Does That Thumb Trigger Finger Release Have You Feeling "Nerve"-ous?

Purpose The purpose of this investigation is to determine anatomical variations in the specific location of the radial and ulnar digital nerves to the thumb crossing the flexion crease. Understanding the precise location of these nerves is crucial for surgical interventions, such as in thumb trigger finger release, where the nerves are in danger of transection. Methods Twenty-one soft-embalmed cadaveric hands were dissected. ImageJ (NIH, Bethesda, MD) was used to determine the distance the ulnar and radial digital nerves to the thumb cross at the proximal flexion crease from the radial aspect of the crease. Results and conclusions The radial digital nerve crossed the crease at 8.38 ± 3.38 mm from the radial aspect of the crease. The ulnar digital nerve crossed the proximal flexion crease of the thumb approximately 16.35 ± 3.80 mm from the radial aspect of the crease. On average, the radial digital nerve crossed at 36.4% ± 9.4% of the distance between the radial and ulnar portions of the flexion crease, while the ulnar digital nerve crossed at approximately 72% ± 8.2%. The radial digital nerve crossed at the radial third of the crease in 43.0% of specimens and in the middle third in 57.0% of specimens. The ulnar digital nerve crossed at the ulnar third of the crease in 81.0% of specimens and in the middle third in 19.0% of specimens.