Influence of the fixing technique on the quality of the cement mantle in knee arthroplasty. Experimental study on a synthetic model

Abstract Objective To assess the quality of the cement mantle obtained with different fixation techniques in knee arthroplasty. Material and method An experimental study with synthetic bone models (16 tibias and 16 femurs), employing a PROFIX ® prosthetic tool and high viscosity cement (Palacos R ® ), applied on the second and fifth minute after mixing the components using two fixation techniques: directly over the bone surface by digital pressure (technique M), or over the prosthetic implant (technique P). We performed a digital analysis on the photographs of the models, determining for each cut plane: mean penetration, percentage penetration and length of the cement mantle. Results Technique M applied in minute 2 achieved a better quality mantle, with a mean penetration of 4.44 mm and a percentage penetration of 79.36%; technique P in minute five obtained poorer results (2.12 mm and 45.79%), these differences being significant (p = 0.029). The femur tangential fixation (anterior and posterior) was unstable, with a mean penetration of 2 mm. The mean length of the mantle in these two planes with technique M was 35 mm and 17.9 mm, compared with technique P (12.5 mm and 7.2 mm), which achieved a coverage of Conclusions Cementing over the bone surface with digital pressure achieves a greater depth and percentage penetration than direct cementing over the prosthetic implant, with greater differences when the cement viscosity is higher. Tangential fixation of the anterior and posterior cuts is very unstable if it is cemented over the implant.