Fibular obscure tubercle

The fibular obscure tubercle (Felix's tubercle) is a distinct bony prominence located on the distal fibula, specifically on its lateral aspect, just proximal to the articular tip of the fibula. It serves as a reliable anatomical landmark for the origin of the anterior talofibular ligament (ATFL) and the calcaneofibular ligament (CFL). In cadaveric studies, the fibular obscure tubercle is consistently present and detectable; it is situated approximately 1.3 mm proximal to the articular tip of the fibula, 2.7 mm from the intersection of the ATFL and CFL, 3.7 mm distal to the ATFL origin, and 4.9 mm proximal to the CFL origin.

This tubercle is clinically relevant for minimally invasive lateral ankle stabilization procedures, as it allows precise localization of the ligamentous attachments. Its consistent presence and proximity to key ligament origins make it a preferred landmark over other less reliably identified tubercles in the region.