Experimental analysis of screw hold as judged by operators v pullout strength.

Abstract

An analysis of the accuracy of the operators' assessments of the hold of bone screws is reported. These assessments of screw hold were compared with measurements from pullout testing. Four operators, encompassing a range of experiences in terms of screw insertion, prepared the pilot holes, and inserted a number of screws, assigning each with a score from 0 to 10 on the basis of how good the hold was felt to be. The pullout strength for each screw was then measured using a tensometer. The results were analysed and correlation coefficients calculated. Significant correlation was observed in all four subjects, with P < 0.001 in two out of the four subjects, and 0.01 > P > 0.001 in the other two. The conclusions were that there is a strong correlation between the subjective assessment of screw hold and actual pullout strength within the four subjects analysed.