[Modified surgical technique for the reduction of bone marrow spilling in knee endoprosthesis]

In the literature 20 cases of fat embolism syndrome (FES) after total knee replacement (TKR) are reported; 16 cases had cemented hinged TKR and 4 resurfacing TKR. Initially, it was believed that the bone cement was responsible for the FES. Since then, however, Fahmy et al. have published extraordinary data, demonstrating the causal relationship between increased intramedullary pressure (IMP) during the insertion of the intramedullary rod (IR) and cardiorespiratory deterioration. The industry responded by developing a fluted IR, disregarding the overdrilling in the distal femur required by Fahmy. In the first part of this paper clinically manifest FES cases after resurfacing TKR are reported. In the second part of the study the conventional surgical technique is compared with a modified technique, which focuses on a reduction of bone-marrow release into the circulation. In the conventional and the modified group, IRs with and without flutes were compared. It was shown that only the opening of the intramedullary canal and insertion of the IR generated relevant IMP peaks during implantation of resurfacing TKR. When compared with the conventional surgical technique, the modified technique revealed significantly lower IMPs, and in neither group was a difference demonstrated between the IR with or without flutes. In 4 patients (2 conventional, 2 modified) transesophageal echocardiography (TEE) was performed for detection of bone-marrow release into the circulation. In the two patients operated on conventionally, TEE showed a markedly higher bone-marrow release than in the patients with modified operations. In conclusion, we recommend the presented modified surgical technique in order to reduce bone-marrow release into the circulation.