Alpha Omega Alpha Honor Medical Society

2012 Research Abstract

Validity of Computed Tomography in Predicting Scaphoid Screw Prominence: A Cadaveric Study

Investigator: Clare E. Griffis, ENS, MC, USN

Mentor: Patricia L. McKay, CAPT, MC, USN

Abstract: CT scans are frequently used post-operatively to evaluate fracture union in the setting of scaphoid fractures treated surgically with headless screws. Hardware prominence is difficult to assess accurately due to the unique surface anatomy of the scaphoid, as well as, metallic artifact and distortion (Bloom artifact) generated by CT. In this cross-sectional study, forty two cadaveric wrists were utilized to examine whether or not CT is a valid tool in predicting scaphoid screw prominence. Based on statistical analysis of the numbers required to achieve significance, the forty two specimens were allotted into four groups: 21 at 0mm prominence (flush or deep to the subchondral bone) for the control group, 7 at 1 mm measured prominence from the subchondral surface, 7 at 2 mm measured prominence, and 7 at 3mm measured prominence for the studied groups. Computed tomography with direct sagittal acquisition and metal suppression technique was performed after placement of screws in control and study groups. Two radiologists, independently interpreted all images, blinded to the study group. Descriptive statistical methods were carried out on the data collected comparing the direct measurement versus the radiographic measurement. Results revealed that only one out of twenty one control specimens was interpreted as prominent. Comparatively, in the studied groups, only two out of twenty one were not interpreted as prominent when in fact there was actual prominence. These results reveal that CT provides an accurate assessment of screw prominence in this model. However, in the study specimens, the radiologist’s measurement exceeded the actual measurement by an average of 0.3mm, which may represent Bloom artifact.

Last Updated: 2/4/14

Updated on February 7, 2014.

© 2017 Alpha Omega Alpha Honor Medical Society