimplantation of the prosthesis and those who retained their implants had a good functional outcome. The gastrocnemius muscle flap provides easy and reliable soft-tissue reconstruction in large defects. In our patients a two-stage operation for reimplantation of the prosthesis was superior to a single-stage procedure. The reconstructed ligament should be reinforced with autologous material to prevent a secondary rupture. Early reconstruction with sufficient soft-tissue coverage and reconstruction of the ligament offers the patient the best chances of obtaining a good functional result and prevents arthrodesis or amputation. In addition, reconstructive surgery reduces the length of hospital stay and costs.