Abstract
Cement pressurisation is recognised as critical to achieving optimal results in cemented arthroplasty of the hip, but relatively little data exists on the pressures generated by different cement introduction systems. An in vitro experiment was consequently undertaken to measure the mean pressures developed by three such systems: the Howmedica Mark 1 and DePuy Cemvac retrograde cementation systems, and a novel antegrade system consisting of a simple 60ml catheter-tipped syringe and a Miller proximal femoral seal (Zimmer Ltd).
Plastic femoral models (Sawbones Europe) were prepared as for hip arthroplasty, and had a series of three transducers attached to their medial wall. Pressure was recorded continuously during cement introduction and pressurisation, before implanting a hip prosthesis and allowing the cement to cure. The experiment was repeated on ten models for each of the three systems. After cement curing, the femora were split in the coronal plane and examined for air-bubble defects in 7 zones analogous to Gruen’s radiographic zones.
Mean pressure was significantly higher for the syringe system (161.45 28.9 kPa) than the Mark 1 (103.51 22.0 kPa) or Cemvac (92.65 30.7 kPa) systems (p=0.0001, ANOVA). The antegrade syringe system also generated a statistically different distribution of pressure in comparison to the two retrograde systems, with particularly high proximal pressurisation in the former. The median number of zones with defects was 1 (interquartile range 1,2) using the syringe system, 3 (IQR 2,4) with the Mark 1 system, and 3 (IQR1,3) using the Cemvac system. These differences were also statistically significant (p=0.0256, Kruskal-Wallis).
These results have relevance for clinical practice and cement system design, and the various design features of the different systems are discussed.
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
