Suction Instrumentation Decreases Intramedullary Pressure and Pulmonary Embolism during Total Knee Arthroplasty

The risk of pulmonary embolism as a grave conse- quence of lower extremity total joint arthroplasty is well docu- mented. Increased intramedullary pressure created during femoral instrumentation has been positively correlated with increased mar- row particle content embolization. The purpose of this two part study is to demonstrate that the use of suction devices during femoral canal instrumentation during total knee arthroplasty de- creases femoral intramedullary pressure and the amount of marrow content embolized to the pulmonary circulation. The first phase of the study included 6 fresh frozen complete cadaveric femurs. Three of the distal femurs were instrumented with a standard intramedullary knee alignment guide. The other three femurs were instrumented with the same alignment rod placed inside of a cannulated suction sleeve connected to wall suction (˛22 in Hg). Intramedullary pressure was monitored with specialized transducers attached at multiple sites along the speci- mens. The second phase of the study included 24 patients who underwent unilateral cemented total knee arthroplasty. Twelve ran- domly selected patients were instrumented with the standard in- tramedullary guide and twelve patients were instrumented with the suction adapted guide. Transesophageal echocardiography and a computerized pixel counter was used to record and quantify em- bolic activity intraoperatively in both groups. The average intramedullary pressures (in Torr) monitored in the cadaveric specimens was 303 with the standard equipment and ˛248 with the suction device. The group of 12 patients who un- derwent femoral preparation with the standard equipment exhib- ited an average of 89 embolic particles registered upon tourniquet release. The average particle count was 31 when the suction equip- ment was used. Postoperatively, 2 patients in the standard group exhibited transient confusion. The knee scores averages were 89 in both groups and there was no notable radiographic differences at an average of 1-year follow-up. Although compliance and pressures are different in the cadaver compared to in vivo, the intramedullary pressures in the distal femurs were consistently reduced with use of the suction device. This model allowed measurement at multiple sites to more accu- rately reflect the pressure changes observed. The device also de- creased the number of embolic particles by 65% during knee ar- throplasty with no increase in operative time. This data supports the use of these devices to decrease femoral pressure and embolic matter in the pulmonary circulation.