Describing the Anatomic Variability of the Dorsal Sulcus of the Distal Radius

Abstract

Objectives Dorsal extensor tendon rupture is a known complication of volar locking plate fixation for treating distal radius fractures. Tenosynovitis or even tendon rupture secondary to dorsal screw protrusion has been reported in numerous case studies. The high anatomic variability in this area, along with difficulty in imaging the necessary anatomic detail, leads to inaccurate screw measurements. A detailed understanding of the dorsal anatomy of the distal radius may reduce future events. The purpose of this study is to describe a dorsal ulnar sulcus of the distal radius that can hide dorsal screw penetration and thus act as a blind spot to standard oblique radiographic images. Methods After obtaining approval from our Institutional Review Board, 59 consecutive magnetic resonance images of different wrists were analyzed. Using the axial cut with the maximum sulcus depth, a line was drawn from the apex of Lister’s tubercle to the dorsal ulnar corner of the radius. A perpendicular line was then drawn from this line to the deepest point in the sulcus. This measurement was recorded as sulcus depth. Results A sulcus was found in 97% (57/59) of individuals with an average depth of 1.3mm. The sulcus measured greater or equal to 2mm in 14% (8/59) of the wrists studied. The radiocarpal joint averaged 6.1 ± 2.9 mm distal to the sulcus measurement location. There was no significant difference between gender or extremity side regarding sulcus depth. Conclusion The dorsal ulnar blind spot is a clinically relevant sulcus on the dorsum of the distal radius. This region demonstrated variable depth in our study and is not easily quantified using standard radiographs. With heightened awareness of the anatomic variability of the dorsal sulcus, we reduced the incidence of dorsal tendon irritation at our institution to 0%. Therefore, caution should be taken when placing volar screws to prevent dorsal cortex penetration and subsequent extensor tendon injury. Level of Evidence 4