Intramedullary reaming causes elevation in intramedullary pressure (IP) and extravasation of intramedullary contents into the venous blood system. This study was to evaluate the effect of an intramedullary suction system (ISS), recently developed in our laboratory, on the IP and fat extravasation in a sheep model.

Twelve skeletal mature sheep were assigned randomly to 2 experimental groups of 6 sheep: instrumentation and reamed intramedullary nailing without the ISS application and instrumentation and reamed intramedullary nailing with ISS application. During reaming, the IP was recorded at each step of the procedure. Haemo-dynamic parameters were monitored at pre-reaming, 10 min post-reaming, and 50 min post-reaming, including, mean arterial blood pressure (MABP), pulmonary artery pressure (PAP), pulmonary arterial CO2 (Paco2), heart rate (HR), and saturated oxygen (SaO2). Blood and lung tissue samples were collected for the examination of medullary fat intravasations.

Dramatic increases in IP were observed in non-ISS group at the six defined measuring times: before drilling, guide wire, reaming 8 mm (reamer size), 9 mm, reaming 10 mm, and reaming 11 mm. The IP during reaming was significantly lower in ISS group (guide wire, 15 mmHg; 8 mm, 13 mmHg; 9 mm, -1 mmHg; 10 mm, 3 mmHg; 11 mm, 16 mmHg) than in non-ISS group (guide wire, 28, 8 mm, 185 mmHg; 9 mm, 168 mmHg; 10 mm, 146 mmHg; 11 mm, 150 mmHg). These reductions were significant with the P values < 0.05 or 0.01. Paco2, was lower in ISS group than non-ISS group (32 and 40 mmHg, respectively), while SaO2 was higher in ISS group than non-ISS group (99 and 91 mmHg, respectively). Histological data revealed fat emboli in sheep lung tissue in non-ISS group. Total lipids in lung specimen was lower in ISS group (7.6 mg/g tissue) than in non-ISS group (13.6 mg/g, P=0.04).

We demonstrate the ISS in controlling the increase in IP occurring in long bone reaming. The ISS allows real time pressure recording and feedback to the operator. With this feedback, the operating surgeon is able to control the rate of forward reaming to prevent major increases in IP