1: Clin Orthop. 1996 Nov;(332):80-9.  

Effect of proximal and distal venting during intramedullary nailing.

Martin R, Leighton RK, Petrie D, Ikejiani C, Smyth B.

Victoria General Hospital, Halifax, Nova Scotia, Canada.

During intramedullary manipulation, 2 main phenomena occur. A dramatic rise in
intramedullary pressure occurs followed by intravasation of damaged marrow
tissue. There are concerns about the development of increased interosseous
pressure during reaming and the potential for this to contribute to fat embolism
syndrome. The intramedullary pressures generated with various intramedullary
devices was determined and the effects of a fracture, with and without proximal
and distal venting on these pressures were studied. Pressures generated in 78
embalmed anatomic specimen femurs and tibias were studied, leaving all soft
tissues intact. Pressures were recorded for awl, guide rod, reamer, and nail
insertion. Venting was done by creating a 4.5-mm hole in the cortex directly
opposite the transducer. Proximal venting reduced proximal pressures to 80 mm Hg
in the tibia (90% reduction) and 460 mm Hg in the femur (70% reduction). Distal
venting reduced distal pressures to 65 mm and 30 mm in the tibias and femurs,
respectively (90% reduction in pressures). Intramedullary pressures generated
during nail or alignment rod insertion in anatomic specimen bone greatly exceeds
the critical thresholds (150 mm Hg) thought to be responsible for fat emboli to
the lung in the dogs. The introduction of a vent may reduce the chance of fat
embolism. Despite the high association of raised intramedullary pressures and
fat emboli in animal studies, there is no known critical threshold for humans.
Therefore, although venting seems effective in reducing the intramedullary
pressure in anatomic specimen bones, its efficacy in the patient with trauma
remains to be determined.

PMID: 8913148 [PubMed - indexed for MEDLINE]