Background: The use of the volar plate to treat distal radius fractures is increasing but despite the theoretical advantages of a volar approach there have been reports of extensor tendon ruptures due to prominent screw tips protruding past the dorsal cortex. The valley in the intermediate column between Lister tubercle and the sigmoid notch of the distal radius makes it difficult to rely on fluoroscopy to judge screw length. Our aim was to quantify the dimensions of this valley and to demonstrate the danger of relying on intraoperative image intensification fluoroscopy to determine lengths of distal screws.
Methods and Results: We measured the depth of this valley in the intermediate column of the distal radius in 33 patients with computed tomographic (9 patients) or magnetic resonance image (24 patients) scans of the wrist. There was a consistent valley in all images examined [average 1.8 mm (95% confidence interval, 1.6-2.0 mm)]. Thirty-nine percent of wrists had a valley depth of at least 2 mm.
Conclusions: Standard lateral views or rotation of the forearm to obtain oblique views does not identify prominent screw tips; and whatever the rotation of the forearm, screw tips protruding beyond dorsal cortex may look as if it is within the bone when in fact it is out. When drilling we suggest noting the depth at which the drill bit just penetrates dorsal cortex and routinely downsize the distal screw length by 2 mm. We caution against relying on flourosocopy when judging the length of the distal subchondral screws.
Department of Orthopaedic Surgery, Whipps Cross University Hospital, Leytonstone, London, UK
Investigation performed at: Department of Orthopaedic Surgery, Whipps Cross University Hospital, Whipps Cross Road, Leytonstone, London E11 1NR, UK.
Conflicts of Interest and Source of Funding: The authors report no conflicts of interest and no source of funding.
Address correspondence and reprint requests to Derek H. Park, FRCS (Tr&Orth), 55 Ryculff Square, Blackheath, London SE3 0SW, UK. E-mail: firstname.lastname@example.org.