Does pronator quadratus muscle tear in distal radius fractures affect patient outcomes? Analyses of 55 patients in a volar locking plate arm of a randomized clinical trial

Abstract Background: The advantage of pronator quadratus (PQ) repair after internal fixation with the volar approach in distal radius fracture surgery has not been confirmed in the literature. The aim of this study was to compare grip strength, patient-reported outcomes and functional results between patients who had an intact PQ and patients who had a ruptured PQ before undergoing surgery with a volar locking plate for dorsally displaced unstable extra-articular distal radius fractures. Methods: A total of 120 patients aged 55 years and older were included in a randomized controlled trial comparing a volar locking plate with a dorsal nail plate. In 55 of 60 patients randomized to the volar plate group, the integrity of the pronator quadratus muscle was recorded during surgery. They were included in this study. The outcomes were the Quick Disabilities of the Arm, Shoulder and Hand Outcome Measure (QuickDASH) score, the Patient-Rated Wrist Evaluation (PRWE) score, EQ-5D index and visual analogue scale (VAS) score, grip strength and range of motion (ROM). Results: The median age was 67 years (55 to 88) and the 1-year follow-up rate was 98%. Patients with an identified intact PQ (28/55) before surgical release had better QuickDASH scores after 1 year (2.5 vs 8.0, mean difference 5.5, 95% CI: 1.3 to 9.8, p=0.028). Patients in the intact group had better EQ-5D Index scores after 1 year (0.94 vs 0.85, mean difference 0.089, 95% CI: 0.004 to 0.174, p=0.031), and had better grip strength throughout the trial, after 1 year: 24 kg vs 20 kg (mean difference 3.9; 95% CI: 0.3 to 7.6, p=0.016). After 1 year the intact group had regained 96% of their grip strength and the nonintact group 93% of their grip strength compared to the uninjured side. The observed differences may be of questionable clinical importance, as they were lower than those of previously proposed MCIDs. Conclusions: Patients with a distal radius fracture and ruptured PQ prior to surgery had higher QuickDASH scores and lower EQ-5D index scores after 1 year. The integrity of the pronator quadratus should be reported in future studies. Level of Evidence: Therapeutic Level 2b: Follow-up of control patients in an RCT.