Impact of Pronator Quadratus Muscle Tear in Distal Radius Fractures on Patient Outcomes: Analyses of 55 Patients in a Volar Locking Plate Arm of a Randomized Clinical Trial.

Background The advantage of pronator quadratus (PQ) repair following internal fixation via the volar approach in distal radius fracture (DRF) surgery remains unconfirmed in the literature. The aim of this study was to compare grip strength, patient-reported outcomes, and functional results between patients with an intact PQ and those with a ruptured PQ before undergoing surgery with a volar locking plate for dorsally displaced unstable extra-articular DRFs. 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. Of the 60 patients randomized to the volar plate group, the integrity of the PQ muscle was recorded during surgery for 55 patients, who were included in this study. The outcomes measured were the Quick Disabilities of the Arm, Shoulder, and Hand Outcome Measure (QuickDASH) score, the Patient-Rated Wrist Evaluation (PRWE) score, the EQ-5D index, the visual analog scale (VAS) score, grip strength, and range of motion (ROM). Results The median age was 67 years (range 55 to 88), and the one-year follow-up rate was 98%. Patients with an identified intact PQ (28/55) before surgical release had better QuickDASH scores after one 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 also had better EQ-5D Index scores after one year (0.94 vs 0.85, mean difference 0.089, 95% CI: 0.004 to 0.174, p=0.031), and demonstrated better grip strength throughout the trial; after one year: 24 kg vs 20 kg (mean difference 3.9; 95% CI: 0.3 to 7.6, p=0.016). After one year, the intact group had regained 96% of their grip strength and the nonintact group had regained 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 minimal clinically important differences (MCIDs). Conclusions Patients with a DRF and a ruptured PQ prior to surgery exhibited higher QuickDASH scores and lower EQ-5D index scores after one year. The integrity of the PQ should be reported in future studies.