SURFACE CHARACTERISTICS FOLLOWING TIBIAL PREPARATION DURING TOTAL KNEE ARTHROPLASTY

A clinical study, where flatness of the cut surface was quantified, wa s performed during 26 tibial bone cuts prepared for noncemented endopr osthetic components. Using sterilized dental imprint material and meas ured by the Zeiss Universal Measuring Centres (UMC) 850 (Oberkochen, G ermany), the characteristics of the cut surface were defined. A clinic ally ''flat'' surface was found to be uneven with a maximum roughness of 1.71 mm (range, 1.06-2.57 mm), and defined as the distance between the uppermost and lowermost points. The flatness, defined as the stand ard deviation of the measuring points, was 0.26 mm (range, 0.16-0.38 m m). This lack of smoothness creates gaps between the bone and prosthes is that are large enough to prevent direct bone contact when using non cemented fixation. This may be one reason why bony ingrowth is found i nconsistently. The surface prepared by a 2-mm thick prototype saw blad e was inferior to that created by a 1-mm blade.