The clinical scenario is consistent with fat emboli syndrome. Figure A, shows a cemented bipolar hemiarthroplasty while Figure B shows marrow embolization into the lungs. Studies have shown that intramedullary pressure and fat embolization are greatest during pressurization of cement and implant insertion.
Intramedullary pressure is influenced by size, shape, sharpness and insertion rate of an implant. Pressurization during cementing of a femoral component generates a large degree of pressure over a much wider surface area than in the other methods described of femoral canal instrumentation or preparation, as the entire femoral canal is pressurized at one time. This results in the highest degree of marrow embolization to the lungs resulting in hypoxia.
Dobrjanski et al studied which variables affected intramedullary pressurization and found that lower implant insertion speed, lower hammering force, a rubber- compared with steel-tipped hammer and a larger synthetic bone-to-implant radial gap reduced intramedullary pressure generated in a femur module.
Buckwalter JA, Einhorn TA, Simon SR (eds): Orthopaedic Basic Science: Biology and Biomechanics of the Musculoskeletal System, ed 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 307-31
Dobrjanski D, Saghir Z, Behdinan K, Zalzal P, de Beer J, Papini M.Intramedullary canal pressure distribution: An experimental parametric study. J Arthroplasty 2007;22:417-427
PMID:17400098 (Link to Abstract)