Lift-Off Screw Results in Accurate Sagittal Tilt Correction in a Distal Radius Fracture Model.

Abstract

To determine the accuracy of a distal-first open reduction internal plate fixation technique in achieving correction of volar tilt in dorsally angulated distal radius fractures. Twenty foam radius models were divided evenly into groups N (normal) and O (osteoporotic). Dorsally angulated extra-articular distal radius fractures were then created. Group O underwent further modification to simulate an osteoporotic model. After static pinning in various degrees of dorsal angulation, opaque fiducial markers were placed and fluoroscopy was used to measure prereduction volar tilt. A variation of the distal-first plate application technique was used where a lift-off screw (LOS) was placed in the proximal most locking hole and propped the proximal aspect of the plate by the screw's length. The LOS length corresponded to the volar tilt correction needed. After fracture reduction using this technique, we measured the volar tilt again. We then compared the actual volar tilt correction with what was predicted based on the LOS length used. We also compared the tilt correction accuracy in the normal and osteoporotic models. Prereduction tilt ranged from 3° to 52° of dorsal tilt from normal (10° volar tilt). Corresponding LOSs ranged from 5 to 42 mm in length. Tilt correction correlated with screw length in a linear fashion (R= 0.9). The mean difference between actual and predicted tilt correction for a given screw length was 0.5° ± 3.0°, and the mean absolute difference was 2.4° ± 1.7° for all specimens. There was no difference between normal and osteoporotic models. Prereduction dorsal tilt can be accurately corrected within a few degrees of the goal by using the distal-first technique with an LOS. The LOS length can be calculated, and this technique can potentially be used with any distal radius periarticular locking plate with locking options in the shaft. A technique that provides accurate tilt correction would be of benefit tosurgeons treating distal radius fractures with volar plates.