Validating the use of qualitative ratings of static wrist postures relative to quantitative measurements

Abstract

This study was conducted to determine the accuracy and reliability of observer estimates of varying degrees of static wrist flexion and extension. Observers' classification of various angles of static wrist flexion and extension into five ordinal categories was also evaluated. With the use of PowerPoint presentations, subjects viewed pictures of static wrist postures that varied from 70⁰ flexion to 80⁰ extension by 10⁰ increments. They then estimated and rated each one using two scales. Generally raters are accurate at estimating static wrist flexion and extension. However, they are inconsistent with one another in their estimates. The results indicate there is essentially no difference in what the raters' cognitive estimate of the wrist deviation is compared to the measured value from the visual analog scale for that same deviation. The findings of this study also indicate that the raters' estimation and rating of various wrist postures was affected by non-posture factors of the operator shown. In addition, raters use 10⁰ wrist flexion to 20⁰ wrist extension to classify a posture as neutral. When the wrist deviations are equal to or greater than 10⁰ wrist flexion and 20⁰ wrist extension, a rater will begin to classify wrist postures into non-neutral categories. Each wrist deviation could be divided into five distinct categories except for 50⁰ wrist extension.