Is it essential to repair the Pronator Quadratus to obtain normal rotation power after open reduction and internal fixation for distal radius fracture? : Comparative study with contralateral wrist

Traditionally, when performing surgery for distal radius fractures, an incision is made along the radial and distal margin of the Pronator Quadratus muscle to expose the fractured bone for plate fixation. While it has been suggested that repairing the muscle is necessary for optimal recovery of pronation power and functional benefits, there is still controversy surrounding the outcomes based on the repair/non-repair decision. This study aims to report favorable results and functional recovery in pronation without Pronator Quadratus repair.

From January 2022 to January 2023, 51 patients undergoing open reduction and internal fixation for distal radius fractures were included. A single expert hand surgeon performed all surgeries using Variable Angle LCP Distal Radius System (DePuy Synthes). Pronator Quadratus repair was intentionally omitted. Pronation power was measured just before hardware removal after complete bone healing, with the non-operated side serving as a control group for comparison. Additionally, supination power was measured to distinguish the overall functional impairment due to pronator quadratus damage from that caused by fractures. Other parameters, such as DASH scores, surgery time, range of motion (ROM), and complications (delayed union, non-union, malunion, Flexor closed rupture), as well as Soong grade, were also assessed.

Among the 51 patients, 32 were female, and 19 were male, with an average age of 58.7 years. All cases achieve bony union. The average time from open reduction and internal fixation to device removal was 8 months. Left-sided fractures were more common, with 36 cases. The measured muscle strength was 113.2 lb in pronation and 117.8 lb in supination on the non-operated side, and 92.5 lb in pronation and 96.1 lb in supination on the operated side, all showing statistically significant differences (p=0.025, 0.020 for each). In other hands, comparing pronation/supination ratios between the operated and non-operated sides revealed ratios of 0.993 and 0.969 (p=0.677), respectively, indicating pronation and supination power decreased by similar ratio. The mean DASH score for the operated and non-operated sides is 22.8 and 14.2, respectively, which also has no significant difference (p=0.16). It is difficult to prove that not performing repair of Pronator Quadratus causes decrease in pronation power.

This study confirms that a longitudinal mid portion incision without repair of the Pronator Quadratus does not result in significant differences in rotation function. This suggests that scar healing in the Pronator Quadratus and pronation motion facilitated by the pronator teres contribute to satisfactory outcomes even without repair. The method used in this study streamlines the Pronator Quadratus detachment process, providing a quick and simple approach. The widened surgical field enhances fracture reduction, omits the repair process, and ultimately reduces surgical time with achieve successful fracture healing. We recommend the aforementioned approach based on these findings.

Keywords: Distal radius fracture, Pronator quadratus, pronation power