Usefulness of CT-based measurement of volar prominence for evaluation of risk of flexor tendon injury following fixation of a distal radius fracture

Optimization of wrist tendon detection in virtual monochromatic images using dual energy-computed tomography

OBJECTIVES

To evaluate the depiction of wrist tendons in virtual monochromatic images (VMIs) during a dual-energy CT (DE-CT) with the VMI image of conventional equivalent to 120 kVp.

MATERIALS AND METHODS

Using Catphan600 and phantom analysis software for CT evaluation, measurements of VMI in a DE-CT were performed corresponding to the tube voltages of single-energy CT at 120 kVp. Using a Discovery CT750 HD CT scanner (GE Healthcare) with DE-CT technology, 73 patients were scanned. We calculated the CT number, image noise, visual score, and contrast noise ratio (CNR) at the extensor pollicis tendon, extensor digitorum tendon, and flexor tendon in 11 VMIs from the DE-CT and VMI image of conventional equivalent to 120 kVp. The results from the optimal VMIs were then compared with that of the VMI image of the conventional equivalent to 120 kVp.

RESULTS

The highest CT number and CNR for the tendon were for the 140 keV VMI in the DE-CT compared to the other energy levels. There were significantly higher CT numbers, CNR values, and visual scores for each tendon at 140 keV VMI with the DE-CT (p < 0.01) compared with a VMI image of conventional equivalent to 120 kVp.

CONCLUSION

Energy level of the VMIs during DE-CT for the best wrist tendon delineation was 140 keV. This value of 140 keV for the DE-CT was significantly higher than the CT number and CNR for the extensor pollicis, extensor digitorum, and flexor tendon compared with a VMI image of conventional equivalent to 120 kVp.

A Prospective Randomized Comparison of Variable-Angle and Fixed-Angle Volar Locking Plating for Intra-Articular Distal Radius Fractures

PURPOSE

To compare clinical and radiographic outcomes of using a variable-angle volar locking plate (VAVLP) with those of using a fixed-angle volar locking plate (FAVLP) for treating unstable intra-articular fractures of the distal radius.

METHODS

One hundred twenty patients with unstable intra-articular fractures of the distal radius were randomized to open reduction and internal fixation with a VAVLP (n = 60) or an FAVLP (n = 60). Supplementary methods (eg., Kirschner wire fixation) were required in 4 patients with a VAVLP and 9 with an FAVLP. Clinical outcomes were evaluated at 6 weeks, 3 months, 6 months, and 1 year after surgery. Posteroanterior and lateral radiographs were used to measure standard radiographic parameters before surgery, in the immediate postoperative period, and at 1 year. Plate prominence and articular congruity were quantified using computed tomography at 6 months.

RESULTS

There were no significant differences in any clinical outcome between the groups at any follow-up time. Volar tilt was significantly greater in patients treated with a FAVLP in the immediate postoperative period (8° vs 6°) and at 1 year (8° vs 5°). Although significant differences were not found in articular gap or stepoff between the 2 plates, the distal and volar prominence of the VAVLP was significantly greater than that of the FAVLP at 6 months. Significantly more patients treated with a VAVLP had a complication (38% vs 19%). However, most secondary surgeries were performed for hardware removal, and no patients from either group had complex regional pain syndrome or tendon rupture.

CONCLUSIONS

Patients with intra-articular distal radius fractures can expect good functional and radiographic outcomes with VAVLP or FAVLP fixation. The VAVLP may be more prone to technical errors, leading to complications, whereas the FAVLP is more likely to require supplementary fixation.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic I.