Developing a prototype device to measure nail bed angle – An exploratory multiphasic study

INTRODUCTION: Digital clubbing is characterized by a focal bulbous enlargement of the terminal segments of the fingers and/or toes due to the proliferation of connective tissue between nail matrix and the distal phalanx. The purpose of this study is to develop a prototype device to measure nail bed angle with significant inter-rater and intra-rater reliability. METHODOLOGY: Assessment eligibility through inclusion and exclusion criteria. Informed consent was signed by the patient before starting the testing procedure and measurement was done using the nail bed angle measuring device in normal and patients with clubbing. RESULTS: The intraclass correlation s test shows that the device has high reliability score ranging from 0.989 to 0.993. DISCUSSION: Lovibond represented the “profile” sign in 1938, which shows the actual clubbing of the fingers if it is >180. Till the day, the Schamroth's window test is used to identify or confirm clubbing where if 2 opposing fingers are held back-to-back against each other, a diamond-shaped space should normally appear between the nail beds and the nails of the two fingers. In clubbing, this space (or window) was missing. This test was useful if the finger clubbing is present graded into class 3 or more as there will not be much angle deviation to be visible in the Schamroth's sign. CONCLUSIONS: This device can measure the angle of the nail bed which will measure the slightest deviation in angle. This device is portable, cost-effective, less time-consuming, and high in accuracy.