INSERTING FEMORAL STEMS SLOWLY GENERATES HIGH CEMENT PRESSURES FOR LONGER

Background Aseptic loosening of cemented femoral stems results from migration of wear particles along the bone-cement interface, producing a foreign body reaction. After cement insertion, blood back pressure can disrupt the bone-cement interface, enabling this spread of wear particles. Our study investigates whether altering timing and speed of stem insertion can reduce this risk. Methods We inserted mock “C-Stem” femoral components (De Puy-Synthes), using Smartset HV cement (De Puy-Synthes) into artificial femora, fitted with proximal and distal pressure transducers. Cement insertion began two, three or four minutes after mixing. Cement pressures were then allowed to settle for one minute and the stems were then inserted over durations of 25, 60 or 90 seconds. Results Quicker insertion led to high peak pressures; however insertion over 90 seconds at 4 and 5 minutes achieved more sustained pressures above blood back pressure. Slower insertion particularly improved proximal pressurisation. Furthermore when the stem was inserted over 90 seconds at 5 minutes then the cement pressures remained high after full insertion of the stem. Conclusions Commonly, femoral stems are inserted rapidly. Our study demonstrates that by inserting the femoral stem more slowly, cement pressure can be maintained above blood back pressure for longer. We believe that after slower stem insertion, the higher cement viscosity enables the surgeon to maintain cement pressure, via the stem, sufficient to resist blood back pressure without inadvertently over inserting the stem. This safe and simple modification of cementing technique generates higher and more sustained cement pressures. Level of evidence 3 Disclosures Depuy-Synthes kindly provided the equipment used in the study. None of the authors received any payment or other benefits.