The Lovibond angle, also known as the "profile sign," is the angle formed by the nail as it exits the proximal nailfold. It was introduced in 1938 as a diagnostic criterion for finger clubbing.
Understanding the Lovibond Angle
Finger clubbing is a physical sign characterized by bulbous enlargement of the distal phalanges (bones of the fingers and toes). The Lovibond angle provides a way to quantify this characteristic.
- Normal Angle: In healthy individuals, the Lovibond angle is typically 160 degrees or less.
- Clubbing Angle: In individuals with finger clubbing, this angle is often greater than 180 degrees. The nail bed also becomes visibly more convex.
Importance in Diagnosis
Assessing the Lovibond angle is a simple, non-invasive method to screen for conditions associated with finger clubbing, such as:
- Lung diseases (e.g., lung cancer, cystic fibrosis, bronchiectasis)
- Heart conditions (e.g., cyanotic heart disease)
- Gastrointestinal disorders (e.g., inflammatory bowel disease, cirrhosis)
While the Lovibond angle is a useful clinical sign, it should be interpreted in conjunction with other clinical findings and diagnostic tests to reach an accurate diagnosis.