The Pronator Quadratus Muscle After Volar Plating: Ultrasound Evaluation of Anatomical Changes Correlated to Patient-Reported Clinical Outcome

Background: Repair of the pronator quadratus (PQ) muscle with sutures has been reported durable after volar plating of distal radius fractures (DRF). It is unclear how the muscle reacts if not repaired and if a retracted muscle correlates to worse functional outcome or complications. In this study, we use ultrasound to investigate the anatomy of the PQ muscle after volar plating with PQ repair or nonrepair and correlate the ultrasound findings with patient-reported outcome. Methods: Participants were recruited from a clinical trial where they were randomly allocated to repair or nonrepair of the PQ muscle after volar plating of DRF. The participants and radiologist were blinded to group allocation. Ultrasound imaging of both fractured and contralateral wrists was performed 3 months after surgery. Ultrasound measurements included the difference in length of PQ muscle between the injured and uninjured side, retraction of PQ muscle, and tendon complications. The length and number of retractions were correlated to complications and Patient-Rated Wrist Evaluation (PRWE). Results: The mean difference of the difference in length measurements was 4.4 mm in the nonrepair group and 2.7 mm in the repair group with a mean difference between groups of 1.7 mm. This was statically significant; however, there were no clinical or statistical differences in complication rate or PRWE between the two groups. Conclusion: The PQ length was significantly shorter and the number of retractions significantly larger without repair of the PQ muscle; however, neither length nor retraction correlated significantly with complication rate or PRWE.