Isokinetic evaluation of pronation after volar plating of a distal radius fracture.

INTRODUCTION

Pronator quadratus (PQ) is an important contributor to forearm pronation, and there is concern that volar plating of a distal radius fracture (DRF) may damage the PQ function. The purpose of this study was to determine whether isokinetic pronation strength would decrease considerably after volar locking plating of a DRF, and whether clinical outcomes would be affected by any pronation strength decrease.

MATERIALS AND METHODS

Thirty-four patients of mean age of 55 years (range, 21-74 years) underwent bilateral isokinetic testing at 6 months and 1 year after open reduction and internal fixation using volar plating. Isokinetic pronation and supination strengths were compared between the operated and normal sides. Clinical outcomes such as grip strengths, range of motions and disabilities of the arm, shoulder and hand (DASH) scores were evaluated and analysed for any associations with isokinetic results.

RESULTS

At 6 months, peak torque and total work values for both pronation and supination were lower in the operated sides than in the normal sides (all p < 0.001). However, at 1 year postoperatively, the differences in pronation strength were not statistically significant (p = 0.188 for peak torque and p = 0.190 for total work), whilst supination torque and total work were still significantly lower in the operated sides (p = 0.015 and p = 0.029, respectively). Decreases in pronation strength were found to correlate significantly with decreases in supination strength and grip power. Wrist motion and DASH scores were not found to be correlated with decrease in pronation or supination strengths.

CONCLUSIONS

In patients with a DRF treated by volar plating, pronation strength was not significantly different between the operated and normal sides at 1 year postoperatively, and decreases in pronation or supination strengths were not found to affect clinical outcomes as assessed by DASH scores. This study suggests that dissection of the PQ may have minimal clinical impact on forearm pronation function.