Rinsing-suction reamer attenuates intramedullary pressure increase and fat intravasation in a sheep model

Reamed intramedullary nailing causes an increase of intramedullary pressure. A new rinsing-suction reamer (RSR) can reduce this problem, and it was evaluated in animal experiments in comparison with the AO reamer (AOR) to see its effects on intramedullary pressure and fat intravasation.

Reamed intramedullary nailing was performed in 14 sheep using the RSR or AOR. The following parameters were evaluated: intramedullary pressure, hemodynamics, blood tests, lung histology, and radiographs of the femur that was operated on.

Intramedullary pressure during reaming was significantly (p < 0.001) lower with RSR (9 mm, 34 mm Hg; 9.5 mm, 4 mm Hg; 10 mm, 1 mm Hg) than AOR (9 mm, 750 mm Hg; 9.5 mm, 292 mm Hg; 10 mm, 138 mm Hg). There was a significantly (p < 0.05) higher increase of pulmonary resistance in AOR (from 144 +/- 84 dyne x s x cm to 391 +/- 169 dyne x s x cm) than in RSR (from 137 +/- 51 dyne x s x cm to 258 +/- 105 dyne x s x cm) after nailing and less intravenous fat measured in RSR (0.9; AOR, 2.9; p < 0.05) at all stages of reaming, at nail insertion (RSR, 0.3; AOR, 2.7; p < 0.05), and 30 seconds after nail insertion (RSR, 0.2; AOR, 1.1; p < 0.05) proved by the Gurd test. Pco2 increased (p < 0.05) in AOR (AOR, 36 +/- 5 vs. 40 +/- 7 mm Hg; RSR, 33 +/- 4 vs. 32 +/- 3 mm Hg) and pH dropped significantly (AOR, 7.49 +/- 0.06 vs. 7.45 +/- 0.05; RSR, 7.53 +/- 0.04 vs. 7.54 +/- 0.04; p < 0.05). Semiquantitative histologic analysis proved a significant higher pulmonary fat load in AOR (13.1 +/- 13.4) versus RSR (3.9 +/- 1.5, p = 0.00002).

Because we found only a minimal increase of the pulmonary arterial pressure as a sign of pulmonary embolism, we conclude that by using the RSR, the systemic side effects caused by intravasation of medullary content during reaming could be reduced as far as possible.