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

PURPOSE

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

CLINICAL RELEVANCE

A technique that provides accurate tilt correction would be of benefit to surgeons treating distal radius fractures with volar plates.

Efficacy of the Anatomical-Pelvic-Plane Positioner in Total Hip Arthroplasty in the Lateral Decubitus Position

BACKGROUND

Total hip arthroplasty in the lateral position involves particularly large variance in the sagittal tilt of pelvis fixation, which affects the imprecision of the cup anteversion leading to poor outcomes. We have added an additional compression pad to an existing device, also to be used in the lateral position, but theoretically enabling fixation on the anatomical pelvic plane (APP) serving as the reference plane. The present study aims to evaluate the usefulness of this device in comparison with the conventional device.

METHODS

We have studied 141 patients who underwent total hip arthroplasty at our hospital. Two frontal plain x-rays of the pelvis were obtained preoperatively for each patient after pelvis fixation; one with the conventional lateral fixation device and the other with an APP lateral fixation device. The sagittal tilt of the pelvis in each position was measured with 3D templating software, and variance in the sagittal tilt was compared between the 2 devices.

RESULTS

The mean bias in sagittal tilt relative to the functional pelvic plane (FPP) in the conventional device was -5.0° ± 4.8° (minus mean backward tilt) and was within 5° relative to the functional pelvic plane in 43%. The mean bias in the sagittal tilt relative to the APP in the APP lateral position device was 1.7° ± 3.1° (forward tilt) and was within 5° relative to the APP in 89%. The APP lateral device significantly reduced the variance in the sagittal tilt.

CONCLUSION

This device holds promise as a means of reducing the sagittal tilt in a simple, minimally invasive, and highly cost-effective manner.