Small variations within normal range of radiographic parameters, except ulnar variance and volar tilt, do not influence the final functional outcome in distal radius fractures.

Introduction: There are many reports in the literature on the relationship between radiographic variables and their influence on the final outcome of distal radius fractures. Most authors report that a good functional result depends on anatomical restoration of the articular surface and extra-articular alignment. The aim of this study was to verify if it is really necessary to restore anatomic radiographic parameters to obtain satisfactory functional outcome in distal radius fractures treated with volar plate.

Materials and methods: We retrospectively evaluated 51 patients treated with volar locked plate for articular unstable distal radius fractures from December 2006 to March 2009. Each fracture was evaluated according to the AO classification. The average follow-up was 40.5 months. Radiological measurements were performed considering radial height, radial inclination, volar tilt and ulnar variance, both preoperatively and postoperatively, to estimate the correction value. We examined range of motion (ROM), grip strength with a Jamar(®) dynamometer and Disabilities of the Arm, Shoulder and Hand (DASH) score. The τ Student test was performed for statistical analysis.

Results: The persistence of articular step-off was assessed in 35.3% of patients. Normal radial inclination (21-25°) was restored in 74.5% of patients (range 15-27.5°). Normal radial height (10-13 mm) was restored in 66.6% of patients (range 6.8-17.3mm). Normal volar tilt (7-15°) was achieved in 90.2% of patients (range 3-17°). Normal ulnar variance (0.7-1.5mm) was restored in 86.3% of patients (range 0.7-4.1mm). There was a statistically significant difference between the preoperative and postoperative radiographic values (p<0.01). The majority of patients showed complete recovery of ROM, with no statistically significant difference (p>0.05) in extension, flexion, supination and pronation compared with the contralateral hand. Eight patients who had postoperative volar tilt and/or ulnar variance out of range had a statistically significant difference (p<0.05) in ROM compared with the non-operated side. At final follow-up, all patients had a statistically significant difference (p<0.05) in grip strength compared with the contralateral side, even with good strength values. The mean DASH score was 12.2 (range 0-61).

Discussion and conclusion: Our experience suggests that ulnar variance and volar tilt are the most important radiographic parameters to be restored to obtain good functional outcome in distal radius fracture. Small variations of other radiographic parameters seem to not affect the final outcome at minimum 3 years' follow-up.