The Clinical Application of Kaplan’s Cardinal Line as a Surface Marker for the Superficial Palmar Arch

We feel the original description of Kaplan’s cardinal line provides a more accurate reference point to the superficial palmar arterial arch. We sought to anatomically correlate the relationship of Kaplan’s cardinal line to the superficial palmar arch. Sixty hands (30 cadavers) were dissected after Kaplan’s original description was drawn on each hand. Measurements we made from Kaplan’s cardinal line to the superficial palmar arch at both the radial and ulnar borders of the ring finger. The superficial palmar arterial arch was an average of 10.4 and 11.8 mm from the radial and ulnar borders of the ring finger with standard deviations of roughly 4 mm for each measurement. Clinically, Kaplan’s cardinal line is a more predictable landmark for the superficial palmar arch. In referencing this landmark as the distal most extent of an open or endoscopic carpal tunnel release, the superficial palmar arch should be free of transection.