[Experimental studies on the role of intramedullary alignment rods in the etiology of fat embolisms in knee endoprostheses].
Fat embolism syndrome (FES) during implantation of an uncemented resurfacing type of total knee replacement is the leading cause of postoperative mortality. A possible explanation might be the insertion of a solid intramedullary alignment rod, resulting in an intrafemoral pressure increase. On 45 cadaveric human femora we measured the resulting intramedullary pressure during insertion of three different alignment rods: a solid rod and a hollow shaped guiding rod, both 10 mm in diameter, and a fluted alignment rod of 8.5 mm in diameter. The highest intramedullary pressures occurred after placement of a solid 10 mm alignment rod (3.77 +/- 0.44 bar), followed by a fluted 8.5 mm rod (2.53 +/- 0.28 bar). In both cases, the increased pressure led to an extrusion of bone marrow contents through the venous system of the proximal femur. The least increase occurred after insertion of a hollow shaped alignment rod (0.26 +/- 0.03 bar) without any fat extrusion. Our study confirms the hypothesis that insertion of solid intramedullary alignment rods during preparation of the femoral shaft results in a dangerous pressure increase, so that embolization can occur. To minimize the risk of a FES, instruments should be modified in a manner, that only hollow shaped alignment rods are used.
Gleitz
M
M
Orthopädische Universitäts- und Poliklinik Homburg/Saar.
Hopf
T
T
Hess
T
T
D001853:Bone Marrow / Q000503:physiopathology; D001858:Bone Nails / Q000009:adverse effects; D004620:Embolism, Fat / Q000503:physiopathology*; D005269:Femur / Q000503:physiopathology*; D006801:Humans; D007720:Knee Prosthesis / Q000009:adverse effects*; D011312:Pressure; D011474:Prosthesis Design
Experimentelle Untersuchungen zur Rolle des intramedullären Führungsstabes bei der Entstehung der Fettembolie in der Knieendoprothetik.